KR20070021204A - Nonwoven composites and related products and methods - Google Patents

Abstract

The present invention, in one embodiment, provides a catalyst substrate suitable for a variety of applications, which is included as a substrate in a catalytic converter. Another aspect of the present invention is a filtration substrate suitable for a variety of applications, including as a substrate in particle filters such as diesel particle filters (DPF) or diesel particle traps (DPT). The present invention also provides an improved substrate for the removal and / or exclusion of contaminants emitted from the exhaust of combustion engines. The catalyst substrate and the filtration substrate, in one embodiment, improve the process of removing contaminants from exhaust gases. The improvements include one or more of the following: increased ignition time, deep filtration of PM, low back pressure, low clogging potential, increased ability to be installed in multiple locations in the exhaust system, including the manifold or the head itself. , High probability catalytic reaction, high conversion of NO _x , HC and CO, fast incineration of PM, minimization of catalyst material use, etc.

Catalytic converter, exhaust system, emission control, nonwoven composite, cordierite, catalyst substrate, filtration substrate

Description

Nonwoven Composites, Associated Products, and Manufacturing Methods {NONWOVEN COMPOSITES AND RELATED PRODUCTS AND METHODS}

The present invention, although not particularly limited, relates to substrates useful for the catalysis of certain reactions, such as the treatment of emissions from internal combustion engines, and for the filtration of particulate matter, and related examples, More specifically, it relates to a combination of catalysts / substrates useful for controlling emissions, processes associated therewith, related products and methods of manufacture. Embodiments of the invention described herein are to substantially enhance the environmental quality of humanity by contributing to the recovery or maintenance of one or more natural elements associated with basic life extension, including air, water and / or soil. The invention and its examples are more fully described in the Summary and Detailed Description section of the invention described below.

Emissions, Industry and Pollution

Engines generate most of the power and mechanical work used throughout the planet. Internal combustion engines are probably the most widespread because they are more efficient than external combustion engines such as those mounted on older trains and steamboats. In an internal combustion engine, combustion of fuel occurs internally. Internal combustion engines produce motion and power for countless purposes. Examples include automobiles, locomotives, marine applications, recreational vehicles, tractors, construction equipment, generators, power plants, manufacturing facilities and industrial devices. Fuels used to power internal combustion engines include, but are not limited to, gasoline, compressed gas, diesel, ethanol and vegetable oils. Inherent inefficiencies of the engine structure and the fuel used to power the engine lead to the release of various pollutants. Thus, despite great technological innovation and convenience, millions of engines used around the world are a real source of air pollution today.

There are two main types of contaminants produced by internal combustion engines: particulate and nonparticulate contaminants. Particulate contaminants are generally small solid and liquid particles. Examples include carbonaceous soot and ash, dust and other related particles. Nonparticulate contaminants include gases and small molecules such as carbon monoxide, nitrogen oxides, sulfur oxides, nonflammable hydrocarbons, volatile organic compounds. Particulate contaminants can be filtered out of the exhaust gas and, in certain circumstances, further burned. Nonparticulate contaminants are converted to pollution free materials. Both types of contaminants may also be produced from engine-independent sources such as "off-gas" chemical reactions and evaporated emissions.

Air pollution can cause serious health problems for people and the environment. Ground-level ozone and atmospheric particles are two pollutants, one of the most threatening human health in the United States. Ozone (O ₃ ) can irritate the respiratory system and cause coughing, irritation in the throat and / or hot feeling in the respiratory tract. Ozone contributes to the formation of smog. Ozone can also reduce lung function, which can cause chest tightness, hard and mild breathing, and worsen asthma. Particle contaminants are made up of fine solids or droplets that are so small that they can get deep into the lungs and cause serious health problems. Exposure to these small particles can cause irritation of the nose and throat, lung damage and bronchitis, and increase the risk of heart or lung disease. Short-term effects of air pollutants include eye, nose and throat irritation. Upper respiratory infections such as bronchitis and pneumonia may also result. Other symptoms may include headaches, vomiting and allergic reactions. Long-term health effects may include chronic respiratory disease, lung cancer, heart disease and even damage to the brain, nerves, liver or kidneys. Continued exposure to air pollutants affects the lungs of growing children and can make medical conditions worse or difficult for older people.

Medical conditions caused by air pollution can be very expensive. Health care costs, lost productivity at work and the impact on human well-being can amount to billions of dollars each year. Understanding the health impacts of contaminants and finding a means to improve, prevent or exclude pollution is not only to improve respiratory health for the entire population, but also to reduce the actual cost of health insurance systems. .

For all these reasons, governments, environmental groups and various industries have decided to lower the level of air pollutants emitted from various sources. Government agencies are the ones who set the emission standards and implement the regulations. In the European Union, European Union legislation forms the basis of the regulations, and the individual countries implement them. For example, most EU countries are taxed on sources that produce excess air pollutants. Recent progress is the Kyoto Protocol, which has called for the reduction of greenhouse gases worldwide. Many countries, including the EU, have ratified the Kyoto Protocol. EU Japan and the United States have enacted some of the strictest standards in the world, but many other countries, such as Argentina, Brazil, Mexico, South Korea, Thailand, India, Singapore and Australia, have enacted regulations on air pollution. There are a variety of organizations in the United States that affect regulations in specific regions, including: state environmental agencies (such as the California Air Resources Board (CARB)), national parks, forestry, and mine safety and health administrations. . Some states and metropolitan areas that do not meet the National Air Quality Standards (NAAQS) are designated as "under-area" and implement their own standards. CARB has historically been one of the most stringent agencies regulating air pollution in the United States. However, the most important US regulator is the Environmental Protection Agency (EPA). EPA was created by the Nixon administration's 1970 amendment to the 1963 Clean Air Act (CAA). The Clean Air Act is a comprehensive federal law that regulates air emissions from local, stationary and mobile sources. (42 U.S.C. SS 7401 et seq. (1970) of the Clean Air Act). The Clean Air Act had five major revisions, the most recent of which was in 1990. The 1990 amendments to the Clean Air Act were primarily intended to address untreated or insufficiently addressed issues such as acid rain, surface ozone, stratospheric ozone depletion, and atmospheric toxicants. The amendment required EPA to enact 175 new regulations, including car emissions, gasoline reforming, and the use of ozone depleting chemicals.

Following the enactment of the Clean Air Act, EPA has established regulations for pollutants that may be harmful or harmful to humans. This series of "reference contaminants" includes (1) ozone (O ₃ ), (2) lead (Pb), (3) nitrogen dioxide (NO ₂ ), (4) carbon monoxide (CO), and (5) particulate matter (PM). ), And (6) sulfur dioxide (SO ₂ ). Each reference contaminant is described in turn.

Surface ozone (a major component of smog) continues to be a problem in the United States. Ozone is not directly released into the atmosphere but is formed by the reaction of volatile organic compounds (VOC) or reactive organic gases (ROG) with nitrogen oxides (NO _x ) in the presence of heat and sunlight. VOC / ROGs are released from a variety of sources, including fuel burned, and from solvents, petroleum treatments and pesticides, which come from sources such as automobiles, chemical plants, refineries, manufacturing plants, consumer goods and commercial products, and other industrial sources. . Nitrogen oxides are emitted from automobiles, power plants, and other combustion sources. Ozone and precursor contaminants that cause ozone can also be carried by the wind for miles. In 1997, EPA revised the US ambient air quality standards for ozone by replacing the 1-hour 0.12 ppm standard with the new 8-hour 0.08 ppm standard.

Nitrogen dioxide (NO ₂ ) is a reactive gas that can be formed by oxidation of nitrogen monoxide (NO). Nitrogen oxide (NO _x ), the term used to refer to oxides of NO, NO ₂ and other nitrogens, plays a major role in the formation of ozone and smog. Main sources of artificial NO _x emissions include high temperature combustion processes such as those found in automobiles, large construction equipment and power plants. Household heaters and gas stoves also produce significant amounts of NO ₂ .

Carbon monoxide (CO) is a colorless, odorless toxic gas that can be formed by incomplete combustion of carbon in fuel. Motor vehicle emissions make up about 60% of CO in the United States. In cities, up to 95% of CO emissions come from automotive emissions. Other sources of CO emissions include natural sources such as fuel combustion and wildfire in industrial processes, non-transportation sectors.

Particulate matter (PM) is a term referring to a mixture of solid particles and droplets found in air. Some of the particles are large and black enough to appear as soot or soot. Other particles are so small that they can only be detected by electron microscopy. These particles, which come in a wide range of sizes (“fine” particles less than 2.5 μm in diameter and coarse particles larger than 2.5 μm), originate from a wide variety of stationary and mobile sources as well as natural sources. Fine particles (PM-2.5) originate from fuel combustion in residential fireplaces and wood stoves, as well as in automotive, power generation and industrial installations. Coarse particles (PM-10) are generally emitted from vehicles running on unpaved roads, from material handling devices and sources such as grinding and grinding operations, and as blown dust. Some particles are emitted directly from the source of the particles, such as smokestacks and vehicles. In other cases, gases such as sulfur oxides, SO ₂ , NO _x and VOC react with other compounds in the air to form fine particles. The chemical and physical composition of the particles varies with region, season and weather. In 1997, EPA added two new PM-2.5 standards, set at 15 μg / m 3 and 65 μg / m 3, for yearly and 24-hour standards, respectively.

Sulfur dioxide can be formed, for example, when sulfur containing fuels (eg coal and oil) are burned during metal smelting and other industrial processes.

Lead, the last reference pollutant, has historically originated from the use of lead-containing fuels in automobiles. As a result of legislative efforts to reduce the content of Pb in gasoline, outbreaks from the transport sector have been reduced over the past decade. Today's metal processing is the main source of Pb's emissions.

The Clean Air Act requires EPA and the state to develop a plan that meets the US ambient air quality standards for these six reference pollutants. Contaminants other than the above six are 188 "toxic air pollutants" in a separate list. Examples of toxic air pollutants include benzene in gasoline; Perchloroethylene released from some dry cleaning facilities; And methylene chloride used as solvent and paint remover in many industries. Some atmospheric toxicants are released from natural sources, but most are from anthropogenic sources, including both mobile sources (eg cars, trucks, buses) and stationary sources (eg manufacturing plants, refineries, power plants). Origin. CAA required EPA to have a two-stage program for these 188 contaminants. The first step consists in developing a source-based standard that will identify a source of toxic contaminants and significantly reduce it. EPA has decided on a list of more than 900 stationary sources, which has resulted in new atmospheric toxic emission standards affecting many industrial sources, including: chemical plants, petroleum refineries, and spacecraft manufacturers. And small sources such as dry cleaners, commercial sterilizers, secondary lead smelters and chrome plating plants, including steel mills. The second phase consists of strategies and programs to assess the remaining risks and to ensure that the overall program achieves a substantial reduction, which is still in progress.

Internal combustion engines are directly affected by these regulations because they emit reference pollutants. These engines run on two fuels. The most common types of fuel used are gasoline and diesel. Each type of fuel contains a complex mixture of hydrocarbon compounds and small amounts of many other substances including sulfur. Even when completely burned, these fuels produce contaminants. Furthermore, because no engine is capable of "perfect" combustion, some fuels are incompletely oxidized, thus creating additional contaminants. Other forms of fuel may also be used, such as ethanol mixtures, vegetable oils, and other fuels known in the art.

In gasoline engines, in order to reduce emissions, the engine of the new car has fine control over the amount of fuel burned. The engine attempts to keep the ratio of air to fuel very close to the stoichiometric value, which is the calculated ideal ratio of air to fuel. In theory, all fuel is burned using this ratio of all the oxygen in the atmosphere. The fuel mixture actually varies considerably from this ideal ratio during driving. Sometimes the mixture may be lean (for example, the ratio of air to fuel is higher than the typical value of 14.7) and in other cases the mixture may be rich (the ratio of air to fuel). Lower than 14.7). This deviation leads to various atmospheric emissions.

Important emissions of gasoline vehicle engines include: nitrogen gas (N ₂ ) (N ₂ 78% in air); Carbon dioxide (CO ₂ ) as a combustion product; Another combustion product, water vapor (H ₂ O). Almost all of these emissions are harmless to humans (although excessive levels of CO ₂ in the air are believed to cause global warming). However, gasoline engines also produce carbon monoxide, nitrogen oxides and unburned hydrocarbons, all of which are included in the EPA's reference contaminants (unburned hydrocarbons form part of the ozone formation mechanism with NO _x ).

Diesel engines also contribute to reference contamination. Diesel engines use hydrocarbon fractions that auto-ignite when fully compressed in the presence of oxygen. In general, diesel combustion in cylinders produces more particulate and pollutant oxides of nitrogen and sulfur (NO _x and SO _x , respectively) than gasoline. Nevertheless, diesel mixtures are generally sparse and relatively rich amounts of oxygen are present. Thus, the combustion of relatively small hydrocarbons is typically more complete, producing less carbon monoxide than gasoline. Long chain hydrocarbons are more difficult to burn completely and can result in the formation of particulate residues such as carbon “soot”.

Despite these drawbacks, fossil fuels are relatively rich, easy to handle and economical. Therefore, these fuels will continue to be represented as important sources of mechanical power and pollution in the future. Furthermore, the spread of internal combustion engines indicates how fossil fuels will continue as a necessary source of energy.

There are at least three markets for internal combustion engines that produce major air pollutants: 1) mobile, on-road engines, devices and vehicles, 2) mobile, non-road engines, devices and vehicles, And 3) stationary or “point” sources. In each of these markets, government agencies and other organizations have limited the level of air pollution. These limits became increasingly strict as the number of internal combustion engines used increased, and we learned more about the harm caused by air pollution. The ever-increasing regulations have required industry to continue to research, develop and invest in new emission control technologies, from fuel formulations to engine redesigns to aftertreatment units. These technologies change in both efficiency and cost, but have become essential for businesses to respond to regulations. Since no emission control technique can remove all relevant contaminants, it is common for a particular type of vehicle or device to use multiple techniques together to meet regulated emission limits. These markets, their regulations and the technologies they depend on are described in the following sections. The above techniques, including advantages and disadvantages, are described in more detail following this section. While the above item focuses on engines, devices and vehicles in the United States, other regions have similar products and regulations. For example, the EU has a similar market size, but focuses more on selective catalytic reduction than on exhaust gas recirculation, such as diesel emission control technology, and uses catalytic converters as a larger percentage of small, off-road engines. And much more weight on diesel engines used in lightweight vehicles. Other regions have their own differences from the United States, but in essence use the same type of equipment and regulate the same type of air pollution.

Mobile, road engines, devices and means of transport, including but not limited to, designed for passenger cars, pickup trucks, minivans, sport utility vehicles (SUVs), buses, delivery trucks, semi trucks, vans, and on-road applications. Two- or three-wheeled motorcycles are included. These markets have historically led the way in emission control, and are still in place today by the following regulations mandating low levels of air pollutants.

The passenger car and truck markets are divided by the crowd. Anything below the Gross Vehicle Weight Rating (RVWR) of 8,500 pounds is considered a light duty vehicle. Vehicles in the 8,500 to 10,000 lbs GVWR range designed for passenger transport are considered medium duty vehicles. Vehicles over 8,500 lbs GVWR that are not designed for personal use are marked heavyweight vehicles.

Passenger cars and light vehicles have been regulated by vehicle weight and fuel type, but will be regulated as a group in future standards. Less than 1% of the 17 million passenger cars and light vehicles produced in the United States use diesel engines. Passenger and light weight vehicles include those manufactured by manufacturers such as Ford, General Motors (GM), DaimlerChrysler, BMW, Honda, Hyundai, Daewoo, First Automobile Group, Toyota, Nissan, SAIC-Chevy and Subaru.

Regulations for passenger cars and light vehicles have been around for decades, but have become much stricter in recent years. The Tier 2 standard, which is staged in Model Year (MY) 2004-2009, will enable OEMs to demonstrate that their manufactured vehicles fall within a specific 'bin' of the standard, and to manufacturers of NO _x emissions. Requires an average Vehicles under 6,000 lbs GVWR must meet regulations by 2007, and vehicles between 6,000 and 8,500 lbs and MDVs by 2009. Contaminants included in the standard include: NO _x , formaldehyde (HCHO), CO, PM and organic gases except for methane. California has historically been more stringent than EPA, and other states, including New Jersey, New York, Vermont, Maine, and Massachusetts, have joined low emission levels for new and used vehicles. Manufacturers who do not meet the standards are essentially not allowed to produce their vehicles in these markets and are fined if found on the market. In the aftermarket, the state regulates passenger cars and light vehicles through inspection and maintenance (I / M) programs. These programs are often created from the State Action Plan (SIP) required by NAAQ in the United States. Compliance with emission control technologies is often required to be compatible with both new vehicles and aftermarket standards.

Historically, three-way catalytic converters have been widely used in passenger cars and light vehicles. Recent improvements in these converters (eg, increased substrate porosity, optimized washcoats, reduced catalyst loads, etc.) have led to incremental improvements in emission control. In order to meet the newest set of US regulations, manufacturers will have to increase the catalyst load or increase the number of substrates per vehicle. Vehicles that do not meet inspection / maintenance standards must either replace the faulty technology or purchase additional equipment. Other emission control devices include, but are not limited to, modern injection systems (e.g., injection timing, injection pressure, rate shaping, common rail injection, and electronic control), varied combustion chamber designs (e.g., Higher compression ratio, piston structure, injector position), variable valve timing, catalytic converter and filter.

Heavy vehicles (HDVs) include personal and commercial trucks and buses larger than 8,500 lbs GVWR. The majority of these engines run on diesel fuel, and more than 300,000 are produced annually in the United States. Manufacturers and engine suppliers include, but are not limited to, Cummins, Caterpillar, Detroit Diesel, GM, Mack / Volvo, International / Navistar, Sterling, Western Star, Kenworth, and Peterbilt. Other companies providing other emission control technologies for aftermarket include, but are not limited to, Donaldson, Engelhard, Johnson Matthey, Lubrizol, Fleetguard, Cleaire, Clean Air Partners, and Engine Control Systems.

Heavy trucks face stringent emission reduction standards for hydrocarbons (NMHC) excluding PM, NO _x , CO and methane. PM standards come into force in 2007 and NO _x and NMHC standards enter 2007-2010. Like light weight vehicles, California, along with certain other state and metropolitan areas, has often set stricter emission standards than EPA. On vehicles below the standard, the manufacturer cannot sell them. Nonconforming penalties for NO _x are less than $ 12,000 per vehicle, based on size and compliance efforts. Other industries such as locomotives, marine, agriculture and construction use engines that are very similar to heavy vehicles, but the HDV market faces the most stringent emission standards. On the other hand, some state and metropolitan areas (eg, California, New York City, Seattle) require additional retrofits or provide incentives for renewal to further reduce pollution levels. These areas have certified technologies that are appropriate for their approved levels and capacities. Examples include Donaldson's diesel oxidative catalytic muffler and diesel particle filter, Cleaire's diesel oxidative catalyst and diesel particle filter, and Johnson Matthey's continuous regeneration technology particle filter.

Emission control techniques that meet the above standards and are used for renewal are not particularly limited, but include, but are not limited to, modern injection systems (e.g. injection timing, injection pressure, grade geometry, common rail injection and electronic control), exhaust gas recirculation, combustion Changes in chamber design (e.g., higher compression ratio, piston structure, injector position), modern turbocharge, ACERT, diesel particle filter, NO _x adsorber, selective catalytic reduction, conventional catalytic converter, catalytic exhaust muffler, and Diesel oxidative catalysts. Meeting the 2007 standard has prompted new research and development on many of these emission control technologies. There was a tremendous amount of money and effort in deciding emission control solutions for the 2007 HDV.

Motorcycles are another type of mobile, on-road vehicle and include both two- and three-wheeled motorcycles designed for road use. Motorcycles inherently use gasoline fuel. Manufacturers include, but are not limited to, Harley Davidson, BMW, Honda, Kawasaki, Triumph, Tianjin Gangtian, Lifan Motorcycle, and Yamaha. Regulations on road motorcycles were adopted in 1978 and remained unrevised until 2003, and in 2003 a new standard based on California was approved. Contaminants monitored in the new standard include HC, NO _x and CO.

Emission control techniques for motorcycles are not particularly limited, but technologies for converting two-stroke engines to four-stroke engines, modern injection systems (injection timing, injection pressure, grade geometry, common rail injection and electronic control), pulsed air systems , Changes in combustion chamber design (higher compression ratios, piston structures, injector positions), and the use of catalytic converters. The limitations in motorcycle emission control technology differ from those of light or heavy vehicles. Motorcycles focus less on the appearance, arrangement, and heat of the aftertreatment device because there are fewer places to "hide" the device, and the occupants are much closer to the exothermic oxidation reaction.

The mobile, non-road engine, device and vehicle categories are not particularly limited but used in agriculture, construction, mining, grass and gardening, private vessels, boats, commercial vessels, locomotives, airplanes, snowmobiles, off-road motorcycles and ATVs. It includes an engine.

Small engines emit significant levels of air pollutants for their size; Small engines are the single largest factor in non-HC inventory. Small engine devices include, but are not limited to, leaf blowers, trimmers, branch cutters, handheld chainsaws, lawn mowers, engine mounted mowers, wood cutters, snow plows, wood mills, and the like. Engine and device manufacturers include, but are not limited to, John Deere, Komatsu, Honda, Ryobi, Electolus (Husqvarna and Poulan also supply Craftsman), Fuji, Tecumseh, Stihl, american Yard Products, and Briggs and Stratton.

EPA began regulation in 1993 (Pace I) as a standard that came into effect in 1997 and continued to lower emissions levels with new standards in 2002 (Pace II). The standard divides the device into smaller categories that are in hand and those that are not, and is classified based on engine displacement. The regulation focuses on hydrocarbon and nitrogen oxide emissions.

Emission control techniques include, but are not limited to, the use of catalysts (ie, John Deere's LE technology and Komatsu's “Stratified Scavenged” design), the conversion of two-stroke engines to four-stroke engines, and the latest injections. Systems (injection timing, injection pressure, grade geometry, common rail injection and electronic control), or changes in combustion chamber design (higher compression ratios, piston structures, injector positions).

The recreational vehicle market includes off-highway motorcycles, snowmobiles and all-terrain vehicles (ATVs). These products are manufactured by the following manufacturers and engine suppliers:

Honda, John Deere, Kawasaki, Mitsubishi Motors, Nissan, Toyota, Yanmar, Arctic Cat, Bombardier, Brunswick, International Powercraft, Polaris, Suzuki and Yamaha.

California had enacted regulations much earlier, but EPA began regulating recreational vehicles later than many other markets. EPA entered the pace in 2006-2009 for snowmobiles and 2006-2007 for off-highway motorcycles and ATVs. Regulated contaminants include HC, CO and NO _x .

Emission control technologies for recreational vehicles include, but are not limited to, technologies for converting two-stroke engines to four-stroke engines, modern injection systems (injection timing, injection pressure, grade geometry, common rail injection and electronic control), pulsed air, Or changes in combustion chamber design (higher compression ratios, piston structures, injector positions).

In mining, regulations are established by the Mine Safety and Health Administration. Mining is often regarded as the most burdensome field for devices due to the high levels of vibration, shock and dust. Temperature and flammability are also big problems in mining. Although new diesel oxidative catalysts have been installed for some mining equipment, diesel particle filters are becoming more common.

In the agricultural and construction markets, EPA regulates both spark ignition and compression ignition engines. These engines can be used in tractors, forklifts, bulldozers, generators, balers, rollers, trenchers, drill rigs, mixers, cranes, balers, compressors, and the like. Manufacturers of engines and devices include, but are not limited to, Agco, Komatsu, CNH Global, Caterpillar, Cummins, Daewoo, John Deere & Co, Dueutz, Detroit Diesel and Kubota.

EPA began regulating the diesel portion of these engines in 1994 (Tier 1), and recently increased the standard to Tier 2 (Pace entry in 2001-2006). The standard is expected to increase back to Tier 3 levels in 2006-2008. Tier 3 levels will likely require the use of emission control devices similar to those used for heavy vehicles (eg tractors, trailers). Regulations on gasoline, liquid propane gas or compressed natural gas (CNG) engines used in agriculture and construction have also recently changed. Tier 1 levels are expected to begin in 2004 and match those already adopted by CARB, and Tier 2 levels will begin in 2007. There is also voluntary regulation of vehicles with lower than standard emissions, the so-called "Blue Skies Series". Based on engine size and fuel type, levels of particulate matter, carbon monoxide, nitrogen oxides and hydrocarbons other than methane should all be significantly reduced for current face-in and upcoming standards.

Emission control techniques are similar to those used for heavy vehicles, and are not particularly limited, but include modern injection systems (injection timing, injection pressure, grade geometry, common rail injection and electronic control), exhaust gas recirculation, and changes in combustion chamber design. (Higher compression ratio, piston structure, injector position), modern turbocharge, ACERT, diesel particle filter, NO _x adsorber, selective catalytic reduction, conventional catalytic converter, catalytic exhaust muffler and diesel oxidative catalyst. Exhaust gas recirculation (EGR) has been a problem due to the tendency to cause the formation of sulfuric acid at the engine intake. In addition, the need for cooling requires a large radiator, which in turn increases the front part of the vehicle, which creates aerodynamic and fuel economy constraints.

In marine applications, engines are generally categorized by gasoline or diesel fuel, personal or commercial use, or by engine size. Marine units range from private vessels to yachts, ferries, tugs and oceangoing vessels. Manufacturers and engine suppliers include, but are not limited to: Bombardier (Evinrude, Johnson, Ski Doo, Rotax, etc.), Caterpillar, Cummins, Detroit Diesel, GM, Isuzu, Yanmar, Alaska Diesel, Daytona Marine, Marine Power , Atlantic Marine, Bender Shipbuilding, Bollinger Shipyards, VT Halter Marine, Eastern Shipbuilding, Gladding-Hearn, JeffBoat, Main Iron Works, Master Boat, Patti Shipyard, Quality shipyards, and Verret Shipyard, MAN B & W Diesel, Wartsila, Mitsubishi, Bath Iron Works, Electric Boat, Northrop Grumman (including Avondale, Ingalls, and Newport News Shipyards).

EPA regulates boats for recreational, personal or commercial purposes. The main category sector is based on engine displacement from recreational vehicles to tankers. Diesel marine non-recreation boats with less than 30 liters in displacement include fishing vessels, tugboats, towboats, dredgers and cargo ships. Between 2004 and 2007, new standards for NO _x and PM come into effect depending on engine size. Diesel marine non-recreation boats larger than 30 liters, including container ships, oil tankers, bulk carriers and cruise ships, are subject to NO _x standards in force in 2004 (Tier 1) and additional HCs in force in 2007 (Tier 2), PM and CO standards. Diesel marine recreational boats, including yachts, cruise ships, and other types of recreational vessels, have standards that match the standards of diesel marine non-recreation boats with a displacement of less than 30L, but run dates are between 2006 and 2009, depending on engine size. . Gasoline and diesel boats only have restrictions that currently apply HC emissions from offshore engines, private vessels and jet boats. The stern drive and the engine on board are inherently cleaner and not yet regulated.

Emission control techniques are similar to those used in heavy vehicles, and are not particularly limited, but include the use of "green terminals" when the boat is docked, conversion of two-stroke engines to four-stroke engines, and water Post-cooling, exhaust gas recirculation, diesel particle filter, selective catalytic reduction, diesel oxidative catalyst, catalytic converter, latest fuel injection (injection timing, injection pressure, grade geometry, common rail injection and electronic control), latest turbocharge, variable valve timing And changes in combustion chamber design (higher compression ratios, piston structures, injector positions). The use of small engines for auxiliary power (eg auxiliary power units, APUs) also helps control emissions. The cooling effect on the brine, its contaminants and the boats presents difficulties in the aftertreatment, but the APU plays a sufficient role with the aftertreatment unit.

Locomotive markets rely primarily on diesel fuel (coal and firewood combustion are of limited use), trains used in freight and passenger railroads, line-haul, local, and switch yard services. (switch yard service) is included. In the United States, more than 600 trains are produced each year. Manufacturers and engine suppliers include, but are not limited to, GM's Electromotive Division, GE Transportation Systems, Caterpillar, Detroit Diesel, Cummins, MotovePower, Peoria Locomotive Works, Republic Locomotives, Trinity, Greenbrier, and CSX .

Regulations on the trains began in 2000 and largely mimic those of heavy vehicles. The standard includes levels for newly produced and regenerated engines (from about four to eight years), depending on whether the engine is for switch or long-range freight trains. Tier 0 applies to engines with model years (MY) from 1973 to 2001, Tier 1 for MY2002 to 2004, and Tier 2 for MY2005 and beyond. Nonconforming penalties are less than $ 25,000 per day per engine. Regulated contaminants include particulate matter, NO _x , HC, CO, and smoke opacity.

Emission control techniques are similar to those used in heavy vehicles, and include, but are not limited to, the latest fuel injection (injection timing, injection pressure, grade geometry, common rail injection and electronic control), exhaust gas recirculation, changes in combustion chamber design ( Higher compression ratios, piston structures, injector positions), selective catalytic reduction, diesel oxidative catalysts, post coolers, split cooling, zeolite sieves and NO _x reducing catalysts. The use of a small auxiliary power unit also becomes one of the emission control quantities, and there is little regulation surrounding the use of the aftertreatment unit.

The aircraft market includes all types of aircraft, including aircraft manufactured by Boeing, Airbus, Cessna, Gulfstream and Lockheed Martin. EPA and the European Union both follow the emission standards of the International Civil Aviation Organization (ICAO). EPA adopted ICAO's current standards for CO and NO _x in gas turbine engines in 1997 and adopted HC levels in 1984. In the United States, the FAA monitors and enforces these standards. Much of the emission control is done through engine technology and fuel changes.

Stationary sources include sources of contaminants that are not mobile. EPA has issued regulations covering more than 80 categories of major industrial sources, including power plants, chemical plants, oil refineries, and spacecraft manufacturers. And steelmaking plants, as well as small sources such as dry cleaners, commercial sterilizers, secondary lead smelters, and chromium plating facilities. Power plants can use stationary diesel engines, stationary gas turbines, and nuclear power, among other sources. Each of these sources produces different contaminants; For example, nuclear power plants use iodine and hydrogen, gas turbines use NO _x , CO, SO _x , CH ₄ and VOCs, and refineries use gaseous steam, CO, NO _x , VOCs, CO ₂ , CH ₄ and PM. Create Each industry needs different control techniques to reduce air emissions.

EPA regulations cover six categories of pollutants and an additional 188 toxic air pollutants. Specific programs implemented include acid rain programs designed to reduce sulfur emissions and NO _x budget programs from the Ozone Transport Commission designed to reduce NO _x emissions. RECLAIM is a program established for the trade of NO _x and SO _x credits. In addition, in some industries and regions, cap and trade programs have been implemented to allow companies to trade their emissions credits.

The techniques used to control emissions from stationary sources vary widely, but examples include filters, scrubbers, absorbents, selective catalytic reduction (SCR), precipitators, zero-slip catalysts, catalysts for turbines or oxidative properties. Catalysts are included. Some of the suppliers of emission control systems for the stationary market include M + W Zander, Crystall, Jacobs E., Takasogo, IDC, ADP, Marshall, Bechtel, Megte, Angui, Adwest, Eisenmann, Catalytic Products, LTG, Durr, Siemens , Alston and the like. As a catalyst supplier, Nikki, BASF, Cormetech, W.R. Grace, Johnson Matthey, UOP, and Sud Chemie.

Due to the importance of improving air quality and the issue of compliance with applicable laws and regulations, significant time, budget and effort have been invested in technologies that can reduce emissions. Three general areas of such technology include a) engine improvement, b) fuel improvement and c) aftertreatment. This approach is typically not mutual exclusion or a single solution. Engine improvements include, but are not particularly limited to, technologies such as modern injection systems, exhaust gas recirculation, electronic sensors and fuel control, combustion chamber design, modern turbocharge and variable valve timing. Fuel improvements include, but are not limited to, high cetane, low aromatics, low sulfur fuels, fuel accompanying catalysts, liquefied petroleum gas (LPG), oxygenation of fuels, compressed natural gas (CNG), and biodiesel. Includes emulation. Post-treatment techniques include, but are not limited to, catalytic converters (two-, three-, and four-membered), particle traps, selective catalytic reduction, NO _x adsorber, HC adsorber, NO _x reductive catalyst, and many others. do. Some systems combine various parts of these and other technologies; Caterpillar's ACERT or catalytic diesel particle traps are examples of system and device combinations. In addition, there are some technologies that are currently limited in use due to technical or commercial constraints.

Modern injection systems include injection timing, injection pressure, grade geometry, air assisted fuel injection, sequential multi-point injection, common rail injection, resizing or movement of injection holes, and some electronic control. In a common rail system, the microcomputerized fuel pump controls the flow rate and timing of the fuel (eg Mercedes-Benz E320 uses this system). Secondary air injection can promote combustion of HC and CO in the manifold. Modifications to the injection system can reduce various emissions and can also increase fuel economy, but this requires significant work on the engine to ensure efficiency.

Exhaust gas recirculation (EGR) returns some of the exhaust gas to the intake port of the engine. By mixing the exhaust gases with fresh intake air, the amount of oxygen entering the engine is reduced, resulting in lower emissions of nitrogen oxides. EGR does not require regular maintenance and works well in combination with highly vortex, turbulent combustion chambers. EGR also has disadvantages such as reduced fuel efficiency and engine life, increased demands on the vehicle's cooling system, and no limitations on other contaminants other than NO _x , requiring control algorithms and sensors. For this reason, EGR is often used in conjunction with another control technique. Companies involved in EGR technology include Doubletree Technologies, ETC, STT Emtec, Cummins, Detroit Diesel, Mack and Volvo.

Optimizing or improving the combustion chamber is another way for manufacturers and developers to control emissions. Reducing the crevice volume can limit the trapping of unburned fuel (hence the formation of HC), but can reduce HC formation by reducing the amount of lubricating oil, and can limit catalyst poisoning. have. Other methods include improving the surface finish of cylinders and pistons, improving piston ring designs and materials, improving exhaust valve stem seals, and the like. In addition, a “fast burn” type combustion chamber may be created by increasing the burn rate, reducing the spark advance, adding a diluent to the air-fuel mixture, and / or increasing turbulence in the chamber. Can be. While optimization of the combustion chamber can reduce emissions, it is another technique that requires rework of the engine, which can be an expensive process.

Variable valve timing includes calibrating the engine valve to open and close the valve to maximize fuel and engine efficiency. Typically, sensors are used to detect engine speed and adjust valve opening and closing accordingly. This technology can increase engine torque and horsepower, improve vortex and intake charge velocity, and thus improve combustion efficiency. Variable valve technology does not reduce emissions as some other technologies and often results in reduced fuel efficiency.

Re-prescription or use of various fuels is another emission control technique, although some fuels contaminate more slowly than others, while some fuels tend to poison catalysts to clean exhaust air. For example, the transition from lead fuel to unleaded fuel in the United States has greatly reduced lead emissions. Since sulfur can poison the catalyst, lowering the sulfur content of the fuel to reduce the SO _x emission and increase the efficiency of many catalytic converters. Another type of fuel, natural gas, typically produces less particulate contaminants than diesel fuel, and can also reduce NO _x and combustion noise. Conversely, natural gas can also increase vehicle weight (because a high pressure tank is needed) and has a refueling limit.

The use of aftertreatment devices-devices that are used after fuel has been burned-is very common in certain industries affected by emission control regulations. One example of an aftertreatment device is a catalytic converter. Catalytic converters can vary widely and have a variety of functions, but are generally described as apparatuses for treating exhaust gases using catalysts. The composition of the substrate and the catalyst on the substrate, as well as the number and installation of converters, have changed over the years.

Two-way catalytic converters perform oxidation of gaseous contaminants such as oxidizing HC and CO to CO ₂ and H ₂ O. Diesel oxidation catalyst (DOC) is another form of two-way catalytic converter used with diesel engines. While these converters are effective for the control of HC and CO and require little maintenance, they can increase NO _x emissions and are susceptible to sulfur.

Three-way catalytic converters perform both oxidation (CO and HC to CO ₂ and H ₂ O) and reduction (NO _x to N ₂ gas). Since the 1970s, three-way catalytic converters have reduced vehicle emissions. Another performance improvement with these devices is limited by the number of factors and catalyst poisoning, such as temperature range and substrate surface area. To meet increasingly stringent regulations, some vehicles require multiple catalytic converters.

Four-way catalytic converters perform oxidation and reduction reactions, which capture and burn particles (regeneration can occur in either active or passive mode).

Suppliers of catalytic converters and related components include, but are not limited to, Corning, NGK, Denso, Ibiden, Emitec, Johnson Matthey, Engelhard, Catalytic Solutions, Delphi, Umicore, 3M, Schwaebische Huetten-Werke GmbH (SHW); Hermann J. Schulte (HJS), Clean Diesel Technology, Cleaire, Clean Air Systems, ArvinMeritor, Tenneco, Eberspacher, Faurecia, Donaldson and Fleetguard.

Since diesel fuel generates more particulate matter than gasoline or some alternative fuels, particle traps or filters are another form of aftertreatment device commonly used in diesel applications. In a diesel particle trap (DPT), particles in the exhaust gas stream are collected through a filter. The removal of particulate matter trapped in the trap is called "regeneration" and can occur in a number of ways. One way is to use an external heater to raise the temperature of the filter to the level necessary for the PM to be incinerated. Another method is to discharge a small amount of diesel fuel in the exhaust stream. When fuel particles come in contact with the filter, the fuel is incinerated at high temperatures. This high temperature burns PM and filters. Another means is to use a fuel entrained catalyst to promote regeneration. In another approach, called "catalytic diesel particle trap", the catalyst is applied directly to the filter itself, which reduces the temperature required for PM to be incinerated. Finally, an oxidative catalyst may be used at the front of the filter to promote incineration of the PM. Johnson Matthey's Continuous Regeneration Trap (CRT) is such a system. Diesel particle traps can reduce PM by 85% in some applications. A trap utilizing a catalyst can also reduce contaminants other than PM (eg, HC, CO, PM) by using a catalyst (as described above). In other words, these traps can be blocked with PM, soot and ash, and catalyst use traps can be poisoned. Such also increases cost and vehicle weight.

Diesel particle traps can use several types of filters, including: ceramic monolithic cell fibers (Corning, NGK), fiber winding filters (3M), knitted fibers (BUCK), woven fibers (HUG) , 3M), sintered metal fibers (SHW, HJS), or filter paper. Sources of these devices and related technologies include, but are not limited to, Donaldson, Engelhard, Johnson Matthey, HJS, Eminos, Deutz, Corning, ETG, Paas, Engine Control Systems, and the like.

Another example of an aftertreatment system is selective catalytic reduction (SCR). In this technique, chemicals that can act as reducing agents, such as urea, are added before the exhaust gas reaches the catalyst chamber. Urea is hydrolyzed to form ammonia. The ammonia then reacts with NO _x in the exhaust gas to produce N ₂ gas to reduce NO _x emissions. Ammonia can be sprayed directly or maintained in solid urea, urea solution or crystalline form. Oxidative catalysts are often used in combination with SCR to reduce CO and HC. However, while SCR is effective for reducing NO _x and has low catalyst deterioration and good fuel economy, it requires an additional tank to the vehicle and an infrastructure for recharging the tank. It also depends on the end user's compliance; The company and operator must refill the tank to maintain emission control. Sources of SCR or its components include, but are not particularly limited to, Engelhard, Johnson Matthey, Miratech Corporation, McDermott, ICT, Sud Chemie, SK Catalysts, and PE Systems. Although used in the United States in a limited mood, SCR is expected to be widely used in Europe for the reduction of emissions, especially in the heavy truck market.

A NO _x adsorber is a substance that stores NO _x in a lean state, releases it in a fuel rich state and reduces it (typically every few minutes) by a catalyst. This technique can function in both gas and diesel applications, but the gas provides a better fuel rich high temperature environment. The NO _x adsorber lowers the levels of HC, NO _x and CO, but has little or no effect on PM. The NO _x adsorber can function over a wide temperature range. In contrast, the NO _x adsorption capacity decreases with temperature, requires engine control and sensors, and the function is hindered or lost by the sulfur content in the fuel. In diesel applications, there are additional constraints, including the amount of oxygen present in the exhaust gas, HC utilization, temperature range and smoke or particle formation.

The NO _x reductive catalyst is characterized in that the oxidation zone leads to 1) a strong injection of a reducing agent into the system at the front of the catalyst, and / or 2) reduction of NO _x using a washcoat with zeolite adsorbing HC. By generating it, it can be used to control the release. While this technique can reduce NO _x and PM, it is more expensive than many other techniques and can result in lower fuel economy or sulfate particles.

The HC adsorbent is designed to capture the VOC while the catalyst is cold and then release the VOC when the catalyst is heated. These functions include: 1) coating the adsorbent directly on the catalytic converter substrate so that the change is minimal but the control is less; 2) placing the adsorbent separately before the catalytic converter but connected to the exhaust gas pipe, Air may be switched on and / or 3) by installing the adsorbent after the catalyst. 2) and 3) of the above options require a cleaning option for the adsorbent. Although this technique reduces cold starting emissions, it is difficult to control and adds cost.

Since release has proven difficult to control, release control techniques are typically incorporated into the system. Examples of coupling systems include DeNOx and DPT (e.g., SCRT systems from HJS), catalytic converters installed on mufflers, SCR integrated with mufflers, or catalytic diesel particle filters.

ACERT is another example of a system that combines multiple emission control techniques. Caterpillar's ACERT targets four areas: intake air handling, combustion, electronics, and exhaust aftertreatment. Key elements include single and series turbochargers for cooling intake air; Variable valve operation to improve fuel combustion; Electronic multiplexing for integrating computer control; And catalytic conversion to reduce end pipe particle emissions. By operating comprehensively, these subsystems allow manufacturers to increase fuel economy. An important drawback of this technique is the need for large volumes of catalyst.

There are many other emission control techniques, some of which are not yet technically feasible.

Catalytic converter

In part, the pollution problem caused by automobiles led to the enactment of the Clean Air Act of 1970, which required a 90% reduction in emissions. Mandatory reductions were considered controversial by some, but were generally recognized as advances in clean air and health promotion.

The automotive industry initially resisted the newly proposed regulation. Some of such resistance may be based on improved fuel developed by the industry. From the mid 1920s to the mid 1980s, automotive gasoline fuels contained an additive, tetraethyl red (TEL). TEL improves fuel performance by preventing pre-ignition in the cylinders of the engine. Preliminary ignition occurs when the fuel / air mixture is ignited too early in the engine's combustion chamber. This results in a reduction in efficiency and power caused by damage to the engine and knocking.

In order to reach the reduced emission standards set by the government, engineers invented catalytic converters. Catalytic converters were added to the vehicle exhaust system, which began around 1976. Catalytic converters were somewhat effective in reducing emissions. However, common gasoline formulations containing TEL have hindered the function of catalytic converters. Since the TEL in the fuel poisoned the metal catalyst of the catalytic converter, the TEL was eventually removed from the fuel.

Many people know that many vehicles are equipped with catalytic converters, but in general this is an unwelcome technology. The purpose of the catalytic converter is to convert pollutant exhaust gases into less harmful compounds such as nitrogen (N ₂ , occupying about 78% of the atmosphere), water (H ₂ 0) and carbon dioxide (CO ₂ , photosynthetic products in plants) or To change.

Catalytic converters are used to facilitate the conversion of undesirable contaminants into molecules such as relatively harmless N ₂ , H ₂ O and CO ₂ . Basically, catalytic converters provide a surface where contaminants are converted into relatively harmless products. The catalyst allows the reaction to proceed faster (or at lower temperatures) by lowering the required activation energy. However, the catalyst is not used in the reaction and can be reused (unless the catalyst is poisoned).

Typical contaminants in exhaust gases include nitrogen oxides (NO _x ), unburned hydrocarbons, carbon monoxide and particulate matter. Nitrogen oxides can be reduced to form nitrogen. When NO or NO ₂ molecules come into contact with the catalyst, the catalyst promotes the removal of nitrogen from the molecule, releasing oxygen in O ₂ form. The nitrogen atoms attached to the catalyst then react to form N2 gas: 2NO → N ₂ + O ₂ and 2NO ₂ → N ₂ + 2O ₂ .

Carbon monoxide, unburned hydrocarbons and particulate matter are further oxidized to form non-contaminants. For example, carbon monoxide is treated as follows: 2CO + O ₂ → 2CO ₂ .

The net result of the catalytic converter is the complete combustion of the fuel into non-pollutants.

Conventional catalytic converters have some limitations on their effectiveness in removing contaminants. For example, if the catalytic converter is located too close to the engine, it may crack due to overheating or rapid temperature changes. Thus, the filter of the conventional catalytic converter is installed immediately adjacent to or inside the engine exhaust manifold in an optimal position having the advantage of in situ high temperature before the temperature is lowered due to the radial cooling due to the high thermal conductivity of the exhaust pipe material. Can't be. Engine vibrations and rapid temperature changes near and inside the exhaust manifold degrade conventional filter materials and dramatically shorten filter life. In addition, some catalysts applied to conventional filters have low operating efficiency or even loss of function at high temperatures, ie temperatures above 500 ° C. Therefore, conventional catalytic converter filters are usually installed in the exhaust path at a position away from the engine.

Structure of catalytic converter and particle filter

Components and materials of the catalytic converter are schematically shown in FIGS. 4A and 4B. The catalyst substrate is secured in the converter shell (also called canister) using a packaging mat (most often made of ceramic fiber). The catalytic converter is connected to the vehicle's exhaust system via an end cone and can be welded to the shell or formed integrally with the shell according to the converter packaging technique. Other components shown in the schematic diagram—end seals and / or steel support rings—are optional; They are not normally present in modern passenger car converters and may be required in higher load applications such as close-coupled converters, large converters for heavy engines or diesel particle filters. Catalytic converters, especially in gasoline applications, may also be equipped with a steel heat shield (not shown in the schematic) to protect adjacent vehicle components from exposure to excessive temperatures.

In general, the catalytic converter consists of at least five major elements: 1) substrate; 2) catalyst coating; 3) washcoat; 4) matting; And 5) canister. A general catalytic converter is shown in FIG. In certain applications, catalyst coating is optional, as described more specifically below.

materials

The substrate is a solid surface from which contaminants can be converted to non-contaminants. Physically, the substrate provides an interface through which various molecular species in any physical state, such as a solid, liquid, or gas, react with each other. The substrate generally has a large surface area to provide a large area where contaminants can be converted to non-contaminants.

Over the past decades, a wide variety of materials and designs have been tested to serve as substrates for chemical reactions. For example, the main physical structures include honeycomb monoliths and beads. (See Figure 1). In the honeycomb structure, a plurality of channels are formed, which are usually drilled parallel to each other in the longitudinal direction of the substrate. The substrate has a channel open to the length of the substrate. The width of the channel varies with the substrate material and the intended use. This channel allows exhaust gas to flow out of the engine through the catalytic converter and through the exhaust pipe. While the exhaust gas flows through the channels of the substrate, the contaminant molecules are converted to non-contaminant molecules through chemical reactions and physical changes.

In the bead structure, the substrate is made of a collection of small beads (similar to putting a bunch of jelly beans in a tube). When the exhaust gas hits the beads, the contaminants are converted to non-contaminants. The bead structure was one of the previous attempts to maximize the surface area of the substrate to which the exhaust gas molecules are exposed.

Many different materials have been used as substrates. Such materials include ceramics, Fiber Reinforced Ceramic Matrix Composites (FRCMC), foams, powder ceramics, nanocomposites, metals and fiber mat-type substrates. The most commonly used is a ceramic called cordierite manufactured by Corning. Cordierite is a ceramic formed from refractory powder. FRCMC is a foam having an open cell in which the catalyst is distributed on the cell wall, and the foam is distributed in the catalyst chamber so that the exhaust gas must pass through the cell path of the foam. The foam is a solid with countless pores formed by bubbling from gas and burned voids. Powdered ceramic substrates differ from cordierite and related ceramics in that they are formed from sintered ceramic powder. Nanocomposites are materials that use nanopowders and / or nanofibers. Metals can also be used as the substrate. Generally, thin sheets of metal foil, such as corrugated steel, are rolled into a honeycomb structure. Fiber mat-like substrates are materials that are woven on a small scale. Certain fiber mat-type substrates use NEXTEL fibers produced by 3M. In addition, in the case where a honeycomb structure is formed by rolling up wrinkles and / or waves, use of a "two-dimensional" nonwoven fibrous composite has been attempted. As examples, reference may be made to US Pat. Nos. 4,894,070, 5,196,120 and 6,444,006 B1.

Catalytic Coating

The third component of the current catalytic converter is a catalytic coating. As the name implies, catalytic coatings are components that actually catalyze the conversion of contaminants into non-contaminants.

A catalyst is usually defined as a substance that affects the rate of a chemical reaction but is not one of the original reactants or the final product, i. In some known catalytic reaction mechanisms, the catalyst forms intermediates with the reactants but is recovered during the reaction. Many other catalytic processes have not been fully described or their full understanding. The principles governing the selection and preparation of catalysts for specific purposes are also not fully understood. Much development is underway in this area through research programs involving the testing of countless substances. Catalysts are widely used in chemical and petrochemical processes, where reactions are slow without catalysts or require high temperatures to increase efficiency. Catalysts are also used to convert harmful components in engine exhaust gases, such as hydrocarbons and carbon monoxide, into harmless substances such as carbon dioxide and water vapor.

A catalyst is a substance that can promote specific chemical reactions between gaseous gas components. In controlled release catalysis, solid catalysts are used for the catalysis of gas phase reactions. The catalytic effect and the observed reaction rate are maximized by good contact between the gas phase and the solid catalyst. In catalysis, this is usually realized by increasing the catalyst surface area by finely dispersing the catalyst on a carrier (support) having a large specific surface area.

Catalytic coating is added to the substrate after the substrate is formed. The coating forms a layer containing a catalyst on the surface of the substrate. For example, different types of catalysts are needed depending on chemical reactions, required applications, temperature conditions, economic factors, and the like. Many metal catalysts are known in the art. For example, the most commonly used are platinum, palladium and rhodium. In-depth work has been done to develop new catalysts.

The rate of chemical reactions involving catalysis generally increases with increasing temperature. The strong dependence of conversion efficiency on temperature is characteristic of all emission control catalysts. A typical relationship between the catalytic conversion of contaminants and the temperature is shown by the solid line A in FIG. The conversion, which is almost zero at low temperatures, initially increases slowly, then accelerates and reaches a plateau at high gas temperatures. When discussing combustion reactions, the term light-off temperature is usually used to characterize this behavior. The catalyst ignition temperature is the lowest temperature required to initiate the catalytic reaction. Since the reaction rate is gradually increased, the definition is not very exact. By more precise definition, the ignition temperature is the temperature at which the conversion reaches 50%. This temperature is often described as T ₅₀ . When comparing the activities of the various catalysts, the most active catalysts are characterized by the lowest complexing temperature for a given reaction.

In some catalyst systems, as indicated by dashed lines B in FIG. 4, an increase in temperature will only increase conversion efficiency up to a certain point. Increasing the temperature further, in spite of the increase in the reaction rate, causes a decrease in the catalytic conversion efficiency. The reduction in efficiency is typically explained by other competing or thermodynamic equilibrium constraints that deplete the reactant concentration.

The temperature corresponding to the high conversion efficiency is often referred to as the catalyst temperature window. This type of conversion curve is typical for selective catalytic processes. A good example is the selective reduction of NO with hydrocarbons or ammonia.

Another important variable affecting conversion efficiency is the size of the reactor. The gas flow rate through the catalytic reactor is usually expressed as space velocity (SV) relative to the size of the reactor. The space velocity, as measured at standard conditions, is defined as the volume of gas per unit time per unit volume of the reactor as follows: (3) SV = V / Vr, where V is the volumetric flow rate of gas in STP (unit M 3 / h), Vr is the reactor volume (unit: m 3), SV has the inverse dimension of time and is usually expressed as 1 / h or h ⁻¹ .

In various catalyst emission control applications, the space velocity ranges from 10,000 1 / h to 300,000 1 / h. The space velocity for the monolithic reactor is calculated based on the external dimensions, for example the diameter and length of the cylindrical ceramic catalyst substrate. Since this method does not take into account the morphological surface area, cell density, wall thickness or catalyst loading of the substrate, this is not always suitable for catalyst comparison. Nevertheless, this is a commonly used and widely accepted industry standard.

Typical platinum loads in filters used in off-road engines since the 1990s were 35-50 g / ft ³ . These filters, installed in relatively contaminated engines, needed a temperature of at least about 400 ° C for regeneration. Later, it was found that when catalyst utilization filters were applied to cleaner city buses and other highway vehicle engines, they were reproducible at much lower temperatures. However, higher platinum loads were needed to support low temperature regeneration. Typical platinum loads with filters used in clean engine, low temperature applications are 50-75 g / ft ³ .

Wash  Wash coat

In most cases, the catalytic coating includes a wash coat as the fourth component. The wash coat increases the surface area of the substrate by being applied to the surface of the substrate. The wash coat also provides a surface to which the catalyst is attached. Metal catalysts may be impregnated into the porous surface area of such inorganic carriers (i.e., washcoat, the term "catalyst support", may be used to represent carrier / washcoat materials as well as ceramic / metal substrates. have).

Many substrates can be used as washcoats. Widely used substrates for catalyst carriers include activated aluminum oxide and silicon oxide (silica).

The washcoat is a layer of porous surface area bound to the surface of the support. The exact role of the washcoat must be very complex and is not clearly understood or explained. The main function of the washcoat is to provide a very large surface area, which is necessary for the dispersion of catalytic metals. In addition, the washcoat can physically separate the components of the complex catalyst system to prevent unnecessary reactions between the components.

The washcoat material includes inorganic metal oxides such as Al ₂ O ₃ (aluminum oxide or alumina), SiO ₂ , TiO ₂ , CeO ₂ , ZrO ₂ , V ₂ O ₅ , La ₂ O ₃ and zeolites. Some of these are used as catalyst carriers. Others are added to the washcoat as accelerators or stabilizers. Others exhibit their own catalytic activity. Good washcoat materials are characterized by high specific surface area and thermal stability. The specific surface area is determined by nitrogen adsorption measurement techniques along with mathematical modeling known as Bruneter, Emmet, Teller (BET). Thermal stability is assessed by exposing a sample of a given material to elevated temperatures in a controlled atmosphere, usually in the presence of oxygen and water vapor. Lower BET surface area when measured at different time intervals during the test indicates the degree of thermal degradation of the tested material.

The washcoat can be applied to the catalyst support from a water based slurry. Next, the wet washcoat portion is dried and calcined at high temperature. The quality of the catalyst washcoat can greatly affect the performance and durability of the finished catalyst. The washcoat load determines the precious metal catalyst load in the finished product, since it is subsequently applied to the washcoat by impregnating the precious metal, ie, "soaking" the washcoat porosity with the catalyst solution. Therefore, it is very important that the washcoat process produces a very reproducible and uniform washcoat layer. Details of the washcoat treatment process and its parameters are protected by trade secrets by all catalyst manufacturers.

Canister

The substrate is packaged in a canister, for example a steel shell, to form a catalytic converter. Canisters perform several functions. The canister holds the catalyzed substrate and protects the substrate from the external environment. In addition, the canister forces forced exhaust gas through and / or over the catalyzed substrate.

The catalyzed substrate may also be packaged inside a muffler, referred to as "catalytic muffler" or "catalytic muffler". In this case, one steel canister holds the catalyst and noise damping elements such as baffles and perforated tubes. Catalytic mufflers can provide a more space-saving design than the combination of a catalytic converter and a muffler.

Catalytic substrates are usually one of several methods, including clamshells, tourniquets, shoeboxes, stuffing and swaging, as shown in FIG. It is installed inside the canister having a shape made according to.

Matting (matting)

In addition to canisters, mating materials are often used to package catalyst substrates in canisters. Packaging mats are generally made of ceramic fibers, which can be used to protect the substrate and evenly distribute pressure from the shell. The mat often contains vermiculite that expands at high temperatures, thus compensating for the thermal expansion of the shell and providing adequate retention under all operating conditions.

For example, ceramic monoliths are packaged in special packaging materials that firmly secure in steel housings to distribute pressure evenly and prevent cracking. Ceramic fiber mats are most commonly used to package catalytic converters in both gasoline and diesel applications. These packaging mats can be classified as follows: intumescent (thermally expandable) mats; Conventional (highly vermiculite) mats; Reduced vermiculite; Non-expandable mats; Or hybrid mat.

Heat insulation

In many applications, catalytic converters are used to avoid damage to surrounding vehicle components (eg, plastic parts, fluid hoses), or, in the case of converters mounted in close proximity to the engine, to prevent an increase in engine compartment temperature. It must be insulated. One method of diverter thermal management is to utilize steel heat shields located around the diverter body. Another method is to provide a thermal insulation layer inside the shell by (1) increasing the thickness of the mounting mat, or (2) further providing a dedicated low thermal conductivity insulation. Heat shields have traditionally been used in underfloor positions, but increasing mat thickness has been suggested as the best solution for the converters installed in the engine compartment (Said Zidat and Michael Pramentier, "Heat Insulation Methods for Manifold Mounted Converters,"). Delphi Automotive Systems, Technical Center Luxembourg, SAE Technical Paper Series 2000-01-0215). One advantage of using thick mats instead of heat shields is that the average mat temperature is low, which minimizes the risk of breaking vermiculite mats in close-coupled gasoline engine applications.

Particle traps

Another device for removing contaminants from exhaust gases is particle traps. A common particle trap used in diesel engines is the diesel particle trap (DPT). The primary purpose of particle traps is to filter and capture particulate matter of various sizes from a fluid stream, such as an exhaust gas stream. The rate of particle filter is generally measured by its ability to filter PMs of various sizes, such as PM-2.5 and PM-10.

Diesel traps are relatively effective at removing carbon soot from the exhaust of diesel engines. The most widely used diesel trap is a wall-flow filter that filters diesel exhaust by trapping soot in the porous walls of the filter body. Wall-flow filters are designed to filter soot almost completely with little obstruction of exhaust gas flow.

As the layer of soot is trapped on the surface of the inlet channel of the filter, the permeability of the soot layer decreases, causing a pressure drop across the filter and gradually increasing the back pressure of the filter relative to the engine, thereby operating the engine. Making it difficult, and thus affecting the engine running efficiency. As a result, the pressure drop becomes unacceptable and requires regeneration of the filter. In conventional systems, the regeneration process involves heating the filter to initiate combustion of carbon soot. In some cases, regeneration is performed under controlled conditions of engine management, where slow combustion is initiated and lasts for several minutes, during which the temperature of the filter rises from about 400 to 600 ° C. up to about 800 to 1,000 ° C.

In certain applications, the highest temperature upon regeneration is due to the cumulative effect of a wave of soot combustion from the inlet side to the outlet side of the filter because the exhaust gas stream carries the heat of combustion downstream of the filter. tends to occur near the exit end. In certain situations, so-called "uncontrolled regeneration" may occur when the onset of combustion coincides with or immediately after the high oxygen content and low flow rate of the exhaust gas (such as engine idle state). During uncontrolled regeneration, burning of soot can cause a temperature rise inside the filter, which can cause thermal shock or cracks, or even melting of the filter. The most common temperature gradients observed are radial temperature gradients where the temperature at the center of the filter is higher than the rest of the substrate and axial temperature where the temperature at the outlet of the filter is higher than the rest of the substrate. gradient).

In addition to trapping carbon soot, the filter also traps metal oxide "ash" particles carried by the exhaust gas. Usually, such ash deposits are derived from unburned lubricating oil with exhaust gases under certain conditions. Since these particles are nonflammable, they are not removed upon regeneration. However, if the temperature during uncontrolled regeneration is high enough, the ash ultimately sinters into the filter or even reacts with the filter resulting in partial melting.

By improving the durability against melting and thermal shock damage, obtaining a filter that not only survives a number of controlled regenerations over its lifetime, but can also survive a much less frequent but more severe uncontrolled regeneration is known in the art. I think it's progress.

Continuous regeneration trap

One conventional method for catalytic conversion is a diesel particle trap ("DPT"). DPT is a filter which collects particulate matter in exhaust gas. The collected particulate matter must be incinerated before the filter is clogged. Incineration of particulate matter is referred to as "regeneration". There are various conventional methods of regeneration of DPT. First, by applying an expensive metal catalyst or base-metal catalyst to the surface of the filter, it is possible to lower the temperature required for oxidation of particulate matter. Second, a filter may be installed in front of the chamber containing the oxidative catalyst that produces NO ₂ to assist incineration of particulate matter. Third, the system can utilize fuel companion catalyst. Finally, in the case of the non-catalyst, an external heat source for burning soot at 550 ° C. and using an expensive metal catalyst may burn soot at about 260 ° C. As ash residues remain with carbon combustion by regeneration, constant maintenance is required for cleaning of the filter.

Another conventional method utilizes diesel oxidation catalysts ("DOCs"). DOC is a catalytic converter that oxidizes CO and hydrocarbons. Hydrocarbon activity extends into polynuclear aromatic hydrocarbons ("PAHs") and soluble organic fractions ("SOF") of particulate matter. Catalytic formulations have been developed to selectively oxidize SOF with minimal oxidation of sulfur dioxide or nitrogen monoxide. However, DOC can produce sulfuric acid and increase the release of NO ₂ .

The function of the catalyst in the Catalytic Diesel Particle Filter (CDPF) is to regenerate the filter by oxidation of the diesel particulate material (DPM) at an exhaust temperature obtained during normal operation of the engine / vehicle, typically in the range of 300 to 400 ° C. It is to lower the soot combustion temperature to promote. In the absence of a catalyst, the DPM can be oxidized at a significant rate at temperatures above 500 ° C., which is rarely seen in diesel engines during actual operation. Reported substrates for use in such catalyst applications include cordierite and silicon carbide wall-flow monoliths, wire mesh, ceramic foams, ceramic fiber media, and the like. The most common form of CDPF is a catalyzed ceramic wall-flow monolith.

Catalytic ceramic traps were developed in the early 1980s. His first applications include diesel powered cars and the underground coal mine machinery behind them. Catalytic filters were commercially introduced in 1985 for Mercedes passenger cars sold in California. Mecerdes model 300SD and 300D with turbocharged engines were fitted with a 5.66 "diameter x 6" filter inserted between the engine and the turbocharger.

The use of diesel traps mounted on passenger cars has since been abandoned due to problems such as lack of durability, increased pressure drop and filter clogging. Today, not all of these problems are solved, but catalyzed ceramic traps remain one of the most important diesel filter technologies. CDPF is being used increasingly in many heavyweight applications such as city buses and rural diesel trucks. Over the years, limited amounts of catalyzed filters have also been used in underground coal mines (North America and Australia) and certain stationary engine applications.

Catalytic ceramic filters are commercially available as OEM and aftermarket (retrofit) products in a variety of highway, off-road and stationary engine applications. The list of sources includes Engelhard, OMG dmc2, and several smaller emission control manufacturers, mainly specialized in the off-road market.

The main component of a conventional filter is a ceramic (typically cordierite or SiC) wall-flow monolith. The porous wall of the monolith is coated with an active catalyst. As the diesel exhaust aerosol penetrates through the wall, soot particles deposit inside the wall's pore network and on the inlet channel surface. The catalyst promotes DPM oxidation by the oxygen present in the exhaust gas.

Pressure drop

The flow of exhaust gas through conventional catalytic converters produces a substantial amount of back pressure. Increasing back pressure in the catalytic converter makes an important contribution to a successful catalytic converter. If the catalytic converter is partially or wholly blocked, it creates a limitation to the exhaust system. Continued increase in back pressure causes a sharp drop in engine performance (eg horsepower and torque) and fuel economy, and can even be stopped after starting if the blockage is severe. Prior attempts to reduce pollutant emissions entail very high costs due to the cost of the material and the cost of retrofitting or manufacturing the original engine with appropriate filters.

The high filtration efficiency of the wall-flow filter is obtained with the inverse of the relatively high pressure drop which increases the filter soot load. Initially, the filter is clean. As the particles begin to deposit inside the pores of the monolith wall (depth filtration), the pressure drop begins and increases in a nonlinear fashion over time. This phase is called the initial load phase, during which time the pores contribute to the continuously varying permeability and filter porosity due to the increased soot deposition inside the pore network. After the filtration capacity of the pores is saturated, soot begins to deposit as a layer inside the inlet monolith channel (cake filtration face). During this time, a linear pressure drop is observed over time. One of the changing properties is the thickness of the soot layer. Some presenters also distinguish between intermediate short transition faces from when particles begin to deposit on the channel surface until the soot layer is fully formed (Tan, JC, et al., 1996, "A Study on the Regeneration". Process in Diesel Particulate Traps Using a Copper Fuel Additive ", SAE 960136; Versaevel, P., et al., 2000," Some Empirical Observations on Diesel Particulate Filter Modeling and Comparison Between Simulations and Experiments ", SAE 2000-01-0477) .

Pressure drop modeling on the clean filter substrate was made. The relatively simple model developed shows excellent agreement with experimental results (Masoudi, M., et al., 2000, "Predicting Pressure Drop of Wall-Flow Diesel Particulate Filters-Theoryand Experiment", SAE 2000-10-0184; Masoudi, M., et al., 2001, "Validation of a Model and Development of a Simulator for Predicting the Pressure Drop of Diesel Particulate Filters," SAE 2001-01-0911). However, in practical applications most filter pressure drops are caused by soot deposition. In practical applications, the pressure drop of a clean wall-flow filter is between 1 and 2 kPa, whereas a loaded filter pressure drop of 10 kPa may be considered low to intermediate in certain situations.

The overall pressure drop of the particle load filter can be divided into four factors: pressure drop due to sudden contraction and expansion at the inlet and outlet of the filter; Pressure drop due to channel wall friction; Pressure drop due to permeability of the particle layer; And pressure drop due to wall permeability.

The pressure drop due to sudden shrinkage and expansion at the inlet and outlet of the filter is the same as in the clean filter except that the soot layer has a small effective channel size (hydraulic diameter), which results in more gas shrinkage. similar.

The pressure drop due to channel wall friction is also increased relative to the clean filter scenario due to the reduction in the channel hydraulic diameter. For thick soot layers, the ΔP _channel can be a very important contributing factor to the overall pressure drop.

The pressure drop (ΔP _particulate ) due to the permeability of the particle layer can be a very important contributing factor to the overall pressure drop.

The pressure drop ΔP _wall due to wall permeability is also higher now than the clean filter because the wall pores are partially filled with soot. The increase in ΔP _wall that may be due to the initial soot loading face in the pores is represented by ΔPI in FIG. 3.

The overall pressure drop can be expressed as:

△ P = △ P _{in / out} + △ P _particulate + △ P _wall

Mathematical modeling of pressure drop in soot loaded diesel filters is a complex and difficult task. Important properties of soot, such as permeability and packing density, depend on the application, engine operating conditions and other parameters. Efforts to simulate pressure drop in wall-flow filters continue, and more complex models are being developed. Predicting the actual soot load will require a theoretical model of the regeneration process itself.

Type of catalytic converter and particle filter

Catalytic converters can be classified according to several factors, including: a) the type of engine in which the converter is used, b) the location of the engine in the engine, c) the number and type of catalysts used in the converter, and d) Form and structure of the substrate used. In addition, each of these catalytic converters is often used with other emission control devices such as CRT, EGR, SCR, ACERT and other devices and methods.

engine

Catalytic converters are used in at least two types of engines: gasoline and diesel engines. Within these two general classes are various types of special gasoline and diesel engines. For example, gasoline and diesel engines are manufactured with various displacements and horsepower. Certain engines are equipped with turbochargers and / or intercoolers. Most passenger car and truck engines are water cooled, while motorcycle engines are air cooled. Certain utilities require the highest available horsepower, while others maximize fuel economy. All of these variables, in addition to others, can affect the level of contaminants produced during combustion of the fuel. In addition, depending on the use of the engine, for example on-road, off-road or stationary, the regulatory requirements for emission fractions differ.

location

Catalytic converters can theoretically be installed at any location along the exhaust flow of the engine. However, its location is limited by the physical characteristics of conventional catalytic converters. Most commonly in vehicles, catalytic converters are installed in the lower portion of the vehicle body, in proximity to the muffler, at a distance from the engine block. Catalytic converters can fail for several reasons, so they are usually not installed in close proximity to the engine. Such reasons include excessive temperature, thermal shock, mechanical vibration, mechanical stress and spatial constraints near the engine. In addition, the physical setup of the stationary engine may limit the location of the catalytic converter or particle filter.

For example, 2004 FOCU.S. ^{At TM} , Ford Motor Company decided to use the same mani-cat that Honda Motor Corporation used in one of its properties. The system is not actually part of the manifold, but in a location adjacent to the manifold. The high temperature and excessive vibration energy generated by the cylinder explosion and moving parts cause the current catalytic converter to be subjected to excessive thermal shock and physical shock when the catalytic converter is installed in the manifold. In addition, a design for a mani-cat was proposed in US Pat. No. 5,692,373 by Northrup Grumman Corporation. It is believed that current cordierite substrates must withstand such environmental challenges.

In other applications, for example motorcycles (eg Harley-Davidson), the presence of catalytic converters installed at specific locations can cause serious injury to the user. Because of the high operating temperature of the catalytic converter, it would be desirable to use catalytic converters that are less likely to cause injury to the user, such as small catalytic converters, converters with less temperature rise, and the like.

In certain cases, an exhaust system (eg, installed in a car) may receive one or more catalytic converters or special filters along the exhaust flow. (See Figure 4). For example, the exhaust system can have an additional catalytic converter between the engine and the main catalytic converter. This configuration is called a pre-cat. The pre-cat can have a more compact configuration. Another set-up is a back-cat with a second catalytic converter before (or after) the main catalytic converter. Back-cats are also often used for exchange of catalytic converters.

2 won vs 3 won vs 4 won

Catalytic converters can generally be classified into two-, three- or four-way converters. Commercially available converters include at least the following forms: oxidation converters, three-way converters (airless), three-plus oxidation converters, and four-way converters.

Oxidation (two-way) converters represent earlier generations of converters designed to oxidize hydrocarbons (HC) and carbon monoxide (CO). These units represent the most basic form of catalytic converter technology, but in some areas remain a viable contaminant reduction option. Oxidation converters usually contain platinum or palladium. However, metals other than precious metals may also be used.

In the early 1980s, most vehicle manufacturers began using converters designed to reduce NO _x in addition to oxidation of HC and CO. These three-way converters, used in conjunction with computer-controlled engine systems and oxygen sensors, have been used to more precisely control the ratio of air to fuel. Such converters are referred to as ternary converters because they treat three compounds: HC, CO and NO _x .

The latest cars are typically equipped with "three-way" catalytic converters in series with one or more substrates using Corning's clay extrusion technology. The term "ternary" refers to the following three regulated emissions at which the converter assists in reduction: carbon monoxide, volatile organic compounds (VOCs such as unburned hydrocarbons) and NO _x molecules. Such converters use two different types of catalysts, reducing and oxidizing catalysts.

In three-way catalytic converters, reductive catalysts are usually used in early stage catalytic converters and serve to reverse the oxidation of nitrogen generated in the combustion chamber. It typically uses platinum and rhodium to assist in the reduction of NO _x emissions. Oxidative catalysts, which may consist of metals such as platinum and / or palladium, are typically installed in the second region of the catalytic converter.

Three-way catalytic converters having a reducing and an oxidative catalyst together in one housing are often referred to as three-plus-oxidation converters. These converters use air injection between the two substrates. This air injection assists the oxidation reaction.

Quaternary converters handle carbon monoxide, nitrogen oxides, unburned hydrocarbons and particulate matter. This includes, for example, a QuadCAT Four-Way catalytic converter manufactured by Ceryx. This is a catalytic converter that, according to the manufacturer, reduces four major sources of air pollutants: NO _x , hydrocarbons, carbon monoxide and particulate matter to levels that diesel engines can meet in 2002/2004 emission standards. Other examples include those described in US Pat. Nos. 4,329,162 and 5,253,476.

Catalytic converters, like other catalysts, promote the reaction by lowering the activation energy required to carry out the desired reaction. For example, if the particles require a temperature of 550 ° C. before reacting with oxygen in the presence of a catalyst, the same reaction will only require a temperature of 260 ° C. This low energy threshold allows the catalyst system to be physically located downstream of the engine where the temperature is lower but the space is more spacious. Alternatively, the catalyst system would have to be located upstream of the higher temperature. However, it is not practical in current technology because the closer it is installed to the engine, the greater the viscosity to damage the substrate.

Diesel engines produce emissions with high concentrations of NO _x and particulate matter due to the relatively high production of CO and hydrocarbons but high temperatures and pressures. Compressed combustion is incomplete compared to sparks in gasoline engines. However, due to the relatively sparse mixture due to the high air content, diesel can provide better gas mileage than gasoline engines. In diesel exhaust, the excess catalyst does not work well with the three way catalyst. NO _x reducing catalysts typically must maintain a good stoichiometric ratio of fuel to air that cannot be readily achieved in diesel combustion engines.

Catalytic converter technology can be applied to a variety of applications, including internal combustion engines and stationary combustion engines. Internal combustion engines are the most common engines used in vehicles. Since the catalytic converter is installed as a device in the vehicle exhaust system, all exhaust gas flows through the substrate and contacts the catalyst before exiting from the tailpipe. However, the catalytic converter may be part of a fairly complex system that incorporates various activation strategies such as injection of reactants or sophisticated engine control algorithms prior to catalyst. Examples include a number of diesel catalyst systems that are being developed for the reduction of NO _x . Among the advantages of catalysts, the attributes of simplicity and passive features that have been discussed no longer apply to these systems.

Conventional attempts to reduce pollutant emissions can be costly, in part due to the cost of the material and, in certain applications, to the retrofit or manufacture of the original engine with appropriate filters.

Advances in Catalytic Converters and Particle Filter Technology

One invention that has led to the development of catalytic converters is the development of Corning's extruded cordierite honeycomb monolith. (See US Pat. No. 4,033,779). Since the 1970s, this approach utilizes a family of precious metals (platinum, palladium, rhodium, etc.) and a base metal family that is tightly coupled to the washcoat on the surface of a rigid substrate that can withstand the harsh environments of engine exhaust systems. Over 1 billion pounds of contaminants were removed from the exhaust stream. Subsequent changes and improvements to this core technology have been derived over the years, including, for example, changes in the location of the catalytic converter and changes in the composition and manufacturing method. However, there still remains a fundamental inadequacy that has not yet been overcome. At present, the state of the art is reaching physical and economic limits with minor improvements at a high cost.

Limit of current mention

Current catalytic converters and particulate filter techniques are useful to some extent in reducing emission pollutants, but current techniques are clearly disadvantageous. There is also a feature that cannot be matched by current catalytic converters. Some imperfections are inherent in the type of substrate used. Thus, improved substrates for use in catalytic converters or particle filters will be an important advance in the fundamental physical and chemical properties of the materials used as catalyst substrates for catalytic converters. In addition, improved substrates will dramatically improve quality and will enable manufacturers and consumers to more easily meet 2007, 2010, and later emission standards.

Conventional monolith catalytic converter substrates are generally formed through an extrusion process. This complex and expensive process has been used for the past 25 years. However, there is a limit to the extrusion process. There are limitations on how to maintain quality control while forming small channels inside the material. The extrusion process also limits the shape of the catalytic converter to cylinders or parallelograms, or to shapes with sides parallel to the extrusion axis. This shape limitation did not matter in previous emission standards. However, non-linear and / or non-cylindrical filter designs and vehicle integration will be required as the need to design catalytic converters and particle filters that can reach near zero emission performance.

Reducing the wall thickness results in an increase in surface area, for example in a particular example, reducing the wall thickness from 0.006 inches to 0.002 inches increases the surface area by 54%. By increasing the surface area, more particulate matter can be deposited in less volume. 1 shows a prior art honeycomb structure 102 formed in a ceramic filter element 100 configured to increase the surface area for a catalytic converter. Honeycomb structure 102 is formed using an extrusion process in which elongated channels are formed having a major axis parallel to the extrusion operation. The openings in these channels face the incoming exhaust air stream.

Advances in technology have enabled the manufacture of ceramic cordierite substrates with reduced wall thickness. The cell density of 400 cpsi and 0.0065 "(or about 0.17 mm), which were once the standard construction for 400 / 6.5, once a passenger car application, were gradually replaced by substrates with thinner walls (0.0055 to 0.004 mil). Physical limitations are imminent Due to the physical properties of ceramics, especially cordierite, the use of substrates made of thinner walled cordierite ceramics is not practical: thin-walled materials have other essential features (eg durability, heat resistance). Cannot match).

Diesel catalysts often have thicker walls than locomotive counterparts, in part because of their large size. Since diesel wall-flow filters generally have thicker walls, there are physical limits to the channels per square inch that these filters can have. In general, there are no commercially available diesel wall-flow filters with more than 200 channels per square inch.

Another limitation of currently available substrates is the reduction in catalyst efficiency at low temperatures. When the converter system is cool, such as starting the engine, the temperature is not high enough to initiate the catalytic reaction. Cordierite, silicon carbide, and various metal substrates, currently used and sold in catalytic converters by Corning, NGK, Denso, and other manufacturers, are very tough and dense with excellent mechanical strength and tolerance to thermal shock and vibration. Made of materials However, these materials take time to absorb heat until they reach a temperature sufficient for catalytic reaction after startup. Due to the delayed initiation of the catalytic reaction, it is estimated that about 50% of all emissions from the new engine are released into the atmosphere during the initial 25 seconds after the engine is started. Even minor improvements during this critical "cold start" time could greatly improve the amount of contaminants that are successfully treated annually. Efforts have been made to address this problem, but there remains a need for catalytic converters that can reduce emissions during this initial cold start period. Cordierite-based catalytic converters, the latest and most expensive technology, also require about 20 seconds to start up.

In order to reach the reaction temperature more quickly, attempts were made to move the diverter closer to the engine exhaust manifold, a position where higher temperatures can be utilized faster and also drive the reaction more violently during operation. Due to the limited space available under the hood of the vehicle, the size of the diverter system and thus the throughput that can be successfully processed is limited. Current substrates cannot be effectively used in the engine compartment of a vehicle. In addition, it is not desirable to add weight to the engine compartment, and many current substrates have high density and limited porosity (approximately 50% or less), requiring large weight and volume systems to handle large exhaust emissions. Do. In addition, substrates such as cordierite are susceptible to melting under many operating conditions, which can result in increased plugging and back pressure.

Other ways to offset cold start include sophisticated adsorption systems that temporarily store NO _x and / or hydrocarbons so that the converter can be treated when the critical temperature is reached. Some of these systems require parallel tubing and sophisticated adsorption surfaces, additional valve and control mechanisms, or multiple layers of different washcoats used to attach catalyst to the substrate and isolate the reaction environment. This problem is particularly interesting for diesel engines that must capture large volumes of soot particles, NO _x and SO _x . In some large industrial diesel engines, rotary banks of diesel particle traps are used to collect, store and process particles. (In another system, NO _x is stored and used as an oxidant to convert CO to CO ₂ while reducing to N ₂ ).

Given the statutory limits on total emissions, a system that can easily reduce approximately 50% of emissions that occur at cold start may preclude the need for some of the costly and sophisticated measures described above. . When used in conjunction with such countermeasures, such a system may result in substantially reduced emissions. However, as previously described, conventional systems are generally complex and expensive, and are easy to operate without ignition and / or unpredictable.

Another inherent limitation of conventional systems is the typical "residence time" required to incinerate particles. In view of the enormous volume of exhaust gas throughput in operation and the speed at which the gas must flow, it is important that the converter has the ability of rapid ignition. Thus, catalytic converters capable of ignition, capable of withstanding extreme thermal shocks and vibrational shocks, and the ability to rapidly rise internal temperatures at cold start, can meet the environmental standards encountered by the industry in 2007 and 2010 by reducing emissions. And greatly increase the ability to produce cleaner cars, trucks, buses and large industrial engines.

If the substrate is also lightweight, it will result in improved fuel economy values for new vehicles. However, there is no description that has been found to solve many or all of these problems so far.

Design Considerations for Substrates for Catalytic Converters or Particle Filters

Catalyst substrates are important components that affect the performance, robustness, and durability of catalytic converter systems. In addition, the filtration substrate has a great influence on the operating performance of the particle filter. Ideally, the substrate used in the catalytic converter or particle filter should have several properties. Such attributes include, but are not necessarily limited to, one or more of the following aspects: a) surface area; b) porosity / permeability; c) emissivity; d) thermal conductivity; e) thermal properties such as impact resistance, expansion and conduction; f) density; g) structural integrity; h) efficiency of contaminant treatment; i) requirement of catalyst; j) weight of the system. Catalysts or filtration substrates that optimize one or more attributes will be one advance in the field of fluid filtration and catalysis.

Brief synthesis of the invention

This section describes various embodiments. These and other embodiments of the present invention are described in the following detailed description section.

The inventors have found that the nonwoven sintered refractory fibrous ceramic (nSiRF-C) composites described herein can be used as an improved substrate for catalytic converters, particle filters and related devices, and can also be molded into such substrates.

The inventors have also found that improved catalyst substrates and improved filtration substrates can be prepared from materials having the particular properties described herein. For example, suitable properties include high melting point, low thermal conductivity, low coefficient of thermal expansion, durability against thermal shock and vibration shock, low density, and very high porosity and permeability. An exemplary material in one embodiment having this property is nSiRF-C.

One example of a material with suitable properties is an nSiRF-C composite. Examples of nSiRF-C can be used in accordance with embodiments of the present invention as alumina enhanced thermal barrier (“AETB”) materials or materials of that kind, as catalyst substrates or filtration substrates. AETB materials are known in the art and include aluminaboria silica (also known as alumina-boria-silica, aluminoborosilicate and aluminoboria silicate) fibers, silica fibers and alumina fibers. One application commonly known for AETB is a tile on the outer wall of a space shuttle, which is ideal for space shuttle reentry. AETB has never been used as a filtration substrate or a catalytic converter substrate.

The inventors have found that the proper attributes for AETB, which are desirable for the space industry, are also desirable for combustion techniques. Among other properties, AETB has high melting point, low thermal conductivity, low coefficient of thermal expansion, durability against thermal shock and vibration shock, low density, and very high porosity and permeability. Combinations of these preferred attributes are lacking in current filtration and catalytic converter substrates.

In addition, nSiRF-C composites, such as AETB and similar suitable substrates, may be manufactured, molded, molded, cut and / or processed (or physically modified) in new forms suitable for use as particle filter and catalytic converter substrates. I also found that.

The present invention has several advantages over the current art. Firstly, the present invention results in improved air quality and respiratory health. The present invention can substantially reduce the potential of carbon monoxide poisoning.

Embodiments of the present invention can be used as catalytic converters and particle filters and exhaust and engine systems as well as direct replacements for currently used catalysts and filtration substrates. As will be described in more detail below, the description of the present invention provides several advantages over the description of the prior art and also solves the various problems left unresolved by the description of the prior art. This can be interpreted as a significant cost saving for the manufacturer. Since the present invention can be used as a direct replacement for the current technology, there is no need to redesign the exhaust system. Thus, enhanced exhaust filtration and cleaning can be achieved with minimal investment in a reasonable amount of time without the need to restructure the manufacturing plant and line.

The improved catalyst and filtration features of the present invention, in certain embodiments, require the use of fewer catalysts. Since most catalysts used in related applications are expensive, this advantage leads to further cost savings.

Preferred thermal properties of some embodiments of the present invention reduce and / or eliminate the need for certain parts of the exhaust system that deal with heat accumulation associated with current catalytic converters and particle filters. In some embodiments of the invention, heat shielding and thermal insulation may be unnecessary. Excluding these components from exhaust systems and vehicles directly reduces costs only (manufacturing costs are lower because no components are used), but indirect costs are also reduced (fuel costs are reduced because vehicle weight is reduced). Other benefits may include better performance, fuel economy and / or horsepower.

In certain embodiments, conventional catalytic converters or particle filters can be replaced with the present invention, which is compact and has the same or better pollutant removal efficiency. By using smaller catalytic converters or particle filters, more space in the vehicle can be used for other purposes. In addition, since the filter or diverter of the present invention is compact, the total weight of the vehicle is reduced.

Another aspect of some embodiments of the present invention is a catalyst substrate suitable for use in a catalytic converter that is wholly or partially installed in the head of an engine. The catalytic converter, referred to herein as a heat-cat, has many advantages over the prior art. For example, such head-cats were not practical because of the limitations of catalyst substrates currently available. Conventional substrate cordierite will absorb too much heat. Because of the preferred thermal properties of the substrate of the present invention, the head-cat comprising the substrate will reduce the turbo thermal stress on the turbocharger and / or the intercooler, if present.

The head-cat also does not require additional external hardware such as heat shields. The use of a head-cat can maintain the desired appearance of the engine and the product, such as in a motorcycle. In certain embodiments, the use of head-cats may also reduce external discoloration of the exhaust system, such as mufflers and header pipes. Several additional advantages of the head-cat in certain embodiments include one or more of the following: increased safety; Filtering the particles that the intercooler will capture in other cases improves the life of the intercooler and provides cost savings; No matting required in one embodiment; The use of head-cats reduces or eliminates rattles in heat shields; And the head-cat can reduce the size of the necessary muffler.

In another embodiment of the head-cat, smaller particulate matter is incinerated more efficiently. If the head-cat fails, only one small cat needs to be replaced. Head-cats also provide this benefit for boats, ships, motorcycles, leaf blowers, and the like.

Many other embodiments of the present invention provide one or more of the following advantages over the prior art: improved appearance; Avoidance of additional hardware; Additional hardware (which may be required due to stricter regulations) will not be needed in the present invention; Reduction or elimination of discoloration of mufflers and exhaust pipes due to exothermic chemical reactions. The present invention, in one embodiment, allows for smaller substrates, and therefore for smaller systems, smaller mufflers or canisters. Since the substrates of the present invention have improved thermal properties and do not absorb heat as certain conventional substrates, they provide increased safety for systems using catalytic converters or particle filters. In addition, the substrate of the present invention cools faster than many conventional substrates, thereby increasing safety. Certain embodiments of the present invention provide improved durability against temperature changes, so that even with rapid temperature changes, they are not as cracked, crushed or damaged as certain conventional substrates. In one embodiment, the substrate is easier to manufacture than a conventional substrate (eg, an nSiRF-C wall flow substrate may be made of a single piece of material rather than a plugging channel). This property saves time as well as cost.

In some embodiments, the present disclosure exhibits less back pressure than competing aftertreatment devices. Such low back pressures can result in increased vehicle performance, increased horsepower and increased fuel economy.

Other embodiments of the present invention are described in more detail below, for example, in catalysis reaction methods, in filtration of fluids, in preparation of catalyst substrates, in preparation of filtration substrates, in substrates prepared according to the above methods, and elsewhere Plan to do

1 is a cross-sectional view of a conventional cordierite substrate incorporating a honeycomb structure. The honeycomb structure 302 is formed in the cordierite filter element 300. The cut structure 302 is formed using an extrusion process in which long channels (or tubes) in which the major axis is parallel to the compression action are created. The openings in these channels face the incoming exhaust gas stream. As the discharge enters the channel, particulate matter is deposited along the inner partition of the tube.

2A and 2B are micrographs of a conventional cordierite substrate. In FIG. 2B, the sphere 210 represents PM-10 sized particles, and the sphere 225 represents PM-2.5 sized particles.

3 is a micrograph of cordierite 205 including a sphere 210 representing PM10 particles and a second sphere 225 representing PM2.5 particles.

4A is a longitudinal cross-sectional view of a typical catalytic converter schematic. Catalytic converter 400 includes a reducing catalyst 402 and an oxidative catalyst 404. As the exhaust gas stream 406 enters the catalytic converter 400, it is filtered and exposed to the reducing catalyst 102 and then to the oxidative catalyst 404. The exhaust gas stream 406 is then treated by an oxidative catalyst 404 to further incinerate unburned hydrocarbons and carbon monoxide.

4B is a schematic diagram of a catalytic converter.

5 is a schematic cross-sectional view of three substrates with different front shapes.

6 is a schematic diagram showing an example of a flow-through configuration of a catalyst substrate or a filtration substrate. The substrate has a plurality of channels 610 formed of channel walls 620. Fluid flow 630 flows into the front, moves through channel 610 and exits to the back.

7 is a schematic diagram illustrating an example of a wall-through configuration of a catalyst substrate or a filtration substrate. The wall-flow pattern consists of the same substrate material 720 and channel 710 except that the channel 710 is not fully connected to the other side. Instead, the channel 710 is formed as a blind hole, leaving a blocked portion 740 of the substrate at the end of the channel 710. Fluid flow 730 passes through channel wall 720 before exiting from the backside of the substrate. One particular advantage of the present invention is that the fluid flow 730 in the wall-flow pattern has substantially the same characteristics as the flow pattern.

8 is a schematic diagram illustrating an example of a wall-pass configuration of a catalyst substrate or a filtration substrate. In this example, fluid flow 830 is introduced at the front of the substrate. Some of the fluid is discharged to the backside of the substrate by flowing through the blocked portion 845 of some channels.

9 is an end view of an embodiment of a substrate 900 using wall flow channels. The alternating channels have a blocked portion 920 at either the inlet or the outlet. The drilled channel 910 is alternately formed with the blocked portion 920 of the channels drilled from the opposite side. As a result, the substrate appears to have a channel of "checkerboard" pattern.

10A to 10D are diagrams for comparing the front surface areas 1020, 1021, 1022, and 1023, and the cell numbers 1010, 1011, 1012, and 1013 are shown. In the comparison of FIGS. 10A and 10C, each embodiment has the same cell density, that is, the number of channels or cells. However, Figure 10C has a much higher front surface area. Ideally, the front surface area is minimized to maintain structural integrity. The same comparison can be made between the embodiments of FIGS. 10B and 10D. With respect to FIGS. 10A-10D, the embodiment of FIG. 10B has a preferred structure; The cell density is maximized and the front surface area is minimized.

11 shows an embodiment of a square channel at a constant rate. In this embodiment, the ratio of cell voids 1110 to cell walls 1120 is 31.83: 1.5 or approximately 20: 1.

12 illustrates an embodiment of substrate 1210 having an exemplary ratio of cell voids to cell walls, shown at a constant rate. Substrate 1210 is four square inches in length and width, and includes four squares 1220, 1221, 1222, 1223, each 1/8 "x 1/8". Four squares 1220, 1221, 1222, 1223 are drilled to have a cell density of 900 for the total substrate cell density 3600, respectively. The wall thickness between cells is 1.5 mils. The spacing between each square 1220, 1221, 1222, 1223 on the substrate 1210 is 7.8 inches, and the squares 1220, 1221, 1222, 1223 are each about 7/16 inches from the proximal edge of the substrate 1210. Away.

13A-13C illustrate various embodiments of a channel structure. 13A-13C show hexagonal channel 1310, triangular channel 1320, and square channel 1330, respectively. Because the walls 1315, 1325, 1335 of the channels 1310, 1320, 13300 are substantially parallel to each other, these embodiments can successfully carry out the present invention.

14 shows an embodiment of the present invention. The micrographs shown represent substantially similar dimensions of the rectangular channels 1410, 1411, 1412, 1413 in the substrates 1415, 1416, 1417, 1418. 14C and 14D show fibers 1420 and 1421 present in the material. These fibers show better porosity than the small platelets of cordierite in conventional systems.

FIG. 15 is a two dimensional view of a comb 1500 that may be used in the combined method of making the catalyst or filtration substrate of the present invention.

FIG. 16 is a diagram of various representations of comb teeth 1600 (or portions thereof) that may be used in certain embodiments of the present invention. 16 also illustrates the physical dimensions of comb 1600 in inches.

17 is a schematic representation of a surface area increasing method, inlet and outlet tubes that may be formed in a filter element according to an embodiment of the invention. 17 shows the flow of fluid 1704 into the channel opening 1702 at the front. The fluid is discharged to the back side 1704 of the substrate on the right side. The substrate shown in FIG. 17 illustrates a substrate having a wall-flow configuration, where the size of the channel decreases gradually as the channel goes from the opening toward the channel end through the substrate.

18 is a longitudinal photograph of a substrate according to an embodiment of the present invention. The filter substrate 1800 of the present invention is shown. The substrate 1800 has a hard coating 1804 on the outer wall 1802. In the sample shown in FIG. 18, the hard coating consists of finely divided cordierite and inorganic fibers. Powder is also applied onto the base 1800 of the filter and cured as described herein. Hard coatings protect and insulate the foundation of the filter without changing the dimensions.

19 is a graph of the residence time required to incinerate particulate matter at various temperatures. 19 provides the residence time required to burn or incinerate particulate matter (soot mass) at various temperatures. As shown, the residence time required to burn or incinerate soot mass with 0.9 soot mass initially at 600 ° K is much longer than the residence time at 1200 ° K.

20 shows an exhaust gas substrate system 2000 that includes a substrate 2002 associated with a wire mesh heating element 2004. Substrate 2002 and wire mesh heating element 2004 are inserted into exhaust casing 2006 at an angle relative to the exhaust flow. Because the wire mesh heating element 2004 is installed below the back of the substrate 2002 due to the angle, the substrate 2002 can be heated more efficiently and uniformly using the known heat rising principle. As mentioned above, more uniform and efficient heating allows the substrate 2002 to burn or incinerate particulate matter more completely, resulting in cleaner exhaust.

FIG. 21 is a front view of the filter element 2102 and the wire mesh heating element 2104 described and mentioned in connection with FIG. 9. As shown, the filter element 2102 and the wire mesh heating element 2104 are oval to fit the casing at a predetermined angle. The shape of the casing, the shape of the filter element 2102, the shape and angle of the heating element 2104 can all be modified to suit the requirements and limitations of the intended exhaust system application.

22A is a micrograph of the substrate of the present invention, specifically AETB.

22B is a micrograph of the substrate of the present invention, specifically AETB. Fiber 2205 can be seen. Sphere 2210 represents particles of PM-10 size, and spheres 2225 represent particles of PM-2.5 size.

FIG. 23 is a graph showing pressure drop (delta P) as a function of gas hourly space velocity (hr ⁻¹ ) for the following seven test materials: Corning 200/12 DPT 932 F (2340); AETB-11 (2310) with 600 cpsi, 6 mil wall thickness and 11 lb / ft ³ , 1100 F; AETB-11 (2320) with 6 mil wall thickness and 11 lb / ft ³ , 932 F; AETB-11 (2330) with 6 mil wall thickness and 11 lb / ft ³ , 662 F; Cordierite 2350 with 1100 F; Cordierite 2360 with 932 F; Cordierite 2370 with 662 F.

24 is a graph showing the percent failure rate with temperature. Substrate 2410 of the present invention exhibits a greater rate of failure of the material at lower temperatures than cordierite substrate 2420.

25 is a cross-sectional view showing an embodiment of the catalytic converter of the present invention. In this embodiment, the catalytic converter comprises a rigid heat resistant casing 2502. Casing 2502 has an inlet 2504 and an exhaust 2506. The substrate 2510 of the present invention has one or a plurality of zones 2512 and 2514. The substrate 2510 of the present invention is enclosed in one or more matting / insulation layers 2515. The mating layer 2515 may be applied to the filter foundation 2510 to shield the foundation 2510 from vibration shocks of the engine and mobile environment and to insulate the external environment from the internal temperature of the filter foundation 2510.

FIG. 26 is a schematic diagram of a catalytic converter or particle filter 2600 having four substrates 2601a, 2601b, 2601c, 2601d arranged in parallel. The filter or diverter has a front opening 2604 and a rear outlet 2605.

27A-27C illustrate a catalytic converter or particle filter 2700 having a laminated membrane-like substrate 2710. Inlet 2720 and outlet 2730 are formed at different heights. 27B and 27C show another embodiment.

summary

In one embodiment, the present invention seeks to provide a catalyst substrate suitable for use in a variety of applications, including substrates used in catalytic converters. Another aspect of the invention is a filtration substrate suitable for use in a variety of applications, including substrates used in particle filters such as diesel particle filters (DPF) or diesel particle traps (DPT). The present invention also provides an improved substrate for the removal and / or exclusion of contaminants from exhaust gases of combustion engines. The catalyst substrate and the filtration substrate, in one embodiment, provide an improvement in the removal of contaminants from the exhaust gas. Such improvements include, but are not limited to, one or more of the following: faster ignition time, increased depth filtration of PM, lower back pressure, lower probability of blockage, multiple in an exhaust system including the manifold or the head itself. Increased ability to be installed at the site, high probability of catalytic reaction, high conversion of NO _x , HC and CO, rapid incineration of PM, minimization of catalyst material use, reduced weight of aftertreatment exhaust system, etc.

Other embodiments of the present invention include catalytic converters, particle filters, diesel particle filters, diesel particle traps, and the like. The invention also provides a process for producing a catalyst substrate and a filtration substrate, a catalytic converter, a particle filter, a catalyst muffler and an exhaust system. Other embodiments of the present invention include pre-cats, back-cats, head-cats and mani-cats, each of which includes a description of the present invention. In addition, the present invention provides a substrate prepared according to the method described herein in another embodiment.

In another aspect, the present invention includes a catalyst substrate or filtration substrate that provides one or more of the following attributes: faster ignition time, increased depth filtration of PM, low back pressure, low probability of clogging, manifold or head Increased ability to be installed in multiple locations in self-contained exhaust systems, high probability catalytic reaction, high conversion of NO _x , HC and CO, fast incineration of PM, less amount of catalyst material required, cold Fast ignition at start, low outer wall temperature of substrate, etc.

The use of the substrate, catalytic converter, particle filter or exhaust system of the present invention provides several advantages and improvements over the prior art. In one embodiment, such an improved catalytic converter and / or particle filter can remove and / or exclude contaminants from the exhaust of a combustion engine with several special advantages, which are described in more detail below. The improved exhaust system is likewise an additional aspect of the invention described herein. The improved exhaust system reduces the amount of contaminants emitted from running engines.

The invention is described in more detail below, including non-limiting examples. The embodiments mentioned herein are for illustrative purposes only. The present invention is not limited to these examples.

Catalyst base

The present invention comprises, consists of, or consists essentially of a nonwoven sintered refractory fibrous ceramic (nSiRF-C) composite, which may be used in catalytic converters, particle filters, and related devices, as described herein. It provides a catalyst substrate. It is preferable that the said catalyst base material contains a catalyst. The nSiRF-C composite can be molded into a form suitable for the uses described herein.

The nSiRF-C composite is nonwoven. In one embodiment, the nSiRF-C composite is a material having a clear, solid three-dimensional shape. The nSiRF-C complexes are not arranged in a neat pattern, but are randomly and unintentionally omnidirectional in three dimensions. In some embodiments, the nSiRF-C complex is in matrix form.

nSiRF-C is a sintered composite. In one embodiment, the sintered composite is a cohesive mass formed by heating without melting. However, since the sintering method of the ceramic material is well known in the prior art, the scope of the present invention is not necessarily limited to the specific examples and descriptions described herein. Sintering off bonds without resin residue. With reference to the present invention, a sintered ceramic is a coherent mass of dispersed fibers formed by heating without melting.

nSiRF-C is a refractory fibrous ceramic composite. Particular examples of nSiRF-C consist of high grade fire resistant fibers of various lengths and compositions, as illustrated in the non-limiting examples herein.

In one embodiment, the present invention seeks to provide a catalyst substrate suitable for use in various applications as described herein. Such substrates include various materials having one or more of the attributes described herein, preferably a plurality of attributes. The substrate of the present invention is made of a nonwoven, fibrous ceramic composite made from fire resistant grade fibers. Such materials are disclosed in US Pat. No. 4,148,962, which is incorporated herein by reference in its entirety. Other suitable materials are disclosed in US Pat. No. 3,953,083.

In one embodiment, the catalyst substrate of the present invention comprises, consists of, or consists essentially of an alumina reinforced thermal barrier ("AETB") material or similar material well known to those skilled in the art. AETB materials are known in the art and are more fully described in the following documents and are incorporated herein by reference: Leiser et al., "Options for Improving Rigidized Ceramic Heatshields", Ceramic Engineering and Science Proceedings, 6 , No. 7-8, pp. 757-768 (1985) and Leiser et al., "Effect of Fiber Size and Composition on Mechanical and Thermal Properties of Low Density Ceramic Composite Insulation Materials", NASA CA 2357, pp. 231-244 (1984).

In another embodiment, the catalyst substrate is a ceramic such as alumina reinforced thermal barrier (AETB) with toughened unipiece fibrous insulation (TUFI) and / or reaction cured glass (RCG) coating. It includes a tile. Such materials are known in the art.

Another suitable material is fibrous refractory ceramic insulation (FRCI). In one embodiment, AETB is made from alumina boria silica (also known as alumina-boria-silica, aluminoborosilicate and aluminoboria silicate) fibers, silica fibers and alumina fibers. One application commonly known for AETB is a tile on the outer wall of a space shuttle, which is ideal for space shuttle reentry. AETB has high melting point, low thermal conductivity and coefficient of thermal expansion, durability against thermal shock and vibration impact, low density and very high porosity and permeability. Thus, in a preferred embodiment, the catalyst substrate has high melting point, low thermal conductivity and coefficient of thermal expansion, durability against thermal shock and vibration shock, low density and very high porosity and high permeability.

In one embodiment, the first component of AETB is alumina fiber. In a preferred embodiment of the present invention, alumina (Al ₂ O ₃ or aluminum oxide such as SAFFIL) typically consists of about 95-97 wt% alumina and about 3-5 wt% silica in commercial form. In another embodiment, alumina with lower purity may be used, for example 90%, 92%, and 94%. In other embodiments, higher purity alumina may also be used. Alumina can be produced by extrusion or spinning. First, a solution of precursor species is prepared. For example, a gradually gradual polymerization process is initiated by manipulation of the pH, with the result that individual precursor molecules combine to form large molecules. As this process proceeds, the average molecular weight / molecular size increases, thereby increasing the viscosity of the solution over time. When the viscosity reaches about 10 cps, the solution turns slightly tacky so that the fibers can be drawn or spun. In this state, the fibers may be extruded through a die. In one embodiment, the average diameter of the fibers is in the range of about 1-6 μm, but larger or smaller diameter fibers are also suitable for the present invention. For example, in another embodiment the fiber diameter is 1-50 μm, preferably 1-25 μm, more preferably 1-10 μm.

In one embodiment, the second component of AETB is silica fiber. In one embodiment, silica (SiO ₂ , such as Q-fibers or quartz fibers) contains more than 99.5% by weight of amorphous silica with very low impurity levels. Lower purity such as 90%, 95% and 97% silica can also be used in the present invention. In one embodiment, amorphous silica having low density (eg, 2.1-2.2 g / cm 3), high fire resistance (1,600 ° C.), low thermal conductivity (about 0.1 W / mK), and near zero thermal expansion Used.

In one embodiment, the third component of AETB is alumina boria silica fibers. In some cases, alumina boria silica fibers (3Al ₂ O ₃ and 2SiO ₂ and B ₂ O _3, for example; NEXTEL 312) is typically of alumina and 62.5% by weight silica, 24.5% by weight, and boria 13% by weight. Of course, the exact percentage of the components of the alumina boria silica can vary. It is largely an amorphous product but may contain crystalline mullite. Suitable alumina boria silica fibers and methods of making them are disclosed, for example, in US Pat. No. 3,795,524, the teachings of which are incorporated herein by reference in their entirety.

Another material suitable for use as the substrate of the present invention includes an Orbital Ceramics Thermal Barrier (OCTB) available from Orbital Ceramics (Valencia, CA).

Other materials suitable for use as nSiRF-C in the present invention include: AETB-12 (about 20% Al ₂ O ₃ , about 12% (14% B ₂ O ₃ , 72% Al ₂ O ₃ , 14% SiO ₂ ; NEXTEL ^™ fiber), and about 68% SiO ₂ ); AETB-8 (about 20% Al ₂ O ₃ , about 12% (14% B ₂ O ₃ , 72% Al ₂ O ₃ , 14% SiO ₂ ; NEXTEL ^™ fiber), and about 68% SiO ₂ ); FRCI-12 (having a composition of about 78 wt% silica (SiO ₂ ) and 22 wt% aluminoborosilicate (62% Al ₂ O ₃ , 24% SiO ₂ , 14% B ₂ O ₃ )); And FRCI-20 (about 78 wt% silica (SiO ₂ ) and about 22 wt% aluminoborosilicate (62% Al ₂ O ₃ , 24% SiO ₂ , 14% B ₂ O ₃ )).

In a preferred embodiment, the components of the inorganic fibers consist of or consist essentially of fibrous silica, alumina fibers, and aluminoborosilicate fibers. In this embodiment, the fibrous silica is about 50-90% inorganic fiber mix, the alumina fiber is about 5-50% inorganic fiber, and the aluminoborosilicate fiber is about 10-25% Inorganic fiber mix. The fibers used to make the substrates of the present invention may, in one embodiment, have both a crystalline phase and a glassy phase.

Other suitable fibers are preferably about 55-75 wt% aluminum oxide, more than 0 wt% and less than about 45 wt% (preferably more than 0 wt% and less than 44 wt%) silicon oxide, and 0 wt. Aluminoborosilicate fibers comprising more than% and in the range of less than about 25% by weight (preferably about 1-5% by weight) (the amounts are theoretical as Al ₂ O ₃ , SiO ₂ and B ₂ O ₃ , respectively) Calculated on the basis of oxide). The aluminoborosilicate fibers preferably have at least 50% by weight crystalline, more preferably at least 75% by weight and most preferably about 100% by weight (ie crystalline fiber). Sized aluminoborosilicate fibers are commercially available, for example, under the trademarks "NEXTEL 312" and "NEXTEL 440" from 3M Company. Suitable aluminoborosilicate fibers may also be prepared as disclosed in US Pat. No. 3,795,524, which is incorporated herein by reference in its entirety.

Other suitable fibers include aluminosilicate fibers, which are typically crystalline and contain about 67 to about 77 weight percent aluminum oxide, such as 69, 71, 73, 75 weight percent, and about 33 to silicon oxide. About 23% by weight, for example 31, 29, 27, 25% by weight. Sized aluminosilicate fibers are commercially available, for example, from the 3M Company under the trademark "NEXTEL 550". Another suitable aluminosilicate fiber can be prepared as disclosed in US Pat. No. 4,047,965 (Karst et al.), The disclosure of which is incorporated herein by reference.

In another embodiment, the fibers used to prepare the substrates of the present invention may be fabricated with α-Al ₂ O ₃ with added Y ₂ O ₃ and ZrO ₂ and / or with addition of SiO ₂ (α-Al ₂ O ₃ / mul). Form a light) α-Al ₂ O ₃ .

Various special materials can be used in the preparation of the catalyst substrate. In one embodiment, the materials used to make the substrates of the present invention include or consist of or consist essentially of refractory silica fibers and refractory aluminum borosilicate fibers. In another embodiment, the materials used to prepare the catalyst substrate include refractory silica fibers, refractory grade alumina fibers and a binder, preferably boron oxide or boron nitride powder. In another embodiment, the fiber is high grade.

In another embodiment, the substrate consists essentially of a refractory composite comprising aluminosilicate fibers and silica fibers in a weight ratio of about 19: 1 to 1:19, and from about 0.5 to 30% boron oxide based on the total weight of the fibers. Include. In other cases, the weight ratio of aluminosilicate fibers to silica fibers is 16: 1, 14: 1, 12: 1, 10: 1, 8: 1, 6: 1, 4: 1, 2: 1, 1: 1, 1: 2, 1: 4, 1: 6, 1: 8, 1:10, 1:12, 1:14, and 1:16. In another embodiment, boron oxide is present in an amount of about 5%, 10%, 15%, 20%, 25% or 30%. In another embodiment, the boron oxide and aluminosilicate fibers are in the form of aluminoborosilicate fibers. In yet another embodiment, the catalyst substrate comprises nSiRF-C having a ratio of aluminosilicate fibers to silica fibers 1: 9 to 2: 3 and a boron oxide content of about 1-6% of the fiber weight.

In another embodiment, suitable fibers for preparing the substrate of the present invention include refractory fibers made by 3M, such as NEXTEL ^™ Ceramic Fiber 312, NEXTEL ^™ Ceramic Fiber 440, NEXTEL ^™ Ceramic Fiber 550, NEXTEL ^™ Ceramic Fiber 610, NEXTEL ^™ Ceramic Fiber 720. Composite grade fibers NEXTEL ^™ Fiber 610, 650, and 720 have a more refined crystal structure, based on α-Al ₂ O ₃ , and contain no glassy phase. This allows the fibers to maintain strength over higher temperatures than industrial fibers. NEXTEL ^™ Fiber 610 has essentially a single phase composition of α-Al ₂ O ₃ . It starts with the highest strength at room temperature but has the lowest strength retention at a given temperature. With a Y ₂ O ₃ and ZrO ₂ added to α-Al ₂ O ₃ of Nextel ^TM Fiber 650 and SiO ₂ is added to the (α-Al ₂ O ₃ / form a mullite) α-Al ₂ O ₃ of Nextel ^TM Fiber Both 720 have good strength retention and low creep at a given temperature.

In another suitable embodiment, nSiRF-C is made from or includes (or consists of or consists essentially of) ceramic fibers comprising Al ₂ O ₃ , SiO ₂ and B ₂ O ₃ , and has the following properties: 1) a melting point of about 1.600 ° C. to about 2,000 ° C., preferably about 1,800 ° C .; 2) a density of about 2 to about 4 g / cc preferably about 2.7 to about 3 g / cc; 3) a refractive index selected from about 1.5 to about 1.8, more preferably 1.56, 1.60, 1.61, 1.67, and 1.74; 4) filament tensile strength (25.4 mm gauge) selected from about 100 to about 3,500 MPa, more preferably about 150 to about 200 MPa or about 2,000 to about 3,000 MPa, or 150, 190, 193, 2100, or 3,100 MPa ; 5) thermal expansion (100 to 1,100 ° C.) selected from about 2 to about 10, preferably about 3 to about 9, more preferably 3, 4, 5.3, 6, and 8; And 6) a surface area of less than about 0.4 m 2 / g, more preferably less than about 0.2 m 2 / g. In another embodiment, the crystalline phase of the fiber is mullite and amorphous, substantially amorphous, γ-Al ₂ O ₃ or amorphous SiO ₂ . In another embodiment, the dielectric constant of the fiber suitable for the preparation of the substrate according to the invention is about 5 to about 9 (at 9.375 GHz), or preferably 5.2, 5.4, 5.6, 5.7, 5.8, 6, 7, 8 , And 9;

In one embodiment, the substrate of the present invention is substantially "shot-free", meaning that there is no particulate ceramic (ie crystalline ceramic, glass, or glass-ceramic) from the fiber manufacturing process. .

In one embodiment, the nSiRF-C composite is "nonflexible". In one embodiment, an inflexible angle is defined as 1 degree, 2 degrees, 3 degrees, 4 degrees, 5 degrees, 6 degrees, 7 degrees, 8 degrees, 9 degrees, 10 degrees, 15 degrees, or 25 degrees (at the bending point Bent over) refers to a substrate that is broken, cracked or permanently deformed or deformed.

The diameter of the fibers used in various embodiments of the present invention can vary. In one embodiment, the average diameter is about 1 to about 50 μm, preferably 1 to about 20 μm. In other embodiments, the average diameter is about 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 μm. In another embodiment, the average diameter of the alumina boria silica fibers is about 10 to about 12 μm.

In another embodiment, the catalyst substrate of the present invention further comprises a binder such as boron nitride. In another embodiment of the present invention, boron nitride is added to replace the alumina boria silica fibers when they are not used. That is, in some embodiments, the substrate comprises (or consists of or consists essentially of or consists of silica fibers, alumina fibers, boron nitride, similar to those described above). In another embodiment, the substrate comprises silica fibers, alumina fibers and a boron binder. Each of these materials may, in certain embodiments, contain small amounts of other materials, such as organic binders, inorganic binders, and some fibrous or nonfibrous impurities. In another embodiment, the substrate does not contain an organic binder. In other cases, the binder used to produce nSiRF-C is also converted to other materials during the manufacturing process, as is known in the art.

Other materials suitable for making the substrates of the present invention are disclosed in US Pat. No. 5,629,186, which discloses a low density made from amorphous silica and / or alumina fibers containing 2-12% by weight of boron nitride. Fused fibrous ceramic composites are described.

In another embodiment, the ceramic fiber used to make the nSiRF-C is at least about 700 MPa (100,000 psi), preferably at least about 1,200 MPa (200,000 psi), more preferably at least about 1,800 MPa (300,000 psi) Most preferably have an average tensile strength of at least about 2,100 MPa (350,000 psi).

In another embodiment, a dispersant is added. Suitable dispersants are known in the art.

In other embodiments, processing, alterations, modifications, and / or enhancements are made in one or more aspects described herein and / or by methods known in the art.

In yet another embodiment, small amounts of impurities from various sources are present. In this case, the impurity does not substantially affect nSiRF-C and / or its properties.

The substrate according to the invention does not comprise NEXTEL ^™ woven fibers or mats.

catalyst

In another aspect, the present invention is directed to providing the above-described substrate comprising a catalyst. Any number of catalysts may be used with the substrate to form the catalyst substrate. The catalyst can be coated on the surface of the substrate. That is, in one embodiment, the catalyst may be adsorbed onto the surface of the catalyst substrate (eg, the wall of the channel). The catalyst may also be present inside the core of the substrate and attached to the individual fibers of the substrate. In one embodiment, the present invention requires less catalyst while still functioning at the same or better level than current technology.

In another embodiment, the catalyst is attached only to the channel wall surface and is not present inside the channel wall. In another embodiment, the catalyst may be attached to the inlet channel wall, the outlet channel wall, the interior of the wall, or a combination thereof. In yet another embodiment, the first catalyst lining, coating or permeating the beginning or proximal portion of the channel wall; The second catalyst lining, coating or permeating the central portion of the channel wall; The third catalyst is in the terminal section of the channel wall.

In one embodiment, the catalyst substrate of the present invention preferably contains a catalyst metal. In another embodiment, the catalyst substrate does not contain a catalytic metal. However, under certain conditions, the substrate can catalyze a suitable reaction without the need for a separate catalyst metal, and in one embodiment, for example, the washcoat described below can function as a catalyst.

Any catalyst that can be applied to the substrate can be used. Such catalysts include, but are not particularly limited to, platinum, palladium (palladium oxide, etc.), rhodium, derivatives and mixtures thereof including oxides thereof. In addition, the catalyst is not limited to only noble metals, combinations of noble metals or oxidative catalysts. Other suitable catalysts include chromium, nickel, rhenium, ruthenium, silver, osmium, iridium, platinum and gold, derivatives and mixtures thereof. Other suitable catalysts include binary oxides of palladium and rare earth metals as disclosed in US Pat. Nos. 5,378,142 and 5,102,639, which are incorporated herein by reference. The binary oxide may be obtained by solid state reaction of palladium oxide and rare earth metal oxide, and for example, Sm ₄ PdO ₇ , Nd ₄ PdO ₇ , Pr ₄ PdO _7, or La ₄ PdO ₇ may be produced. Other catalysts that may be used in the present invention include those disclosed in US Pat. No. 6,090,744, assigned to Mazda Motor Corporation. Other suitable catalysts include nonmetallic catalysts, organic catalysts, base metal catalysts, and noble metal catalysts.

Other suitable catalysts are disclosed in the 6,692,712 patent assigned to the Johnson Matthey Public Limited Company. Catalysts that do not contain precious metals can be used in the present invention. Such catalysts are shown in US Pat. No. 5,182,249.

Another suitable platinum catalyst, developed by Engelhard, is a 5: 1 ratio of Pt / Rh (applied in amounts of about 5 to 150 g / ft ³ ) and MgO (applied in amounts of about 30 to 1500 g / ft ³ ) Is made of.

In another embodiment, vanadium and its derivatives such as V ₂ O ₅ are particularly useful catalysts for diesel particle filters. Such catalysts have been obtained commercially from diesel particle filters.

Catalysts utilizing vanadium compounds other than V ₂ O ₅ , such as silver vanadate or copper vanadate, have been developed. As an example a copper vanadate metal catalyst was developed by Heraeus (Strutz 1989). The catalyst may be prepared by doping and calcining copper vanadate Cu ₃ V ₂ O ₈ with potassium carbonate in a molar ratio of about 3: 2: 0.13. The catalyst load was 10-80 g / m 2 of filtration surface area. Another suitable catalyst is Cu / ZSM5 which can be used as DeNox catalyst.

Although precious metals such as platinum, palladium and rhodium are the most common and preferred, other known catalysts may be used. The three metals have been known as excellent and very efficient catalysts for internal combustion engine emissions. Over 25 years of using catalytic converters, there has actually been no meaningful replacement for this trinity. However, there are thousands of combinations of these catalysts configured according to the original manufacturer of the device, vehicle, vehicle load, environmental regulations, engine, transmission and the like. Throughout the truck and locomotive manufacturing industry, various combinations and formulations of catalysts are used. The catalyst substrate according to the invention comprises any one or more of these catalyst combinations. Many combinations are considered to be proprietary materials. Manufacturers like Ford, GM and Toydta have unique catalyst formulas for each vehicle due to varying vehicle weight and engine performance requirements. Manufacturers also have different catalyst formulas for the same vehicle depending on the region in which the vehicle is to be sold or technically affiliated, for example Canada, the United States, California, Mexico. At present, such formulations may vary from two to three times per vehicle per model year due to strict government regulations. For this reason, most manufacturers deal with the application of catalyst coatings themselves.

In yet another embodiment, the catalyst substrate includes a catalyst used in nSiRF-C and a commercially available catalyst environment.

In one aspect, once the substrate is finished to final dimensions and the washcoat is applied and cured, one or more catalysts are applied using known techniques and methods, examples of which include US Pat. Nos. 5,224,852 and 5,272,125. Palladium-platinum-based catalyst as disclosed in the present invention, and the teachings of this patent are incorporated herein by reference in their entirety.

In one embodiment, the catalyst is used in an amount sufficient to effect catalysis effectively. For example, in one embodiment, a sufficient amount means that a catalyst, such as a noble metal that reacts with the emissions, is 80%, 85%, 90%, 95%, 97%, 98%, and 99 It means an amount sufficient to react as maximum as possible, such as%.

In one embodiment, the catalyst is preferably deposited on the washcoat or impregnated in the washcoat as individual crystals. In this example, the catalyst is not applied as a veneer-like coating on the washcoat (like paint on walls). When the catalyst is impregnated in the washcoat, the catalyst is applied such that the final product is partly or substantially a collection of individual crystals. This can be visualized like salt crystals on pretzel. At the same time, the fluid path, such as the exhaust path, must have sufficient precious metal at the optimum catalysis operating temperature, ie the ignition temperature, and the precious metal must fit within the spaces allowed by the physical constraints, namely the functionality and design of the vehicle and engine.

The manufacturing goal is to maximize the contaminant removed while minimizing the amount of catalyst required on the substrate. Each vehicle produces a different amount of contaminants, and accordingly to the embodiment, the substrate is custom made to treat the level of contaminants and to minimize the amount of precious metals.

In another embodiment, the addition of catalyst to the catalyst substrate may occur during the slurry process in the manufacture of the substrate, or after the processing process (as described below). In this case, the catalyst is mixed with the slurry of fibers before every heating step.

Single and multiple catalyst formulations can be applied to a single substrate, or due to the small size of the filter compared to conventional catalytic converters and exhaust systems, installation of multiple substrates is possible. Thus, in one embodiment, the catalyst substrate of the present invention comprises or consists of or consists essentially of one or more zones, each zone having a different catalyst. Alternatively, one or more zones can be made without catalyst. For example, the catalyst substrate of the present invention may include an oxidative catalyst in one zone that accommodates the front side of the substrate, and a reducing catalyst in another zone that accommodates the backside.

If the substrate is to be used in circulating form, it is not necessary, but it is preferred that the catalyst or most of the catalyst is present along the channel surface. When the substrate is processed to form a wall flow, it is desirable that the catalyst is uniformly distributed throughout the substrate so that the gas moves through the substrate and does not simply pass through.

For example, the substrate of the present invention can be used in a catalyzed diesel particle filter (CDPF). CDPF utilizes a catalyst deposited directly on the substrate. Both precious and nonmetallic catalysts such as platinum, silver, copper, vanadium, iron, molybdenum, manganese, chromium, nickel, derivatives thereof (such as oxides) and the like can be used. Depending on the type of filter, the catalyst can be impregnated directly into the medium, or an intermediate washcoat layer can be used. CDPF may utilize an exhaust temperature of about 325-420 ° C. for regeneration, depending on engine technology (PM emissions) and fuel quality (sulfur content).

Platinum is one of the most active and most commonly used precious metal catalysts, but palladium, rhodium or ruthenium catalysts are also suitable for use in the present invention, usually in admixture. The list of metals other than the conventional platinum group used in catalytic converters includes vanadium, manganese, calcium, strontium, barium, copper and silver. In one embodiment, platinum is the preferred catalyst for use with diesel engines. In another embodiment, palladium and rhodium are suitable for use with gasoline engines.

Catalysts are typically very expensive. Therefore, it is desirable to use the minimum amount of catalyst to achieve maximum contamination reduction. Two common catalysts, platinum and palladium, are both expensive precious metals. Substrates having a porous, permeable nature with a large surface area in which the catalyst can be present as uniformly distributed crystals or layers make it possible to achieve this object. An advantage of the present invention is that it requires a smaller amount of catalyst than conventional substrates.

Throughout the 1990s, typical platinum loads on filters used in off-road engines were 35-50 g / ft ³ . These filters, installed in relatively contaminated engines, required the lowest temperatures close to 400 ° C for regeneration. It was then found that when the catalyzed filter was applied to cleaner city buses and other highway vehicle engines, the catalyzed filter could be regenerated at much lower temperatures. However, higher platinum loads were needed to support low temperature regeneration. Filters used in clean engines and at low temperatures typically have a platinum load of 50 to 75 g / ft ³ .

In one embodiment, the catalyst substrate is in an amount of about 1 to about 100 g / ft ³ , about 1 to about 50 g / ft ³ , about 1 to about 30 g / ft ^3, or about 10 to about 40 g / ft ³ It includes a catalyst.

In another embodiment, the catalyst substrate, preferably nSiRF-C, such as AETB, OCTB and FRCI, comprises as a catalyst a ratio of about 5: 1 platinum and rhodium and an amount of about 30 g / ft ³ .

Filtration substrate

The present invention seeks to provide a catalyst substrate comprising a nonwoven sintered refractory fibrous ceramic (nSiRF-C) composite that can be used in particular filters and related devices, as described herein. Filtration substrates are made of special shapes, designs, sizes and configurations, which are particularly useful for filtration of particulate matter. Filtration substrates are particularly useful for filtering particulate matter under harsh conditions (temperature, pressure, etc.), such as to filter the flow of exhaust gas. Filtration substrates can be used in additional applications requiring filtration of small particulate matter.

In one embodiment, the filtration substrate comprises, consists of, or consists essentially of the nSiRF-C composite as described above, for the catalyst substrate. The filtration substrate does not contain a catalyst. All variations, examples and examples of materials suitable for use as substrates for catalyst substrates are likewise suitable for the filter substrates of the present invention.

The filter substrate is shaped into a form suitable for use in the applications described herein, in particular in particle traps such as diesel particle traps and diesel particle filters.

In one embodiment, the filtration substrate of the present invention is an alumina reinforced thermal barrier ("AETB") material or similar material known to those skilled in the art. AETB is made of alumina boria silica (also known as alumina-boria-silica, aluminoborosilicate and aluminoboria silicate) fibers, silica fibers and alumina fibers. A commonly known application for AETB is exterior wall tiles installed on space shuttles, ideal for re-entry into space shuttles. The properties that make AETB unique and desirable in the space industry are also desirable in organic combustion technology. AETB has high melting point, low thermal conductivity, low coefficient of thermal expansion, durability against thermal shock and vibration shock, low density, and very high porosity and permeability.

The filter substrate of the present invention is optionally treated with one or more chemical additives.

In another embodiment, the present invention seeks to provide a diesel particle trap comprising a filter as described above, with no catalyst applied.

In another embodiment, the present invention seeks to provide a diesel particle trap comprising a filter as described above in combination with a CRT ^® diesel particle trap (NO _x , HC adsorbent).

In yet another embodiment, the present invention is directed to providing a diesel particle trap comprising a filter as described above, in combination with an SCR.

In another embodiment, the filtration substrate comprises a plurality of channels, described in more detail below. In addition, the filtration substrate may be modified, modified and / or reinforced in one or more aspects disclosed herein and known in the art.

Properties of catalyst substrates and filtration substrates

The present invention has one or more, preferably at least three, four, five, six, seven, eight, nine, or ten attributes that are advantageous over conventional catalyst substrates or filtration substrates.

Suitability for use

The present invention seeks to provide, in one embodiment, a catalyst substrate or filtration substrate and catalyst comprising nSiRF-C, suitable for catalytic converters. The substrate is suitable for use in any number of catalytic converters, filtration devices, and applications thereof.

For example, the catalyst substrate and filtration substrate of the present invention are suitable for use in any application commonly used for prior art substrates. Suitable uses include, but are not limited to, the use of the substrate of the present invention in any of the following exhaust systems: 1) passenger cars and light trucks; Highway and driveway motorcycles, three-wheeled motorcycles (eg, motor-driven three-wheeled motorcycles, autorichshaw), motor-driven three-wheeled motorcycles; Mobile, on-road engines, devices and vehicles, including medium highway engines such as trucks and buses; 2) compressed ignition engines (farm, construction, coal mine, etc.); Small spark ignition engines (grass mowers, blade blowers, chainsaws, etc.); Large spark ignition engines (forklifts, generators, etc.); Marine diesel engines (merchant marine, recreational diesel, etc.); Marine spark ignition engines (boats, personal vessels, etc.); Recreational vehicles (snowmobiles, mountain motorcycles, all-rounder vehicles, etc.); locomotive; Stationary sources including mobile, non-road engines, devices and vehicles, including aircraft (airplanes, ground support devices, etc.), and 3) hundreds of sources such as power plants, refineries, and manufacturing facilities.

In another embodiment, the catalyst substrate of the present invention functions so that the vehicle described herein conforms to the emission standard of any of 1990, 2007 and 2010 as defined by EPA as part of the catalytic converter. If so, it is suitable for use in special vehicles.

In another embodiment, the catalyst substrate catalyzes the reaction of converting contaminants into non-contaminants at high levels. For example, it catalyzes with greater than 50% efficiency for reactions that convert contaminants into non-contaminants. In another embodiment, catalyze at greater than 60% efficiency for the reaction of converting contaminants into non-contaminants. In another embodiment, the conversion rate consists of 70%, 80%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, and 99.9% Selected from the group. In one embodiment, the conversion rate refers to the total conversion of nonparticulate contaminants. In another embodiment, the conversion refers to conversion of specific nonparticulate contaminants, for example NO _x to N ₂ , CO to CO ₂ , or HCs to CO ₂ and H ₂ O. In another embodiment, the conversion refers to the percentage of particulate matter removed from the exhaust gas.

In another embodiment, the catalyst substrate of the present invention is suitable for use in a particular application if it passes the preferred test of a particular OEM designation, such as US Federal Test Protocol 75 (U.S. FTP75). Such tests are known in the art. (Reference literature example: Document No. EPA20-R92-009, published by U.S. EPA, available at http: //www.demgovotaq/inventory/r92009.pdf, which is hereby incorporated by reference in its entirety. Included). Additionally, as a back-cat or DPT in renewal applications, EPA and / or state / local agencies will have to approve the use of the product, including nested descriptions.

Surface area

The available surface area of the substrate is an important property of the filtration substrate or the catalyst substrate. One of the properties of substrates suitable for catalytic converters is that they have a high geometric surface area (GSA). Higher GSAs allow for maximum response probabilities.

The large open frontal area (OFA) allows large amounts of gas to pass without disturbing the flow of gas and creating back pressure. Open front area (OFA) is defined as the portion of the total substrate cross-sectional area (ie, the cross-sectional area of the filter inlet channel) that the gas can utilize to flow. OFA is typically expressed relative to the total substrate cross section.

The nature of the substrate of the invention is high surface area, ie high GSA. The surface area of the substrate is an important feature in catalytic reaction applications. The surface area is the sum of the faces that must pass when the exhaust gas emissions flow through the exhaust filter. The increase in surface area translates to faster and more efficient catalytic converter processes as the area of chemistry between contaminants and catalytic and thermal processes increases. Speed and efficiency may result in little or no blockage that can cause failure of the exhaust system. In addition, increasing the surface area of a substrate according to certain embodiments also entails an increase in filtration efficiency and / or capacity.

The geometric surface area is the total surface area that can be impregnated within 1 in ³ . Substrates with high gross surface areas are preferred. Certain embodiments of the present invention have much more geometric surface area that can be impregnated with a catalyst than conventional substrates such as cordierite and SiC.

The gross wall volume is the total amount of wall volume present within 1 in ³ of the constructed substrate. The gross wall volume is calculated by multiplying each wall surface area by its thickness and then summing. Substrates with low gross wall volumes are preferred. In one embodiment, the gross wall volume of the substrate according to the invention is lower than conventional substrates such as cordierite and SiC.

In one embodiment, the gross wall volume of the catalyst substrate is about 0.5 to about 0.1 in ³ / in ³ , about 0.4 to about 0.2 in ³ / in ³ , or about 0.3 in ³ / in ³ . In a preferred embodiment, the gross wall volume of the substrate is from about 0.25 to about 0.28 in ³ / in ³ , more preferably about 0.27 in ³ / in ³ , more preferably about 0.272 in ³ / in ³ .

In one embodiment, due to the low gross wall volume of the present invention, the amount of catalyst required to carry out the catalysis according to the invention is less than that of cordierite of similar size.

Porosity  And permeability

Pore properties also affect the mechanical and thermal properties of the substrate. There is a trade-off between porosity and mechanical strength: that is, for certain conventional substrates, substrates with smaller pore sizes and lower porosities are stronger than substrates with higher porosities. Thermal transmission, meaning both specific heat capacity and thermal conductivity, can be reduced with increasing porosity in certain materials (Yuuki 2003).

The first wall-flow monolith, introduced in the 1980s, had channels with a diameter of 35 μm. To maximize filtration efficiency, the filters used in the 1990s were made smaller, typically in the range of 10-15 μm. In developing new materials, filter manufacturers differentiate their target pore properties primarily by considering the catalyst system to be applied (Ogyu, K., et al., 2003, "Characterization of Thin Wall SiC-DPF", SAE 2003-01 Yuuki, K., et al., 2003, "The Effect of SiC Properties on the Performance of Catalyzed Diesel Particulate Filter (DPF)," SAE 2003-01-0383). The application can be classified as follows:

Non-catalyzed filters such as those used in fuel additive type regeneration systems: The main requirement is high soot retention capacity. Certain conventional filters have pores in the range of 10-20 μm and porosity of about 40-45%.

Catalytic filters, such as those in passively regenerated systems, allow for coating with progressively more complex catalyst systems (often as opposed to simple catalysts used in the 1990s with very little or no washcoat material). It requires more porosity and possibly larger pore size. The substrate should be coated with a catalyst / washcoat system at about 50 g / dm ³ load and then have an acceptable low pressure loss. Certain prior art filters have a porosity in the range of about 45-55%. Additional heaters may be applied.

Filter / NO _x adsorption devices, such as DPNR systems or CRT (Continuous Regeneration Traps) RHK combine NO _x storage / reduction systems and require high washcoat loads, possibly over 100 g / dm ³ . Certain prior art substrates have a porosity of about 60% (65% porosity substrates have been reported) and mechanical strength is a major constraint in increasing porosity (Ichikawa, S., et al., 2003, "Material Development of High Porous SiC for Catalyzed Diesel Particulate Filters, "SAE 2003-01-0380).

Another property of certain embodiments of catalysts or filtration substrates according to the invention is high porosity. In one embodiment, the porosity of the substrate of the present invention is about 60%, 70%, 80% or 90%. In another embodiment, the substrate has a porosity of about 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% (expressed as a percentage of pore space relative to the solid substrate). value).

In one embodiment, the porosity of an embodiment of the invention is about 97.26%. In comparison, cordierite is about 18 to 42%. In this embodiment, the material of the present invention has only about 2.74% of the material blocking the flow of exhaust gas. The fine web of this material actively captures the particles and incinerates the particles very effectively. By trapping particles in the deep filtration as well as trapping along the channel wall, PM accumulation does not occur even if the regeneration time is longer than the PM accumulation time. High porosity means that the interaction between the contaminant and the surface of the catalyzed or noncatalytic substrate is better and more effective. At the same time, gas flow accumulation can be released laterally as well as along the intended gas flow direction.

22A and 22B, exemplary substrates 2200 and 2205 of the present invention are shown. Substrates 2200 and 2205 are about 97% porous. Compared with the samples of cordierite in FIGS. 2A and 2B and silicon carbide in FIG. 3, shown at the same scale, the substrates 2200 and 2205 are more porous and have lower density. In FIG. 22B, particulate matter PM-10 2210 and PM-2.5 2225 are shown in proportion. Particulate matter PM-10 2210 and PM-2.5 2225 can easily penetrate the filter of substrate 2205 as compared to the cordieride sample 205 illustrated in FIG. 2B. In addition, compared with the silicon carbide 300 of FIG. 3, the density of the silicon carbide is about 30 to 50 times the density of the substrates 2200 and 2205.

High porosity in one embodiment of the present invention provides high surface area and low back pressure. As a result, the present invention is more efficient in NO _x reduction, oxidation of hydrocarbons and CO and capture of particulate matter.

Pore properties, including volume percent porosity, size distribution, structure, and interconnectivity, determine the monolithic ability for the filter particles. In addition, when gas molecules can diffuse into the porous substrate, the probability of catalytic reaction is significantly increased. Along with cellular geometry, porosity properties also affect the hydraulic resistance of the monolith to flow and pressure drop. Some properties desirable for high filtration efficiency (eg low porosity and small pore size) are opposed to those required for low pressure drop. Preferred for both low pressure drop and high efficiency are other properties such as good pore interconnectivity and the absence of closed "dead end" pores. In another embodiment, the substrate of the present invention provides both high filtration efficiency and low pressure drop.

Emissivity and Thermal Conductivity

Another property of substrates used in catalytic converters and particle filters is emissivity. Emissivity is the tendency to release heat, the relative ease of release, ie the rate at which release occurs for heat from the surface of the heating body.

For an ideal substrate, (1) the fastest temperature rises with high conversion efficiency; (2) the safest temperatures from thermal hazards (eg, due to thermal shock or hot melt / crack generation of the substrate); (3) the temperature at which the minimum amount of auxiliary energy is used; And (4) temperatures that are not expensive to produce are contemplated. Temperature rises require additional energy and cost. In addition, a predetermined amount of energy source is conducted through the thermal conductivity and exits or flows out.

Emissivity is the ratio of reflectances having values between 0 and 1, with 1 being complete reflection. Various substrates used in catalytic converters and particle filters have different emissivity values. The high emissivity allows the catalyst substrate to heat up the air inside the catalytic converter or particle filter faster by minimizing heat transfer from the system to the outside. Emissivity is a measure of the heat reflectivity of a material, with a high value being preferred.

In one embodiment, the substrate of the present invention preferably has an emissivity of about 0.8 to 1.0. In another embodiment, the emissivity of the substrate of the present invention is about 0.82, 0.84, 0.86, 0.88, and 0.9. More suitable values for emissivity of substrates of the present invention include 0.81, 0.83, 0.85, 0.87, and 0.89. In another embodiment, the emissivity is about 0.9, 0.92, 0.94, 0.96, and 0.98. The reflectance of heat allows the gaseous material in the pores to heat up much faster because there is very little heat retained by the substrate itself. As a result, ignition is rapid and there is little temperature rise of the substrate outer surface.

The thermal conductivity of a material is the amount of heat passing in unit time through the unit area of the plate when the opposite side of the plate is in a unit temperature gradient (eg, a 1 degree temperature difference across a unit of thickness). . Thermal conductivity has units of energy watts per Kelvin (W / m-K) per meter of thickness. In a preferred embodiment, the substrate of the present invention has a low thermal conductivity. For example, in one embodiment, the thermal conductivity of the substrate of the present invention is less than about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. In yet another embodiment, the thermal conductivity of the substrate of the present invention is less than about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, or 0.09. In another embodiment, the thermal conductivity of a substrate of the present invention is about 0.1 to about 0.01, about 0.2 to 0.02, about 0.3 to about 0.03, about 0.4 to about 0.04, about 0.5 to about 0.05, about 0.6 to about 0.06, about 0.7 to about 0.07, about 0.8 to about 0.08, or about 0.9 to about 0.09. In yet another embodiment, the thermal conductivity of the substrate of the present invention is about 0.0604 W / m-K.

In comparison, the sample of cordierite is about 1.3 to 1.8 W / m-K. This result is that only 33 Watts are lost from the same volume of the material according to the invention when a particular embodiment, for example, assumes that the thermal energy of 1,000 Watts is lost from a given volume of cordierite material. Thus, cordierite has 30 times greater thermal conductivity than the material of the present invention.

Additionally in another embodiment, the method of preparing the substrate further comprises the step of preparing a catalyst substrate or a filtration substrate, further comprising an emissivity enhancer, the method further comprising the substrate, preferably nSiRF-C, more preferably. Preferably, applying an emissivity enhancer to the AETB, OCTB or FRCI material.

Other preferred substrates include any of the special substrates described above. In another embodiment, the catalyst substrate further comprises an emissivity enhancer and a catalyst selected from the group consisting of palladium, platinum, rhodium, derivatives and mixtures thereof. Other physical and chemical modifications described above can be applied to this embodiment. Emissivity enhancers are known in the art.

Thermal properties

Substrates with low coefficients of thermal expansion allow the substrates to withstand rapid changes in temperature without significant expansion or contraction. Also, with a suitable coefficient of thermal expansion, the substrate can expand with heat in the same proportion as the protective matting and canister surrounding it.

It is also desirable for the material of the substrate to withstand a high temperature range so as not to melt the catalytic converter or particle filter even when the temperature rises to a high value, for example during irregular fuel combustion. In addition, if the material of the substrate can withstand high temperatures, the catalytic converter or filter can be installed in a position closer to the engine.

Related properties include low thermal mass and heat capacity. Materials with low thermal mass and heat capacity make less heat energy wasted when raising the temperature of the catalyst substrate. When the catalyst substrate is heated rapidly, more heat energy coming through the exhaust gas is used to cause the ignition of the catalyst component.

Thermal conductivity is the ability of a material to conduct heat as a result of molecular motion. More specifically, thermal conductivity is also a measure of the amount of heat passing in unit time through a unit area of a plate having one unit thickness when the opposite sides of the plate have a temperature difference by unit temperature. The more heat the material conducts, the more energy is needed to overcome the heat loss and reach the required temperature. It is desirable for the material to reflect without conducting heat. Lower thermal conductivity values are preferred, so that more thermal energy is utilized in the spaces within the pores and not lost from absorption by the substrate. The chemistry of various materials determines the level of thermal conductivity. In addition, the thermal conductivity of the filter medium has a major influence on the efficiency of the exhaust emission filter, since the drop in temperature negatively affects the reactivity. Low thermal conductivity is desirable because the generated heat will be more reflected and returned to the particles and will remain in the pore space. In other words, the lower the thermal conductivity, the lower the heat loss. Lower heat loss means less energy and higher energy efficiency to achieve the desired temperature range for catalytic conversion.

Specific heat is the heat (in calories) needed to raise the temperature of 1 g of material to 1 ° C. High specific heat substrates reflect ambient heat, such as heat from an exhaust or auxiliary source, and return it into the pore space where the combustion or catalytic reduction and oxidation process requires heat. For example, under extreme conditions, such as the Arctic, it takes longer to heat the low specific heat filter and cool the hot filter, increasing the chance of external thermal damage. Low specific heat is desirable because it reaches operating temperatures faster with relatively less energy.

In one embodiment, the present disclosure has a variety of desirable thermal properties. It is preferable that heating of the air in a pore space is a material which takes place preferentially compared with heating of a base material. Preferably, the substrate of the present invention has a high melting point, and in one embodiment, has a higher melting point than conventional substrates. High melting points are desirable, in part due to the extreme temperatures at which the catalyst substrate or filtration substrate is exposed.

In a preferred embodiment, the substrate of the present invention preferably has a high melting point. In one embodiment, the melting point is higher than 1,500 ° F. In another embodiment, the melting point is higher than 2,000 degrees Fahrenheit. In yet another embodiment, the melting point is higher than 2,500 ° F. In yet another embodiment, the melting point of the substrate is from about 2,000 ° F. to about 4,000 ° F. In yet another embodiment, the melting point of the substrate is from about 3,000 ° F to about 4,000 ° F. Other suitable melting points range from about 3,000 ° F to about 3,100 ° F, about 3,100 ° F to about 3,200 ° F, about 3,200 ° F to about 3,300 ° F, about 3,300 ° F to about 3,400 ° F, about 3,400 ° F to about 3,500 ° F, about 3,500 ° F to About 3,600 ° F., about 3,600 ° F. to about 3,700 ° F., about 3,700 ° F. to about 3,800 ° F., about 3,800 ° F. to about 3,900 ° F., and about 3,900 ° F. to about 4,000 ° F. In another preferred embodiment, the substrate has a melting point of about 3,632 ° F.

In one embodiment of the invention, the substrate has a melting point of about 3,632 ° F. For example, if the vehicle is exposed to temperatures below freezing, a blast of 1,500 ° F. exhaust will not crack or break the substrate. Likewise, certain embodiments of the substrate will not cause overheating and cracking. Certain samples of cordierite have a melting point of about 1,400 ° C.

The specific heat of one embodiment of the present invention is about 640 J / kg-K (Joules per Kilogram-Kelvin). The specific heat of the sample of cordierite is about 750 J / kg-K. Cordierite has a greater specific heat, but cordierite filters have a higher mass to heat. As a result, more thermal energy is required to reach operating temperature, making cordierite less efficient.

The multiple use temperature limit is the maximum temperature at which the substrate can be used multiple times without substantially degrading. The higher the temperature at which the substrate can continue to operate without fine breakage or spalllation, the less likely the substrate will break or crack over time. This also means that the substrate is more durable over a wide temperature range. Higher multiple use temperature limits are desirable. Suitable multiple use temperature limits in certain embodiments of the catalyst substrate or filtration substrate of the present invention are about 2,000 ° C., 2,100 ° C., 2,200 ° C., 2,300 ° C., 2,400 ° C., 2,500 ° C., 2,600 ° C., 2,700 ° C., 2,800 ° C., 2,900 ° C. , 3,000 ° C, and 3,100 ° C.

The multiple use temperature limit of one embodiment of the present invention is 2,980 ° C. The sample of cordierite is about 1,400 ° C. Embodiments of the present invention can withstand twice as much temperature as cordierite until broken. In this way, the material can function in a wider exhaust environment.

The coefficient of thermal expansion is the ratio of the length (linear coefficient), area (surface) or volume increase of the object and the original length, area or volume, respectively, to a given temperature rise (usually 0 to 1 ° C.). These three coefficients are a ratio of about 1: 2: 3. When not specifically expressed, it usually refers to the coefficient of the cube. The less expansion of the substrate when heated, the less chance of leakage, fracture or damage to the filter assembly. A low coefficient of thermal expansion is desirable to maintain the dimensions even when the substrate is heated or cooled.

The coefficient of thermal expansion for one embodiment of the invention is about 2.65 × 10 ⁻⁶ W / mK. Samples of cordierite range from about 2.5 × 10 ⁻⁶ W / mK to 3.0 × 10 ⁻⁶ W / mK. The coefficient of thermal expansion of the material according to the invention is less than 10 times the coefficient of thermal expansion of cordierite.

It is preferable that the coefficient of thermal expansion of the substrate is comparable to that of any washcoat.

In one embodiment, the catalyst or filtration substrate of the present invention has increased durability against damage due to thermal or mechanical stress, as compared to certain prior art substrates such as cordierite, and has a low risk of clogging with soot and / or ash. However, when used with fuel additive regeneration, the tolerances for additive ash accumulation are greater and have good efficiency for particle number reduction.

density

When considering the substrate to be used in the catalytic converter or diesel particle filter, it is preferable to use a substrate having a low density. Low density materials reduce the weight of the substrate, thus reducing the total weight of the vehicle. In addition, low density compensates for high porosity and permeability.

Higher density means higher weight. Weight is an important factor relating to all engines in operation. The heavier the part, the more energy it takes to move it. In order to adapt such a filter to the increased volume of particles generated by the engine, it is necessary to increase the filter size, which adds vehicle weight and increases manufacturing and running costs. Therefore, low density materials are preferred. Of course, the density should not be so low that structural integrity is insufficient.

Another property of the substrate according to the invention is the density. The density of the substrate is lower than conventional substrates used as certain conventional filter and filtration and catalyst substrates. Density is the ratio of the mass to the volume of a portion of the material. Higher density requires more energy to reach operating temperature. In other words, heating more dense materials requires more energy than less dense materials. Higher density directly leads to greater weight for the set volume. The weight is disadvantageous for the fuel economy and performance of the vehicle, as the engine must be operated harder to move heavy devices. Increased density also means that more heat is needed to obtain the proper temperature for the catalytic activity or "ignition" to occur. The density of some materials currently used as substrates or filters is above optimum. For example, the density of the cordierite sample is about 2.0 to 2.1 g / cm 3. Thus, there is a need for substrates and filters with lower densities. The density of the substrate of the present invention is lower than that of cordierite.

In one embodiment, the catalyst substrate of the present invention preferably has a low density. The density of the substrate according to the invention may range from about 2 to about 50 lb / ft ³ . In a preferred embodiment, the density of the substrate is about 5 to about 30 lb / ft ³ , more preferably about 8 to 16 lb / ft ³ . Another preferred embodiment includes a catalyst substrate having a density of about 8, 9, 10, 11, 12, 13, 14, 15, and 16 lb / ft ³ . It is desirable to provide structural integrity while having a low density.

In one embodiment, the substrate of the present invention has a density of about 8 lb / ft ³ and 22 lb / ft ³ , preferably about 8-22 lb / ft ³ . In yet another embodiment, the substrate comprises AETB-8 or AETB-16 having a density of about 8 lb / ft ³ and about 16 lb / ft ³ , respectively. Other suitable densities include densities selected from 9, 10, 11, 12, 13, 14, 15, and 16 lb / ft ³ .

In yet another embodiment, the density of the substrate is about 0.10 to 0.25 g / cm 3.

Structural integrity

Structural integrity of the base material is an important feature to consider. Structural integrity refers to the ability of a material to withstand vibration and mechanical stresses, namely shakes and bakes. For example, substrate strength is important to withstand exposure to various stresses, including use in packaging loads and continued engine exhaust flow, and associated engine vibrations, road impacts, and temperature gradients. High strength substrates are preferred for robust catalytic converter systems and particle filters. The strength of the substrate material can be controlled according to the shape of the intercrystall and intercrystallity, porosity, pore size distribution and flaw population. Additionally, the substrate can be strengthened by applying a chemical coating on the inside of the outside. The strength of the cell structure of the substrate can further be determined by cell properties such as cell density, channel shape and wall thickness as well as dimensions, cross-sectional symmetry. The strength of the substrate should be greater than the stress the material is exposed to during packaging and operation. If the stress is greater than the strength, the substrate will break.

The structural integrity of the material can be measured by the tensile modulus of the material. Tensile modulus is the durability of the material against rupture. In particular, the material can withstand greater longitudinal stresses without tearing apart. Tensile modulus is usually expressed in pounds per square inch, or kg per cm 3, required to cause rupture, based on unit cross-sectional area. Tensile modulus relates to whether the substrate can withstand the forces generated by the violent exhaust gas flow pressure.

In addition, the substrate must have good coatability so that the washcoat and / or catalyst coat can be applied to the substrate. Likewise, the substrate should have washcoat compatibility so that the catalyst can be well mounted to the substrate surface so that the catalyst does not displace from its position upon normal wear and tear of the system. Good coatability and washcoat compatibility also increase the long term effectiveness of the catalytic converter system. Good coatability and washcoat compatibility also increase the life of the catalyst.

Another attribute of the substrate according to the invention is the structural integrity.

The catalyst substrate according to the invention preferably has a high tensile modulus. For example, in one embodiment the substrate of the present invention has an axial strength of about 2.21 MPa. Of course, higher axial strength is suitable. Other suitable values include 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 MPa.

In addition, the structural integrity of the catalyst substrate according to the invention is such that the substrate can withstand the conditions encountered while being used in catalytic converters in commercial vehicles.

In another embodiment, the substrates of the present invention, such as nSiRF-C, preferably have high structural integrity and low density.

Reduction of contaminants

The substrate plays an important role in increasing the catalytic activity of the catalytic material coated on its surface. In addition, the substrate is used to trap particulate matter, and the trapped particulate matter is incinerated as a volatile gas.

Another advantage of the substrate according to the invention is the increase in the ability to reduce the amount of contaminants in the exhaust gas. The present invention has enhanced catalytic and filtration capabilities over certain prior art techniques.

In one embodiment, the substrate of the present invention can reduce CO emissions from exhaust gas by at least about 50%. In one embodiment, the substrate of the present invention can reduce CO emissions from exhaust gas by at least about 60%, 70%, 80%, or 90%. In yet another embodiment, the substrates of the present invention provide at least about 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, or Can be reduced by 100%.

In one embodiment, the substrate of the present invention can reduce NO _x emissions from exhaust gas by at least about 50%. In one embodiment, the substrate of the present invention can reduce NO _x emissions from exhaust gas by at least about 60%, 70%, 80%, or 90%. In another embodiment, the substrates of the present invention exhibit NO _x emissions of at least about 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, Or by 100%.

In one embodiment, the substrate of the present invention can reduce HC emissions from exhaust gas by at least about 50%. In one embodiment, the substrate of the present invention can reduce HC emissions from exhaust gas by at least about 60%, 70%, 80%, or 90%. In another embodiment, the substrate of the present invention provides HC release of at least about 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, Or by 100%.

In yet another embodiment, the present disclosure can reduce VOC emissions from exhaust gas by at least about 50%. In one embodiment, the substrate of the present invention can reduce VOC emissions from exhaust gas by at least about 60%, 70%, 80%, or 90%. In yet another embodiment, the substrates of the present invention have at least about 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, or Can be reduced by 100%.

In yet another embodiment, the present disclosure can reduce PM-10 emissions from exhaust gas by at least about 50%. In one embodiment, the substrate of the present invention can reduce PM-10 emissions from exhaust gas by at least about 60%, 70%, 80%, or 90%. In yet another embodiment, the present disclosure provides at least about 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9% PM-10 release. , Or by 100%.

In another embodiment, the present disclosure can reduce PM-2.5 emissions from exhaust gas by at least about 50%. In one embodiment, the substrate of the present invention may reduce PM-2.5 emissions from exhaust gas by at least about 60%, 70%, 80%, or 90%. In another embodiment, the present disclosure provides at least about 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9% PM-2.5 release. , Or by 100%.

Weight loss

The goal of vehicle manufacturers is to reduce the total weight of the vehicle to improve the fuel economy and engine efficiency of the vehicle. Heavy substrates add unnecessary weight to the vehicle. In addition, if the substrate is not efficient enough to reduce contaminants, two or more substrates will need to be lined up to reach the desired contaminant level. This greatly increases the total weight of the vehicle.

In addition, current catalytic converters often require the use of additional equipment that is heavy and crude. Some of these devices, such as heat shields and special matting, are used to handle the temperature of the catalytic converter. In addition, something like an oxygen sensor is needed to meet certain government regulations.

In one embodiment of the invention, the catalyst substrate or filtration substrate has reduced weight compared to conventional catalyst substrates or filtration substrates. This is due in part to the lower density of the substrate according to the invention as compared to certain conventional substrates. Otherwise, such lower weight may be due to the need for a smaller amount of catalyst or filtration substrate due to the improved filtration and catalyst functionality of some embodiments of the present invention as compared to the prior art. The low weight of catalyst or filtration substrate has several advantages. For example, low weight of the substrate may mean improved fuel efficiency in a vehicle. Lower weight will also mean easier handling and safer hand operated engine arrangements.

In a preferred embodiment, the outer surface of the substrate is not heated to the same extent as conventional catalytic converter substrates in use. In some embodiments, the need for heat shields and / or thermal insulation is reduced.

Acoustic attribute

Acoustical properties include reduced thickness, shallowness, tapering; Decrease in density, decrease in force or strength; Or attenuation of acoustic energy (sound). In one embodiment of the invention, acoustic attenuation is the ability of a substrate to attenuate or blunt acoustic energy in engine exhaust. The description of the present invention may replace or supplement the muffler assembly of the engine as described above, thus reducing exhaust noise and exhaust system costs. Higher acoustic attenuation is desirable.

In yet another embodiment, the porosity, density and size of the substrate can be varied to 'tune' the acoustic attenuation for the desired application.

In another embodiment, the acoustic attenuation of the substrate can be combined with standard metal-muffler based techniques to blunt and / or 'tune' the sound present in the exhaust system.

Form of flow

Flow - Thru (flow-through)

In one aspect, the substrate is structured for flow-through use. Flow-through structures are known in the art. In one embodiment, the channels (or pores) are essentially aligned parallel to each other over the entire length of the substrate. The gas flow enters the substrate at one end and flows through the channel through the entire length of the substrate to the outlet on the other.

Any number of flow-through structures are useful and suitable for the catalyst substrate of the present invention. Flow-through structures known in the art can be applied to the catalyst substrate of the present invention.

In one embodiment, the flow-through structure includes a plurality of substantially parallel channels extending through the length of the substrate.

In another embodiment, the walls of the channels are not parallel to the side or surface of the substrate.

Wall-flow

Another embodiment of the present invention is the catalyst substrate or filtration substrate of the present invention constructed in a wall-flow structure. It has been surprisingly found that the catalyst substrate comprising the nSiRF-C of the present invention can be constructed in a wall flow structure.

In another aspect of the invention, the substrate has a wall-flow structure. For example, substrates are used in wall-flow catalytic converters or wall-flow particle filters. The wall-flow structure can take on any of a variety of physical arrangements. Substrates with wall-flow structures can have one or more of the aforementioned attributes. In addition, the substrate with a wall-flow structure may further comprise one or more of the following: catalyst, washcoat, oxygen storage oxide and emissivity enhancer. In addition, the substrate configured of the wall-flow structure can be further modified, augmented or altered as described above.

In one embodiment, the channel wall thickness is any value described above. Preferred channel wall thicknesses are from about 2 mils to about 6 mils. In another embodiment, the channel wall thickness ranges from about 10 mils to about 17 mils. Other suitable values include 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 and 20 mils.

In another embodiment of a wall-flow substrate, the cell density of the substrate is about 400 cpsi (cells per square inch) when the wall thickness is about 6 mils, or about 900 cpsi when the wall thickness is about 2 mils. Additional embodiments include those with a cpsi of about 50, 100, 150, 200, 250, 300, or 350.

Ceramic wall-flow monoliths derived from flow-through cell supports used for catalytic converters have become the most common form of diesel filter substrates. Such monoliths are distinguished by high surface area and high filtration efficiency per unit volume, among other diesel filter designs. Monolith diesel filters are typically composed of many small parallel channels that are square in cross section and run axially through the part. Diesel filter monoliths are obtained from flow-through monoliths by plugging channels. Adjacent channels are alternately plugged at each end to force the diesel aerosol through the porous substrate wall, which acts as a mechanical filter. To reflect this flow pattern, the substrate is referred to as a wall-flow monolith. Wall-flow monoliths are most commonly available in cylindrical shapes, but elliptical cross-section parts are also available for space-constrained applications.

In wall-flow filters the walls have a distribution of micropores that must be controlled in the manufacturing process. The filtration mechanism in the monolith wall-flow filter is a combination of cake filtration and deep filtration. Deep filtration is a potent mechanism for clean filters when particles are deposited inside the pores. As the soot load increases, the particle layer forms on the inlet channel walls, making cake filtration the predominant mechanism. Certain conventional monolith filters have a filtration efficiency of about 70% of the total particulate matter (TPM). Higher efficiencies can be observed for solid PM fractions such as carbon and metal ash in the elemental state.

According to a particular embodiment of the invention, it is desirable to have a porous material so that more gas can easily pass through the pores and interact with the catalyst deposited on the core of the fibrous composite. In addition, having a porous wall allows for high depth filtration, which may be a desired attribute in one embodiment.

The substrate of the present invention, which is of a wall-flow structure, is in much more direct contact with the exhaust gases. The pore properties of the material (size, percent porosity, pore connectivity, open-to-closed porosity, etc.) affect the physical behavior between the gas and the filter material and affect properties such as filtration efficiency and pressure drop. The durability of the substrate also depends on the resistance of the material to chemical attack by the exhaust gas component. In particular, the material needs to be resistant to corrosion by metal ash, which may be part of diesel particles. Durability against sulfuric acid corrosion is also required, especially when filters are used with fuels with high sulfur content. In addition, since a large amount of heat may be released during filter regeneration, the filter material should exhibit excellent thermal properties in terms of durability to both high temperatures and high temperature gradients. Insufficient temperature tolerances can lead to melting of the material, and lack of thermal shock resistance can lead to cracking. Other potential problems include microcracks and fractures. In a particular embodiment, the filtration substrate and catalyst substrate of the present invention solve one or more of these problems.

Important considerations for designing the exact shape of the wall-flow monolith include the following parameters: cell density, repetition distance (even distribution of pressure drop across the wall flow filter), wall thickness, open front, filtration Specific filtration area, and mechanical integrity factor.

In a particular embodiment of the invention, half of the channels of the wall flow structure are blocked. In another configuration, the substrate of the present invention has a wall flow structure in which the blocking wall of the channel is located at the beginning or end of the channel. In another configuration, the blocking wall is located at the center of the channel or else at any point between the beginning and the end of the channel.

Additionally, it may include any percentage of the channels in the wall flow structure, such as 10%, 25%, 50%, 75%, 90%, 95%, and the like.

Channel and channel opening

In one embodiment, the catalyst or filtration substrate does not have a plurality of channels extending through the length of the substrate. In one embodiment, given the porosity and permeability, the catalyst or filtration substrate does not need to have a channel installed in the substrate to serve the intended use, for example a catalytic converter. All potential back pressures are relaxed by porosity and permeability simply by placing the effluent in the path of the catalyst substrate. When using membrane shapes without channels, a preferred use is for use in low flow-rate environments to reduce the likelihood of substrate failure structurally. Thin membrane shapes are preferably used in "low flow" environments, such as in a fireplace or possibly a power plant. Here, the flow rate is low and in some cases constant (power plant). Of course, such a configuration is understood to be suitable for use in other applications, including vehicle and stationary engines. In another embodiment, the catalyst or filtration substrate of the present invention has a plurality of channels extending longitudinally through at least a portion of the substrate in one embodiment. The plurality of channels allow a fluid medium, such as a gas or liquid, to flow through the substrate. The plurality of channels extend from the front to the back. Other channels may extend from the rear to the front.

The channel may extend through the full length of the substrate. In such an embodiment, the channel will have a first channel opening on the front side of the substrate and a second channel opening on the back side. Alternatively, the channel extends through a portion of the substrate. In one embodiment, the channel extends through about 99%, 97%, 95%, 90%, 85%, 80%, 70%, 60%, or 50% of the length of the substrate.

The channel holes, or channel openings, of the substrate may be formed in any number of shapes. For example, the channel openings can be circular, triangular, square, hexagonal, or the like. In a preferred embodiment, the channel openings are triangular, square or hexagonal.

In one embodiment, the channel openings are formed such that the thickness of the substrate material between adjacent channels is substantially uniform throughout the substrate. The variation in wall thickness may be about 1% to about 50% in one embodiment.

In another embodiment, the channels are arranged such that the walls of adjacent channels are parallel to each other. For example, triangular, square or hexagonal channels may be formed such that the walls of adjacent channels are parallel to each other.

The diameter or cross-sectional distance of the channels of the substrate according to the invention can vary. In one embodiment, the channel has a diameter or cross-sectional distance of about 5 cm to about 100 nm. In one embodiment, the channel has a diameter of about 100 nm. Other suitable values select from about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 mil Distance or diameter to be included.

The channel may vary in size along its length. For example, the channel may be about 0.04 inches crosswise at its opening, but may gradually decrease in size as it approaches either the end wall or the opening at the channel point or end of the channel. In one embodiment, the channel is a square opening with about 10 mils on one side in the front. The channel extends through the length of the substrate and has a second opening on the back side. The rear channel opening has a square shape with one side about 4 mils. The channel gradually decreases along the length from the front to the back. Other similar shapes are of course conceivable.

The size of the channel opening can also vary. For example, in one embodiment, the diameter or cross section distance is from about 1 mil to about 100 mil. Other ranges suitable for the size of the channel openings include, but are not limited to, about 1 to about 500 mils, about 1 to about 100 mils, about 1 to about 10 mils. Other suitable sizes are selected from about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 mil Or diameter. The substrate of the present invention may also have channels of various sizes. That is, some channels in one embodiment of the substrate have a plurality of first channels having a first diameter or cross-sectional distance and a plurality of second channels having a second diameter or cross-sectional distance. For example, the present disclosure includes, in one embodiment, one or more channels having a cross sectional distance of about 5 mils, and further includes one or more channels having a cross sectional distance of about 7 mils. It is understood that other variations of these embodiments are included in the scope of the present invention.

In other embodiments, the channel diameter or cross-sectional distance may be about 5 cm, 4 cm, 3 cm, 2 cm, or 1 cm. For large exhaust systems that can have exhaust pipes of 1 foot or more in diameter, substrates with channels of larger diameter or cross-sectional distance are preferred.

The thickness of the channel walls can also vary. For example, the thickness of the channel wall may be less than 1 mil. Other suitable values for channel wall thickness include 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 mils. Other embodiments include a catalyst substrate or filtration substrate with 2,000 channels per square inch.

In one embodiment, the substrate of the present invention consists of 600 cpsi and a wall thickness of 6 mils. The cell density of the sample substrate according to the invention is compared with two samples of cordierite. The first and second cordierite samples were 100 cpsi with a wall thickness of 17 mils and 200 cpsi with a wall thickness of 12 mils, respectively. In contrast, the substrate of the present invention has 600 cpsi with a wall thickness of 6 mils in this example.

In one embodiment, the substrate is perforated with a channel of 0.04 in diameter at 0.06 in intervals across the filter. These channels are smaller than conventional cordierite wall flow channels. As a result, a greatly increased surface area is obtained compared to cordierite without considering the surface area present in many pore spaces of the base material. The channel is preferably a "blind" channel. Exhaust emissions do not enter and exit the channel without reacting with the catalyst and are forced through the channel.

Yet another embodiment is to provide a catalyst or filtration substrate comprising a plurality of channels having a pyramid shape. The pyramid shape of the channel is intended to include the substrate of the present invention, such as sSiRF-C, and in addition, to be applied to any number of substrate materials. The pyramidal channels can be configured in a flow through structure, with one on the front of the substrate and one on the back of the substrate, for example, so that each channel has two channel openings. Otherwise, the pyramidal channels can be configured, for example, in a wall flow structure such that each channel has only one opening. In this embodiment, the openings of certain channels are located at the front and the openings of the other channels are located at the back. Preferably, the channel is positioned such that adjacent channels have a shape facing each other with respect to the position of the channel opening. In addition, in one embodiment of the pyramidal wall flow structure, the channel ends at the unperforated portion of the substrate. If the unperforated part is flat, the longitudinal cross-sectional area of the channel appears trapezoidal. If the non-perforated part is pointed, the longitudinal cross section of the channel appears as a triangle.

Shape and form

Catalyst substrates and filtration substrates include any number of suitable, ever known formations. The substrates are three dimensional and generally have a front (or region or face) and a back (or region or face) connected to one or more sides by the body of the substrate. The front and rear surfaces may be any number of shapes as described above. The front face refers to the surface through which fluid enters the substrate. The backside refers to the surface on which fluid flows out of the substrate. Generally the surface is flat, but may not be flat in one embodiment.

In one embodiment, the substrate has a cylindrical shape. Cylinders made of substrates are used, for example, to catalyze NO in exhaust gases.

Suitable length and width or diameter values for the substrate according to the invention are arbitrary. Suitable lengths include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 in. Of course, longer lengths may be desirable in diesel applications and for stationary engines such as pharmaceutical and chemical plants, manufacturing plants, power plants, and the like. In another aspect, the shape of the substrate can be described with reference to the front surface shape. The substrate of the present invention may be made so that the front surface has one of several physical shapes. The front face shape is not particularly limited, but may be any number of shapes including round, triangular, square, oval, trapezoidal, rectangular, and the like. In three dimensions, the substrate may be in the form of a cylindrical or substantially flat disk. Commercially available substrates generally exist in one of these three designs. The substrate may have right angled corners or rounded corners. Rounded corners are preferred for the front surface shape of the substrate. Thus, in one embodiment, the substrate of the present invention has a square shape with rounded corners. In yet another embodiment, the substrate has a rectangular front shape with rounded corners. In yet another embodiment, the substrate has a trapezoidal front shape with rounded corners.

Exemplary dimensions for the catalyst substrate according to the present invention, although not particularly limited, have a circular cross section and are about 3.66 in, about 4.00 in, about 4.16 in, about 4.66 in, about 5.20 in, about 5.60 in, or about Includes a diameter of 6.00 in. In another embodiment, the catalyst substrate has a multi-cylindrical cylinder shape with a cross-sectional dimension (uniaxial and long axis, respectively) of about 3.15 × 4.75 in, about 3.54 × 5.16 in, or about 4.00 × 6.00 in.

In yet another embodiment, the catalyst substrate has a shape and size suitable for use in a head-cat. In general, the head-cat will be smaller in size than conventional catalytic converters found in the engine's exhaust system. Determination of the appropriate size and shape of the head-cat is within the ability of those skilled in the art. The size and shape of the head-cat is based on the specific head and engine the head-cat is used for. For example, a conventional cordierite circular substrate having a diameter of about 4½ inches has a front surface area of about 28.27 in ² . Ford 4.6 V-8, for example, has two pre-cats with descriptions of this dimension. These two conventional pre-cats can be replaced with eight head-cats including nSiRF-C substrates with diameters of about 1.13 in.

Alternatively, cylinders are used to catalyze the oxidation of carbon monoxide and unburned hydrocarbons in the exhaust gas. The length of the cylinder may be greater than, equal to, or less than the diameter of the cylinder.

Filter substrates and catalyst substrates of different shapes and configurations may be used depending on the particular application, such as stationary engines, on-road vehicles, off-road vehicles, and the like.

In another embodiment, the catalyst substrate is shaped to replace a commercially available substrate of a commercially available catalytic converter. In this embodiment, the substrates of the present invention have substantially the same shape and dimensions as the substrates of available catalytic converters using different substrates. For example, many catalytic converters in use today accept substrates made of cordierite. The shape and size of the cordierite of the catalytic converter are known or can be determined by analysis. Then, as described below, the substrate of the present invention is produced by processing or molding so that the shape and size of the substrate of the present invention are substantially the same as a known cordierite substrate.

Membrane  Configuration

As an alternative, the substrate has a membrane configuration. In such a shape, the length of the substrate is substantially smaller than the width or diameter of the substrate. The longer travel distance through which the exhaust gas passes through the substrate corresponds to the accumulation of back pressure in certain conventional catalytic converters and particle filters. In thinner substrates according to certain embodiments of the invention, the back pressure will be minimized and the exhaust gases will be moved through the filter system with increased filtration capacity with less effort. This reduction in back pressure results in more efficient engine drive, which means better fuel economy and greater power.

In one embodiment of the present invention, the substrate has a surface area of 400 times the surface area of a conventional cordierite filter having a diameter of 2 inches, a thickness of 1/16 inches, a diameter of 4 inches, and a length of 6 inches. Since the size of the substrate itself has been reduced, the size of the canister can also be reduced, resulting in only a small bulb in the exhaust line. Alternatively, the substrate can be installed in an exhaust manifold.

In another embodiment, the substrate is in the form of a membrane. In this case, the membrane comprising the substrate material as described above has any number of shapes as described above, and the length of the substrate is substantially smaller than the width or diameter. Dimensions can be described, for example, in width to length, or ratio of diameter to length. Suitable ratios of diameter to width include, but are not particularly limited to, about 20: 1, 19: 1, 18: 1, 17: 1, 16: 1, 15: 1, 14: 1, 13: 1, 12: 1 , 11: 1, 10: 1, 9: 1, 8: 1, 7: 1, 6: 1, and 5: 1.

In addition, substrates having a membrane configuration may be laminated together with one or more substrate types. In the membrane configuration, a predetermined number of catalyst or filtration substrates having a membrane configuration can be stacked on each other. For example, a substrate file having a predetermined length, such as about 1 in, by stacking a plurality of, for example, five catalyst or filtration substrates having a cylinder (or disk) shape of about 1 in diameter and about 0.2 in long. It can form a pile.

In the case of a membrane configuration, in one embodiment, the catalyst substrate is not formed with a plurality of channels extending through the substrate. Because of the short distance the gas has to travel through, partly high porosity, and low pressure drop caused by the present invention, it is possible to form a substrate file comprising a plurality of catalyst substrates having a membrane configuration.

In addition, the laminated membrane configuration also includes a laminated membrane configuration in which the individual substrates are not perpendicular to the bottom of the catalytic converter or particle filter. In this embodiment, the substrate may be processed or molded such that the angle between the side (lateral surface) and the side (front or back) of the substrate is about 90 degrees or less, or 90 degrees or more, such as 80 degrees, 70 degrees, or the like. Can be.

Addition of pre-sintering catalyst

In another embodiment, the aforementioned catalyst substrate further comprises a catalyst, which is added to the substrate material prior to the sintering process. In this case, the catalyst is generally added to the slurry before the green billet is produced. In another embodiment, the catalyst is added to the fibers in a mixer. Alternatively, when the catalyst is in liquid form, it is added to the slurry in one embodiment. The substrate may be formed from a slurry comprising one or more catalysts. In one embodiment, the catalyst adheres to the fibers of the substrate when sintered. In another embodiment, the catalyst is located in the pores of the channel wall as opposed to being primarily attached to the surface of the channel wall.

Mention Zoning ( zonation )

In yet another embodiment, the aforementioned catalyst substrate is made so that different zones in the substrate have different properties. In other words, one or more of the physical properties or attributes of the catalyst substrate are not uniform or the same throughout the substrate.

For example, in one embodiment, different zones or regions of the substrate have different densities, different catalysts, different catalyst mixtures, different channel shapes, different porosities, different permeabilities, and / or different thermal properties. For example, in one embodiment, the catalyst substrate of the present invention comprises an nSiRF-C complex and first and second catalysts, the first catalyst being applied to the first zone of the substrate, and the second catalyst being the Applied to the second zone of the substrate. In yet another embodiment, the substrate has a different degree of structural integrity through the body of the substrate. For example, as described above, a densification coating may be added to the surface of the substrate to increase surface hardness that mitigates possible damage.

Washcoat

Another aspect of the invention is to provide a catalyst or filtration substrate as described above further comprising a washcoat. In another embodiment, the catalyst substrate further comprises a catalyst washcoat, such as a washcoat comprising a catalyst, in addition to the washcoat. Alternatively, in another embodiment, the washcoat material has catalytic activity.

Suitable washcoats include silica, titania, unimpregnated zirconia, zirconia impregnated with rare earth metal oxides, and combinations thereof. Other suitable washcoats are described, for example, in US Pat. No. 6,682,706; No. 6,667,012; 4,529,718; 4,529,718; 4,722,920; 4,722,920; 5,795,456; 5,795,456; And 5,856,263, which are incorporated by reference in their entirety.

In general, the washcoat can be applied from an aqueous slurry, in one embodiment. Alumina powder and / or other washcoat oxides are ground to the required particle size. The particle size distribution of the washcoat powder affects the mechanical strength and adhesion of the finished washcoat to the substrate and the rheological properties of the slurry during the washcoat application process. Alumina, a very high hardness material, is ground in one embodiment using an air-jet or ball mill.

In the next step, the material is dispersed in acidified water in a tank equipped with a high shear mixer. The solids content in the slurry is typically 30-50%. After prolonged mixing, the alumina suspension becomes a stable colloidal system.

The amount of washcoat deposited on the substrate depends on the rheological properties (viscosity) of the slurry and can be controlled thereby. Aluminum oxide slurries are non-newtonian fluids whose viscosity varies from time to time and the mechanical energy (shear rate) supplied to the system. At any constant shear rate, the viscosity of the slurry is a function of the pH of the slurry. In one embodiment, the viscosity can be controlled by pH adjustment. However, precise viscosity control will be the most difficult task in wash coating processes due to the non-Newtonian nature of alumina systems.

The washcoat slurry may be applied to the substrate using any known methods and procedures, including immersion or pouring of the part, and / or in a special coating machine. Excess slurry is removed from the channel by compressed air. The substrate can then be dried and calcined to bond the washcoat to the monolith wall.

In one embodiment, the washcoat can be applied in one, two or three layers. Each layer is dried and calcined before treatment of the next layer. There are several reasons for applying a multilayer washcoat: (1) the catalyst design may require different chemical formulations for each layer, and (2) the constraints of the coating / processing equipment, eg For example, it cannot handle very viscous slurries that require a thick washcoat to be applied in a one-pass operation.

Typical thicknesses of the washcoat layer are 20-40 μm, but values outside the above ranges may also be used in the present invention. This figure corresponds, for example, to a washcoat load of about 100 g / L on a 200 cpsi substrate, up to a washcoat load of about 200 g / L on a 400 cpsi substrate. The specific surface area of the catalyst washcoat material is 100-200 m 2 / g in one embodiment. Of course, other values may be used in the present invention.

Precious metals and other catalysts in the composite catalyst system can react with each other, with the washcoat component, or with the support material, and produce unwanted catalytically inert compounds. If such reactions occur in a given catalyst system, such reactions are difficult to prevent in conventional washcoat techniques. Since the catalytic metal is impregnated into the finished washcoat layer, contact between the reaction components is inevitable.

Separate washcoat techniques have been developed to physically separate the precious metal by immobilizing the precious metal on a particular base metal oxide of the washcoat before the washcoat is applied to the substrate. By using washcoat layers containing different oxides and / or precious metals, the components of the catalyst system can be separated. Additional advantages of this technique include control of the precious metal / nonmetal ratio and improved precious metal dispersion. Such techniques can be applied to the present invention. Thus, in a preferred embodiment, the present invention seeks to provide a catalyst substrate comprising nSiRF-C, two or more catalytic metals physically separated and a washcoat.

Separated Washcoat Overview: Separated washcoats were first applied to three-way catalysts in automobiles. Examples of such catalysts are three-metal systems comprising platinum, palladium and rhodium. The first layer of the catalyst consists of Pd / Al ₂ O ₃ . The second (surface) layer consists of Rh / Pt / Ce-Zr. This design prevents the formation of a palladium-rhodium alloy that could otherwise lead to catalyst deactivation.

Aluminum oxide, ie alumina, is the base material for the emission control catalyst washcoat. A high surface area gamma crystalline structure (γ-Al ₂ O ₃ ) is used for the catalyst application, which is characterized by high purity. Certain elements present in Al ₂ O ₃ can have both negative and positive effects on thermal stability. A small amount of Na ₂ O present in Al ₂ O ₃ acts as a flux to enhance the sintering of the alumina. In contrast, some metal oxides, including La ₂ O ₃ , SiO ₂ , BaO and CeO ₂ , have a stabilizing effect on the alumina surface area and thus reduce the sintering rate. Stabilized alumina is commercially available.

In another embodiment, cerium dioxide, ie ceria, is a component of the catalyst washcoat that is added in an amount of, for example, 25% or less. In another embodiment, ceria is added in an amount of about 5%, 10%, 15%, 20%, and 25%. One of the functions of ceria in the three-way catalyst has an oxygen storage function, it is possible by the rotation between the Ce ^{4 +} and Ce ^{3 +.} Other effects attributable to ceria include stabilization of alumina, promotion of steam reforming reactions, promotion of noble metal dispersion, and promotion of noble metal reduction.

Certain diesel oxidative catalyst formulations involve high loads of ceria. The function of ceria is catalytic catalytic oxidation / cracking of soluble organic fractions in diesel particles.

For example, by calcining cerium compounds, cerium oxides with high surface areas can be produced. The CET surface area of ceria can be as high as 270 m 2 / g. In other embodiments, for example, three-way catalysts, ceria with a surface area of about 150 m 2 / g is used. Other high temperature stabilized species that can withstand 900 to 1,000 ° C. have a surface area of about 6 to 60 m 2 / g and are suitable for use in the present invention.

The catalyst substrate or filtration substrate of the present invention further comprises zirconium oxide in another embodiment. In certain embodiments, zirconium oxide increases the thermal stability of the substrate.

Titanium dioxide is used with some diesel catalysts as inert, non-sulfating carriers. Two important crystal structures of titanium dioxide are anatase and rutile. Anatase forms are important forms for catalyst applications. It has the highest surface area of 50-120 m 2 / g and is thermally stable up to 500 ° C. Rutile structures have a low surface area of less than 10 m 2 / g. The conversion of anatase to rutile occurs at about 550 ° C., resulting in catalyst deactivation. In another embodiment of the invention, the catalyst substrate comprises sSiRF-C, preferably AETB or OCTB, a catalyst and titanium dioxide.

Zirconium oxide can be used as a heat stabilizer and accelerator of ceria in a three-way catalyst of automobiles, and also as a non-sulphurized component of diesel oxidative catalyst washcoats. Zirconium oxide has a BET surface area of 100 to 150 m 2 / g and rapidly loses surface area at 500 to 700 ° C. Better thermal stability can be obtained by using a wide range of dopants including La, Si, Ce and Y.

Zeolites are synthetic or naturally occurring alumina-silicate compounds with clearly partitioned crystalline structures and pore sizes. Zeolite pores typically range in size from 3 to 8 mm 3 and fall in the molecular size range. None of the molecules with a larger cross-sectional area can enter the channels of the zeolite cage. For this reason, zeolites are often called molecular sieves. Zeolites are characterized by high specific surface areas. For example, ZSM-5 zeolite has a surface area of about 400 m 2 / g. Zeolite mordenite has a surface area of about 400-500 m 2 / g. Most zeolites are thermally stable up to 500 ° C.

Zeolites used in some catalytic applications are ion exchanged with metal cations. The acidic form (HZ) of the zeolite is first treated with an aqueous solution containing NH ^{4 +} (NH ₄ NO ₃ ) to form an ammonium exchange zeolite (NH ^{4 +} Z). It is then treated with a salt solution containing a catalytic cation to form a metal exchange zeolite (MZ).

Zeolites are excellent adsorbents due to their reproducibility and clearly partitioned pore structure. Zeolites have been used as adsorbents in many applications, including drying, purification and separation. Synthetic zeolites are also used as catalysts in petrochemical processing.

Recently, zeolites have been used gradually for diesel emission control as catalysts (SCR, lean NO _x catalysts) and adsorbents (hydrocarbon traps in diesel oxidative catalysts).

Additional embodiments of the present invention are understood to include any of the specific description embodiments described above and further include any specific washcoat embodiments.

Oxygen-storage oxide

In another embodiment, the catalyst substrate or filtration substrate of the present invention further comprises an oxygen-storing oxide. Oxygen-storing oxides such as CeO _{2 have the} ability to store oxygen (hereinafter referred to as “OSC”), that is, to trap gaseous oxygen and release the trapped oxygen. More specifically, CeO ₂ is added to control the oxygen concentration in the gas atmosphere, so that excess oxygen in the gas atmosphere is referred to as an oxygen rich state (ie, fuel lean state, simply “lean state”) in the crystalline structure of CeO ₂ . Confined to assist the catalytic converter in reducing NO _x to N ₂ , while confined oxygen is referred to as CO rich and / or HC rich (ie, fuel rich, simply “rich”). By assisting the catalytic converter in oxidizing CO and HC into CO ₂ and H ₂ O. Thus, the catalytic activity of the catalyst substrate is enhanced by the addition of CeO ₂ . Other oxygen storage oxides include Pr ₆ O ₁₁ as disclosed in US Pat. No. 6,576,200. Another embodiment includes any of the special substrates described above and further includes an oxygen storage oxide, such as, for example, CeO ₂ .

In the presence of certain metal catalysts, especially platinum, sulfur present in fuels such as diesel fuel is converted to SO _x , which can then produce environmentally harmful sulfur compounds such as sulfuric acid fume in the exhaust gas. Most sulfates are typically formed on platinum catalysts at relatively high exhaust temperatures of about 350-450 ° C. While there is an urgent need to remove sulfur from gasoline and diesel fuel formulations, meanwhile, catalyst formulations have been attempted to reduce the problem to the extent possible.

As an exemplary platinum catalyst, the catalyst developed by Engelhard consists of Pt / Rh 5 to 150 g / ft ³ and MgO 30 to 1500 g / ft ³ in a 5: 1 ratio (US Pat. No. 5,100,632 to Engelhard Corporation). . The catalyst can be impregnated onto the substrate from an aqueous solution. The catalyst coated filter is preferably used for regeneration at an exhaust temperature of 375 to 400 ° C. The function of rhodium in the formulation is to inhibit the catalytic oxidation of SO ₂ and thus the function of the sulfate mask in the catalyst.

The catalyst substrate of the present invention can provide a solution to this problem by reducing the thermal breakdown of the catalyst in one embodiment, for example by having an improved thermal profile.

Catalyst poisoning is an important factor for catalyst deactivation. This can occur when the material present in the exhaust gas chemically inactivates the catalyst site or causes fouling of the catalyst surface. Inhibitors in the exhaust gases from internal combustion engines can be derived from lubricating oil components or fuels.

The interaction between various catalyst species or catalyst species and carrier components is another temperature-induced mode of catalyst deactivation. One example is the reaction between rhodium and CeO ₂ in a three way catalyst in an automobile. This type of problem can be reduced by physically separating the reaction components and using other carriers and special washcoat techniques known in the art.

A further advantage of the present invention is that it is possible to pump nSiRF-C in different zones to separate physically incompatible components, or otherwise utilize nSiRF-C as a membrane shape laminated with incompatible components in a separate membrane substrate. Is that there is.

Catalyst deactivation may also occur due to physical loss of the washcoat through erosion and attrition. In controlled release catalysts, the mechanism may also be important because of the high gas velocity, temperature change and differences in thermal expansion between the washcoat and the substrate material.

Catalyst cover

In one embodiment, the adsorbent catalyst is used to convert NO _x to salt, which salt may then be manually removed in the regeneration process. However, the sulfur present in the fuel can lead to the formation of insoluble SO ₄ salts, such as barium sulfate, which can form a protective coating on top of the catalyst and reduce the efficiency of the catalyst. An advantage of certain embodiments of the present invention is that there is less chance of efficiency degradation due to the coating of sulfates.

In another embodiment, the catalyst substrate or filtration substrate of the present invention further comprises a protective coating suitable for ceramic. Examples of suitable for such protective coatings are disclosed in US Pat. No. 5,296,288, which is incorporated herein by reference in its entirety. This coating is also known as a protective coating of ceramic material (PCC). Another suitable related coating is available as Emisshield ^™ coating (Wessex Incorporated, Blacksburg, Va.). Emissivity agents in Emisshield ^™ increase the emissivity of materials, especially at high temperatures. In addition, the protective coating can mitigate damage from external impact and abrasion forces. Suitable coatings are DiChiara, Jr. US Patent Nos. 5,702,761 and 5,928,775, issued to US Pat. No. 5,079,082 to Leiser et al., The contents of which are incorporated herein by reference. The coating can be used with one or more of the special filtration and catalyst substrates described above.

In one embodiment, the catalyst substrate or filtration substrate is resistant to damage by thermal shock and thermal cycling. However, certain substrates are relatively flexible and can be damaged by external impact and abrasion forces. To reduce such damage, in a preferred embodiment the catalyst or filtration substrate of the present invention further comprises one or more protective coatings on the surface, preferably on the outer surface of the substrate. Examples of suitable protective coatings are disclosed in US Pat. Nos. 5,702,761, 5,928,775 and 5,079,082, the contents of which are incorporated herein by reference. Thus, in one preferred embodiment, the present invention provides, among other properties, a substrate having higher porosity, higher permeability and sufficient hardness compared to conventional substrates. The coating can be used with one or more of the special filtration and catalyst substrates described above.

Pressure drop

The present invention also provides a substrate in which the pressure drop is improved for the catalytic converter and the particle filter. Thus, in one embodiment, the present disclosure provides a means for the user to remove and / or filter the exhaust gas without substantial accumulation of back pressure or with less backpressure than conventional catalyst and particle filters. Enable to provide

The flow of exhaust gases through conventional catalytic converters produces a significant amount of back pressure. Back pressure buildup in the catalytic converter is an important attribute for the catalytic converter. If the catalytic converter is partially or wholly closed, the exhaust system is restricted. Continued build-up of back pressure causes a significant drop in engine performance (eg horsepower and torque) and fuel economy, and can even shut down the engine after start if the blockage is severe. Conventional attempts to reduce pollutant emissions are very expensive due to the cost of refitting or manufacturing filters suitable for materials and original engines.

The substrate of the present invention, in one embodiment, has the property of causing lower or smaller pressure drops compared to conventional substrates used in catalytic converters or particle filters. The present invention, in some embodiments, provides a lower accumulation of soot in the particle filter compared to the conventional particle filter, and in some cases can reduce the frequency of filter replacement.

Special Example

The present invention also seeks to provide specific examples of the catalyst and filtration substrate described above. Specific examples include substrates comprising, consisting of, or consisting essentially of nSiRF-C and a catalyst. An additional embodiment is a filtration substrate comprising nSiRF-C and a plurality of channels.

For example, certain embodiments of the description have a plurality of the foregoing attributes. In another embodiment, the present disclosure has two, three, four, five, six, seven, eight, nine, or ten of the foregoing attributes. Special embodiments include any combination of attributes. The catalyst substrate is further illustrated by the following non-limiting special examples.

In one embodiment, a substrate of the present invention comprises an nSiRF-C composite having a porosity of about 96% to about 99%; A density of about 10 to about 14 lb / ft ³ ; A plurality of channels with wall-flow structures; And optionally a catalyst.

In one embodiment, a substrate of the present invention comprises an nSiRF-C composite comprising alumina boria silica fibers, silica fibers and alumina fibers, having a porosity of about 96% to about 99%; A density of about 10 to about 16 lb / ft ³ , preferably about 10, 11, 12, 13, 14, 15, or 16 lb / ft ³ ; A plurality of channels with wall-flow structures; And optionally a catalyst. In another embodiment, the substrate further comprises a washcoat, preferably alumina oxide or derivatives thereof.

In yet another embodiment, the substrate of the present invention includes a substrate having one or more of the following attributes: a tensile strength of about 100 to about 150 psi, preferably about 130 to about 140 psi, more preferably about 133 psi ; About 0.5 to about 0.9 BTU-ft ^* / hr ft ² ° F, preferably about 0.7 to about 0.8 BTU-ft ^* / hr ft ² ° F, more preferably about 0.770 BTU-ft ^* / hr ft ² ° F conductivity; A thermal expansion coefficient (tested at 77 ° F. to 1,000 ° F.) of about 1 to about 5 × 10 ⁻⁶ , preferably about 1 to about 3 × 10 ⁻⁶ , more preferably about 1.95 × 10 ⁻⁶ ; An average density of about 15.5 to about 17 lb / ft ³ , preferably about 16 to 16.8 lb / ft ³ , more preferably about 16.30 lb / ft ³ ; And optionally a catalyst.

In yet another embodiment, the substrate of the present invention includes a substrate having one or more of the following attributes: a tensile strength of about 50 to about 70 psi, preferably about 60 to about 65 psi, more preferably about 63 psi ; About 0.5 to about 0.9 BTU-ft ^* / hr ft ² ° F, preferably about 0.7 to about 0.8 BTU-ft ^* / hr ft ² ° F, more preferably about 0.770 BTU-ft ^* / hr ft ² ° F conductivity; A thermal expansion coefficient (tested at 77 ° F. to 1,000 ° F.) of about 1 to about 5 × 10 ⁻⁶ , preferably about 1 to about 3 × 10 ⁻⁶ , more preferably about 1.77 × 10 ⁻⁶ ; An average density of about 7 to about 9 lb / ft ³ , preferably about 8.2 to 8.6 lb / ft ³ , more preferably about 8.40 lb / ft ³ ; And optionally a catalyst.

In yet another embodiment, the substrate of the present invention includes a substrate having one or more of the following attributes: a tensile strength of about 60 to about 80 psi, preferably about 70 to about 79 psi, more preferably about 74 psi ; About 0.5 to about 0.9 BTU-ft ^* / hr ft ² ° F, preferably about 0.7 to about 0.8 BTU-ft ^* / hr ft ² ° F, more preferably about 0.765 BTU-ft ^* / hr ft ² ° F Conductivity; A coefficient of thermal expansion (tested at 77 ° F. to 1,000 ° F.) of about 1 to about 5 × 10 ⁻⁶ , preferably about 1 to about 3 × 10 ⁻⁶ , more preferably about 1.84 × 10 ⁻⁶ ; An average density of about 9 to about 11 lb / ft ³ , preferably about 9.5 to 10.5 lb / ft ³ , more preferably about 10 lb / ft ³ ; And optionally a catalyst.

Another suitable catalyst substrate of the present invention is the aforementioned nSiRF-C; And a catalyst comprising: a carrier pre-doped with copper oxide (CuO); At least one precious metal selected from the group consisting of platinum (Pt), palladium (Pd), rhodium (Rh) and rhenium (Re) as the main catalyst; And at least one metal oxide selected from the group consisting of antimony trioxide (Sb ₂ O ₃ ), bismuth trioxide (Bi ₂ O ₃ ), tin dioxide (SnO ₂ ) and mixtures thereof as a co-catalyst Wherein the at least one precious metal is doped on the surface of the pre-doped carrier and the at least one metal oxide is doped on the surface of the pre-doped carrier. Such catalysts are described in US Pat. No. 6,685,899, which is incorporated herein by reference in its entirety.

In one embodiment, the substrate is suitable for use in a catalytic converter installed inside the engine head before the exhaust manifold with respect to the flow of exhaust gas.

Additional examples of catalyst substrates include catalyst substrates comprising nSiRF-C composites with the approximate properties set forth in the table below.

Another particular example is to provide a catalyst substrate comprising nSiRF-C as described in Table 1 and a catalyst selected from the group consisting of palladium, platinum, rhodium, derivatives thereof and combinations thereof.

Preferred substrates comprising high grade nonwoven refractory fibers are 90% to 98% porous and have emissivity values ranging from 0.8 to 1.0.

In one embodiment, the filtration substrate of the present invention comprises or consists essentially of nSiRF-C, further comprising a front inlet end and an outlet end, a thin, porous and vertically extending wall; A matrix that traverses a horizontally extending wall and defines a plurality of channels extending substantially parallel to each other between the front inlet and outlet ends in a longitudinal direction; The front entrance includes a first section of cells closed in a non-checkered pattern along a portion of the length and a second section of cells closed in a checkered pattern, the non-checked pattern The first section of the cell closed in shape is smaller than the second section of the cell closed in checkered shape. Such shapes are described in more detail in US Pat. No. 6,673,414, which is incorporated herein by reference in its entirety. Up to three quarters of the cells of the first section may not be closed. Alternatively, up to one half of the cells in the first section may not be closed. Alternatively, up to one quarter of the cells in the first section may not be closed.

Furthermore, it is understood that the present invention is intended to provide embodiments that consist of or consist essentially of the limitations of the various embodiments. Thus, while one embodiment has been described, for example, as a catalyst substrate comprising nSiRF-C and a catalyst, it is understood that the present invention further encompasses a catalyst substrate composed or consisting essentially of nSiRF-C and a catalyst.

Reaction Catalysis  Method and filtration method

Another aspect of the invention is a method of catalyzing a reaction, comprising providing a catalyst substrate of the invention, and over and / or over the catalyst substrate at a temperature sufficient to catalyze the reaction. It is to provide a method of directing the flow of a fluid through the catalyst.

The catalysis process is carried out using a substrate comprising an alumina reinforced thermal barrier as described above.

In a preferred embodiment, the substrate contains a suitable catalyst.

In one embodiment, the present invention is a method of filtering exhaust gas, comprising the steps of providing a filtration substrate or catalyst substrate of the invention as described above and directing a flow of a fluid, such as a gas or a liquid, through the substrate. It is to provide a filtration method comprising the step, wherein the gas contains particulate matter.

In another embodiment, the method further comprises incinerating the filtered particulate matter. Incineration of filtered particulate matter converts most of the accumulated particulate matter into non-contaminants.

This aspect of the present invention is particularly useful for diesel engines. In another aspect, the present invention seeks to provide a filtration method utilizing a diesel particle filter.

Diesel engines (only when fuel is ignited by compression) have recently been monitored worldwide for exhaust emissions containing a large number of harmful particles in addition to toxic gases. Manufacturers' response was to apply known catalytic converter technology to diesel engines. Unfortunately, regulations on emission standards have exceeded the physical and economic limitations of conventional catalytic converters. Diesel emissions differ from gasoline emissions in that much larger amounts of particulate matter are produced. For this reason, existing techniques for capturing, burning and oxidizing exhaust emissions do not fully comply with the most stringent emission standards.

Most buses are manufactured with diesel particle traps ("DPT") with efficiency 85% or are retrofitted to such traps. DPT is very expensive, very complex, low fuel economy, and low durability. Additional regulations require 100 percent compliance by 2010, and DPT alone will not meet these regulatory requirements. The high temperature of the engine or exhaust gas can burn particulate matter in a shorter residence time. Moving the filter closer to the engine's combustion chamber, or adding an auxiliary heat source, can provide increased heat. Thus, what is needed may be (1) be installed at a very high temperature, such as in the vicinity of the combustion chamber, i. (2) can be more resistant to degradation due to vibration; (3) A filter that maintains or improves the incineration of particulate matters. The ability to achieve particulate matter incineration without catalyst will also provide significant savings on catalyst and coating costs.

If the filter traps particulate matter (eg soot), the particulate matter must be completely burned out by raising the temperature sufficiently in the presence of oxygen. Combustion of particulate matter can be achieved by utilizing the temperature of the existing exhaust and / or by providing an auxiliary heat source. The time it takes to burn particulate matter at this temperature is referred to as the required "retention time", "regeneration time", or "burnoff time". The short residence time of particles in substrate pores means that the occurrence of pore-closed accumulation is reduced, which can lead to an increase in gas flow back pressure that requires excessive energy to operate efficiently. have. Therefore, short residence times are preferred.

One example of a conventional DPT is disclosed in US Pat. No. 5,611,832 to Isuzu Ceramics Research Institute Co., Ltd., which discloses a DPT that collects particles from exhaust gas emitted from a diesel engine. The DPT filter consists of a woven inorganic fiber coated with silicon carbide ceramic and a metal wire net disposed therebetween.

Still other uses for filtration substrates or catalyst substrates include chemicals listed as 188 "toxic air contaminants" of EPA, including dust / soot, smoke, pollen, fluids, bacteria / viruses, odors, oils, volatile organic compounds, And the ability to clean or filter contaminants and impurities such as liquids, methane, ethylene, and a wide variety of other chemicals from the fluid stream.

Catalysis of reactions and / or methods of filtration of fluids will be useful in any number of industries or applications, particularly one or more of the following: aerospace industry; asbestos; Asphalt roofing and processing; Auto and light trucks (surface coating), benzene waste operations; Boat manufacturing, brick and structure applications; Manufacture of clay products; Manufacturing of cellulose products; Carboxymethyl cellulose production; Cellulose ether production, cellulose food casing manufacturing; Cellophane production; Chromium electroplating; Coke oven; Pushing, quenching and battery stacks; Combustion turbine; Degreasing organic cleaners; dry cleaning; Engine test cell / stand; Textile printing, coating and dyeing; Ferroalloy production; Flexible polyurethane foams; Assembly work; Flexible polyurethane foam production; Friction product manufacturing; Gasoline distribution (stage 1); General food; Generic MACT; Hazardous waste combustion; Hazardous organic NESHAP; Hydrochloric acid production; Industrial, commercial and laboratory boilers; Industrial cooling tower process heaters; Comprehensive steel industry; Iron castings (surface coatings); Leather finishing work; Lime manufacturing; Magnetic tape manufacturing; Nutritional yeast; Marine ship loading operations; Mercury cell chlor-alkali plants; Metal coils (surface coating); Metal cans (surface coating); Metal furniture (surface coating); Mineral wool products; Manufacturing of various coatings; Various metal parts and production; Municipal solid waste landfill; Natural gas transportation and storage; Offsite waste recovery operations; Oil and natural gas production; Organic liquid distribution (non-gasoline); Paper and other webs (surface coatings); Production of pesticide active ingredients; Petroleum refining; Pharmaceutical production; Phosphoric acid / phosphate fertilizers; Plastic parts (surface coating); Polymers and resins; Polyether polyol products; Polybutadiene rubber; Polysulfide rubber; Lenol resins; Polyethylene terephthalate; Polyvinyl chloride and copolymer production; Portland cement manufacturing; Primary aluminium production; Primary lead smelting; Primary copper; Primary magnesium tablets; Printing / publishing; Publicly owned processing operations (POTW); Pulp and paper (combustion source) MACT II; Pulp and paper mills; Reciprocating internal combustion engines; Manufacture of refractory products; Production of reinforced plastic composites; Secondary aluminum; Secondary lead smelting; Semiconductor manufacturing; Shipbuilding and ship repair; Site improvement; Solvent extraction for vehicle oil production; Steel hydrochloric acid treatment process; Taconite ironite treatment; Tetrahydrobenzaldehyde preparation; Tire manufacturing; Wet molded glass fibers; Mat production; Timber building products; Wooden furniture; And wool fiberglass manufacturing. These industries and applications often utilize stationary emission sources as defined by EPA.

Other suitable uses include filtration or catalytic processes in one or more of the following applications: automobiles (dust / soot, odors, oil filtration, VOCs, methane, other chemicals (gas, solid or liquid)); Water jet (dust / soot, odor, oil filtration, VOC, methane, other chemicals (gas, solid or liquid)); Snowmobiles (dust / soot, odors, oil filtration, VOCs, methane, other chemicals (gas, solid or liquid)); Small engines (dust / soot, odor, oil filtration, VOCs, methane, other chemicals (gas, solid or liquid)); Motorcycles (dust / soot, odor, oil filtration, VOCs, methane, other chemicals (gas, solid or liquid)); Mobile diesel engines (dust / soot, odors, VOCs, methane, other chemicals (gas, solid or liquid)); Stationary diesel engines (dust / soot, odors, VOCs, methane, other chemicals (gas, solid or liquid)); Power plants (dust / soot, odors, VOCs, methane, other chemicals (gas, solid or liquid)); Purified cow (VOC, other chemicals (gas, solid or liquid)); And chemical and pharmaceutical preparation (dust / soot, bacteria / viruses, odors, oil filtration, VOCs, methane, other chemicals (gases, solids or liquids)).

Further catalyst and / or filtration applications also include the use of the substrate according to the invention in one or more of the following fields: agriculture and forestry incineration emissions; Confectionery (dust / soot, smoke, odors, VOCs, other chemicals (gas, solid or liquid)); Biomedical fluid filtration; Beer and winemaking (smell); Cabin air (cars, submarines, aerospace, aircraft) (dust / soot, smoke, pollen, bacteria / viruses, odors, VOCs, other chemicals (gas, solid or liquid)); Clean room applications (dust / soot, smoke, pollen, bacteria / viruses, odors, oils, VOCs, methane, other chemicals); Commercial incineration emissions (odors, VOCs, other chemicals (gases, solids or liquids)); Commercial toxic organics release; Dry cleaners (VOCs, other chemicals (gases, solids or liquids)); Evaporative release (fuel evaporation management, etc.); fireplace; Flame grilling (fast food) (dust / soot, smoke, odors, VOCs, other chemicals (gas, solid or liquid)); Fitness center; General fluid filtration (drinking water treatment); Food processing and storage (smell, other chemicals (gas, solid or liquid); casting (smell); fuel cells (VOC, methane, other chemicals (gas, solid or liquid); gas masks (dust / soot, smoke, Pollen, bacteria / viruses, odors, VOCs, other chemicals (gas, solid or liquid); general VOC applications for processing / manufacturing (wood products, coatings industry, textile industry, etc.); glass / ceramic; greenhouses; household appliances- Low temperature (rechargeable appliances) (odor, oil, VOC, other chemicals (gas, solid or liquid)); home appliances-high temperature (water heaters and household heater appliances) (odor, oil, VOC, other chemicals (gas, Solid or liquid)); HVAC sanitary installations; hydrogen reforming (VOC, methane, other chemicals (gas, solid or liquid)); medical growth media; office buildings; oil / refinery transportation; other electro-magnetic insulation (electromagnetic shielding) ; Paint applications; gas stations (smell, VOC); polymer processing (smell, VOC, other chemicals (gas, Solid or liquid); recovery of precious metals / catalysts from hot gases and liquids; restaurant haze; sewage and bio waste (bacteria / viruses, odors, VOCs, methane, other chemicals (gas, solid or liquid); slaughterhouses, smokehouses ( Dust / soot, smoke); sound insulation; swimming pools; tennis courts; tunnels and parking lots (dust / soot, odor, VOC, methane, other chemicals (gas, solid or liquid); and waste incineration (dust / soot, odor, VOC) , Methane and other chemicals (gas, solid or liquid).

Process for producing catalyst or filtration substrate

In another aspect, the present invention seeks to provide a method of making any one of the foregoing substrates (for catalysts and for filtration). The present invention also seeks to provide a method for producing the substrate of the present invention. In another aspect, the present invention seeks to provide a method of making a diesel particle filter. Various methods described below can be used to prepare the substrate.

In one aspect of the invention, the catalyst substrate described above can be prepared using commercially available billets of nSiRF-C. Commercially available billets of nSiRF-C are machined to suitable shapes, shapes and sizes. The substrates of the present invention can be made by making brick-like lumps of suitable substrate materials and molding the lumps into shapes suitable for use in the present invention. Crude blocks can be easily cut or sawed into a preformed shape, then sanded and finally turned or machined into a "slug" with the desired shape. . The composition of the base material is highly resilient to chemical, thermal and vibrational impacts, but the hardness of the base material is low. Due to this low hardness, it can be machined with little or no resistance or can be worn by a tool. Although the blocks are low hardness and soft, they are durable and easy to machine, engrave or form. For example, in one embodiment, the base material has the softest term talc of 1 (Knoop hardness 1-22) and the hardest diamond 10 (Knoop hardness) as measured by Moh's hardness scale. It is usually 0.5 to 1.0 (or 1 to 22 in Knoop hardness), as compared to 8,000 to 8,500). Certain substrate materials of the prior art have a higher hardness than this. For example, silicon carbide has a Mohs' Hardness (2,000 to 2,950 in Knoop's hardness) of 9 to 10.

It requires less force compared to certain conventional substrates, such as cordierite, and the billets are molded, sanded, turned or machined, providing unlimited forming capacity of slug formation. The scope of machining is commonly used and known in the art for cylinder turning on lathes, keyhole saws, sawing formed by band saws or jig saws, or other solid materials. Any machining method. The billets can be machined to very tight tolerances with the same precision as processing metal, wood or plastic. When the billet is cast from the cylindrical mold to the desired diameter of the final shape, machining simply cuts and sands the cylindrical billet to the desired thickness. This process also reduces the loss of substrates due to excessive machining and increases the rate of preforms.

In one embodiment, as shown in FIG. 5, the front shape of the substrate is circular 510, elliptical 520, and racetrack 530. As can be easily understood, the shape need not be accurate. In three dimensions, the substrate may have the form of a cylinder or a substantially flat disk. In certain applications, designs with right angled corners are not very effective. Although easy to machine, square or angled designs have proven to be traps for rust and corrosive materials, for example road salts. Thus, in one embodiment, rounded corners are preferred for the front shape of the slug.

Billets may be molded by band saws, jigsaws, CNCs or other methods known to those skilled in the art. Billets may also be molded by hand rubbing, lathe sanding, belt sanding or orbital sanding. Particles floating in the air are preferably suctioned in a vacuum so as not to close the pores of the material. In addition, these particles can enter the bearings of the drill press, destroy and wear and mark the bearings. Ceramic dust is also very fine and can be easily inhaled by the operator.

In another embodiment, the present invention comprises the step of preparing a billet of an nSiRF-C composite, and optionally, machining the billet to form the substrate of the present invention, wherein the catalyst or filter substrate according to the present invention is prepared. To provide. If the billet is made into a shape suitable for use in one or more of the methods of the invention, the billet does not necessarily have to be machined into another shape. In this case, the billet is produced by a mold having a suitable shape, as described above. Alternatively, the billet or substrate can be machined into a suitable shape. In addition, as will be described in more detail below, a plurality of channels are machined into the substrate.

Preparation of the billet (or substrate) includes known methods of making these materials. Any known method of making suitable billets or substrates can be used. By way of example, suitable methods are disclosed in US Pat. Nos. 4,148,962 and 6,613,255, which are incorporated herein by reference in their entirety.

As a non-limiting example, in one embodiment, preparing a suitable substrate is:

Heating the plurality of refractory silica fibers, refractory alumina fibers, and refractory aluminoborosilicate fibers;

Mixing the fibers;

Washing the fibers;

Optionally, chopping the fibers to one or more lengths;

Blending or mixing the chopped fibers into a slurry;

Adjusting the viscosity of the slurry, preferably by addition of a thickener;

Adding a dispersant;

Placing the slurry in a mold;

Removing water from the slurry to form a green billet;

Removing the green billet from the mold;

Drying the green billet preferably at a temperature of about 250 ° F. to about 500 ° F .; And

Heating the green billet in an oven to about 2,000-2,500 ° F., preferably preheating and heating gradually.

As mentioned above, the billet is then optionally machined to form the substrate of the present invention.

In another embodiment, the method further comprises machining a plurality of channels in the substrate.

In another embodiment, the method further comprises adding a catalyst coating to the substrate.

In another embodiment, the mixing of the fibers is performed after washing and heating the fibers.

In another embodiment, boron nitride is used in the method of making the substrate of the present invention. BN → B + N ₂

In another embodiment, thickeners are used. Preferably, the thickeners and dispersants used in the process are substantially removed from the substrate during the heating step. For example, thickeners and dispersants may be combusted during the sintering step.

The substrate 2510 is derived from a billet made by forming a rigid shape of the binder with chopped and / or nonwoven inorganic fibers. The billet is machined or fabricated to the desired external dimensions for the substrate 2510. Next, the interior of the substrate 2510 is machined or fabricated to provide the desired surface area enhancement shape, such as a channel, washcoat or catalyst. A durable inorganic cured coating 2511 may be applied to the substrate 2510 by brushing, spraying, dipping or any other conventional application method. Additionally, substrate 2510 may include an oxidative or reducing catalyst applied by brushing, spraying, dipping or any other conventional application method.

In one embodiment, the catalyst or filtration substrate of the present invention is nSiRF-C; And 23.0-45.0 wt% silicon dioxide powder, 25.0-45.0 wt% colloidal silicon dioxide, 19.0-39.0 wt% water, and silicon tetraboride, silicon hexaboride, silicon carbide, molybdenum di One or more release agents selected from the group consisting of silicides, tungsten disilicides and zirconium diboride; The protective coating has a solids content of 45 to 55% by weight. Such coatings are disclosed in US Pat. No. 5,296,288.

The present invention utilizes a plurality of high grade nonwoven sintered inorganic refractory fibers such as those present in AETB. Other suitable materials used as nSiRF-C in the present invention include: AETB-12 (about 20% Al ₂ O ₃ , about 12% (14% B ₂ O ₃ , 72% Al ₂ O ₃ , 14% SiO ₂ ; NEXTEL ^™ fiber), and about 68% SiO ₂ ); AETB-8 (about 20% Al ₂ O ₃ , about 12% (14% B ₂ O ₃ , 72% Al ₂ O ₃ , 14% SiO ₂ ; NEXTEL ^™ fiber), and about 68% SiO ₂ ); FRCI-12 (having a composition of about 78 wt% silica (SiO ₂ ) and 22 wt% aluminoborosilicate (62% Al ₂ O ₃ , 24% SiO ₂ , 14% B ₂ O ₃ )); And FRCI-20 (about 78 wt% silica (SiO ₂ ) and about 22 wt% aluminoborosilicate (62% Al ₂ O ₃ , 24% SiO ₂ , 14% B ₂ O ₃ )).

In a preferred embodiment, the components of the inorganic fibers consist of or consist essentially of fibrous silica, alumina fibers and aluminoborosilicate fibers. In this embodiment, the fibrous silica comprises about 50-90% of the inorganic fiber mix, the alumina fiber comprises about 5-50% of the inorganic fiber, and the aluminoborosilicate fiber contains about 10-25% of the inorganic fiber mix. Include. The fibers used to make the substrates of the present invention may, in one embodiment, have both a crystalline phase and a glassy phase.

Other suitable fibers are preferably about 55-75 wt% aluminum oxide, more than 0 wt% and less than about 45 wt% (preferably more than 0 wt% and less than 44 wt%) silicon oxide, and 0 wt. Aluminoborosilicate fibers comprising more than% and in the range of less than about 25% by weight (preferably about 1-5% by weight) (the amounts are theoretical as Al ₂ O ₃ , SiO ₂ and B ₂ O ₃ , respectively) Calculated on the basis of oxide). The aluminoborosilicate fibers preferably have at least 50% by weight crystalline, more preferably at least 75% by weight and most preferably about 100% by weight (ie crystalline fiber). Sized aluminoborosilicate fibers are commercially available, for example, from the 3M Company under the trademarks "NEXTEL 312" and "NEXTEL 440". Suitable aluminoborosilicate fibers can also be prepared as disclosed in US Pat. No. 3,795,524, which is incorporated herein by reference in its entirety.

Other suitable fibers include aluminosilicate fibers, which are typically crystalline and contain about 67 to about 77 weight percent aluminum oxide, such as 69, 71, 73, 75 weight percent, and about 33 to silicon oxide. About 23% by weight, for example 31, 29, 27, 25% by weight. Sized aluminosilicate fibers are commercially available, for example, from the 3M Company under the trademark "NEXTEL 550". Another suitable aluminosilicate fiber can be prepared as disclosed in US Pat. No. 4,047,965 (Karst et al.), The disclosure of which is incorporated herein by reference.

In another embodiment, the fibers used to prepare the substrates of the present invention may be fabricated with α-Al ₂ O ₃ with added Y ₂ O ₃ and ZrO ₂ and / or with addition of SiO ₂ (α-Al ₂ O ₃ / mul). Form a light) α-Al ₂ O ₃ .

Various special materials can be used in the preparation of the catalyst substrate. In one embodiment, the materials used to make the substrates of the present invention include or consist of or consist essentially of refractory silica fibers and refractory aluminum borosilicate fibers. In another embodiment, the materials used to prepare the catalyst substrate include refractory silica fibers, refractory grade alumina fibers and a binder, preferably boron oxide or boron nitride powder.

In one embodiment, the catalyst substrate of the present invention comprises, consists of, or consists essentially of alumina reinforced thermal barrier ("AETB") materials or similar materials known to those skilled in the art. AETB materials are known in the art and are more specifically described in the following documents, both of which are incorporated herein by reference: Leiser et al., "Options for Improving Rigidized Ceramic Heatshields", Ceramic Engineering and Science Proceedings, 6, No. 7-8, pp. 757-768 (1985) and Leiser et al., "Effect of Fiber Size and Composition on Mechanical and Thermal Properties of Low Density Ceramic Composite Insulation Materials", NASA CA 2357, pp. 231-244 (1984).

In another embodiment, the catalyst substrate comprises a ceramic tile, such as an alumina reinforced thermal barrier (AETB) with a toughened monolithic fibrous insulation (TUFI) and / or reactive cured glass (RCG) coating. Such materials are known in the art.

Another suitable material is fibrous refractory ceramic insulation (FRCI). In one embodiment, AETB is made from alumina boria silica (also known as alumina-boria-silica, aluminoborosilicate and aluminoboria silicate) fibers, silica fibers and alumina fibers. One application commonly known for AETB is a tile on the outer wall of a space shuttle, which is ideal for space shuttle reentry. AETB has high melting point, low thermal conductivity and coefficient of thermal expansion, durability against thermal shock and vibration impact, low density and very high porosity and permeability.

In one embodiment, the first component of AETB is alumina fiber. In a preferred embodiment of the present invention, alumina (Al ₂ O ₃ or aluminum oxide such as SAFFIL) typically consists of about 95-97 wt% alumina and about 3-5 wt% silica in commercial form. In other embodiments, alumina with lower purity may be used, such as, for example, 90%, 92%, and 94%. In other embodiments, higher purity alumina may also be used. Alumina can be produced by extrusion or spinning. First, a solution of precursor species is prepared. For example, a gradually gradual polymerization process is initiated by manipulation of the pH, with the result that individual precursor molecules combine to form large molecules. As this process proceeds, the average molecular weight / molecular size increases, thereby increasing the viscosity of the solution over time. When the viscosity reaches about 10 cps, the solution turns slightly tacky so that the fibers can be drawn or spun. In this state, the fibers may be extruded through a die. In one embodiment, the average diameter of the fibers is in the range of about 1-6 μm, but larger or smaller diameter fibers are also suitable for the present invention.

In one embodiment, the second component of AETB is silica fiber. In one embodiment, silica (SiO ₂ , such as Q-fibers or quartz fibers) contains more than 99.5% by weight of amorphous silica with very low impurity levels. Lower purity such as 90%, 95% and 97% silica can also be used in the present invention. In one embodiment, amorphous silica having low density (eg, 2.1-2.2 g / cm 3), high fire resistance (1,600 ° C.), low thermal conductivity (about 0.1 W / mK), and near zero thermal expansion Used.

In one embodiment, the third component of AETB is alumina boria silica fibers. In some cases, alumina boria silica fibers (3Al ₂ O ₃ and 2SiO ₂ and B ₂ O _3, for example; NEXTEL 312) is typically of alumina and 62.5% by weight silica, 24.5% by weight, and boria 13% by weight. Of course, the exact percentage of the components of the alumina boria silica can vary. It is largely an amorphous product but may contain crystalline mullite. Suitable alumina boria silica fibers and methods of making them are disclosed, for example, in US Pat. No. 3,795,524, the teachings of which are incorporated herein by reference in their entirety.

Other materials suitable for use as nSiRF-C in the present invention include: AETB-12 (about 20% Al ₂ O ₃ , about 12% (14% B ₂ O ₃ , 72% Al ₂ O ₃ , 14% SiO ₂ ; NEXTEL ^™ fiber), and about 68% SiO ₂ ); AETB-8 (about 20% Al ₂ O ₃ , about 12% (14% B ₂ O ₃ , 72% Al ₂ O ₃ , 14% SiO ₂ ; NEXTEL ^™ fiber), and about 68% SiO ₂ ); FRCI-12 (having a composition of about 78 wt% silica (SiO ₂ ) and 22 wt% aluminoborosilicate (62% Al ₂ O ₃ , 24% SiO ₂ , 14% B ₂ O ₃ )); And FRCI-20 (about 78 wt% silica (SiO ₂ ) and about 22 wt% aluminoborosilicate (62% Al ₂ O ₃ , 24% SiO ₂ , 14% B ₂ O ₃ )).

In a preferred embodiment, the components of the inorganic fibers consist of or consist essentially of fibrous silica, alumina fibers, and aluminoborosilicate fibers. In this embodiment, the fibrous silica is about 50-90% inorganic fiber mix, the alumina fiber is about 5-50% inorganic fiber, and the aluminoborosilicate fiber is about 10-25% inorganic fiber mix. It includes.

Fibers similar to AETB as described above may be used in addition to or instead of AETB fibers.

The production of fibers through melting can be carried out in two general ways. The first method involves a combination of centrifugal spinning and gaseous attenuation. A glass stream of appropriate viscosity flows continuously from the furnace on a spinner plate rotating at a speed of several thousand rpm. Centrifugal force projects the glass towards the spinner wall with thousands of holes. The glass is driven again by centrifugal force to pass through the hole, attenuated by the blast of heated gas and collected.

In the second melting technique, melt gas is fed into a heated tank with hundreds or thousands of holes at the bottom, depending on the application. The glass flows and is drawn through the holes to form individual fibers. The fibers merge into strands and are collected in the mandrel.

In one embodiment, the AETB fiber mix in the slurry preferably comprises three components comprising fibrous glass, alumina fibers, and aluminoborosilicate fibers. Fibrous silica comprises about 50-90% inorganic fiber mix, the alumina fiber comprises about 5-50% inorganic fiber mix, and the aluminoborosilicate fiber comprises about 10-25% inorganic fiber mix. In another embodiment, the slurry comprises any fiber mixture that can be used for the preparation of the substrate according to the invention described above.

In a preferred embodiment, the fibrous component of the substrate comprises 64% of amorphous silica, 21% of alumina, and 15% of alumina boria silica, and traces used to aid dispersion of bulk fibers in the slurry before and during casting. , 0.3 to 1.0 mg / m 2) of a surfactant.

In one embodiment, the fibers in the slurry are primarily inorganic fibers. Preferably, in one embodiment the invention does not use carbon at all in the formation of the substrate.

Alumina-zirconia fibers can be added to the inorganic fiber mix as a replacement for the fourth component or other fibers.

Blend of fibers

In one step of an embodiment of the present invention, the fibers are mixed. Any number of known fiber mixing methods can be used for mixing the fibers. One example that may be used is high shear mixing.

Heating of fiber

In one step of the invention, the fibers are heated according to known methods. First, the fibers are heated so that the fibers can be chopped more uniformly. The heat treated fibers are washed to remove all dust, dirt and loose particles, leaving only the fibers to be processed.

In a preferred embodiment, the fibers are heat cleaned.

Washing of textiles

In one step of the invention, the fibers are washed. In a preferred method, the fibers are washed so that the fibers are substantially free of dust and dirt. In one embodiment, the silica fibers are immersed in acid to remove impurities, rinsed, dried and then heat treated to impart structural integrity.

Fibrous Chopping

In another step of the present invention, the fibers are chopped. The fibers used in the present invention can typically be obtained as bulk fibers or chopped fibers. Methods of chopping fibers are known in the art. Most methods are continuous processes that can process several sugars, ie strands, simultaneously. Typically, the product consists of a pair, one of which is fed between the rotating wheels or drums that support the evenly spaced cutting blades. When the fiber is drawn out through the cutter, the fiber is chopped to the desired length. While special manufacturing details remain exclusive in forming blanks from chopped fibers, such techniques typically involve one of the production mechanisms, melting and sol gels. It is desirable to heat treat the fibers before final chopping.

Preferably, the fibers are then chopped to the desired size. Suitable lengths of the fibers are not particularly limited, but are about 0.1, 0.2, 0.3, 0.4, 0.5, or 0.6 in. Other suitable lengths are 1/8 ", 1/4", and 1/2 ". It is preferred that the fibers have a relatively uniform size. In another embodiment, the fibers consisting of a catalyst substrate or a filtration substrate It has an average length of 1/4 in (about 1/100 m) and an average fiber diameter of 3 μm with a diameter of about 1-12 μm, or a diameter of 1-6 μm, or a diameter of 10-12 μm. In the examples, particulate matter is not added since it may close the pore space Fibers suitable for use in the present invention are commercially available, for example, from 3M. Is used.

Slurry  Produce

In another step of the process according to the invention, a slurry comprising the fibers is prepared. The substrate can be prepared by conventional sol-gel processes without extruding ceramics or surrounding the spinning or fabric around the perforated tube. This is accomplished by first pulling (via vacuum or gravity withdrawal) a sol of well mixed inorganic fiber and colloidal solution into a sol blank or green billet or fiber mold that produces a billet.

Alternatively, a squeeze-cast pressurizing process can be used when the pressure is reduced to a negative value or is vacuum. The vacuum process allows inorganic fiber blanks to be formed at extremely low densities while maintaining their length. The sol-gel process, together with the pressurization process or the vacuum process, helps to produce particularly low densities, which is very helpful for the filtration of particles.

The fibers are mixed together in the slurry. In one embodiment, the slurry may contain 1-2% by weight of solids and is substantially fluid, such as water. Alternatively, the slurry may contain about 0.5 to about 5 weight percent solids. Other weight percentages may be acceptable as is known in the art.

The chopped fibers are mixed together in a slurry using a high shear mixer. Preferably, deionized water is used in the slurry to avoid impurities that may act as a flux or degrade the stability of the fibers used. In one embodiment, the slurry may be pumped through centrifugal cyclones to remove other contaminants, including shot glass and high concentrations of soda particles.

Alternatively, organic fibers or particles may be added to the fiber slurry in a proportion of up to 30% by weight. During the ignition phase of production, the organic fibers are either volatilized or incinerated from the object. Incineration of the fiber creates voids that can provide a path for the gas to escape. By changing the shape and proportion of the polymer fibers, the permeability of the tiles can be controlled. The blanks produced through this method are porous and thus can be actively cooled through the introduction of bleed air.

Control of viscosity

In another embodiment, the viscosity is adjusted to a suitable range. The high viscosity prevents the fibers from "laying down", i.e. lying flat or oriented substantially in the horizontal direction. Boron nitride may be added as a thickener for coating the fibers in the preparation for high strength sintering. In one embodiment of the invention, boron nitride is added and alumina boria silica fibers are not used in the slurry.

Addition of dispersant

In one embodiment, the method includes adding one or more dispersants to the mixture or slurry.

In one embodiment of the present invention, one or more surface active agents are added to the slurry during the process of the present invention. Surface active agents are used in amounts of about 5 to about 10 weight percent. Surface active agents are used to assist in dispersing the bulk fibers in the slurry before and during casting to prevent the fibers from clumping together.

In one embodiment of the invention, one or more of the catalysts described above is added to the slurry. By adding a catalyst at this stage of the process, a substrate with a catalyst impregnated into the porous material is made. In one embodiment, this shape precludes the need for additional washcoat or catalysis.

molding

In one embodiment, slurry is injected into a mold to form a billet. The shape of the mold can have any shape desired. In one embodiment, the shape of the mold produces a substrate having a shape suitable for use in a catalytic converter or particle filter. For example, the mold may be in the shape of a cylinder. Alternatively, the mold may be pentagonal in shape. Since the fibers can be laid down, the slurry should not settle in the mold. In one embodiment, a vacuum suction method is used to keep the fibers from settling and to keep the porosity and density uniform throughout the billet. Vacuum suction techniques can be used from any number of directions to control fiber arrangement and density with the green billet.

For example, a billet of catalyst or filtration substrate material is made in a mold of size 24 in x 24 in (576 in ² ) x 4 in with rounded corners. Of course, larger or smaller sized billets can be produced.

The material of the mold may be any material stable to water, including but not limited to metal or plastic. Other suitable materials include aluminum, PLEXIGLAS, and other synthetic materials. Aluminum is very durable over long periods of time, but PLEXIGLAS is inexpensive and easy to machine. Suitable permeable surfaces can be used in the form of fine metal mesh screens. In some circumstances it may be desirable to use a semipermeable surface larger than 50 in ² as a support structure to prevent sagging.

There are embodiments in which an anaerobic atmosphere, ie an oxygen free atmosphere, may be desirable in casting. An oxygen free atmosphere creates an environment that minimizes oxidation of the metal and uniquely strengthens fiber bonding. The impregnated billet is placed in a chamber filled with ammonia gas, for example a large plastic bag. Ammonia is most commonly used because of its low cost and ease of availability. Nitrogen and / or hydrogen gas may also be introduced. Since hydrogen is volatile, nitrogen is preferred over hydrogen. In fact, any gas can be introduced as long as the reducing and oxygen free environment is maintained. Preferably, the gas is provided at a constant flow rate until the impregnated sol billet forms a gel billet. At this point, the gas is shut off and the gel billet is exposed outdoors to allow the gas to escape.

Carbon or organic shape-formers may be used as the hole forming rods, which are introduced into the green billet during the molding step. Upon sintering at high temperatures, these rods are dismantled and the desired plurality of channels are left behind.

Slurry  dehydration

In an embodiment of making a billet, at least one dimension can be adjusted and the slurry is placed in a closed mold where the at least one wall is semipermeable. A compressive force is applied through the adjustable wall and the water is pushed out of the slurry through a semipermeable wall where the fibers are collected to form a felt. Compression continues until the desired preform, ie billet, dimension is obtained. This method is generally limited to simple shapes such as blocks or cylinders.

Since gravity is usually not enough to drive, you should use a vacuum pump. Vacuum pumps use little or no pressure. In some cases, vacuum is used for dehydration, but suction is used very little. Vacuum is used as a means of accelerating the sensitive drying process to avoid an increase in density. It is preferable to use only a vacuum which is not strong as an aid.

More complex shaped billets may be prepared by other methods, for example by placing the head of the slurry and holding it on the semipermeable mold form. Low pressure is applied outside the permeable form via a vacuum pump. The pressure differential drives water through a permeable form in which fibers are collected to form felt. The pressure difference is maintained until the desired thickness is obtained. This method is suitable for applications in which the desired substrate is heavily curved since the billet can be made close to a net-like shape or final form.

By introducing or mixing multiple (two or more) slurry recipes and changing the vacuum rate of the pull (multiple times), billets are denser than some other regions and / or regions of different physical properties. This is provided. Billets may have graduated or different layers or cores, which differ in chemical composition and density. The billet may have one or a plurality of zones with unique shapes, locations and required physical properties. Each zone can be modified as required to modify strength, thermal or electrical conductivity, catalyst adhesion capability, thermal expansion, vibration shock or thermal shock, weight, porosity and permeability, acoustic damping or any other desired property. .

By using different slurry formulation and molding techniques, the billets may be laminated. In addition, the billet is not limited to parallel planar layers such as the layers on the cake, and the billet may be formed in male, angular, spherical, pyramidal and free form layers, or any other shape known in the art. . It should be noted that the density of the billet may be changed chemically and physically during the process if necessary.

The billet may also be formed by placing a plurality of billets of different chemicals and arbitrary shapes, inside or outside the other bill, whether or not cured. The core billet may be manually installed in the billet or injected into the core. As a result, one or more cores with lower or higher density are obtained. The shape and form of these cores and billets are not limited as in the combination of lamination of cores. The core may even be created inside the core. The method can be repeated as many times as needed, with the result that a unique number of billet combinations are obtained in an unlimited form.

Green Billet  dry

In one step of one embodiment, the slurry in the mold is dried in an oven for a sufficient time to dehydrate, ie, remove any water that may be contained in the slurry. Water can be drained by gravity. Weak vacuum can be used as an aid. Of course, other methods known in the art may be used.

From mold  Green Billet  Removed and painted Billet  dry

In one step of one embodiment, the green billet is removed from the mold. In general, the billet can remove the billet when it is dry enough for handling. Alternatively, the billet is removed when the billet is dry enough to be processed by the machine.

For example, when the billet is dry enough to handle, it is removed from the mold. The billet is then dried in an oven. Use a sufficiently low temperature to complete the dehydration process and allow the fibers to remain in a substantially intended shape. More specifically, the temperature is the temperature at which the billet is sufficiently dried as required, but should be at least or insufficient to substantially sinter the billet. In another preferred embodiment, a temperature of about 250-500 ° F. is used in this step. In another embodiment, the billet is dried for about 2 to about 6 hours, preferably about 4 hours at a temperature of about 180 ° C. Other times and temperatures known in the art may be used.

The dried billet is then optionally immersed in a sol-gel binder, preferably an alumina sol-gel binder for a period of time, such as for several days, at various temperatures known in the art, since the billet sucks up the binder solution. . Suitable binders are known in the art and will be necessary to impart structural integrity of the preforms and to promote sintering. Billets may utilize single or multiple binder treatments to alter the strength and conductivity of the billets. Applying the binder multiple times will increase the strength of the billet, but may reduce or close the pore space. The binder may be an oxide binder such as SiO ₂ or Al ₂ O ₃ . The oxide binder may also be in glass form, crystalline form or other inorganic binder. The binder can be applied using known techniques and methods, as disclosed in US Pat. No. 3,549,473. The teachings of these patents are incorporated herein by reference in their entirety.

Green Billet  Drying (sintering)

In another step of an embodiment of the invention, the green billet is heat cured. The temperature for thermal curing or sintering is generally higher than the temperature used for drying the green billet. In one embodiment, the temperature is raised gradually over one hour, preferably several hours, until the desired temperature is reached. In one embodiment, the oven is preheated and gradually heated to about 2,000-2500 ° F. Other temperatures known in the art are also suitable.

In a preferred embodiment, after the binder has gelled, the billet is heated to about 200 ° F. for about 4 hours and then the billet is cured by slowly raising the temperature to about 600 ° F. over about 5 hours. After reaching and maintaining the maximum temperature, the billet is quenched in a short time. As a final result, a rigid inorganic fiber billet is obtained. In addition, it is possible to change the temperature, curing time, quenching temperature and time, temperature rise and temperature rise time used in the step of heat curing the blank.

The billet is roasted to provide the energy needed to sinter the fiber-to-fiber contact to form a bond that gives strength to the substrate. For example, the strength can be increased by increasing the number of fibers and fiber to fiber contacts. Increasing the number of contacts increases density and tortuosity. The more bends of the pore network, the lower the permeability. Sintering does not melt the fibers together but chemically bonds the fibers together. The billet is gradually heated in a high temperature furnace. The billet is preheated and then heated to about 2,000-2,500 ° F. until the desired density and fusion is achieved. In a preferred embodiment, the second chemical, such as thickener, is burned off. Substrates comprising, or consisting of or consisting essentially of sintered fibers remain.

In a preferred embodiment, the viscous chemicals (thickeners) and dispersants are combusted and removed.

In another embodiment, multiple curing steps are performed. This can be done to increase the hardness of the substrate.

Parameters in the drying and curing process can be adjusted according to the density, strength, porosity, permeability, or durability to high temperatures of the target fiber blank. In one embodiment, the curing process may utilize a plurality of curing applications and may alter the spacing and approach of heating and cooling. The billet can also be cooled rapidly for quenching or tempering. The slurry may be treated with additional heat, or other treatments such as densification coating or multiple curing and sintering may be performed.

Physical deformation

In one embodiment of the method, the billet is coated with a catalyst. In one method of applying a catalyst to a substrate, the substrate may be formed from a slurry containing the catalyst. Other suitable methods of applying the catalyst may be used. Another advantage of the present invention is that it has been found that the catalyst can be applied to nSiRF-C materials using methods that can apply the catalyst to other materials.

In another embodiment of the invention, the catalyst is added to the slurry prior to molding. In this case, a catalyst substrate is formed in which the catalyst is directly attached to the individual fibers constituting the substrate. This method of adding a catalyst to the substrate, in one embodiment, provides an efficient way to disperse the catalyst in the core of the catalyst substrate and does not leave the catalyst only along the channel wall. In this embodiment, no washcoat is needed.

Machining

Billets in the form of crude blocks may be cut or sawed into a particular shape, then sanded and finally turned or machined into "slugs" having the desired shape. In a preferred embodiment, the composition of base material has high resilience to chemical, thermal and vibrational impacts, but low hardness. Due to this low hardness, it can be machined with little or no resistance or can be worn by a tool. In one embodiment, although the billet has a low hardness and is soft, the billet is highly durable and easy to machine, engrave or mold. The material is usually soft, as measured by the Moh's hardness scale, with the softest term talc being 1 (1 to 22 in Knoop hardness) and the hardest diamond being 10 (8,000 to 8,500 in Knoop hardness). 0.5 to 1.0 (or 1 to 22 in Knoop hardness). For example, silicon carbide has a Mohs' Hardness (2,000 to 2,950 in Knoop's hardness) of 9 to 10. Compared to other known materials, the billet is very soft and is Styrofoam, which does not require as much machining or engraving as Balsa wood.

The billets are molded, sanded, turned or machined to provide formability without limit of slug formation. The scope of machining includes cylinder turning on lathes, sawing to form keyholes, band saws or jigsaws, sanding of shapes or smoothing of surfaces, or other methods known in the art, as are commonly used in solid materials. And the like. The billets can be machined to very tight tolerances with the same precision as processing metal, wood or plastic. When the billet is cast from the cylindrical mold to the desired diameter of the final shape, machining simply cuts and sands the cylindrical billet to the desired thickness. This process also reduces the loss of substrates due to excessive machining and increases the rate of preforms.

The shape of the front and back sides of the substrate is many, including a circle 510, an ellipse 520, and a racetrack 530, as shown in FIG. 5. In three dimensions, the substrate may have the form of a cylinder or a substantially flat disk. Conventional substrates exist in one of these three designs. Designs with squared corners are not very effective. Although easy to machine, the square or angled design has proven to be a trap for rust and corrosive substances such as road salts. Therefore, rounded corners are preferable for the front shape of the slug.

Billets, substrates or slugs may be molded by band saws, jigsaws, CNCs or other methods known to those skilled in the art. Slugs may also be molded by hand rubbing, lathe sanding, belt sanding or orbital sanding. Particles floating in the air should be vacuumed in such a way as to not close the pores of the material. In addition, these particles can enter the bearings of the drill press, destroy and wear and mark the bearings. Ceramic dust is also very fine and can be easily inhaled by the operator.

Molded slugs are utilized as substrates in the present invention. The surface area of the substrate is an important property in catalyst application. Surface area is the total amount of surface that must pass through when exhaust emissions travel through the exhaust filter. Increasing the surface area means that more space is provided for chemical reactions and thermal processes that take place between contaminants and catalysts, making the catalytic converter process faster and more efficient. Speed and efficiency may result in little or no blockage that can cause failure of the exhaust system.

In one embodiment, the substrate of the present invention has a gross surface area of 83.58 in ² / in ³ . This means that the area that can be impregnated with the noble metal is large compared to cordierite samples having the compared macro dimension (eg diameter, length and width). However, it should be noted that this gross surface area calculation does not include the density, porosity and permeability of the different materials.

In an exemplary embodiment of the invention, the substrate is used in an exhaust filter system for a diesel engine. The substrate is shaped into a billet of about 13 "x 13" x 5 "with a density of 8-25 lb / ft ³ using an AETB formulation. From the billet, a diamond tip saw or tungsten-carbide band saw Using a 6 in diameter, 5 in. Long or regular ellipsoidal cylinder slug is cut, which is precisely permitted by a spinning lathe (for circular cylinders) or a belt sander forming the substrate. Further machining to tolerances is possible.

Fabrication of holes and channels of substrate

In one embodiment of the present invention, a plurality of channels are formed in the filtration or catalyst substrate substantially in the longitudinal direction of the intended gas flow. The channel extends partially or fully through the length of the substrate. 5-14 are schematic diagrams illustrating a particular embodiment of the invention with a plurality of channels. In one embodiment, the channel extends at an angle with respect to the flow of the fluid.

The inner surface of these channels can be chemically coated to capture and treat more contaminants within a small volume of the substrate. When the channel is formed in the substrate, for the small channel to have a high surface area, for example, 200, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, Smaller diameter channels with 1800, 1900, 2000, 2100, 2200, 2300, 2400, or 2500 cpsi are preferred.

In another embodiment, the channel extends through the full length of the substrate. Such substrates have a flow through structure.

In contrast, the channel does not extend through the full length of the substrate, but extends by about 50% to about 99% through the length of the substrate. Such substrates are considered wall-flow structures. The unrilled portion of the wall-flowing channel can have various thicknesses. 8 shows a substrate 820 of a wall-flow pattern in accordance with an embodiment of the present invention having unperforated portions 840 and 845 with various thicknesses. In this embodiment, the alternate inlet channel has a larger wall thickness than the other inlet and outlet channels. However, the various thicknesses of the unperforated portions can be configured in any combination such that the inlet or outlet channels have thinner or thicker unperforated portions, and all of the unperforated portions may not be substantially equal in thickness. The wall thickness is so thin and porous that the exhaust gas 830 passes from the inlet inlet channel through the wall into the outlet channel to capture the emission particles. The length between the inner edges 850 and 855 of the unperforated portion is known as the crossover region. If the unperforated portion 840 is thicker in some or all of the inlet channels, the discharge stream 830 is likely to exit the substrate 820 through the channel wall of the substrate in the crossover region. Emission stream 830 will still pass through thin microperforated portion 845. In another embodiment of the invention, the amount of catalyst differs from the amount present in the channel wall since the unperforated portion of the channel has a selective impregnation of the catalyst.

The thickness of the unperforated part is limited. Gas flow is increased by increasing the surface area of the walls with equivalent thickness. If the unperforated portion is too thin, it may burst due to excessive back pressure.

Mechanical perforation

After the substrate of the embodiment has been cut from the billet and machined, the substrate is inserted into a drilling holder for drilling. A plurality of channels can be drilled into the substrate in a direction substantially parallel to the main axis of the cylinder and the exhaust emission flow. The smaller the channel diameter, the more channels can be drilled into the substrate.

In another embodiment, the channel is perforated into the substrate. The substrate is installed in a metal holder for drilling. The holder can be, for example, a pair of large metal arms that firmly holds the substrate slug in place and keeps the substrate from moving without breaking the substrate. The holder engages the substrate and keeps the substrate stable for drilling. After one side of the substrate has been perforated, the holder is rotated exactly 180 degrees to be perforated on the opposite side of the substrate. If the rotation is not exactly 180 degrees, the perforated channels are not properly aligned or parallel. In addition, the pressure at the inlet should be substantially the same or similar to the pressure at the outlet. Preferably, in order to ensure parallel walls, the holder should not move the substrate more than 0.0001 in in any undesired direction.

The channels of the substrate according to the invention can be produced using a mechanical drilling process. In one embodiment, computer numerical control ("CNC") drilling is used, which is a common and preferred method among machine shops. CNC drilling is much slower and is not economically feasible in mass production environments where thousands of filters are produced per day. CNC drilling is performed with high precision and accuracy. CNC drilling is done by making multiple passes with drill bits. The CNC drills a little more into the substrate in one pass and removes the fibrous material when the bit comes out.

Drill bits may be tungsten carbide or similar materials known to those skilled in the art because of their tough and brittle properties.

The drill bit penetrates at a feed rate of about 10 ft / min. A slow feed rate is necessary to prevent the drill bit from melting. If the drill bit penetrates at a feed rate of 25 ft / min, the drill bit melts. In addition, due to the enormous pore space, the drill bit tends to "walk" or roam. This problem is solved by slowing the penetration rate.

Slow rotation of the drill bit is preferred. The drill bit should rotate at about 200 rpm. If the drill bit rotates at a speed higher than this, for example 10,000 rpm, melting of the drill bit may result. The drill bit is kept cooled throughout the drilling process by lubricating oils such as water, alcohol or glycerin.

Once the substrate is cut and sanded to the final dimensions, the channel is cut or drilled into the substrate. In this exemplary embodiment, the channel is truncated using DPSSL. Since the substrate is very porous and permeable, the substrate need not be as thick as a conventional filter. In addition, when the substrate is thin or small, one billet can be cut to produce several substrates, and the production cost is low because the requirement of coating or catalyst to be applied is reduced.

Water Drilling (water drilling)

In another embodiment, water cutting (or water drilling) is used to form the channel. Water cutting finely sprays water at high pressure to puncture the substrate. However, the water jet cannot stop during the cutting process to leave blind holes (ie, channels that do not completely penetrate the substrate). The physical properties of the water jets limit the size of the channel openings to diameters above the diameter of the jets. In one embodiment, jets may be used to form rectangular holes.

gas- Drilling

In another aspect of the invention, a gas drilling method is used for the manufacture of a substrate. Gas-drilling is known in the art and can be applied to the substrates of the present invention to produce channels in the substrate.

Combing

In yet another embodiment, the channel is formed or shaped using a combing process. The comb is preferably a metal instrument with a plurality of tines that can be forced into the substrate (broaching). The comb used for broaching includes a plurality of combs. The length, width, thickness and shape of the comb teeth may vary depending on the nature, shape and dimensions of the desired channel.

In one embodiment, the comb is forced into the substrate substantially perpendicular to the surface of the substrate. In another embodiment, the comb is forced into the substrate at an angle to the surface of the substrate. The use of a comb is a particularly preferred method for the formation of blind channels. Suitable combs are also understood that combs can be made up, for example, in rows and columns of 4x4 or 16x16.

Generally, the combing process involves repeatedly forcing the comb several times into the substrate material until most or all of the channels have been formed. This process is referred to herein as peking. Optionally, after forced combing each time, the comb can be removed from the channel so that excess substrate material to be removed can be removed from the channel, for example by air. It is desirable to prevent the fibers from accumulating during the peking / broaching step. Accumulation of fibers can rupture some or all of the walls. To control this property, vacuum and / or compressed air can be used to clean the channel and drill bit surfaces.

In one embodiment, the comb is forced into the substrate with a force sufficient to displace or dislodge an amount of substrate material from the channel wall. In a preferred embodiment, the comb teeth exert a force of sufficient magnitude to enter about 0.1 inches into the channel. Other suitable values include 0.05, 0.15 and 0.2 in. Preferably, the magnitude of the force applied to form or form the channel is sufficient to form or form the channel without substantially damaging the channel wall. This process involves repeatedly forcing a comb into the substrate until a channel of the desired length and shape is produced.

The shape of the comb teeth determines the shape of the channel. For example, a rectangular channel having rectangular channel openings is formed by rectangular comb teeth attached to the comb.

Wedge comb attached to the comb is used to form a wedge channel. The use of a wedge comb creates a channel parallel to the square opening and wall. As shown in FIG. 17, the substrate 1700 consists of a parallel, wedge-shaped “blind” channel 1702, ie, a substrate without an exit hole. The blind channel 1702 forces the gas 1704 to pass through the pore space channel before exiting.

A tetrahedral pyramidal comb attached to the comb is used to form a pyramidal channel. The walls are parallel and the openings are substantially square. However, in the channel opening, the wall thickness is minimal because the channels meet at one point without adjoining the wall and the flat front. This results in a reduction of the front surface area, thus reducing the back pressure. For tetrahedral pyramidal combs, no shim is needed to separate the comb. In this embodiment, referring to FIG. 16, a suitable comb does not have a flat end and has combs that gather at a point. Of course, various other shapes of combs are included in the present invention.

Tent shaped combs attached to the comb are used to form a polygonal channel. The front surface area is minimized by the polygonal shaped channel.

Referring to FIG. 16, dimensions of an exemplary comb 1600 in accordance with an embodiment of the present invention are shown. The comb 1600 is about 6.000 in long and 0.0308 in wide. Comb 1600 includes a base 1610 from which a plurality of combs 1620 extend. The height of the base 1610 is 0.4375 in. The plurality of combs 1620 are 1.250 in long and 0.0308 in wide, with a spacing of 0.010 in.

In one embodiment of the combing process, a circular channel is first formed by the drill bit. To produce shaped channels with parallel walls, according to one embodiment of the present invention, the comb teeth broach (ie press or stamp) the circular channels to produce shaped channels. An example of a comb 150 is shown in FIG. 15. Broaching is preferably carried out on a CNC press. The marks left behind are the channels and channel openings to be shaped. The cell wall thickness can vary as described above. In one embodiment, the combing process produces a catalyst or filtration substrate having a channel wall thickness of about 4 mils to about 20 mils, preferably about 6 mils to about 10 mils.

In the combing process, the metal comb can be installed in a box called a jig and mounted on a broaching CNC press. Within the jig, the comb is separated by a shim. The spacing between the combs is low and the combs need to be firmly fixed to the jig to limit movement during broaching. Referring to FIG. 16, shim 1630 is used as a spacer for comb 1600. Shim 1630 has dimensions of 0.010 in width, 6.000 in length and 0.4375 in height.

Preferably, at least one screen is provided on top of the comb to keep the comb aligned. Preferably, the screen is floating to distribute the alignment as needed. In addition, the screen helps with combs of various lengths, for example from about 0.5 in to about 6.0 in. The at least one screen can be installed, for example, floating, spring-loaded or fixed at any position along the comb. The at least one screen may float along the comb teeth. The comb is not fixed to at least one screen, but is installed on the comb so that the screen can be adjusted. The at least one screen may be spring-loaded to the comb teeth. By means of a spring-loaded screen, the pressure of the substrate against the screen maintains the distance between the combs approximately at the edge of the substrate. The at least one screen may also be secured to the comb at any position along the length of the comb.

Another embodiment of the present invention is to provide a method for preparing a catalyst or filtration substrate having a plurality of channels, the method comprising the step of peking the substrate using a comb to form the plurality of channels. In a preferred embodiment, this method is a stepwise process. That is, instead of inserting the comb teeth once to form the entire channel, the comb teeth are repeatedly inserted and taken out in small increments until the desired length of the channel is obtained. It is desirable to clean the substrate material in the channel that is removed between each peck and the next peck.

In another embodiment, the combing process is an automated process using a machine and / or robot to form a channel.

How to make a comb

There are several methods for producing a comb for use in the present invention. The comb may be made of a material including, but not limited to, stainless steel, tungsten, or key stock. Comb shaping methods include laser cutting, water cutting and electronic discharge machining, or the use of other shaping methods available to those skilled in the art.

DPSSL can be used to make combs. Water cutting may also be used to make the comb. For example, in one embodiment 30 to 50 combs are made in one cut using water cutting.

Electron emission processing ("EDM") is another method for manufacturing combs. EDM is a thermal erosion process in which a conductive material is removed by a series of repeated electron emission in the presence of a dielectric fluid between an electrode and a conductive workpiece. EDM is likewise used on a substrate when the substrate is made of a conductive material. There are at least two forms of EDM: (1) ram and (2) wire.

Using EDM ram, i.e. die sinking, an electrode / tool is attached to a ram that is connected to one pole, usually a positive pole of a pulsed power supply. The workpiece is connected to a negative pole. The workpiece is then positioned so that there is a gap between the workpiece and the electrode. The gap is then filled with a dielectric fluid. When the power supply is turned on, thousands of direct current (DC) pulses per second cross the gap and begin the erosion process. The spark temperature generated may range from 14,000 ° F. to 21,000 ° F. While erosion continues, the electrode advances into the workpiece while keeping the gap dimension constant.

The wire EDM method is preferable for comb manufacture. The wire method uses consumable electrically charged wires as electrodes to make complex cuts when the wire moves around the workpiece in a predetermined pattern.

If the wall is too thin, any rough edges on the comb can tear the wall in and out during broaching. Thus, the comb must be polished to remove any burrs or sharp edges that may be caught on the fiber. Cutting and polishing of the comb can generate heat, which can bend the comb. To ensure that the resulting holes are parallel and not ruptured, it is desirable to maintain the tolerance to about 0.0001 in.

The comb used for broaching includes a plurality of combs. The length, width, thickness and shape of the comb teeth may vary depending on the properties of the desired channel. Referring to Figure 16, the dimensions of the comb 1600 are shown in accordance with an embodiment of the present invention. The comb 1600 is about 6.000 in long and 0.0308 in wide. Comb 1600 includes a base 1610 from which a plurality of combs 1620 extend. Base 1610 is 0.4375 inches in length. The plurality of combs 1620 are 1.250 in long, 0.0308 in wide, and have a spacing of 0.010 in.

Laser processing

Other methods include diode-pumped solid-state laser ("Ennie") drilling; Chemical lasers, for example with CO ₂ ; Electron beam (“EB”) drilling; Or the use of an electrode drilling apparatus ('EDM') or other methods known to those skilled in the art, Any laser suitable for cutting the material of the comb can be used.

The substrate is cut using laser drilling such as DPSSL drilling. This method drills with a laser programmed using a CAD program. The CAD program is loaded into the CAM program. The laser cuts into fine pulses with oxygen or preferably nitrogen. DPSSL can cut a channel at a rate of about 2,000 channels per minute. In one embodiment, the channel has a diameter of about 100 nm. Laser drilling can be performed using known techniques and methods disclosed in US Pat. No. 4,686,128. The teachings of these patents are incorporated herein by reference in their entirety. In one embodiment, the method uses laser drilling to produce a channel having a depth (or length) of about 0.5 inches or less.

Also in one embodiment, the substrate material is about 97% porous, which means that there is an enormous amount of space through which the gas can pass through the substrate. Such large porosity also provides additional surface area where particles can be deposited.

Pulsed laser

(Note): 1) measured at 10 kHz repetition rate; 2) Externally triggered at 0-15,000 Hz (damped power). 7,500 Hz Internally triggered at 15,000 Hz. The actual random firing mode for external triggering of 0-15,000 Hz in full power mode is optional; 3) Gator lasers utilize a closed loop water system for temperature control.

Preferably, the base material is substantially free of impurities such as carbon when processed by the laser.

Molding of the hole

In another embodiment, the substrate of the present invention is made with channels preformed in billets. In this embodiment, the channel forming tool is used to form a channel in the billet. The channel former is a rod having a size and shape suitable for forming a desired channel when the green billet is formed.

Various types of materials may be used for the channel forming tool. For example, the channel former may be a strong durable material, such as a metal, or a polymer capable of withstanding the temperature of the drying process. Once the green billet or final billet is formed, the rod is removed leaving the channel. The channel can be further machined as described above.

Alternatively, in another embodiment, the rod is made of a material that can evaporate or disassemble upon exposure to a suitable radiation source or heat source, such as a laser or heat. In another embodiment, the channel former is made of carbon, carbon derivatives, and the like.

Special Example

In one embodiment, the channel is drilled using a CNC drill and the CNC drill is computer controlled to maintain uniformity as described below. The drilling process is carried out with constant spraying of water in order to prevent dust from entering the bearings of the drill which can enter the bearings of the drill and break the bearings.

The drilled substrate is optionally dried in an oven to push or bake off any moisture or other liquids that may remain in the pore space before any catalyst is applied. Baking time is not important. Sufficient time is used to remove most or substantially all moisture. Evaporation of water can be determined by simply weighing the substrate. Baking time mainly accelerates the dehydration process. After the filter elements have been heated at various different intervals and the weight is constant, the substrate is ready for any catalyst or coating application.

In a preferred embodiment, the channel of the substrate is first produced by drilling and then shaped by the combing method. Due to the low thermal conductivity of the preferred substrate, when the substrate is drilled, most of the heat generated during the drilling and cutting process is conveyed away from the drill bit and removed from the substrate. For this reason, the drill bit may absorb some of the heat, causing it to expand, overheat and / or melt. Preferably, the cooling of the drill bit is preferably carried out with water. In another embodiment, the drill is operated at a reduced drill speed, for example at 200 rpm, to minimize the generation of heat. Of course, other drill speeds that are faster or slower are also suitable. In another preferred embodiment, the drilling uses a two-sided, four-sided or six-sided drill with a modified twist and head (drill tip) shape.

In addition, in a preferred embodiment, the channel is drilled through several drilling operations. For example, a channel about 1 in long can be made by drilling into the substrate to a depth of about 0.1 in at a time until the final length is reached. Substrate material drilled between drilling operations can be removed from the channel.

Center-Punching and Pilot Hall

Peking methods are utilized because the cut fibers have to be removed by vacuum suction.

In a preferred embodiment, the blind channel was drilled slightly deeper than the target depth to allow the fiber to be packed into extra areas during the combing process. The comb was programmed to proceed to the depth of the indicated wall flow structure, with the extra space containing any loose substrate material remaining in the channel.

Product by process

In another embodiment, the present invention is to provide a product manufactured according to the above-described process. In particular, it is an object of the present invention to provide a catalyst substrate prepared according to any one of the specific examples described above. In another aspect, the present invention is directed to providing a filtration substrate made according to any one of the specific embodiments described above.

Applications

Various embodiments and applications of the present invention are described below. These exemplary applications are for illustrative purposes only and do not limit the scope of the invention. Any of the examples of catalyst substrates and filtration substrates described above can be used in a variety of applications.

Catalytic converter

In yet another embodiment, the present invention is directed to providing a catalytic converter comprising a catalyst substrate of the present invention. The catalytic converter of the present invention can be used in an engine exhaust system in a manner similar to that of known catalytic converters. Of course, the catalytic converter of the present invention has an advantage over the catalytic converter of the prior art. Due to this advantage, the catalytic converter of the present invention can be used in such a way that known catalytic converters cannot be used.

As mentioned above, any particular embodiment of the substrate according to the present invention can be used for one or more special applications such as catalytic converters. In a particular embodiment, the catalytic converter comprises a catalyst substrate of the present invention; Matting surrounding the catalyst substrate; And canisters, preferably metal canisters; And optionally a washcoat.

Another aspect of the present invention is to provide a catalytic converter located in or adjacent to an exhaust manifold of an exhaust system of an engine, the catalytic converter comprising a catalyst substrate of the present invention. The catalytic converter is referred to as a manifold catalytic converter (other terms include mani-cat, manifold converter, and the like). The mani-cat of the present invention includes known mani-cats, and the catalytic converter of the present invention is used instead of the description of the prior art. Such mani-cats are disclosed in US Pat. Nos. 6,605,259 and 5,692,373.

In yet another embodiment, the present invention seeks to provide an improved catalytic converter comprising a novel substrate as described above. Any of the particular embodiments of the substrate can be used in the improved catalytic converter.

In another embodiment, the present invention provides an improved catalytic converter for treating internal combustion engine exhaust, comprising a substrate, a metal oxide washcoat, and at least one catalyst attached to the metal oxide particles, wherein the nSiRF-C composite And catalytic converters characterized by a substrate comprising a catalytic metal.

In yet another embodiment, the present invention provides an improved catalytic converter for treating internal combustion engine exhaust, comprising a substrate, a metal oxide washcoat, and at least one catalyst attached to the metal oxide particles, the nSiRF-C composite and It is to provide a catalytic converter characterized by a substrate comprising a catalytic metal.

In another embodiment, the present invention provides an improved catalytic converter for treating an internal combustion engine exhaust, comprising a substrate, a metal oxide washcoat, and at least one catalyst attached to the metal oxide particles, comprising an AETB composite It is to provide a catalytic converter characterized by the substrate.

In another embodiment, the present invention is to provide a main-cat having a catalyst substrate comprising an nSiRF-C composite and a catalyst. The main-cat (sometimes referred to as underfloor catalytic converter) is located partially or completely within the head of the engine. In one embodiment, the main-cat comprises the catalyst substrate of the present invention, the catalyst substrate having a density of about 12 lb / ft ³ , porosity of about 97%, low thermal expansion, high structural integrity and low thermal conductivity Has In a preferred embodiment, the main-cat has about 600 cpsi and has a wall thickness of about 6 mils. In this embodiment, the main-cat has a wall-flow structure. In a preferred embodiment, the main-cat has a substantially box-shaped (variable length through the substrate) channel shape with substantially square openings (or holes). In a preferred embodiment, the catalyst substrate of the main-cat is prepared using a combing method. Also in this example, the catalyst substrate comprises an alumina washcoat. In this embodiment, the main-cat can catalyze both oxidation and reduction of contaminants. For example, the main-cat has the ability to oxidize contaminants and reduce contaminants. The canister of the main-cat is manufactured by the swagging method. In a preferred embodiment, the main-cat comprises two substrate units. In one embodiment, the main-cat is used alone or in combination with the pre-cat. In a preferred embodiment, the main-cat includes intumescent matting. The main-cat can be used in all internal combustion engines. The main-cat can be used with fuel-borne catalysts. In addition, the main-cat substrate may be reinforced with protection.

The main catalytic converter of the present invention as described above is also used with one or more aftertreatment systems in one embodiment. Such aftertreatment systems include NO _x adsorbers, HC adsorbers, SCR systems and the like.

In addition, embodiments having the same or similar shape and properties as the main catalytic converters described above for the membrane catalyst can be used. The membrane catalyst includes a catalyst substrate having a membrane shape as described above.

In another embodiment, the present invention is to provide a head-cat having a catalyst substrate comprising an nSiRF-C composite and a catalyst. The head-cat is located partially or completely within the head of the engine. In one embodiment, the head-cat comprises a catalyst substrate of the present invention, the substrate having a density of about 12 lb / ft ³ , porosity of about 97%, low thermal expansion, high structural integrity, and low thermal conductivity. . In a preferred embodiment, the head-cat has about 600 cpsi and has a wall thickness of about 6 mils. In this embodiment, the head-cat has a wall-flow structure. In a preferred embodiment, the head-cat has a substantially pyramidal channel shape with substantially square openings (or holes). In a preferred embodiment, the catalyst substrate of the head-cat is prepared using a combing method. In this embodiment, the head-cat can catalyze both oxidation and reduction of contaminants. For example, the head-cat has the ability to oxidize contaminants and reduce contaminants. In one embodiment, the head-cat is used alone or in combination with the pre-cat. In a preferred embodiment, the head-cat comprises hybrid matting. The head-cat can be used in all internal combustion engines. Head-cats can be used with fuel companion catalysts.

More than one head-cat can be used in the same engine. The use of the head-cat according to the invention also has one or more of the following advantages: weight reduction of the underfloor exhaust system; The life of the intercooler is improved by increasing the filtration of exhaust particulate matter that the intercooler will pick up; No matting required; Reduction of rattle noise in heat shields; Reduction in muffler size; Incineration of particulate matter; In one embodiment, when one head-cat fails, the exhaust gas continues to be effectively treated by another functioning head-cat, for example three other head-cats mounted on a four-cylinder engine. Head-cats are advantageous for boats, ships, motorcycles, small handheld engines, leaf blowers, and related engines, and are advantageously used in other applications where an unexposed catalytic converter is desired.

In yet another embodiment, the catalytic converter of the present invention may be installed between the head and the exhaust manifold as shown in FIG. 41. In this embodiment, the catalytic converter section is installed between the engine head and the exhaust manifold. An advantage over conventional systems is that the converter is very close to the combustion chamber, thus increasing efficiency. For example, this embodiment could be mounted on a Ford 4.6 liter engine and fitted to all of the engines. It also fits into all other Ford engines such as Ford Explorer, Mustang, Crown Victoria, Econoline, 150/250/350 pickup, Expedition, and Lincoln. In addition, in one embodiment, it fits into various model ages that have used it for years. One such 4.6 casting can be used for millions of vehicles in the United States alone. It is also friendly for future oxygen sensors.

In another embodiment, the present invention is directed to providing a back-cat having a catalyst substrate comprising an nSiRF-C composite and a catalyst. In yet another embodiment, the catalytic converter of the present invention is a back-cat. The back-cat is located behind the main catalytic converter. In one embodiment, the back-cat comprises a catalyst substrate of the present invention, the catalyst substrate having a density of about 12 lb / ft ³ , porosity of about 97%, low thermal expansion, high structural integrity, and low thermal conductivity Has In a preferred embodiment, the back-cat has about 600 cpsi and has a wall thickness of about 6 mils. In this embodiment, the back-cat has a wall-flow structure. In a preferred embodiment, the catalyst substrate of the back-cat is prepared using the combing method. In a preferred embodiment, the back-cat has channel holes of various shapes, including triangles, squares, circles and hexagons. In this embodiment, the back-cat can catalyze both oxidation and reduction of contaminants. For example, the back-cat has the ability to oxidize contaminants and reduce contaminants. In one embodiment, the back-cat is used alone or in combination with the pre-cat. In a preferred embodiment, the back-cat includes non-intumescent matting. The back-cat can be used in all internal combustion engines. In yet another embodiment, the back-cat can be used with fuel companion catalyst. Generally, the back-cat of this embodiment is installed near the standard muffler position, although other positions are possible. In another embodiment, the back-cat is integrally installed in the muffler. Such embodiments may include a) a substrate that itself acts as a muffler to replace the muffler, or b) a substrate that is integrally installed within the muffler by being installed inside a typical metal muffler assembly.

In another embodiment, the present invention seeks to provide a diesel oxidation catalyst (DOC), wherein the base of the DOC is a diesel oxidation catalyst wherein the base of the catalyst is the aforementioned catalyst. In a preferred embodiment, the description of the DOC according to the invention is AEBT or OCBT, preferably AEBT-10, AEBT-12, AEBT-16 or OCBT-10. Examples of DOC have a catalyst selected from the group consisting of palladium, platinum, rhodium, mixtures thereof and derivatives thereof.

Another suitable embodiment includes a catalyst substrate of the present invention, preferably an AEBT material such as AEBT-12, and a catalyzed DPF further comprising a catalyst.

Particle filter ( DPF , DPT )

In another embodiment, the present invention is to provide a particle filter comprising the catalyst substrate of the present invention. The particle filter of the present invention can be used in an engine exhaust system in a manner similar to that of known catalytic converters. Of course, the particle filter of the present invention has an advantage over prior art catalytic converters. Because of this advantage, the catalytic converter can be used in such a way that known catalytic converters cannot be used.

In yet another embodiment, the present invention seeks to provide an improved particle filter comprising the novel substrate as described above. Any of the particular embodiments of the substrate can be used in the improved particle filter.

In another embodiment, the present invention provides an improved particulate filter for treating internal combustion engine exhaust, comprising a filter substrate, the substrate having a plurality of channels extending into the substrate and optionally extending through the substrate. It is an object of the present invention to provide a particle filter comprising a -C composite.

In another embodiment, the present invention provides an improved particulate filter for treating internal combustion engine exhaust, comprising a filter substrate, wherein the substrate extends partially through the substrate, preferably from about 100 to about 1,000 channels, preferably Is intended to provide a particle filter comprising an nSiRF-C composite with about 600 channels.

In yet another embodiment, the present invention seeks to provide a filter substrate characterized by an improved particle filter for treating internal combustion engine exhaust, comprising a substrate and a metal oxide washcoat, the substrate comprising AETB.

In another embodiment, the present invention is to provide a diesel particulate filter (DPF) having a filtration substrate comprising an nSiRF-C composite as described above. The filtration substrate is configured to be suitable for use in a DPF. The DPF is located partially or completely within the head of the engine. In one embodiment, the DPF comprises a filtration substrate of the present invention, which has a density of about 12 lb / ft ³ , porosity of about 97%, low thermal expansion, high structural integrity, and low thermal conductivity. In a preferred embodiment, the main-cat has about 600 cpsi and has a wall thickness of about 6 mils. In this embodiment, the main-cat has a wall-flow structure. In a preferred embodiment, the main-cat has a substantially box-shaped (variable length through the substrate) channel shape with substantially square openings (or holes). In a preferred embodiment, the filtration substrate of the main-cat is prepared using a combing method. Also in this example, the catalyst substrate comprises an alumina washcoat. In this embodiment, the main-cat can catalyze both oxidation and reduction of contaminants. For example, the main-cat has the ability to oxidize contaminants and reduce contaminants. The canister of the main-cat is manufactured by the method of swaging. In a preferred embodiment, the main-cat comprises two substrate units. In one embodiment, the main-cat is used alone or in combination with the pre-cat. In a preferred embodiment, the main-cat comprises an inflatable mat. The main-cat can be used in all internal combustion engines. The main-cat can be used with fuel companion catalysts. In addition, the main-cat substrate may be reinforced with protection. The protective coating can be applied to the inner or outer surface of the substrate.

Canning  Canning type

The catalytic converter of the present invention has a canister. Canisters can be manufactured according to methods known in the art. In addition, the canister of the catalytic converter or particle filter of the present invention may use a known material used for its production, for example steel.

In a preferred embodiment, the catalytic converter of the present invention has a discharge pipe that can be attached to the tailpipe of a commercialized vehicle. Preferably, the catalytic converter fits into a tailpipe about 2½ in or 3 in in diameter.

For example, suitable canisters include those prepared according to any of the following methods: clamshells, presses, shoeboxes, stuffing and swaging. The canning method utilizes two gap control mechanisms: (1) fixed gap and (2) fixed canning force. In view of the welding process, the method produces one or two seams with a seam. This classification is illustrated in Table 4 (Rajadurai 1999).

Fixed gap Fixed power  Single seam Stuffing, swaging Pressure  Double seam Clamshell Shoebox

Sealing the can with a fixed force provides more accurate gap density control by excluding the influence of the dimensional tolerances of the substrate, the can, and the mat itself. Sealing the can with a fixed gap has the advantage of producing a diverter of fixed final dimensions, primarily simplifying the diverter design in welding the cone to a finished can.

Single seam designs are usually preferred for circular or elliptical diverters with low aspect ratios, in which case the design can provide a uniform gap density distribution. Single seams also provide more manufacturing flexibility and require less expensive tooling. Double seam designs are usually required for elliptical converters with high aspect ratios. In this case, a reinforcing rib is stamped into the shell in order to prevent deformation and gap unevenness due to deformation. Double seam shells are manufactured in a stamping process that requires the use of costly tools and are justified by their high yields.

Clamshell

In one embodiment, the catalytic converter of the present invention comprises a canister made by the clamshell technique. In yet another embodiment, the particle filter comprises a canister made by clamshell technology. In North America, clamshells have traditionally been the design of the most common underfloor diverters used in passenger cars and hard goods vehicles. The structure of the clamshell catalytic converter is shown in FIG. The ceramic catalyst substrate (s) are wrapped around the mat and placed in the bottom of the shell. Then, the symmetrical part of another shell is installed on the upper side and pressed and welded.

Tongue and groove designs are used to mount the mat to avoid exhaust gases bypassing the substrate. The converter exemplified above also includes an end seal. The seal is used here to protect the mat from gas collisions and erosion, rather than to prevent leakage. Most diverters using mats do not have end seals. When using wire mesh mounting instead of mats, end seals are always required at least on the inlet side of the substrate.

Clamshell diverters are often equipped with external heat shields. An internal thermal design has also been developed in which the interior of the clamshell stamping has an extra thermal layer and heat.

Old-fashioned designs of catalytic converters include support rings or deep pockets in clamshell stamping to prevent axial movement of the substrate inside the can. Such a countermeasure is not necessary in a properly designed diverter utilizing a high holding pressure expandable mat. There are many automotive converters without the axial support of the substrate, which still show a noteworthy durability record. However, for larger or heavier substrates, or when non-expandable mats with low holding pressures are used, an axial support is required. Another consideration is the erosion of the mat. The diverter shell profile or end cone should be designed to protect the mat from direct collisions of hot exhaust gases. Some converter manufacturers improve chemical resistance by immersing the mat edges exposed to gases with chemicals. High holding pressures in modern converters also improve the mat's durability against erosion.

In many automotive applications, dual monolithic converters are used. Due to manufacturing limitations of monolith length two or more monoliths can be used to combine catalysts of different specifications in one converter. In most dual monolithic converters, the substrate is spaced apart and maintained by forming separate pockets in the clamshell stamping. In some designs, the space between the substrates is maintained by metal or ceramic rings. Butted monolithic installations with no spaces between them are also possible. Butted designs with less pressure drop than spatial designs have been used in some commercial converters for gasoline engines (Kuisell, R.C., 1996, "Butting Monoliths in Catalytic Converters," SAE 960555).

The diverter shell form must provide the required mat compression. The clamshell profile includes stamped reinforcement ribs to provide the necessary rigidity and uniform pressure distribution. This is particularly important for fine elliptical catalyst substrates. In designing the ribs, care should be taken to ensure that there are no excessive pressure zones that could damage the substrate or mat. The clamshell method places high requirements on the dimensional tolerances of monolithic and clamshell stamping. Mat clamping in clamshell canning proceeds until the half-shell is closed to produce the desired gap thickness. The gap thickness is determined by the dimensions of the monolith and the shell. Thus, even slight variations in the size of the monolith will result in variations in the mat density, resulting in canning pressures that can lead to durability problems in the converter.

The rod method is the most common way to directly control the mounting pressure during the canning process. The pressure zones are not sensitive to the dimensional differences that may occur in the substrate monoliths, thereby producing the most robust catalytic converters. In practice, the pressure zone method is limited to catalyst substrates that are elliptical or circular in cross section or near circular. The suitability of the push rod for elliptical or flat elliptical car diverters used in the underfloor position is very limited. Pressure bars were popular among carmakers in Europe, but they became more common in North America as car changers moved from the underfloor position to the engine close coupling position. The press is also suitable for large diameter catalytic converters for medium diesel engines.

In the pressure zone technique, the substrate is first wrapped in a tongue-groove shaped mat. The surrounding monolith is then installed inside the can, which is split longitudinally. The can is produced by rolling a rectangular metal plate. The rectangular portion below the overlap is usually tapered and gradually thinner. In some designs, the overlapping portions of the cans are formed through additional stamping operations into protruding lips to provide space for can edges below the overlaps. Such a design prevents local pressure build-up from occurring that can cause the inner edge of the can to be scraped into the mat or damage the can formation, especially when a thin mat is used. Next, the cans with the enclosed monoliths are placed in press seat makers that apply a controlled force to the assembly. The can is tack welded under pressure, taken out of the machine and seam welded. As a quality assurance method, push-out tests are sometimes performed. In special test equipment, axial monolithic displacements caused by the application of controlled forces are measured. Finally, the diverter header or end cone, and the flange and / or port are welded to the diverter body in a separate operation. The final assembly is immersed in water and pressurized with air to test for weld quality.

The pressure bar maker includes a loop of steel bands that exerts force on the can formation. One end of the loop is firmly attached to the machine and the other end is pulled by a pneumatic or hydraulic actuator. In some machines, vibration is applied during the canning process to minimize sealing forces and ensure a more even pressure distribution.

The canning force actually required to achieve the target mounting density for a given mat can be determined through a series of tests. Several converters must be sealed using different sealing forces. The canning force must be chosen to produce the desired mat density. Due to the mat pressure relaxation, it is important for the pressure bar maker to produce reproducible closing speeds and time patterns. After reaching the target sealing force, the manufacturer must maintain the can in a constant position, not a constant force, to allow for tack welding. Applying a constant force to the can when the mat pressure is relaxed causes excessive mating of the mat.

The shoebox technique uses a two-part shell that is similar to the clamshell method. However, the shell is closed with a fixed force, with the edge of one of the half-shells superimposed on the other. Thus, the shoebox provides a robust packaging advantage of the press with respect to insensitivity to dimensional tolerances of the substrate.

Reinforcement ribs can be stamped onto the shoebox shell. Thus, this technique allows for the canning of a flat elliptical substrate when the compression band technique is not suitable.

Stuffing

In the stuffing technique, a monolith wrapped with a mat is pushed into a cylindrical can. The cans are usually made of sections of tubes, but can also be welded by winding a sheet of metal. Non-cylindrical shapes (eg, trapezoids) are possible. This method can be applied to both small car converters and large engines for medium engines. To facilitate smooth insertion of the monolith, a stuffing cone is used as shown in the figures (Li, FZ, 2000, "The Assembly Deformation and Pressure of Stuffed Catalytic Converter Accounting for the Hysteresis Behavior of Pressure vs. Density Curve of the Intumescent Mat , "SAE 2000-01-0223). After completing the operation, the end cone is welded to each end of the cylinder to complete the can assembly.

The stuffed diverter has a similar appearance to the compression assembly, but the actual mechanism of holding the substrate is the same as the clamshell design. In particular, the mat mounting pressure is determined by the geometric dimensions of the shell and monolith. As a result, high reproducibility of the substrate diameter is required when using the stuffing technique.

A modified stuffing technique called SoftMount Technology has been proposed by Corning (Eisenstock, G., et al., 2002, "Evaluation of SoftMount Technology for Use in Packaging Ultra Thinwall Ceramic Susbstates", SAE 2002-01-1097) . Its purpose is to minimize peak mat pressure during the stuffing process to enable canning of ultra thin wall substrates characterized by low strength. The key idea is to use a tapered cylindrical tool called an arbor, located in front of the substrate, to receive the peak pressure response of the mat upon insertion.

In the SoftMount method, the mat is first inserted into the can and the mat is secured to the flange during the process. The can then aligns the can with the mat aligned over the arbor and the substrate (ie, the arbor is positioned over the substrate). The arbor is grooved inward at the end for easy sliding into the can-mat assembly. The arbor squeezes the mat into the can while moving through it. Since the substrate moves to the position where the arbor in the can is replaced, it is not exposed to the instantaneous peak load required to compress the mat.

Swaging

In a swaged diverter, the diverter shell is machined to the desired diameter after the mated substrate is inserted. Swaging is a new packaging technique that runs on a fully automated CNC control unit, suitable for mass production for passenger car applications. Swaged converters can be made from one section of the tube with end cones obtained in a spin forming process on the same production machine.

The gap adjustment mechanism can be classified to a constant gap thickness, as in the case of stuffing, but the CNC controlled production line can automatically account for differences in substrate diameters. Swaged diverters should initially be formed with a diameter slightly smaller than the target diameter of the finished product so that the shell can "spring back" after machining. This is a disadvantage of this method and can result in excessive peak pressure and damage to the substrate during canning.

Catalytic converter headers provide a transition between the inlet and outlet pipes and the substrate cross section. Most diverter headers have a cone or funnel shape with axial gas flow. Other designs are possible, for example truncated headers (Wendland, EW et al., 1992, "Effect of Header Truncation on Monolith Converter Emission Control Performance", SAE 922340) or headers with tangential gas inlets. rare. The function of the inlet header is to spread the inlet flow, i.e. increase the static pressure with reduced gas velocity and as little loss of total pressure as possible. In practice, combined header losses can range from 10% to 50% of the pressure drop across the converter, depending on the shape and flow conditions. This pressure loss can be minimized by designing a diverter inlet header that provides a more uniform flow distribution. There is also the view that uniform flow distribution within the catalytic converter improves discharge performance and / or durability. In one embodiment of the invention, the catalytic converter or particle filter has a header having an angle of about 30%.

Matting

The catalytic converter or particle filter of the present invention also optionally includes matting. Any of the embodiments mentioned above or below will include matting. In one embodiment, the invention further comprises a mat (or matting or betting). For example, the catalytic converter of the present invention includes a catalyst substrate, mat and canister as described above in one embodiment. Mats that can be used in the present invention are known in the art.

In one embodiment, the mat may be selected based on several visible attributes as described herein and known in the art. The catalytic converter canister is preferably designed to provide the required mounting pressure for a given catalyst substrate and a given mat. The mounting pressure of the mat increases exponentially during compression from the initial bulk density to the final target density. Mounting pressure indicates viscoelastic relaxation. That is, the peak initial pressure that occurs during canning is significantly reduced for the first few seconds or minutes thereafter due to the rearrangement of the mat fibers (Myers 2000). The mounting pressure loss of the expandable mat due to this relaxation varies between 30% and 60% of the initial peak mounting pressure.

Due to mat relaxation and later loss of pressure during use, the mounting pressure is not a convenient parameter for the canning process specification. Rather, mounting density, often referred to as gap bulk density (GBD), is commonly used for that purpose. Typical mat mounting densities along with bulk (uncompressed) densities are listed in Table 2. Consult the mat manufacturer for the exact density for a given application. Weight / area is expressed in units of g / m 2 or kg / m 2 (because these are mass units, not weight units, and the generic term “weight / area” will have to be replaced strictly with “mass / area”). ). Available mats have a weight / area in the range of 1,050 to 6,200 g / m 2 and an uncompressed thickness in the range of 1.5 to 10 mm. For automobile converters, expandable mats of 3,000 to 4,000 g / m 2 are typically used. Higher mat weights, such as 6,200 g / m 2 (6.2 kg / m 2), are recommended for heavier applications or large converters.

Another important property of the catalytic converter mounting mat is the weight / area ratio, often referred to as the reference weight. Weight / area is expressed in units of g / m 2 or kg / m 2 (because these are mass units, not weight units, and the generic term “weight / area” will have to be replaced strictly with “mass / area”). ). Available mats have a weight / area in the range of 1,050 to 6,200 g / m 2 and an uncompressed thickness in the range of 1.5 to 10 mm. For automobile converters, expandable mats of 3,000 to 4,000 g / m 2 are typically used. Higher mat weights, such as 6,200 g / m 2 (6.2 kg / m 2), are recommended for heavier applications or large converters.

The packaging mat may be subjected to erosion caused by the collision of hot exhaust gases. Resistance to erosion is an important property of the mat. Resistance to erosion is highly dependent on gap bulk density. (Rajadurai, S., et al., 1999, "Single Seam Stuffed Converter Design for Thinwall Substrates", SAE 1999-01-3628).

Many other attributes of the mounting mat are defined and / or tested and are available from the mat manufacturer. The list of these properties includes thermal conductivity, gas sealing properties, friction coefficients, and so on.

In designing the mounting system, the following considerations are taken into account in one embodiment:

Mounting pressure: Assuming that the mounting mat is the only means of connecting the substrate to the shell (ie, the diverter does not have end seals or support rings), the mechanical connection is a radial pressure with friction on the mat surface. Provided by The mounting pressure is the minimum pressure necessary to hold the substrate in place.

Peak Mounting Pressure: As mentioned earlier, the mat behaves like a viscoelastic solid, creating a high peak mounting pressure upon initial compression and then gradually relaxing to reach the residual mounting pressure. In thin-walled substrates, the peak pressure can cause damage to the catalyst core during packaging. When designing a canning method that relies on a constant force, as opposed to a constant gap size, such as a compression zone, the transient behavior of the mat must also be taken into account.

Temperature Behavior: For the press mat, the mat pressure is dependent on obtaining a temperature sufficient to activate vermiculite. Inlet temperature of at least 500 ° C. is required for vermiculite activation; Higher inlet temperatures may be necessary depending on the heat transfer conditions in the particular system. In gasoline applications, the mat is activated during the initial time of engine operation in the vehicle. In diesel applications, oven-treatment of the catalytic converter may be required, in which case the exhaust gas temperature will never reach a sufficient level during normal vehicle operation. Vermiculite expansion is partially reversible, thus expanding the mat when the temperature rises and shrinking when the converter cools. This property of vermiculite goes beyond compensating expansion of the diverter shell, creating a very high mounting pressure at higher temperatures. In contrast, non-expandable mats exhibit a nearly constant mounting pressure over the temperature range. The small decrease in pressure with increasing temperature seen in FIG. 4 may be due to gap expansion due to thermal expansion of the diverter shell. At temperatures above 500 ° C., expandable mats provide a higher holding pressure than non-expandable mats. However, at temperatures below 500 ° C., the mounting pressure from the inflatable mat is actually much lower than the pressure from the non-expandable mat. Thus, in many diesel applications where the converter inlet temperature is maintained below 500 ° C., the double-expandable mat is the preferred mounting material. Expandable mats with reduced vermiculite content create a mounting pressure between conventional expandable mats and non-expandable mats. Hybrid mats exhibit pressure levels similar to non-expandable mats, but these mats maintain a certain pressure boost at high temperatures, which prevents gap expansion.

Gap Expansion: When the converter is exposed to high temperatures, the gap thickness increases due to the difference in coefficient of thermal expansion between the substrate and the shell. Thermal expansion of the gap can be an important source of mounting pressure loss. Gap expansion is particularly fatal in applications where non-expandable mats are used because they cannot be compensated by vermiculite expansion. As a design guideline, the gap expansion should be kept below 10% (Olson, J.R., 2004, "Diesel Emission Control Devices-Design Factor Affecting Mounting Mat Selection," SAE 2004-01-1420).

Gap expansion depends on the following design factors:

Substrate Diameter: Larger substrates result in larger gap expansion percentages. Thus, gap expansion can still be a problem in medium diesel applications despite relatively low converter temperatures.

Gap thickness; Thick gaps result in less gap expansion.

Shell Temperature: Higher temperatures cause greater gap expansion.

Shell material CTE: Steel with high coefficient of thermal expansion results in higher gap expansion. Thus, gap expansion is more easily controlled using ferritic (as opposed to austenitic) steel grades.

Mat aging: When the diverter enters use, the expandable mat expands causing an increase in mounting pressure. Several other aging factors are responsible for the gradual irreversible loss of mounting pressure: thermal cycling; Vibration acceleration and other mechanical factors; Soaking of the mat with water (condensation, vehicle wash); And organic binder incineration when the mat is first heated.

Advantages and disadvantages of the mats currently in use

Conventional applications utilize expandable and non-expandable fibrous mats for mounting honeycomb substrates in canisters, examples of which are given in Locker's European Patent EP0884459 and Hwang's European Patent EP0912820. According to one conventional system, it is possible to mount a large catalyst member to the canister by means of a fibrous mat.

Swelling  mat

Inflatable mats were originally developed for gasoline converters. By the early 1990s, such mats became the most common type of ceramic mats used in catalytic converters for all internal combustion engine applications, including diesel. Intumescent mats have the property of partially irreversible expansion upon exposure to high temperatures. Thermal expansion curves for inflatable mats are available from various manufacturers, including 3M and Unifrax. The expandable mat, once inflated, increases the holding pressure on the substrate to provide a very firm mounting system. Because of such temperature expansion properties, the expandable mat can actually increase the mounting pressure at high temperatures, thereby compensating for the mounting pressure loss due to thermal expansion of the steel housing.

The expandable mat is made of alumina-silica ceramic fibers, contains vermiculite, and this material provides thermal expansion. Typical compositions have 30-50% alumina-silica fibers, 40-60% vermiculite, and 4-9% organic binder (typically acrylic latex). After the converter is assembled, the mat must be exposed to a temperature of about 500 ° C. in order to obtain initial expansion, which is usually achieved during the initial hours of engine operation in a vehicle. Organic mat binders that decompose at high temperatures are the cause of the characteristic odor released when the mat is first heated.

The vermiculite component imposes a relatively low maximum operating temperature limit for the expandable mat. The mat rapidly loses the holding pressure at a temperature of about 750 ° C. This temperature is usually defined as the average mat temperature. Thus, the mat can be used at higher exhaust temperatures if there is a temperature gradient across the mat due to heat loss from the external converter shell. The use of expandable mats is limited in high temperature isothermal applications where no heat loss occurs through the converter walls. Such situations include catalysts mounted inside mufflers, for example in motorcycle applications.

The high content of vermiculite components is also the cause of the high mounting pressure, especially at high exhaust temperatures. It has been found that the pressure from the expandable mat may be excessive in the ultra-thin wall substrate and cause damage to the part. In these applications, mat manufacturers have introduced expandable mats (sometimes referred to as "advanced" or "second generation" expandable mats) with reduced vermiculite, which provides lower mounting pressures than conventional designs. .

ratio- Swelling  mat

Non-expandable mats do not contain vermiculite. Thus, this mat provides a much higher temperature limit of about 1,250 ° C. The main component of the non-expandable mat is alumina fibers to which an organic binder is added. In one embodiment of the invention, the catalytic converter or particle filter comprises a substrate as described above, and the non-expandable mat may be better when it comprises a fibrous material.

The dorsal support relies on embedded compression or fiber "spring", which supplies a constant holding pressure over the application temperature range. Since the diverter shell expands with temperature, an effective decrease in diverter mounting pressure is observed at higher temperatures. Thus, non-expandable mats hold the catalyst substrate very firm at low temperatures, in stark contrast to vermiculite mats. As the temperature rises, the substrate inside the converter is maintained at a reduced force.

Non-expandable mats can be used in low temperature converters, such as in diesel engines, as well as in high temperature applications (thin walled substrates) that do not withstand high mounting pressures. Non-expandable mats do not depend on vermiculite expansion and therefore do not require oven treatment in low temperature diesel converters.

Hybrid mat

The improved catalytic converter or particle filter of the present invention may further comprise a hybrid mat. Such mats are known in the art. Hybrid mats, in one embodiment, incorporate a two-layer design: a layer of expandable mats on top of the layer of non-expandable mats. The properties and performance of the hybrid mats are intermediate and the cold mounting pressure is better than the expandable mats, but the hot temperature is higher than the non-expandable mats. In a preferred embodiment, the improved diesel particulate filter of the present invention comprises a hybrid mat that can be used for both light weight and heavy weight applications.

wire Mesh

Knitted stainless steel wire mesh may be used in place of the mat in the packaging of the ceramic catalyst substrate. Wire mesh is often thought to exhibit less desirable mounting pressure properties than mats, but is still used in some catalytic converters (traditionally, wire mesh has been used by Ford). In wire mesh, end seals are always needed to prevent gas from bypassing the substrate.

assistant Heating source

As another configuration or embodiment from the one previously disclosed, the filter element may comprise a series of electrical heating rods added to the substrate after catalyst application. Preferably, the heating element is applied after the catalyst to prevent the curing process from harming all electrical contacts. In one embodiment, the heating element or rod is installed about 1/4 inch or any distance desired from each edge. In one embodiment, a wire mesh configuration or other heating elements described above may be used that are installed perpendicular to the gas flow direction and installed while forming the fiber blank. The electrical contact can be operated before the engine is started as a preheater and remains in either partial or full operation until the exhaust temperature is higher than the temperature obtained by the auxiliary heating element.

The use of an auxiliary heating source applied to the filter foundation is useful for increasing the internal temperature of the filter foundation and / or for evenly distributing additional heat to better efficiency throughout the filter foundation. The auxiliary heat source may consist of an elastic electrical heating element. The heating element may have a rod shape that can be inserted after the filter base has been formed or during the sol-gel process. One or more electrical heating elements can be applied to the filter base, and the heating elements can be heated simultaneously, independently, cyclically, in a pattern, or in a random order. The heating element may be in the form of a wire mesh configuration that can be inserted during or after forming the filter foundation. The filter can use a single wire mesh or a plurality of wire mesh heating elements, and these heating elements can be heated simultaneously or independently. In addition, the mesh heating elements may be heated in a circulatory, patterned, or random order. The heating element can also use rod-shaped, spiral-shaped inserts during or after formation. The filter base may combine one or more helical heating elements that may be heated simultaneously or independently, cyclically, in a pattern, or using a random order. Finally, the filter base may combine a combination of any of the heating elements described above.

In addition to the elastic electrical heating elements described above, the auxiliary heating source may also use infrared or microwave heating elements. Various heating sources may be mounted inside the filter base or may be used to heat the filter base as an external heating element. Even in this case, various heating sources can be applied independently or in conjunction with any other heating element or heating source.

The filter base is encased in a casing with sufficient durability to protect the filter base from the typical impacts encountered during vehicle transport. Such casings may include universal metal casings such as stainless steel, steel or other metal alloys. The casing material may be a nonmetal including a ceramic casing. The filter base may be encapsulated in an insulator or batting prior to being received in the casing. The present invention may combine heat shields.

The inlet and outlet tubes of the filter base may be coated with an oxidative catalyst. The catalyst can speed up the radiation process, which achieves exhaust treatment of the entire system at a much faster time. The catalyst may be a noble metal catalyst including platinum, palladium, or rhodium-based and others. The catalyst can be applied directly to the filter base surface. Application of the catalyst may be by spraying on the filter surface, by dipping the filter base in solution, or by pouring into the filter base itself. The use of oxidative catalysts will promote ignition of particulate matter at lower temperatures. In addition, the catalyst may be used as a supplemental heater inside the filter base itself.

The exhaust filter system may be integrated with the engine exhaust path, including integration within the exhaust manifold of the engine itself. Since the filter foundation is very durable against heat and vibration, it can be installed next to the engine exhaust exiting the engine block. The unique ability of the filter base to withstand high heat and increasing vibrational stress allows the arrangement of the present invention to be much closer to the engine. Proximity arrangements offer advantages over conventional exhaust filters or catalytic converters that do not withstand such high thermal or vibrational stresses.

While the invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention. Therefore, modifications and variations of the present invention should be included in the present invention as long as it is included in the appended claims and their equivalents.

Specialty of catalytic converter Example

The catalytic converter and particle filter of the present invention are further illustrated by the following non-limiting special examples. The various specific embodiments cited herein are exemplary and do not necessarily limit the scope of the invention. The catalytic converter of the present invention can be mounted and used in any number of engines and vehicles. Thus, in one embodiment, the catalytic converter of the present invention is suitably used in a vehicle or engine produced by any of the following companies: Daimler-Chrysler; Chrysler; Dodge; Eagle; Jeep; Plymouth; General Motors; AM General (eg HUMMERs); Buick; Cadillac; Chevrolet; Geo; GMC; Hummer; LaSalle; Oldsmobile; Pontiac; Saturn; Ford; Continental; Lincoln; Mercury; Ace Motor Corp; American Motors; Avanti BMW; Daimler-Chrysler; Fiat; Ford; GAZ; General Motors; Honda; Mitsubishi; Renault; Peugeot; Toyota; And Volkswagen Group. Others include: Holden; Lightburn; Hartnett; Alpha Sports; Finch; Amuza; Australian Kitcar; FPV; Bavariacars; Birchfleld; G-Force; Bomac; Bullet; Homebush; Carbontech; HSV; Classic Glass; Kiaftwerkz; Classic Revival; Cobra Craft; Piper; Daktari; PRB; Daytona; Python; Deuce Customs; RCM; Devaux; RMC; DRB; Roaring Forties; Elfin; Robnell; Evans; Austro-Daimler; OAF; Puch; Steyr; Steyr-Daimler-Puch; FN; Germain; Miesse; Minerva; Nagant; Vivinus; Gurgel; Puma; A-E; AC; Allard; Alvis; Ariel; Armstrong Siddeley; Ashley; Aston Martin; Austin; Austin-Healey; Bentley; Berkeley; Bond; Bristol; BSA; Caterham; Clan; Daimler; Dellow; De Lorean; Elva; F-L; Fairthorpe; Ford; Frazer Nash; Gilbern; Ginetta; Gordon-Keeble; Hillman; Humber; Jaguar; James and Browne; Jensen; Jowett; Lagonda; Lanchester; Land Rover; Lea-Francis; Lister; Locost; Lotus; M-R; Marcos; McLaren; MG; Morgan; Morris; Mini; Ogle; Panther; Peerless / Warwick; Piper; Range Rover; Reliant; Riley; Rochdale; Rolls-Royce; Rover; S-W; Singer; Standard; Sterling; Sunbeam; Swallow; Talbot; Tornado; Trident; Triumph; Turner; TVR; Vanden Plas; Vauxhall; Wolseley; Bricklin; McLaughlin; Aero; Jawa; Laurin &Klement;Praga;Skoda;Tatra;Walter;Kewet;Elcat;Valmet;RaceAbout;Amilcar; Alpine, aka. Alpine-Renault; Bonnet; Bugatti; CD; CG; Citroen; DB; De Dion-Bouton; Delage; Delahaye; Delaunay-Belleville; Facel Vega; Gordini; Hispano-Suiza; Hotchkiss; Peugeot; Renault; Rosengart; Simca; Sizaire-Naudin; Talbot; Tracta; Venturi; Voisin; A-G; Amphicar; Audi; Auto-Union; BMW; Fendt; Glas; Goggomobil; H-P; Heinkel from Heinkel Trojan; Horch; Kasbohrer-Setra; Kleinschnittger; MAN; Magirus; Maybach; Mercedes-Benz; Merkur; Messerschmitt; Neoplan; NSU; Opel; Porsche; S-W; Smart; Stoewer; Titan; Trabant; Volkswagen (VW); Wartburg; Wanderer; Thomond; Bajaj Tempo; Hindustan; Mahindra; Maruti; Premier; Reva; San Storm; Sipani; Tata; Abarth; Alfa Romeo; Autobianchi; Bugatti Automobili SpA; De Tomaso; Dino; Ferrari; Fiat; Iso; Innocenti; Isotta Fraschini; Itala; Lamborghini; Lancia; Maserati; OM; Piaggio; Qvale; Vespa; Zust; Daihatsu; Honda (also Acura); Isuzu; Mazda; Mitsubishi; Mitsuoka; Nissan aka. Datsun (also Infiniti); Subaru; Suzuki; Toyota (also Lexus); Proton; ACE; AME; AMI; AMM; Bufori; Inokom; Naza; Perodua; Swedish Assembly; Tan Chong; TD 2000; Donkervoort; Spyker; DAF; Pyonghwa; Tokchon; Kewet; Think aka. Pivco; Troll; Syrena; UMM; Aro; Dacia; Marta; Oltcit; Volga; Moskvitch; GM Daewoo Motors; Hyundai Motor Company; Kia Motors; Renault Samsung Motors; SsangYong Motor Company; Nilsson; Nordic Uhr; S.A.M .; Saab; Scania; Thulin; Tidaholm; Tjorven (sold as Kalmar in the export market); Volvo; And Yugo.

Catalyst or filtration muffler

In another embodiment, the present invention also seeks to provide a catalyst muffler comprising the catalyst substrate or filtration substrate of the invention. As mentioned above, the catalyst substrate or filtration substrate is housed together with the muffler in a single canister.

In one embodiment, the catalyst muffler of the present invention comprises a catalyst muffler of known design, replacing the prior art catalyst substrate with the catalyst substrate of the present invention. Suitable catalyst mufflers are known from US Pat. No. 6,622,482; 6,604,600; 6,604,600; No. 6,341,662; And 4,457,895.

Exhaust system

In yet another embodiment, the present invention is directed to providing an exhaust system comprising the catalyst substrate of the present invention. The exhaust system generally includes a certain number of components. The exhaust system includes suitable means for directing the engine and exhaust gas away from the engine.

The exhaust system includes a conduit for guiding the internal combustion engine and exhaust gas away from the exhaust port of the combustion chamber. Other optional components of the exhaust system include exhaust manifolds, mufflers and exhaust pipes.

In yet another embodiment, the present invention is directed to providing an exhaust system comprising the filtration substrate of the present invention.

In another aspect, the present invention seeks to provide an improved exhaust system utilizing the catalyst substrate of the present invention. In another aspect, the present invention seeks to provide an improved exhaust system utilizing the filtration substrate of the present invention.

The exhaust system of the present invention is suitable for use with any of the following fields:

1) passenger cars and light trucks; Highway and driveway motorcycles; Mobile, on-road engines, devices and vehicles, including medium highway engines such as trucks and buses; 2) compressed ignition engines (farm, construction, coal mine, etc.); Small spark ignition engines (grass mowers, blade blowers, chainsaws, etc.); Large spark ignition engines (forklifts, generators, etc.); Marine diesel engines (merchant marine, recreational diesel, etc.); Marine spark ignition engines (boats, personal vessels, etc.); Recreational vehicles (snowmobiles, mountain motorcycles, all-rounder vehicles, etc.); locomotive; Stationary sources including mobile, non-road engines, devices and vehicles, including aircraft (airplanes, ground support devices, etc.), and 3) hundreds of sources such as power plants, refineries, and manufacturing facilities. In another embodiment, the present invention is directed to providing an exhaust system comprising the substrate, catalytic converter, particle filter, or catalyst muffler of the present invention.

Other systems suitable for the exhaust system of the present invention include those used in certain marine vehicles. The catalyst is typically located in an exhaust pipe connected from the engine. These exhaust pipes are connected to the outlet near the stern through the inboard chamber of the ship. This arrangement makes the exhaust pipe susceptible to vibration, in particular in conventional substrates. In addition, in personal vessels, the size of the space in which the engine can be installed is limited to keep the size of the vessel small and to lower the center of gravity. In addition, certain conventional substrates such as cordierite should not be installed too close to the engine (as there is a possibility of overheating and melting). Exhaust systems for offshore vehicles comprising catalytic converters or particle filters of the present invention may overcome one or more of these problems. The catalytic converter or particle filter may be installed in the marine exhaust system at the same location where the conventional converter or filter is located, or at another location. For example, in one embodiment, the catalytic converter is smaller than a conventional catalytic converter, but has substantially the same efficiency in removing and / or filtering contaminants. An example can be found in US Pat. No. 5,936,313 (Yamaha hatsudoki Kabushiki Kaisha).

In yet another embodiment, the exhaust system of the present invention includes one or more additional aftertreatment devices or methods used to reduce or limit contaminants emitted from the exhaust system. Suitable devices and methods include CRT, EGR, SCR, ACERT, and the like. By way of example, in one embodiment, the exhaust system comprises the catalytic converter and CRT of the present invention. The exhaust system may further comprise an SCR system. Additional combinations and variations are possible and are understood to be included within the scope of the present invention.

In another embodiment, the present invention seeks to provide an exhaust system comprising an NO _x adsorber having a catalyst substrate comprising an nSiRF-C composite and a catalyst. The main-cat is installed in part or in whole in the head of the engine. In one embodiment, the main-cat comprises a catalyst substrate of the present invention, the substrate having a density of about 12 lb / ft ³ , porosity of about 97%, low thermal expansion, high structural integrity, and low thermal conductivity. . In a preferred embodiment, the main-cat has about 600 cpsi and has a wall thickness of about 6 mils. In this embodiment, the main-cat has a wall-flow structure. In a preferred embodiment, the main-cat has a channel. In a preferred embodiment, the catalyst-based channels of the main-cat are prepared using a combing method. Also in this embodiment, the catalyst substrate comprises an optional washcoat. In this embodiment, the main-cat can catalyze both oxidation and reduction of contaminants. For example, the main-cat has the ability to oxidize contaminants and reduce contaminants. In a preferred embodiment, the NO _x combination exhaust system includes an expandable mating. The main-cat can be used in all internal combustion engines. The NO _x combination system is preferably used without a fuel entrained catalyst. In general, the NO _x combination exhaust system has a substrate located near the muffler, and other locations are possible.

vehicle

In another embodiment, the present invention is to provide an improved vehicle comprising a catalytic converter or filtration filter according to the present invention. The improved vehicle includes the various embodiments described above, any particular embodiment of the catalytic converter and the particle filter.

Suitable examples of improved vehicles include vehicles manufactured by one or more of the following companies: Daimler-Chrysler; Chryssler; Dodge; Eagle; Jeep; Plymouth; General Motors; AM General (eg, HUMMERs); Buick; Cadillac; Chevrolet; Geo; GMC; Hummer; LaSalle; Oldsmobile; Poniac; Saturn; Ford; Continental; Lincoln; Mercury; Ace Motor Corp; American Motors; Avanti BMW; Fiat; GAZ; Honda; Mitsubishi; Renault; Peugeot; Toyota; Volkswagen Group; And Yugo.

Example

Example  One

The residence time or incineration time is the time that the hydrocarbons from the exhaust emission stay until completely combusted or oxidized in the emission filter. The residence time of the present invention is much better than conventional systems. FIG. 19 provides a graph of the residence times 1902, 1904, 1906, and 1908 required to burn or incinerate soot at temperatures of 600 degrees Kelvin, 900 degrees Kelvin, 1,000 degrees Kelvin, and 1,200 degrees Kelvin, respectively. The more kinetic energy the particle has, the higher the probability that the reaction will be successful. As shown in FIG. 19, the residence time 1902 for burning or incineration of soot with 0.9 soot mass at 600 degrees Kelvin is much longer than the residence time 1908 at 1200 degrees Kelvin. The longer the residence time, the smaller the allowable treatment volume and the greater the risk that more particles will accumulate and close in the filter pores. The closure may be the result of blocking or closing the pores by overheating the ceramic material to the melting point. Retention time values 1902, 1904, 1906 represent cordierite samples. Retention times 1902, 1904, 1906 range from about 2 minutes to 20 hours to complete combustion. Retention time 1908 represents an embodiment of the present invention and takes only about 0.75 seconds to complete combustion.

Example  2

materials

As described above, the substrates 1 to 7 were manufactured. AETB-12 was purchased from COI Ceramics and used as nSiRF-C with a density of 12 lb / ft ³ selected. Substrates / filters were machined from AETB-12 billets with dimensions 8 × 8 × 4 using standard carbide drill bits using the processing methods described herein. The substrate was processed into a cylindrical shape with the following dimensions: radius 2 in, length 1 in.

The substrates were drilled with flow-through channels, wall-flow channels, and mixed flow-through / wall-flow channels using standard CNC drilling methods described herein and known in the art. The drill in this channel used a stainless steel drill bit with a diameter of 0.042 "at 10,000 RPM. During the drilling process, due to the high heat radiation and conductivity of the material, the drill bit is exposed to a high temperature environment resulting in damage and ultimate melting of the drill bit. This was observed, the wall thickness was not measured.

The substrates 1 and 2 had a flow-through structure. Substrates 3-6 had wall-flow structures. The substrate 3 had about 25% of the channel as flow-through and about 50% of the channel as wall-flow. The substrate 4 had about 50% of the channel as flow-through and about 50% of the channel as wall-flow. The substrates 5, 6 had about 75% of the channels as flow-through and about 25% of the channels as wall-flow.

Some of the substrates were coated with alumina washcoat followed by a catalyst coating with a Pt: Rh ratio of 5: 1. Specifically, the substrates 1, 2, 7 were not coated with any chemicals. Substrates 3, 4, 5, 6 were provided with uniform wash coating utilizing known standard techniques. The mass of washcoat applied to each substrate was provided in a column named Mass of Washcoat. Following washcoating, a catalyst mixture comprising 5: 1 Pt / Rh was applied to the substrates 3, 4, 5, 6 using standard methods. The mass of catalyst mixture applied to each substrate / filter was given in a column named Mass of Catalyst (g / ft ³ ). Substrates with washcoat and precious metal catalyst loads were canned using techniques known in the art.

Example  3

Preparation of Catalyst Substrate and Filter Substrate

The substrate / filter was prepared exactly as described in Example 2 unless explicitly stated.

As a significant difference from the substrate / filter of Example 1, the CNC removes the final depth of 3/4 in into the 1 in slug of the comb assembly, mounts the opposing (mirror) comb assembly to the CNC punch, and The same process as the peking method was used. The final result of this processing method is 600 cpsi with a wall of 6 mils and a wall-flow overlap of 1/2 in. As shown in FIG. 28, the dimensions of the substrate / filter in the wall-flow structure were 1 ″ × thickness 1 ″ in diameter, and the slug inner pattern was 0.8 ″ × 0.8 ″ square. Using this substrate, an early stage successful Delta P-test was performed to observe the pressure drop observed in the N ₂ gas flow due to the disturbance in flow caused by the wall-flow structure. FIG. 29 shows the pressure drop in a reactor-tube flow measurement system as a function of gas flow rate for temperatures of 27 ° C., 29 ° C., and 400 ° C. FIG. 30 shows the pressure drop measured as a function of temperature at a constant flow rate of 125 SLPM in the same reactor. These initial results are positive, indicating that the nSiRF-C substrate / filter does not generate high back pressure in the wall-flow structure.

Example  4

Preparation of Catalyst Substrate and Filter Substrate

The substrate / filter was prepared exactly as described in Example 2 unless explicitly stated.

As a noticeable difference from the substrate of Example 1, ^three were obtained using AETB-11, AETB-12, and AETB-16 with densities of 11, 12, and 16 lb / ft ³ purchased from COI Ceramics, respectively. Different substrates were prepared.

For substrates / filters generated from AETB-11, the final depth of 3/4 in is removed by CNC into the 1 in slug of the comb assembly, the opposing (mirror) comb assembly is mounted on the CNC punch, and the broaching The same process as the method was used. The final result of this processing method is 600 cpsi with a wall of 6 mils and a wall-flow overlap of 1/2 in. For substrates / filters produced from AETB-12 and AETB-16, the final depth of 7/8 in is removed by CNC into the 1 in slug of the comb assembly, and the opposing (mirror) comb assembly is mounted on the CNC punch. The same process as the peking method of broaching was used. The final result of this processing method is 600 cpsi with 6 mil walls and 3/4 in wall-flow overlap.

The dimensions of all substrates / filters tested at this stage were 1 "in diameter and 1" in thickness. The substrate was exposed to another initial stage Delta P-test to observe the pressure drop observed for the wall material and the density of the substrate material as a function of space velocity per hour. This particular test was performed at a temperature of 932 ° F. The results of this test are summarized in FIG. 31. In addition to the data observed for AETB-11, AETB-12 and AETB-16 substrates / filters, the results indicate that Corning has incorporated its 400 / 6.6 flow-through cordierite substrates / filters and 200/12 cordierite DPT ( Wall-flow structure). Corning data was obtained through Corning Technical Reports. The results of the present invention show that Corning DPT in the wall-flow structure causes excessive back pressure compared to the cordierite flow-through filter, while the niRF-C filter of the present invention is used as a cordierite flow- It indicates that back pressure is generated equivalent to through substrate. Since back pressure is a big problem for wall-flow DPTs, as observed in FIG. 31, it is inferred that using wall-flow DPTs made of nSiRF-C materials, such as the invention in this patent, is an excellent alternative. can do. In addition, it can be inferred that increasing the 'overlap' channel length by comparing the back pressures observed in AETB-12 and AETB-16 substrates / filters versus AETB-11 results in better back pressure performance.

32 is the same test run at an operating temperature of 1,100 ° F., and the trend of the results is nearly identical.

Example  5

Preparation of Catalyst Substrate and Filter Substrate

Substrates / filters were prepared as described in Example 2 unless explicitly stated.

AETB-12 was purchased from COI Ceramics and used as nSiRF-C selection material with a density of 12 lb / ft ³ . Laser-based channel drilling techniques were tested to form holes at 3,000 cpsi and 30,000 cpsi. The holes were drilled using the DPSS laser system described in this specification and related prior art. The holes produced by the pulsed, high energy laser system were square in shape and showed a high front surface area due to this particular shape. The presence of a high front surface area (resulting in a large volume for the wall thickness of the channel) was evident in the Delta-P test performed using the same test-flow reactor as described in Example 3. In order for the early stage prototype produced by the laser-based drilling technique to be successful, it was observed that the Delta back pressure should be less than 10 inches of water column. Further changes can be made to reduce (or increase) the cell density and to vary the wall thickness as defined by the needs of the application.

FIG. 33 shows the change in pressure as a function of N ₂ gas flow rate for AETB-12 substrate / filter with 30,000 cpsi cell density at 27 ° C. and 400 ° C. FIG. 34 shows the change in pressure as a function of operating temperature for various N ₂ gas flow rates for an AETB-12 substrate / filter with a 30,000 cpsi cell density.

FIG. 35 shows the change in pressure as a function of N ₂ gas flow rate for AETB-12 substrate / filter with 3,000 cpsi cell density at 29 ° C. and 400 ° C. FIG.

Example  6

Diesel particle filter

The substrate was prepared using an AETB formulation and molded into billets having dimensions of about 13 inches by about 13 inches by about 5 inches and a density of about 8 lb / ft ³ . From the billet, a cylindrical slug of about 6 inches in diameter and 5 inches in length was cut using a saw equipped with a diamond tip. The substrate was further processed on a spinning lathe with accurate tolerances (within 0.001 in).

Next, a plurality of channels are formed in the substrate to accommodate 600 channels per square inch and to form a substrate having a wall-flow structure. The channel is formed using a combination of the drilling and combing techniques described above. The channel has a square shape with dimensions of about 6 mil x about 6 mil. Adjacent walls of adjacent channels are substantially parallel to each other. The channels do not extend through the full length of the substrate and are about 4.9 in long.

Example  7

Gross Surface area  Measure

The first and second cordierite samples have a gross surface area of 33.2 in ² / in ³ and 46.97 in ² / in ³ , respectively. Thus, there is a surface of 33.20 in ² for imparting a precious metal load within 1 in ³ of the first cordierite sample. Samples of the substrate according to the invention have a gross surface area of 83.58 in ² / in ³ .

The gross wall volume for both the first and second cordierite samples is 0.311 in ³ / in ³ . The gross wall volume of the substrate according to the invention is 0.272 in ³ / in ³ . This value is smaller than the first and second cordierite samples, but the present invention has much higher porosity and permeability, making the small gross wall volume more efficient.

Example  8

Activity test

Activity tests measure the amount of contaminants entering and exiting the filter. In the activity test, a sample filter is placed in a reactor and the material is pumped through a gas of known flow and temperature. The activity test then measures the amount of contaminants flowing out of the filter. Referring to FIG. 24, an activity test of an exemplary substrate 2410 of the present invention and a sample 2420 of cordierite is shown. The test measured the activity of toluene at a concentration of 500 ppm and a space velocity of 40,000 / hr. The cell density of both samples was 400 cpsi.

The test indicates that the substrate 2410 of the present invention has a faster ignition time and significantly lower ignition temperature than the cordierite sample 2420. Substrate 2410 was destroyed by 85% in about 3-4 seconds at a temperature of about 335 ° F. Cordierite 2420 was 85% destroyed at about 380 ° F. Subsequently, the substrate 2410 was destroyed 90% in about 4 to 5 seconds at a temperature of about 360 ° F. Cordierite 2420 was 90% destroyed in about 8 seconds at about 450 ° F. Substrate 2410 was 100% destroyed in about 5 seconds at a temperature of about 425 ° F. Cordierite 2420 was expected to experience substantially 100% destruction in about 28 seconds at a temperature of about 800 ° F.

Example  9

Permeability of catalyst substrate

The permeability of the embodiment of Example 2 of the present invention is about 1,093 cd (centidarcies). Other test values exceeded the highest values measured by the test apparatus. In comparison to conventional systems, the sample of cordierite has a permeability of about 268 cd.

Example  9

Example  2, the test of catalytic converter

Similar to the activity test, EPA is a test known as the Federal Test Procedure ("FTP") 75, which utilizes a test that actually mounts a filter into the tailpipe of a vehicle and drives the vehicle under certain conditions. EPA uses this test to verify vehicle emissions. FTP 75 tests the vehicle's condition in three phases. The first step includes crank and non-idle hold and drive for 505 seconds. This stage allows the engine and emission control system to start operating at ambient temperature and reach the optimum level (ie the "ignition" temperature required to effectively control emissions from the engine as the catalyst is cooled down to the partway state through driving). When not running, the state experienced at the start of driving is reflected. The second stage includes 864 seconds of drive, shutdown, and an extra 5 seconds of sampling with non-idle hold. This step reflects the state of the engine when the vehicle has been running continuously long enough for all systems to have a stable operating temperature. Next, the vehicle has a soak time of 540 seconds to 660 seconds. This immersion time reflects the condition of the engine when the ignition is off and not cooled to ambient conditions. The third step includes crank and non-idle hold and drive for 505 seconds. Under these circumstances, the engine and catalyst warm up and are not at peak running efficiency at startup, but still have significantly improved emission performance compared to cold start mode.

Example  11

Thermal test of catalyst substrate

The thermal conductivity of the embodiment according to the present invention is about 0.0604 W / m-K (energy for 1 m thickness and 1 degree Kelvin change, Watt). In comparison, the sample of cordierite is about 1.3-1.8 W / m-K. This result indicates that when 1,000 Watts of thermal energy is lost from a given volume of cordierite material, only 33 Watts are lost from the same volume of material made with the present invention. Thus, the material of the present invention has a thermal conductivity of 30 times greater than cordierite.

The specific heat of an embodiment according to the invention is about 640 J / kg-K. The specific heat of the sample of cordierite is about 750 J / kg-K. Cordierite has a greater specific heat, but cordierite filters have a greater mass to heat. As a result, more thermal energy is required to reach the operating temperature, making cordierite less efficient.

The multiple use temperature limit is the highest temperature at which a substance can be exposed multiple times without any degradation. The higher the temperature at which the substrate can continue operation without microburst or fracture, the less likely the substrate is to break or crack over time. This means that the substrate is more durable over a wide temperature range. The temperature limit is preferably high.

The multiple use temperature limit of the examples according to the invention is 2,980 ° C and the sample of cordierite is about 1,400 ° C. Thus, the material of the present invention can withstand twice the temperature of cordierite until broken. This allows the materials of the present invention to function in a larger range of exhaust environments.

The coefficient of thermal expansion is the ratio of the increase in length (linear coefficient), area (surface), or volume of an object over a given temperature rise (usually from 0 ° C to 1 ° C) over the original length, area, or volume. . The ratio of these three coefficients is approximately 1: 2: 3. Unless specifically expressed, cubic coefficients are usually used. Substrates with less expansion when heated have less chance of leakage, rupture or damage to the filter assembly. Low thermal expansion is desirable to maintain dimensions even when the substrate is heated or cooled.

The coefficient of thermal expansion for an embodiment according to the invention is about 2.65 × 10 ⁻⁶ W / mK, and the sample of cordierite is about 2.5 × 10 ⁻⁶ W / mK to 3.0 × 10 ⁻⁶ W / mK. The thermal expansion of the material of the invention is less than 10 times the thermal expansion of cordierite.

The thermal expansion coefficient of the substrate, in one embodiment, is preferably matched to the thermal expansion coefficient of the washcoat. If the coefficients of thermal expansion are not similar, the washcoat will fracture, delaminate, or "flake", ie, peel off the substrate, resulting in noble metals being blown out or filling the pore space. This eventually increases the back pressure, resulting in overheating and system failure.

Example  13

Structural integrity

The tensile constant of AETB-12 is about 2.21 MPa (mega-Pascal, pressure equal to about 100,000 times one atmosphere). The sample of cordierite is about 25.0 MPa. Cordierite is about 10 times stronger, but the material of the present invention can withstand 200,000 atmospheres of pressure before it bursts. This value is sufficient for the applications described above.

Example  13

Acoustic test

Acoustical properties include reduced thickness, shallowness, tapering; Decrease in density, decrease in force or strength; Or attenuation. In one embodiment of the present invention, acoustic attenuation is the ability of the substrate to dampen or blunt the acoustic energy in the engine exhaust. The description of the present invention may replace or supplement the muffler assembly of the engine as described above, thus reducing exhaust noise and exhaust system costs. Higher acoustic attenuation is desirable.

At present, there are no approved laboratory tests that can be applied to the present invention in any configuration. All acoustic tests of the US Material Test Specification ("ASTM") apply to large spaces such as soundproof rooms, not materials. However, in a solid test with a sound meter, the noise from the automobile was found to be at least decibels less than a vehicle equipped with a conventional muffler when the substrate of the present invention is mounted in an exhaust system. For reference, 110 decibels can cause permanent damage to a person's ear, and 60 decibels is the amount of noise produced by a luxury car with the windows closed.

Example  14

Comparison to Prior Art Substrates

Samples of a suitable nSiRF-C (AETB-12) were compared with cordierite and SiC by measuring numerical values of the properties.

In one embodiment, the substrate of the present invention has 600 cpsi with a wall thickness of 6 mils. The cell density of the sample substrate of the present invention is compared with two cordierite samples. In comparison, the first and second cordierite samples were 100 cpsi with a wall thickness of 17 mils and 200 cpsi with a wall thickness of 12 mils, respectively. In comparison, the substrate of the present invention has 600 cpsi with a wall thickness of 6 mils.

In this embodiment, the substrate is perforated with a 0.04 in diameter channel at 0.06 in intervals across the filter. These channels are smaller than conventional cordierite channels. As a result, a greatly increased surface area is obtained compared to cordierite without considering the surface area present in many pore spaces of the base material. The channel is preferably a "blind" channel. Exhaust emissions do not enter and exit the channel without reacting with the catalyst and are forced through the channel.

The channel is drilled using a CNC drill, which is computer controlled to maintain uniformity. The drilling process is carried out with constant spraying of water to prevent dust from entering the bearings of the drill as OSHA pests, which can break the bearings, into the air.

The drilled substrate is dried in an oven to push or bake out any moisture or other liquid that may remain in the pore space before any catalyst application is made. The baking time is not a variable and the evaporation of water can be determined by simply measuring the weight of the substrate. Baking time mainly accelerates the dehydration process. After the filter elements have been heated at various different intervals and the weight is constant, the substrate is ready for any catalyst or coating application.

Glossary of Terms

As used herein, the term "substrate" means a solid surface from which contaminants can be converted to non-contaminants. The substrate is understood to include a filter element, a catalyst substrate or a filtration substrate.

The term "high grade fire resistant fiber" as used herein.

As used herein, the term "sintered material" means a material that is heated without melting.

The term "nonwoven" as used herein means that there is no entangled or woven pattern of fibers.

As used herein, the term " billlet " means a block of base material that is not molded or processed.

As used herein, the term "green billet" refers to an uncured billet.

As used herein, the term "front" means a surface through which fluid enters the substrate. In one embodiment, the channel has an opening in the front, and the channel is perpendicular to the front.

The term "back side" as used herein refers to the surface through which fluid flows out of the substrate. In one embodiment, the channel has an opening in the back, and the channel is perpendicular to the back.

As used herein, the term "mil" refers to a unit of measurement and is equal to 1/1000 in.

The term "light off temperature" as used herein refers to the temperature at which the conversion of the reaction in the catalytic converter is 50%. That is, is the temperature at which one or more contaminants, or 50% of the total contaminants, are converted to non-contaminants.

As used herein, the term "burn off" refers to the process of burning particulate matter and other materials filtered by a substrate. For example, incineration can occur in diesel particulate filters (DPF).

As used herein, the term "channel" refers to a three-dimensional opening in a substrate that extends through at least a portion of the substrate and has a clear shape and length.

As used herein, the term "channels per square inch (cpsi)" refers to the number of channels present in one square inch of cross section of a substrate. It is synonymous with the term cell per square inch.

The term "channel shape" as used herein refers to the three-dimensional shape of the channel.

The term "PM" as used herein refers to particulate matter. Common measurements of PM include PM-10 and PM-2.5.

The term "gross surface area" as used herein refers to the total surface area and refers to the total surface area where the precious metal can be impregnated in one cubic inch.

As used herein, the term "binary catalytic converter" refers to a catalytic converter that oxidizes only gaseous contaminants, HC and CO, to CO ₂ and H ₂ O.

The term "three-way catalytic converter" as used herein refers to a catalytic converter which oxidizes CO and HC to CO ₂ and H ₂ O and also reduces NO _x to N ₂ .

As used herein, the term "four-way catalytic converter" refers to a catalytic converter that performs oxidation and reduction as described for a three-way catalytic converter, as well as captures particulate matter for incineration (regeneration in an active or passive manner). This can happen).

As used herein, the term "suitable for use" means compliance with the requirements of specific regulatory guidelines.

As used herein, the term "section distance" means.

As used herein, the term "aftertreatment system" means.

The term "thermal conductivity" as used herein refers to the unit through the unit area of the plate when there is a unit temperature gradient (i.e., a 1 degree temperature difference across a unit thickness) on the opposite side of the plate of a given material. It means the amount of heat passing through time.

As used herein, the term "matting" refers to any material used to provide thermal insulation and / or protection for a substrate. Matting is also sometimes referred to as batting.

As used herein, the term "boron binder" refers to an agent derived from a boron binder present in nSiRF-C after a sintering process.

As used herein, the term "pecking" refers to the process of forming or reshaping a channel in a substrate in a manner that is repeatedly inserted into and removed from the substrate by applying force to the tine until the desired length of the channel is obtained. do.

Having described the invention above, it will be understood by those skilled in the art that the invention can be practiced over a wide range of equivalent conditions, formulations and other parameters without affecting the scope of the invention or embodiments of the invention. All patents and documents cited herein are incorporated by reference in their entirety.

Claims (47)

Non-woven sintered refractory fibrous ceramic composites and catalysts, Optionally, further comprising a washcoat, Optionally, further comprising a plurality of channels Catalyst substrate or filtration substrate. The method of claim 1, Catalyst substrate, characterized in that the composite comprises alumina-boria-silica fibers. The method of claim 1, Catalyst substrate, characterized in that the composite comprises alumina-zirconia fibers. The method of claim 1, A catalyst substrate, characterized in that the composite comprises alumina-boria-silica fibers and alumina fibers. The method of claim 1, Catalyst substrate, characterized in that the composite comprises alumina-oxide fibers. The method of claim 1, A catalyst substrate, characterized in that the composite comprises silica-oxide fibers. The method of claim 1, A catalyst substrate, characterized in that the composite comprises alumina boria silica fibers, silica fibers, and alumina fibers. The method of claim 1, Wherein the composite comprises about 50% to about 90% silica, about 5% to about 50% alumina, and about 10% to about 25% aluminoborosilicate. The method of claim 1, A catalyst substrate, characterized in that the composite is an alumina enhanced thermal barrier (AETB) composite. The method of claim 9, A catalyst substrate, characterized in that the AETB is selected from the group consisting of AETB-8, AETB-12, AETB-14 and AETB-16. The method of claim 1, A catalyst substrate, characterized in that the composite is an Orbital Ceramics Thermal Barrier (OCTB) composite. The method according to any one of claims 1 to 11, Catalyst substrate, characterized in that the composite comprises a boron binder. The method according to any one of claims 1 to 12, Catalyst substrate, characterized in that the catalyst comprises a metal catalyst. The method according to any one of claims 1 to 13, A catalyst substrate, characterized in that the catalyst is selected from the group consisting of palladium, platinum, rhodium, mixtures thereof and derivatives thereof. The method according to any one of claims 1 to 14, A catalyst substrate, characterized in that the catalyst is present in an amount of about 1 to about 50 g / ft ³ . The method according to any one of claims 1 to 15, Catalyst substrate, characterized in that the washcoat comprises aluminum oxide. The method according to any one of claims 1 to 16, A plurality of channels extending longitudinally through the substrate, the substrate comprising a wall flow configuration, a flow through configuration, or a combination thereof. The method according to any one of claims 1 to 17, A catalyst substrate, having from about 100 to about 100,000 channels per square inch. The method according to any one of claims 1 to 18, A catalytic substrate having about 600 channels per square inch. The method according to any one of claims 1 to 19, Said channel comprising square, triangular, hexagonal shapes and having a longitudinal cross-sectional shape that is substantially rectangular, trapezoidal or triangular. The method according to any one of claims 1 to 20, A catalyst substrate having a frontal surface area of about 1 in ² to about 50 in ² . The method according to any one of claims 1 to 21, A catalyst substrate, characterized in that it is suitable for use in commercially available catalytic converters or diesel oxidation catalysts (DOCs). The method according to any one of claims 1 to 21, Catalyst substrate, characterized in that it is suitable for use with stationary engines. The method according to any one of claims 1 to 21, A catalyst substrate characterized by being suitable for use in head-cat, mani-cat, or pre-cat. The method according to any one of claims 1 to 21, A catalyst substrate, having a density of about 6 to about 16 lb / ft ³ . The method according to any one of claims 1 to 25, Catalytic substrate, characterized in that the substrate has an emissivity of about 0.8 to about 0.95. The method according to any one of claims 1 to 26, Catalyst substrate, characterized in that the substrate has a porosity of about 90% to about 99%. The method according to any one of claims 1 to 27, A catalyst substrate, further comprising oxygen storing oxide. The method according to any one of claims 1 to 28, The substrate is a catalyst substrate, characterized in that it causes a pressure drop lower than the pressure drop caused by cordierite. A catalytic converter comprising the catalyst substrate according to any one of claims 1 to 29. The method of claim 30, The converter is characterized in that it is suitable for use in commercial vehicles. The method of claim 31, wherein The converter is selected from the group consisting of a main-cat, a pre-cat, a back-cat, or a mani-cat. A particulate filter comprising the catalyst substrate or filtration substrate according to any one of claims 1 to 29. The method of claim 33, wherein The filter is a particle filter, characterized in that the diesel particle filter. As a method of catalyzing the reaction, 33. A method of catalysis comprising exposing a flow of one or more fluids to the catalyst substrate or catalytic converter of any one of claims 1 to 32. 36. The method of claim 35 wherein The fluid is exhaust gas from an internal combustion engine. The method of claim 36, And said exhaust gas comprises at least one of six criteria pollutants. As a filtration method of gas, 35. A method of filtration comprising exposing the flow of one or more fluids to the filtration substrate, catalyst substrate, particle filter or catalytic converter of any one of claims 1 to 34. The method of claim 38, And the fluid is exhaust gas from an internal combustion engine. The method of claim 39, Wherein said exhaust gas comprises at least one of six reference contaminants. A method for producing the catalyst substrate or the filtration substrate according to any one of claims 1 to 29, Heating the plurality of refractory silica fibers, refractory alumina fibers and refractory aluminoborosilicate fibers; Mixing the fibers; Washing the fibers; Optionally chopping the fibers to one or more lengths; Blending or mixing the chopped fibers into a slurry; Adjusting the viscosity of the slurry, preferably by adding a thickener; Adding a dispersant; Injecting the slurry into a mold; Removing water from the slurry to form a green billet; Removing the green billet from the mold; Drying the green billet in an oven, preferably at a temperature of about 250 ° F. to about 500 ° F .; Heating the green billet in an oven, preferably preheating and gradually at about 2,000 to 2500 ° F .; Optionally machining the billet; Optionally forming a plurality of channels in the billet; Optionally adding a catalyst; And Optionally, adding a washcoat to form the substrate Method for producing a catalyst substrate or filtration substrate comprising a. A method for producing the filtration substrate according to any one of claims 1 to 29, Machining a plurality of channels in the nonwoven sintered refractory fibrous ceramic composite, The machining step includes using a combinatorial method of forming or shaping the channel. Method for producing a filtration substrate. 43. A filtration substrate prepared according to the method of claim 42 or 43. A composition comprising refractory grade alumina fibers, refractory grade silica fibers, refractory grade alumina boria silica fibers, water and a catalyst. The method of claim 44, Wherein the fibers have an average length of about 10 μm. The method of claim 44, Wherein the alumina comprises about 50-90% of an inorganic fiber mix, the alumina fiber comprises about 5-50% of an inorganic fiber mix, and the alumina boria silica comprises about 10-25% A composition, characterized in that. 35. An improved engine exhaust system comprising the catalyst substrate, filtration substrate, catalytic converter, or particle filter of any one of claims 1 to 34.

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