EP0424377A1 - Reduction de la temperature d'inflammation de suie de carburant diesel - Google Patents

Reduction de la temperature d'inflammation de suie de carburant diesel

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Publication number
EP0424377A1
EP0424377A1 EP88910353A EP88910353A EP0424377A1 EP 0424377 A1 EP0424377 A1 EP 0424377A1 EP 88910353 A EP88910353 A EP 88910353A EP 88910353 A EP88910353 A EP 88910353A EP 0424377 A1 EP0424377 A1 EP 0424377A1
Authority
EP
European Patent Office
Prior art keywords
diesel
soot
titania
filter
zirconia
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP88910353A
Other languages
German (de)
English (en)
Inventor
Edwin H. Homeier
George C. Joy, Iii
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Honeywell International Inc
Original Assignee
AlliedSignal Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by AlliedSignal Inc filed Critical AlliedSignal Inc
Publication of EP0424377A1 publication Critical patent/EP0424377A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J35/56—
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
    • F01N3/0231—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using special exhaust apparatus upstream of the filter for producing nitrogen dioxide, e.g. for continuous filter regeneration systems [CRT]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/033—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices
    • F01N3/035—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices with catalytic reactors, e.g. catalysed diesel particulate filters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2882—Catalytic reactors combined or associated with other devices, e.g. exhaust silencers or other exhaust purification devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2250/00—Combinations of different methods of purification
    • F01N2250/02—Combinations of different methods of purification filtering and catalytic conversion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B1/00—Engines characterised by fuel-air mixture compression
    • F02B1/02—Engines characterised by fuel-air mixture compression with positive ignition
    • F02B1/04—Engines characterised by fuel-air mixture compression with positive ignition with fuel-air mixture admission into cylinder
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B3/00—Engines characterised by air compression and subsequent fuel addition
    • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • Diesel engines enjoy an advantage over gasoline engines in that the diesel engines are much more fuel efficient than gasoline engines. It is well known that the gaseous waste products, hydrocarbons, pcarbon monoxide and nitrogen oxides, from gasoline engines pose a serious health problem to the population at large. In addition to these gaseous pollutants, diesel engines also emit "soot" particles comprising carbonaceous solids containing adsorbed hydrocarbons and inorganic compounds or very fine droplets of condensate or a conglomerate of the two "particulates". The "particulates” referred to herein as “diesel soot" are particularly rich in condensed polynuclear hydrocarbons, some of which have been found to be carcinogenic.
  • Ceramic and metallic filters have proven to be the best technology available to deal with this problem.
  • the literature also shows that ceramic filters are preferred over metallic filters because the ceramic filters are apparently more durable.
  • Ceramic filters have been described in the prior art and can be divided into two categories: 1) foam type and 2) honeycomb wall-flow type. Ceramic foam filters have been described in U.S. Patent 4,083,905. This type of filter is prepared by . depositing a ceramic material onto an organic sponge and sintering said sponge at a high temperature to burn out the organic sponge material.
  • honeycomb wall-flow type filters are very similar to the honeycomb substrates used as catalyst structural supports for gasoline engine pollution control applications, except that alternate flow channels are closed on each face of the substrate.
  • the channels are plugged in such a manner that a channel open on one face is closed at the opposite face.
  • Such filters are called “wall-flow filters” because the exhaust flows down a channel and must go through the walls of the channel which are macroporous in order to exit.
  • These filters are described in U.S. Patent Nos. 4,329,162, 4,340,403, 4,364,760 and 4,423,090.
  • These wall-flow filters have been used more extensively than the foam filters because the wall-flow filters more efficiently trap the diesel soot.
  • the biggest drawback to these filters is that the diesel soot accumulates, clogging the filter, thereby causing an undesirable backpressure on the engine.
  • the reason for this accumulation is that diesel soot ignites at about 650°C, but the maximum exhaust temperature in a diesel vehicle is only about 300°-400°C. Therefore, the diesel soot continues to build up and causes excessive backpressure on the engine which results in a decrease in fuel economy and eventually may cause damage to the engine. To alleviate this problem, the diesel soot must be burned off.
  • the first approach has many disadvantages including: 1) reduction of fuel economy; 2) complexity of the control system; and 3) reliability of the overall system.
  • the second approach is much simpler and more reliable.
  • the major problem with the second approach is developing a catalytic composite which lowers the ignition temperature of the diesel soot so that combustion of the diesel soot occurs during normal operating conditions.
  • diesel fuel typically contains at least ten times more sulfur compounds than gasoline fuel.
  • the low temperature of the diesel exhaust facilitates the production and storage of sulfates and sulfuric acid which contribute to the particulate emissions during high temperature modes, like regenerations.
  • U.S. Patents 4,515,758 and 4,588,707 teach the use of rhenium plus substances such as lithium oxide, copper chloride, vanadium oxide and optionally a noble metal. Again the noble metal is used only for treating the gaseous emissions. These patents also teach that the soot burning elements, i.e. rhenium, lithium oxide, etc. are deposited on an inorganic oxide support such as alumina, titania, etc.
  • the present invention provides a process to reduce the ignition temperature of diesel soot comprising contacting a hot exhaust from a diesel engine with a catalytic composite comprising a particulate filter having deposited thereon a sulfur resistant refractory inorganic oxide such as titania, zirconia, etc. and dispersing on said oxide at least one catalytic element selected from the group consisting of Pt, Pd and Rh.
  • the present invention shows unexpected results in lowering the ignition temperature of diesel soot.
  • This invention relates to a process for reducing the ignition temperature of diesel soot in a hot exhaust gas from an internal combustion diesel engine comprising contacting said exhaust gas at combustion conditions with a catalytic composite comprising a particulate filter having deposited thereon a sulfur resistant refractory inorganic oxide support selected from the group consisting of titania, zirconia, alumina treated with titania, alumina treated with zirconia and mixtures thereof, said support having deposited thereon a catalytic element or compound selected from the group consisting of Pt, Pd, Rh and mixtures thereof.
  • one specific embodiment of the invention comprises a process for reducing the ignition temperature of diesel soot in an exhaust gas from a diesel engine, said exhaust gas containing at least carbon monoxide, hydrocarbons, nitrogen oxides, soot particles and sulfur oxides.
  • the process comprises contacting at combustion conditions said exhaust gas with a catalytic composite comprising a ceramic honeycomb wall-flow filter coated with a layer of a titania support and having dispersed thereon a platinum component.
  • the present invention relates to a process for reducing the ignition temperature of diesel soot in the hot exhaust gas from a diesel engine.
  • the process comprises contacting at combustion conditions the hot exhaust gas with a catalytic composite comprising a particulate filter coated with at least one sulfur resistant refractory inorganic oxide support selected from the group consisting of titania, zirconia, silica, silica-alumina and aluminas treated to improve sulfur resistance, such as alumina treated with titania, tungsten oxide, zirconia, etc., said support having dispersed thereon at least one catalytic element or compound selected from the group consisting of Pt, Pd and Rh.
  • sulfur resistant refractory * oxide it is intended to cover those oxides that do not form a stable sulfate when exposed to S0 2 and 0 2 at a temperature of 300 to 400°C.
  • the inorganic refractory oxide and the catalytic element may be deposited on several types of particulate filters .
  • These filters include metallic and ceramic particulate filters.
  • ceramic filters can be divided into two categories; 1) foam type and 2) honeycomb wall-flow type being preferred.
  • ceramic filters When ceramic filters are employed, it is important that the ceramic material be inert and therefore unreactive with the refractory inorganic oxide coating and with the gas to which it is exposed.
  • suitable ceramic materials include sillimanite, petalite, cordierite, mullite, zircon, zircon mullite, spodumene, alumina, alumina-titanate, etc.
  • the desired ceramic or metallic particulate filter can be washcoated using a slurry or dispersion of one or more sulfur resistant refractory inorganic oxides.
  • the preparation of slurries and methods of washcoating a filter element with a slurry are well known in the art.
  • the appropriate amount of oxide is combined with water and an acid such as nitric, hydrochloric, sulfuric acid, etc.
  • the resultant slurry is milled for 2 to 6 hours and then used to deposit a thin film or washcoat onto a filter substrate.
  • the quantity of washcoat to be applied to a filter element is less critical with regard to the lower limit than with regard to the upper limit.
  • a minimum amount will be when the filter element contains about 0.20 grams of washcoat per cubic inch (12.2 g/1) of filter volume.
  • the upper range is limited by the maximum permissible backpressure which the filter exerts on the diesel engine. Accordingly, an appropriate range is from about 0.2 g/in 3 (12.2 g/1) to about 3.5 g/in 3 (213.6 g/1) with a preferred range being from about 0.8 g/in 3 (48.8 g/1) to about 2.5 g/in 3 (152.6 g/1) .
  • titania is used as the inorganic oxide support.
  • the titania support has a specific surface area ranging from about 1 to about 200 m 2 /g and more preferably ranges from about 25 to about 100 m 2 /g.
  • a slurry can be prepared by combining the appropriate amount of titania with water and nitric acid. The resultant slurry is milled for 2 to 6 hours and used to deposit a thin film or washcoat of titania on the filter element. It is preferred that the washcoat deposit be present on the filter element in an amount in the range from about 0.8 g/in 3 to about 2.5 g/in 3 (48.8 g/1 to about 152.6 g/1).
  • the catalytic element can be dispersed onto a sulfur resistant refractory inorganic support by conventional methods found in the prior art.
  • the preferred method involves impregnating the filter element after it has been coated with a sulfur resistant refractory inorganic oxide with a water soluble decomposable compound of the appropriate catalytic element, calcining the resultant impregnated filter element at a temperature of about 350° to about 650°C, optionally reducing the catalytic element with a reducing agent well known in the art and recovering the resultant catalytic composite.
  • the sulfur resistant refractory inorganic oxide can first be impregnated with a water soluble decomposable compound of the appropriate catalytic element, the resultant mixture calcined at a temperature of about 350° to about 650°C in air, optionally reducing the dispersed catalytic element with a reducing agent known in the art, preparing a slurry from the resultant catalytically active oxide support and .. depositing said support onto a filter element. It is to be noted, however, that the two methods of preparation do not give equivalent results.
  • a filter element that has been coated with a titania washcoat is impregnated with an aqueous solution of chloroplatinic acid. Subsequently, the impregnated filter element is dried and calcined at a temperature of 450° to 550°C in air.
  • Other water soluble platinum compounds or complexes may be employed to prepare the impregnation solutions. These include ammonium chloroplatinate, bromoplatinic acid, platinum trichloride ⁇ platinum tetrachloride hydrate, platinum dichlorocarbonyl dichloride, dinitrodiamino platinum, sodium tetranitroplatinate.
  • a platinum compound such as chloroplatinic acid
  • Hydrogen chloride, nitric acid or other suitable materials may be added to the solution in order to further facilitate the uniform distribution of the metallic components through the titania support material.
  • the platinum metal is present in an amount from 5 to 250 g of platinum per cubic foot (0.18 to 8.8 g/1) of volume particulate filter. If a palladium component is desired, the palladium component may be impregnated by utilizing an aqueous solution of chloropalladic acid.
  • palladium chloride palladium nitrate
  • palladium dioxide palladium dioxide
  • diamminopalladium hydroxide diamminopalladium hydroxide
  • tetramminepalladium chloride a water soluble compound or complexes of palladium
  • the palladium is present in an amount from 5 to 250 g of palladium per cubic foot (0.18 to 8.8 g/1) of volume of particulate filter.
  • the rhodium component may be impregnated by utilizing an aqueous solution of rhodium trichloride.
  • rhodium water soluble compounds or complexes of rhodium may be employed such as hexamminerhodiu chloride, rhodium carbonylchloride, rhodium trichloride hydrate, rhodium nitrate, sodium hexachlororhodate, and sodium hexanitrorhodate.
  • the rhodium is present in an amount from about 2 to about 70 g of rhodium per cubic foot (0.07 to 2.47 g/1) of volume of particulate filter.
  • the essential feature of the present invention is the combination of a sulfur resistant refractory oxide support and a noble metal catalytic element.
  • Diesel fuel contains large amounts of sulfur compounds which are converted to sulfur oxides during the combustion process. Since a diesel exhaust environment virtually always contains excess oxygen, compounds such as sulfur dioxide (S0 2 ) can react with the oxygen over the catalyst to yield sulfites or sulfates. These sulfites or sulfates in turn can react with a conventional refractory inorganic oxide such as alumina to form stable sulfates, i.e. A1 2 (S0 4 ) 3 . The result is that catalyst activity quickly deteriorates. Alumina can accumulate sulfates, which are then released when the temperature is raised.
  • titania and zirconia do not form stable sulfates under gasoline fueled engine exhaust. Therefore, one would expect less sulfate storage and better durability for diesel applications.
  • a noble metal catalytic element such as platinum
  • EXAMPLE I In order to facilitate obtaining data, all measurements were conducted on conventional honeycomb substrates, i.e. all flow channels open, instead of wall- flow honeycomb substrates. A special procedure was also developed to accurately determine the activity of the various catalytic composites. The first part of the procedure involved depositing diesel soot onto the catalytic composite. A catalytic composite was placed in ⁇ a demountable catalyst holder and placed in the exhaust of a diesel vehicle which was driven over a prescribed cycle on a chassis dynamometer. The diesel vehicle used for this purpose was a 1977 International Harvester diesel Scout equipped with an indirect injected 3.2 liter six cylinder engine. Commercial number two diesel fuel was used to run the vehicle. The driving cycle which was used to deposit the soot onto the catalytic composite is described in Table 1. The maximum temperature at the inlet of the catalytic composite was maintained at 288°C by adjusting the dynamometer load. The cycle was run for 48 hours. Mode
  • the second part of the procedure involved evaluating the activity of the catalytic composite in a laboratory test apparatus after the soot was deposited.
  • Cylindrical cores measuring 2.22 cm in diameter by 1.27 cm high, were drilled and cut from the catalytic composite after the 48 hour sooting cycle.
  • a slice was placed in a reactor which in turn was placed in a vertical furnace.
  • a synthetic gas feed was flowed over the solid catalyst slice being tested.
  • the feed gas composition was selected to simulate a highly oxidizing diesel exhaust gas except that C0 2 was absent. This gas composition is summarized in Table 2.
  • the temperature at the catalyst inlet position was increased from 120°C to 750°C at 15°C/minute with 15 minute holds at 300, 350, and 400°C.
  • the analysis of the product gas for CO, C0 2 , C 3 H 8 and 0 permitted determination of soot-carbon (i.e., carbon and adsorbed hydrocarbon) burning rate versus the inlet temperature.
  • a conventional catalytic composite was prepared by the following method.
  • a dilute solution of nitric acid (HN0 3 ) was prepared by adding 285 g of concentrated nitric acid to a container which contained 8000 L of deionized water. This solution was stirred and to it there were added 5300 grams of gamma alumina. The resultant slurry was ball milled for 2.0 hours.
  • An oval shaped cordierite monolith with a minor axis of 3.2 inches (8.1 cm), a major axis of 5.7 inches (14.5 cm), a length of 5 inches (12.7 cm) and having 400 square channels per square inch of facial area was dipped into the slurry. After dipping, the excess slurry was blown out with an air gun.
  • the slurry coated monolith was calcined for about 2 hours at 540°C.
  • the above described dipping, blow out and calcining steps were repeated until the monolith contained 1.5 g of alumina per cubic inch (91.5 g/1) of monolith volume.
  • the platinum metal was impregnated onto the above-described washcoated monolith.
  • the above-described monolith was dipped into an aqueous solution containing 1.7 g of chloroplatinic acid. After dipping, the excess solution was blown out with an air gun and calcined for about 2 hours at 540°C.
  • This catalytic composite was designated Catalyst A. Analysis of this composite showed a platinum content of 15 g Pt per cubic foot (0.53 g/1) of support.
  • EXAMPLE III An catalytic composite was prepared by the following method.
  • a dilute solution of nitric acid (HN0 3 ) was prepared by adding 28.1 g of concentrated nitric acid to a container which contained 9100 mL of deionized water. This solution was stirred and to it there were added 3600 grams of titania. The resultant slurry was ball milled for 3 hours.
  • An oval shaped cordierite monolith with a minor axis of 3.2 inches (8.1 cm), a major axis of 5.7 inches (14.5 cm), a length of 5 inches (12.7 cm) and having 400 square channels per square inch of facial area was dipped into the above-described slurry. After dipping, the excess slurry was blown out with an air gun.
  • the slurry coated monolith was calcined for about 1 hour at 540°C.
  • the above-described dipping, blow-out and calcining steps were repeated until the monolith contained 1.5 g per cubic inch (91.5 g/1) of monolith volume.
  • the platinum metal was impregnated onto the above-described washcoated monolith.
  • the above-described monolith was dipped into an aqueous solution containing 1.7 g of chloroplatinic acid. After dipping, the excess solution was blown out with an air gun and calcined for about 2 hours at 540°C.
  • This catalytic composite was designated Catalyst B. Analysis of this composite showed a platinum content of 17 g Pt per cubic foot (0.6 g/1) of support. The platinum content of this composite is equivalent to that of Catalyst A within experimental error of the analysis.
  • a dilute solution of nitric acid (HN0 3 ) was prepared by adding 285 g of concentrated nitric acid to a container which contained 8000 mL of deionized water.
  • EXAMPLE V A dilute solution of nitric acid (NH0 3 ) was prepared by adding 28.1 g of concentrated nitric acid to a container which contained 9100 mL of deionized water. This solution was stirred and to it there were added 3600 grams of titania. The resultant slurry was ball milled for 3 hours. An oval shaped cordierite monolith with a minor axis of 3.2 inches (8.1 cm), a major axis of 5.7 inches (14.5 cm), a length of 5 inches (12.7 cm) and having 400 square channels per square inch of facial area was dipped into the above-described slurry. After dipping, the excess slurry was blown out with an air gun.
  • the slurry coated monolith was calcined for about 1 hour at 5 0°C.
  • the above-described dipping, blow-out and calcining steps were repeated until the monolith contained 1.5 g per cubic inch (91.5 g/1) of monolith volume. This * sample was designated Sample D.
  • Samples A, B, C and D were cut lengthwise into quarter sections and recombined to form a complete honeycomb monolith by cementing the quartered sections together with Sauereisen Number 8, a ceramic adhesive.
  • this combined monolith was put into the exhaust of a diesel engine and then evaluated according to the procedures set forth in Example I.
  • the results of the laboratory evaluations are presented in Table 3.
  • Table 3 clearly shows that platinum dispersed on titania (Sample B) burns considerably more soot at 350°C than platinum dispersed on alumina (Sample A) .
  • Table 3 also shows the unexpected results that titania (Sample D) is better at combusting diesel soot than alumina (Sample C) at 400°C.
  • the combination of platinum and titania leads to the unexpected lowering of the diesel soot combustion temperature from 400°C to 350°C.
  • ⁇ 'Efficiency is defined as the percentage of diesel soot combusted at the indicated temperature.

Abstract

Le procédé décrit, qui sert à abaisser la température d'inflammation de la suie provenant d'un carburant diesel, consiste à mettre en contact des gaz d'échappement chauds provenant d'un moteur Diesel, lesquels contiennent de la suie de carburant diesel, à des conditions de combustion, avec un composite catalytique comprenant un filtre particulaire recouvert d'un support d'oxyde inorganique réfractaire résistant au soufre et choisi dans le groupe composé de dioxyde de titane, de zircone, d'alumine traitée avec du dioxyde de titane ou avec du zircone et de mélanges de ces divers éléments, au moins un élément ou un composé catalytiques choisis dans le groupe composé de Pt, de Pd, de Rh et de mélanges de ces divers éléments étant déposés sur ledit support.
EP88910353A 1988-07-13 1988-07-13 Reduction de la temperature d'inflammation de suie de carburant diesel Withdrawn EP0424377A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1988/002379 WO1990000439A1 (fr) 1988-07-13 1988-07-13 Reduction de la temperature d'inflammation de suie de carburant diesel

Publications (1)

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EP0424377A1 true EP0424377A1 (fr) 1991-05-02

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EP (1) EP0424377A1 (fr)
JP (1) JPH03505836A (fr)
WO (1) WO1990000439A1 (fr)

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Publication number Priority date Publication date Assignee Title
JP2821033B2 (ja) * 1991-01-07 1998-11-05 株式会社日本触媒 ディーゼルエンジン排ガス浄化用触媒
US5145825A (en) * 1991-04-08 1992-09-08 Engelhard Corporation Oxidation catalyst resistant to sulfation
FI90830C (fi) * 1992-04-23 1994-04-11 Kemira Oy Katalysaattori dieselpakokaasujen puhdistukseen

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Publication number Priority date Publication date Assignee Title
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Non-Patent Citations (1)

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Title
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WO1990000439A1 (fr) 1990-01-25

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