KR101532444B1 - Treatment of Cold Start Engine Exhaust - Google Patents

Abstract

(1) an 8-membered ring selected from the group consisting of SSZ-13, SSZ-16, SSZ-36, SSZ-39, SSZ-50, SSZ- (B) a molar ratio of an oxide of a trivalent element, a pentavalent element, a quadrivalent quadrivalent element different from the primary quadrivalent element, or an oxide of a mixture thereof to the primary quadrivalent element is at least 10 (2) a mixture of small pore crystalline molecular sieves or molecular sieves having an average particle size of from about 1 to about 10 nm, and (2) a mixture of SSZ-26, SSZ-33, SSZ-64, zeolite beta, CIT-1, CIT-6 and ITQ- (A) an oxide of a primary quadrivalent element, (b) a quadrivalent quadrivalent element which is different from a trivalent element, a pentavalent element, and a primary quadrivalent element, Or a mixture of oxides of these oxides is at least 10, is contacted with the effluent gas stream to form an effluent gas stream (Such as from an internal combustion engine). ≪ RTI ID = 0.0 > [0002] < / RTI >

Cold start discharge, molecular sieve, pore, zeolite

Description

{Processing of Cold Start Engine Exhaust}

The present invention relates to the treatment of cold start engine emissions with specific zeolites having different pore sizes.

Gaseous waste products generated by combustion of hydrocarbonaceous fuels such as gasoline and fuel oil contain carbon monoxide, hydrocarbons and nitrogen oxides as combustion or incomplete combustion products and present serious health problems associated with air pollution. Exhaust gases from other hydrocarbon fuel-burning sources, such as stationary engines, industrial furnaces, etc., contribute substantially to air pollution, while exhaust gases from automotive engines are a major source of pollution. Because of this interest in health issues, the US Environmental Protection Agency (EPA) has published stringent controls on the amount of carbon monoxide, hydrocarbons and nitrogen oxides emitted by automobiles. The implementation of such regulation has led to the use of catalytic converters to reduce the amount of pollutants emitted from the vehicle.

In order to achieve simultaneous conversion of carbon monoxide, hydrocarbons and nitrogen oxide pollutants, the use of catalysts with air-to-fuel ratio control means functioning in response to feedback signals from oxygen sensors in engine exhaust systems has been implemented. Although these three component conditioning catalysts work very well after reaching an operating temperature of about 300 ° C, at lower temperatures the catalysts do not convert substantial amounts of contaminants. This means that when the engine and especially the car engine are shut down, the three component conditioning catalysts can not convert hydrocarbons and other contaminants into harmless compounds.

The adsorbent bed has been used to adsorb hydrocarbons during the cold start portion of the engine. Although the process is generally used with hydrocarbon fuels, the adsorbent layer can also be used to treat an exhaust stream from an alcohol-fueled engine. The adsorbent layer is generally located just before the catalyst. As a result, the effluent stream primarily flows through the adsorbent bed and then flows through the catalyst. The adsorbent layer preferably adsorbs hydrocarbons on water under the presence of an effluent stream. After a period of time, the adsorbent layer reaches a temperature at which the layer is no longer able to remove hydrocarbons from the exhaust stream (typically about 150 ° C). That is, the hydrocarbons are desorbed from the adsorbent layer instead of being substantially adsorbed. This makes it possible to regenerate the adsorbent bed and to adsorb the hydrocarbons during the subsequent cold start.

The prior art teaches a number of references dealing with the use of adsorbent beds to minimize hydrocarbon emissions during cold start engine operation. One such reference is U.S. Patent No. 3,699,683, wherein the adsorbent layer is located behind both the reduction catalyst and the oxidation catalyst. The patentees disclose that when the effluent gas stream is below 200 ° C, the gas stream flows through the reduction catalyst, then flows through the oxidation catalyst, and finally flows through the adsorbent bed to adsorb hydrocarbons on the adsorbent bed . When the temperature is higher than 200 ° C, the gas stream discharged from the oxidation catalyst is separated into a main portion and a minor portion, the major portion is directly discharged to the atmosphere, the minor portion desorbs unburned hydrocarbons by passing through the adsorbent layer, The fractional part of the discharge stream containing the unburned hydrocarbons flows into the engine where it is burned.

Another reference is U.S. Patent No. 2,942,932, which teaches how to oxidize carbon monoxide and hydrocarbons contained in the exhaust gas stream. The process disclosed in this patent consists of flowing an effluent stream below 800 ° F. to an adsorption zone for adsorbing carbon monoxide and hydrocarbons and then passing the stream produced from the adsorption zone to the oxidation zone. When the temperature of the exhaust gas stream reaches about 800 [deg.] F, the exhaust stream no longer passes through the adsorption zone, but is passed directly to the oxidation zone with excess air being added.

U.S. Patent No. 5,078,979, Dunne, which was filed on January 7, 1992, which is incorporated herein by reference in its entirety, discloses a process for removing exhaust gas from an engine using a molecular sieve adsorbent layer to prevent cold- Stream of the < / RTI > Examples of molecular sieves include faujasites, clinoptilolites, mordenites, chabazite, silicalite, zeolite Y, zeolite Y, Stable zeolite Y, and ZSM-5.

Canadian Patent No. 1,205,980 discloses a method for reducing emissions from an alcohol-fueled automobile. This process consists of directing the cooling engine start-up exhaust gas towards the zeolite particle layer, then onto an oxidation catalyst and then into the atmosphere. The exhaust gas stream continues to be warmed and transferred onto the adsorbent bed and then transferred onto the oxide layer.

U.S. Patent No. 5,744,103, issued April 28, 1998 to Yamada et al., Discloses a hydrocarbon adsorbent for engine exhaust gas cleaning. The adsorbent comprises an airborne zeolite with a ring ("MR") consisting of more than 12 atoms, a small pore zeolite with 8 MR and an in-between pore zeolite with 10 MR. Examples of disclosed zeolites are zeolites with a topology (as determined by the International Zeolite Association (IZA)), wherein the topology is FAU (e.g., zeolite Y), AFY and beta (i.e., 12MR zeolite); CHA (8 MR); And MFI (e.g., ZSM-5), MEL, and FER (10MR).

U.S. Patent No. 5,603,216, issued Feb. 18, 1997 to Guile et al., Describes the use of two zones in an exhaust system using the same or different zeolite adsorbents in each zone, Discloses a method for reducing the amount of hydrocarbons released during combustion. Zeolites may be small pore zeolites that absorb low molecular weight alkenes (ethylene and propylene) and atmospheric zeolites that absorb high molecular weight hydrocarbons (e.g., pentane). Examples of the disclosed zeolites include ZSM-5, beta, gmelinite, mazzite, offretite, ZSM-12, ZSM-18, beryllophosphate- Boggsite, SAPO-40, SAPO-41, ultrastable Y, mordenite, and combinations thereof.

Elangovan et al., Journal of Physical Chemistry B, 108, 13059-13061, (2004) describe crossed 10 and 12 MR pores for use as hydrocarbon traps to reduce cold start- (Zeolite with crossed 10 and 12 MR pores with large spacing at the cross-points), named SSZ-33. The performance of SSZ-33 is compared to that of beta, Y, mordenite and ZSM-5 zeolite. SSZ-33 is superior to beta, Y, mordenite and ZSM-5 zeolite.

United States Patent Application Publication No. 2005/0166581 to Davis et al., Published Aug. 4, 2005, discloses a molecular sieve used as an adsorbent in an engine release hydrocarbon trap. The method includes contacting the effluent gas with a molecular sieve having a CON topology (per IZA). CON molecular sieve may be used as such or may be used with another adsorbent. Examples of disclosed CON molecular sieves are the molecular sieves named SSZ-33, SSZ-26, and CIT-1. ITQ-4 is also disclosed, but ITQ-4 is assumed to have IFR topology rather than CON topology. Examples of other adsorbents disclosed are SSZ-23, SSZ-31, SSZ-35, SSZ-41, SSZ-42, SSZ-43, SSZ-44, SSZ-45, SSZ- , SSZ-55, SSZ-57, SSZ-58, SSZ-59, SSZ-60, SSZ-63, SSZ-64 and SSZ-65.

The present invention relates to a method for minimizing emissions of an engine exhaust stream during a cold start operation of a process, particularly an engine. Accordingly, the present invention relates to a process for the production of hydrocarbons, comprising the steps of: flowing an engine exhaust stream, preferably over a combination of molecular sieve absorbing hydrocarbons on water, to provide a primary effluent stream; Flowing the primary effluent gas stream over the catalyst to convert any residual hydrocarbons and other contaminants contained in the primary effluent gas stream to a harmless product and providing a treated effluent stream; And discharging the treated effluent stream to the atmosphere, the method comprising the steps of:

The molecular sieve combination is composed of (1) a ring composed of 8 or fewer atoms selected from the group consisting of SSZ-13, SSZ-16, SSZ-36, SSZ-39, SSZ-50, SSZ- 8 membered ring) ("8 MR") pores and having (a) an oxide of a primary tetravalent element, (b) a quaternary element, a pentavalent element, a quaternary tetravalent element different from the primary tetravalent element, SSZ-33, SSZ-64, zeolite beta, CIT-1, CIT-6 and ITQ- (B) at least one element selected from the group consisting of a trivalent element, a pentavalent element, a tetravalent element, and a tetravalent element, Comprising a medium sized pore crystalline molecular sieve having a molar ratio of oxides of a primary quadrivalent element to a quaternary quadrivalent element or a mixture of oxides of different quadrivalent elements or mixtures thereof, And provides a method of processing an exit stream. The present invention is also directed to a method of manufacturing a semiconductor device, wherein the oxides (1) (a) and (2) (a) are silicon oxides and the oxides (1) The present invention provides a method of treating a cold start engine exhaust gas stream comprising hydrocarbons and other contaminants selected from titanium oxides, indium oxides, zinc oxides, magnesium oxides, cobalt oxides, and mixtures thereof. In one embodiment the molecular sieve 1 is SSZ-13, SSZ-39 or a mixture thereof and the molecular sieve 2 is SSZ-26, SSZ-33, CIT-1, / RTI > In another embodiment, the molecular sieve 1, the molecular sieve 2, or both all comprise a metal selected from Cu, Ag, Au or mixtures thereof.

The present invention further provides such a method in which the engine is an internal combustion engine including an automobile engine using hydrocarbon fuel.

A method of depositing a metal on the molecular sieve surface, wherein the molecular sieve is selected from the group consisting of platinum, palladium, rhodium, ruthenium, and mixtures thereof, is provided by the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method of treating an engine exhaust stream, and more particularly, to a method for minimizing emissions during cold start operation of an engine. The engine consists of any internal or external engine that produces an exhaust gas stream containing harmful components or contaminants, including unburned or pyrolysed hydrocarbons or similar organics. Other harmful components generally present in the exhaust gas include nitrogen oxides and carbon monoxide. The engine uses hydrocarbon fuel as fuel. As used herein and in the claims, "hydrocarbonaceous fuel" includes hydrocarbons, alcohols, and mixtures thereof. Examples of hydrocarbons that can be used as engine fuels are mixtures of hydrocarbons that make up gasoline and diesel fuels. The alcohols that can be used as engine fuel are ethanol and methanol. Mixtures of alcohols and mixtures of alcohols and hydrocarbons can also be used. The engine may be an internal combustion engine such as a jet engine, a gas turbine, an automobile, a truck or bus engine, a diesel engine, and the like. The process is particularly suited for hydrocarbon, alcohol or hydrocarbon-alcohol mixtures, internal combustion engines installed in automobiles. For convenience, the technique will use hydrocarbons as fuel to illustrate the present invention. The use of hydrocarbons in the following description is not intended to limit the present invention to hydrocarbons-fueled engines.

When the engine is started, it produces relatively high concentrations of hydrocarbons and other contaminants in the engine exhaust gas stream. The contaminants will be used to collectively summarize any unburned fuel components and combustion by-products found in the exhaust stream. For example, if the fuel is a hydrocarbon fuel, hydrocarbons, nitrogen oxides, carbon monoxide and other combustion by-products will be found in the engine exhaust gas stream. The temperature of the engine exhaust stream is relatively low, typically 500 ° C or less, generally 200 to 400 ° C. Such an engine exhaust stream has the above characteristics for an initial period of engine operation, typically 30 to 120 seconds after startup of the cooling engine. The engine effluent stream will generally contain about 500 to 1000 ppm of hydrocarbon by volume.

The engine exhaust gas stream to be treated flows over a combination of molecular sieves in the primary exhaust stream. The combination of molecular sieves is described below. The primary effluent stream discharged from the molecular sieve combination flows over the catalyst that converts the contaminants contained in the primary effluent stream to harmless components and provides a treated effluent stream discharged into the atmosphere. The treated effluent stream prior to release to the atmosphere may be flowed through a muffler or other sound reduction device as is well known in the art.

The catalyst used to convert the contaminants into a harmless component is to oxidize any residual hydrocarbons present in the primary effluent stream to carbon dioxide and water while simultaneously oxidizing any residual carbon monoxide to carbon dioxide and at the same time removing any residual nitric oxide with nitrogen Oxygen, which is generally referred to in the art as a ternary control catalyst. In some cases, for example, when the alcohol is used as fuel, the catalyst may not need to convert nitrogen oxide to nitrogen and oxygen. In this case, the catalyst is referred to as an oxidation catalyst. Due to the relatively low temperatures of the engine exhaust stream and the primary effluent stream, such catalysts do not operate at very high efficiencies and require molecular sieve adsorbents.

When the molecular sieve adsorbent reaches a sufficient temperature, typically about 150-200 占 폚, contaminants adsorbed on the molecular sieve begin to desorb and are carried over the catalyst by the primary effluent stream. At this point, the catalyst can reach its working temperature and ultimately completely convert the contaminants into harmless components.

The adsorption performance of molecular sieves depends on the size of the hydrocarbon molecules (molecular weight and shape). For example, when molecular sieves having small pore diameters (such as 8 MR pores) are used, hydrocarbons having high molecular weights (e.g., paraffins, olefins, or aromatics having at least 6 carbon atoms) have. Conversely, hydrocarbons with low molecular weight (such as methane, propane, propylene) are desorbed at a temperature below the desired temperature when molecular sieves having open diameters of medium pores (such as 12 and / or 10 MR pores) It is difficult to maintain such hydrocarbons in the pores of the mesoporous molecular sieve medium until the temperature is sufficiently high to activate the noble metal.

The molecular sieve adsorbent used in the present invention comprises (1) eight or less reactors selected from the group consisting of SSZ-13, SSZ-16, SSZ-36, SSZ-39, SSZ-50, SSZ- (B) a quadrivalent element, a pentavalent element, a quadrivalent quadrivalent element different from the primary quadrivalent element, or a quadrivalent quadrivalent element having a pore of 8 membered rings SSZ-33, SSZ-64, zeolite beta, CIT-1, CIT-6, or a mixture of small crystal crystalline molecular sieves or molecular sieves having a molar ratio of oxides of these mixtures of at least 10, And 10-membered ring ("10 MR") selected from the group consisting of ITQ-4 and ITQ-4, wherein (a) the oxides of the primary tetravalent elements versus the trivalent elements (b) , A mesoporous crystalline molecular sieve having a molar ratio of the oxides of the quaternary elements differing from the primary quadrivalent element to the oxides of the quaternary elements differing from the primary quadrivalent element or a mixture thereof, .

The small pore molecular sieve of the present invention has (two-dimensional or three-dimensional) cross-channel. Examples of such molecular sieves include: where the three-letter structure code, the number of atoms in the pore ring, and the channel arrangement are derived from the International Zeolite Association Database.

A molecular sieve designated SSZ-13 (CHA) as disclosed in U.S. Patent No. 4,544,538 to Zones, which was registered October 1, 1985.

Molecular sieve named SSZ-16 (AFX, (8 6 4), 3D) as disclosed in U.S. Patent No. 5,958,370 to Zones et al., Filed September 28,

A molecular sieve named SSZ-36 (ITE-RTH structural intermediate) disclosed in U.S. Patent No. 5,939,044, Nakagawa et al., Issued August 17, 1999.

SSZ-39 (AEI, (864), 3D) disclosed in U.S. Patent No. 5,958,370, filed September 28, 1999.

Molecular sieves named SSZ-50 (RTH, (8654), 2D) disclosed in U.S. Patent No. 6,605,267,

A molecular sieve named SSZ-52, which is disclosed in U.S. Patent No. 6,254,849, filed July 3, 2001.

A molecular sieve designated SSZ-73 as disclosed in U.S. Patent No. 7,138,099, filed on November 21, 2006.

The above-cited patents cited for identifying small pore molecular sieves useful in the present invention are incorporated herein by reference in their entirety.

The small pore molecular sieves described above can be used as molecular sieves of the present invention (referred to herein as "high silica" molecular sieves) having a large micropore volume and a high oxide (1), such as silica to oxide (2) . These two features make these small pore molecular sieves distinct from the existing molecular sieves, which are small pore powders with high aluminum content. This latter feature makes conventional molecular sieves more susceptible to degradation than the high silica small pore molecular sieve of the present invention (susceptibility to steam under operating conditions).

The mesoporous molecular sieves useful in the present invention have (two or three dimensional) crossover channels. The medium size pore molecular sieve should have a high internal pore volume (e.g., nitrogen adsorption capability of greater than about 0.18 cc / gm). Examples of such molecular sieves include: where the three-letter structure code, the number of atoms in the pore ring, and the channel arrangement are derived from the International Zeolite Association Database.

A molecular sieve designated SSZ-26 (CON), as disclosed in U.S. Patent No. 4,910,006 to Zones et al., Issued March 20, 1990.

A molecular sieve designated SSZ-33 (CON) as disclosed in U.S. Patent No. 4,963,337 to Zones, issued October 16, 1990.

The molecular sieve, denoted SSZ-64, disclosed in US Patent No. 6,569,401 to Elomari, which was registered May 27, 2003, has a disordered structure with at least one 12 MR in the structure and a molecular weight of more than 0.20 cc / g The micropore volume is considered to have a micropore volume.

U. S. Patent No. 3,308, 069 to Wadlinger et al., Filed March 7, 1967, and Re Re-registered Waddlinger et al. The molecular sieve named zeolite beta (BEA) disclosed in U.S. Patent No. 28,341.

A molecular sieve designated CIT-1 (CON) as disclosed in U.S. Patent No. 5,512,267, filed April 30,

A molecular sieve designated CIT-6 (BEA) as disclosed in U.S. Patent No. 6,117,411 to Takewaki et al., Issued September 12, 2000.

egg. &Quot; Synthesis of a new zeolite structure IT-24 with interesting 10- and 12-membered pores " by R. Castaneda et al., J. Am. Chem. Soc., 125, 7820-7821 (2003).

The aforementioned patents and papers describing the intermediate size pore molecular sieve used in the present invention are incorporated herein by reference in their entirety.

The molecular sieves may include structural heteroatoms such as Al, B, Ga, Fe, Zn, Mg, Co and mixtures thereof in addition to Si. The molecular sieve may comprise metal cations selected from rare earth metals, Group 2 metals, Group 8-10 metals, and mixtures thereof. In other words. The metal cation may be selected from Mn, Ca, Mg, Zn, Cd, Pt, Pd, Ni, Co, Ti, Al, Sn, Fe, Co and mixtures thereof. The molecular sieve may also comprise a metal selected from Cu, Ag, Au and mixtures thereof. The molecular sieve may include other partially substituted atoms for Si, such as Ge. Techniques for replacing Si with Ge are known in the art (see, for example, U.S. Patent Nos. 4,910,006 and 4,963,337).

In one embodiment, the combination of small pores and medium size pore molecular sieves is (1) SSZ-13 and (2) SSZ-26, SSZ-33 or a combination of mixtures thereof. In another embodiment, the combination of small pores and medium pore molecular sieves is a combination of (1) SSZ-13 and (2) SSZ-26.

The molecular sieve must be thermally stable to about 700 ° C, such as the presence of steam. The steam can remove some metals from the skeletal structure of some zeolites that disrupt the skeletal structure, such as aluminum. As a result, it is important that the molecular sieve used in the present invention is stable to steam. If the molecular sieve to be used contains a metal such as zinc in its skeletal structure to make the molecular sieve unstable in a vapor environment, the metal can be replaced with an element that stabilizes the molecular sieve to vapor.

If the hydrocarbon fuel burns incompletely in the engine, the exhaust gas may include carbon dioxide and water. If water is present in the exhaust gas, some molecular sieves may be unstable. One way to stabilize such molecular sieves is to increase the amount of silicon oxide in the molecular sieve. Generally, as the content of silicon oxide increases, more hydrophobic molecular sieve will be stabilized and will be stable even in the presence of water vapor. As a result, it is desirable to increase hydrophobicity by partially or completely replacing some metal (such as zinc) in the skeleton structure of the molecular sieve with silicon. In some cases, molecular sieves in which all are silicon oxides may be preferred.

The small pore molecular sieve and the mid-size pore molecular sieve of the present invention are used in combination to treat the cold start engine exhaust gas stream. As used herein, "combination" means that the cold starting engine exhaust gas stream is contacted with both the small pore molecular sieve of the present invention and the mid-size pore molecular sieve of the present invention before the exhaust stream enters the catalytic converter. This can be accomplished by several methods. For example, "combination" may include, for example, a mixture of small pore molecular sieves and medium sized pore molecular sieves in a single bed. Small pores and atmospheric pores themselves can be used in separate layers, or in a single layer including small pores and medium pore molecular sieves. Small pores and medium pore molecular sieves can be used in a single layer, where a single layer has a high concentration of one molecular sieve, e.g., small pore molecular sieve, in the upstream (upstream) side of the layer and a low concentration of medium pore molecular sieve (0 if possible). Thereafter, the concentration of the small pores and the medium pore molecular sieve are gradually reversed toward the downstream (downstream), so that at the end downstream of the layer, for example, the concentration of the small pore molecular sieve is low (possibly zero) Size The concentration of the pore molecular sieve is high. However, small pores and medium pore molecular sieves are conveniently located in separate individual layers. When used in this way, it is possible to replace only the clogged layer and leave the other layer intact if one layer is clogged (foul).

The order in which the cold start exhaust gas contacts the small pore molecular sieve and the medium size pore molecular sieve may not be important. However, it may be advantageous to contact the cold starting discharge gas with the small pore molecular sieve before contacting the medium size pore molecular sieve. In such an arrangement, small hydrocarbons (e.g., methane, propane and / or propylene) can be adsorbed by small pore molecular sieves, while large hydrocarbons bypass small pore molecular sieves (large hydrocarbons are small Because it is too large to fit in the pore, the medium sized pore molecular sieve makes it possible to adsorb large hydrocarbons freely. The opposite arrangement (i.e., the mid-size pore molecular sieve is located upstream of the small pore molecular sieve) can also be used. However, in such cases, small hydrocarbons fill the pores of the medium pore molecular sieve, and there is a risk that the entry of large hydrocarbons may be hindered. In this case, large hydrocarbons can bypass the pore-clogged mid-sized pore molecular sieve and the downstream pore-sized molecular sieve (which can not adsorb large hydrocarbons), and the temperature of the catalytic converter is sufficient to convert large hydrocarbons Lt; RTI ID = 0.0 > to < / RTI >

The particular arrangement of combinations can take many forms. For example, the adsorbent layer can conveniently be used in particulate form, or the adsorbent can be deposited onto a solid monolithic carrier. If a particular particulate form is desired, the adsorbent may be used in the form of a powder, pill, pellet, granule, ring, sphere, or the like. In monolithic embodiments, it is most convenient to use an adsorbent as a thin film or coating deposited on an inert carrier material that provides structural support to the adsorbent. The inert carrier material may be any refractory material such as a ceramic or metallic material. It is preferred that the unitary material is non-reactive with the adsorbent and not decomposed by the exposed gas. Examples of suitable ceramic materials include, but are not limited to, sillimanite, petalite, cordierite, mullite, zircon, zircon mullite, spondumene, alumina-titanate -titanate) and the like. Examples of metallic materials provided as inert carrier materials include metals and alloys disclosed in U.S. Patent No. 3,982,583, which are oxidation resistant and otherwise capable of withstanding high temperatures.

The carrier material may be used in any solid arrangement to provide a plurality of pores or channels extending in the gas flow direction. Conveniently, the arrangement may be a honeycomb arrangement. The honeycomb structure can be advantageously used in both single-type or multi-module alignment. The honeycomb structure is generally oriented such that the gas flow is generally in the same direction as the cell or channel direction of the honeycomb structure. For a more detailed discussion of monolithic structures, see U.S. Patent Nos. 3,785,998 and 3,767,453, which are incorporated herein by reference.

The molecular sieve combination may be deposited on a carrier in any convenient manner known in the art. One convenient method involves preparing slurries using molecular sieves that form a combination (together in a single slurry, or separately in different slurries), and coating the monolithic honeycomb carrier with the slurry. The slurry may be prepared through means known in the art, such as coupling an appropriate amount of molecular sieve and binder to water. The resulting mixture is then compounded using means such as sonication, milling, and the like. Such slurries are used to dip the honeycomb into the slurry, drain the channel or blow out the excess slurry, and heat the monolithic honeycomb by heating to about 100 ° C. If the desired molecular sieve combination is not achieved, the above process may be repeated as many times as necessary to achieve the desired loading.

Instead of depositing the molecular sieve combination in a monolithic honeycomb structure, it may be possible to take a molecular sieve combination and form it into the monolithic honeycomb structure by means known in the art.

The adsorbent may optionally comprise one or more catalytic metals dispersed on the surface. The metals that can be dispersed on the adsorbent surface are noble metals consisting of platinum, palladium, rhodium, ruthenium, and mixtures thereof. The preferred noble metal can be deposited with an adsorbent that acts as a support in any suitable manner well known in the art. One example of a method of dispersing a noble metal on an adsorbent support is by impregnating the adsorbent support with an aqueous solution of the desired noble metal or decomposable compound of metals and drying the adsorbent with the noble metal compound dispersed on the surface, Lt; RTI ID = 0.0 > 1 < / RTI > to 4 hours in air. A decomposable compound means a compound which is heated in air to provide a metal or metal oxide. Examples of degradable compounds that may be used are described in U.S. Patent No. 4,791,091, which is incorporated herein by reference. Preferred decomposable compounds are chloroplatinic acid, rhodium trichloride, chloropalladic acid, hexachloroiridate acid, and hexachlororuthenate. It is preferred that the noble metal be present in an amount ranging from about 0.01 to about 4 weight percent based on the adsorbent support. Especially 0.1 to 4% by weight for platinum and palladium, and about 0.01 to 2% by weight for rhodium and ruthenium.

Such catalytic metals can oxidize hydrocarbons and carbon monoxide and reduce the nitrogen oxide component to a harmless product. Thus, the adsorbent layer can act as both an adsorbent and a catalyst.

The catalyst in the catalytic converter can be selected from any three component conditioning or oxidation catalyst well known in the art. Examples of catalysts are those described in U.S. Patent Nos. 4,528,279, 4,791,091, 4,760,044, 4,868,148 and 4,868,149, which are incorporated herein by reference. Preferred catalysts well known in the art are catalysts comprising platinum and rhodium, and optionally palladium, while oxidation catalysts generally do not contain rhodium. The oxidation catalyst generally comprises platinum and / or palladium metal. Such catalysts may include promoters and stabilizers such as barium, cerium, lanthanum, nickel and iron. The noble metal promoter and stabilizer are generally deposited on a support such as alumina, silica, titania, zirconia, aluminosilicate, and mixtures thereof. The catalyst may conveniently be used in particulate form, or the catalytic composite may be deposited on a solid monolithic carrier using the preferred monolithic carrier. The particulate and monolithic catalysts are prepared as described above for adsorbents.

Example  One

Adsorption properties of zeolites have been tested for adsorption efficiency of hydrocarbon materials commonly found in automotive exhaust streams. The SSZ-13 sample used in this test has a silica / alumina ratio of 15.6. The SSZ-33 sample used in this test has a silica / alumina ratio of 14.6.

Approximately 70 mg of a zeolite SSZ-13 powder sample was alternately loaded into a VTI Scientific Instruments GHP-FS Gravimetric Sorpotion Analyzer (VTI Scientific Instruments). Sample preparation consisted of drying the sample at 350 ° C for 300 minutes (or until the sample weight changed to less than 0.005% over 10 minutes). The sample was then equilibrated with methane at 30 ° C., 500 torr pressure for 30 minutes or until the sample weight varied below 0.005% over 15 minute intervals. The pressure was increased to 500 torr up to 5000 torr, and after each pressure increase, the sample was equilibrated with methane gas. At each pressure, the amount of methane adsorption was measured by the weight change of the sample.

The above procedure was repeated using a zeolite SSZ-33 powder sample.

The process was repeated using a physical mixture of zeolite SSZ-13 powder and zeolite SSZ-33 powder.

The methane uptake (mmole / g) by the following physical mixture of zeolite and homogeneous zeolite is shown in FIG.

Sample ID Zeolite SSZ13 $ 100 SSZ-13 0.8SSZ13 SSZ-13: SSZ-33 in a weight ratio of 4: 1 0.75SSZ13 3: 1 weight ratio of SSZ-13: SSZ-33 0.5SSZ13 1: 1 weight ratio of SSZ-13: SSZ-33 SSZ33 100% SSZ-33

The data shown in Figure 1 shows that the methane absorption by SSZ-13 at 30 占 폚 on a weight basis is greater than the absorption by SSZ-33. SSZ-13: A 1: 1 mixture of SSZ-33 (denoted 0.5SSZ13 in FIG. 1) shows a moderate methane uptake between methane uptake performed with two zeolites alone. However, the 4: 1 and 3: 1 mixtures of SSZ-13: SSZ-33 (denoted as 0.8SSZ13 and 0.75SSZ13, respectively in FIG. 1) are equivalent to or higher than the methane absorptions performed with SSZ-13 and SSZ- Methane absorption.

Example  2

Example 1 was repeated using ethane as the adsorbent. The ethane absorption (mmole / g) by the zeolite sample shown below is shown in FIG.

Sample ID Zeolite SSZ13 100% SSZ-13 0.5SSZ13 1: 1 weight ratio of SSZ-13: SSZ-33 SSZ33 100% SSZ-33

The data shown in Figure 2 shows a moderate 30 < 0 > C ethane uptake between the 1: 1 mixture of SSZ13: SSZ33 (denoted 0.5SSZ13) and the ethane absorption performed with SSZ-13 and SSZ-33 alone.

Example  3

Example 1 was repeated using ethylene as the adsorbent. The ethylene absorption (mmole / g) by the following zeolite sample is shown in Fig.

Sample ID Zeolite SSZ13 100% SSZ-13 0.75SSZ13 3: 1 weight ratio of SSZ-13: SSZ-33 0.5SSZ13 1: 1 weight ratio of SSZ-13: SSZ-33 SSZ33 100% SSZ-33

The data shown in FIG. 3 show a 3O < 0 > C ethylene absorption of the 3: 1 and 1: 1 mixture of SSZ13: SSZ33 much higher than that of SSZ-13 and SSZ-33 alone.

1-3 show data comparing the adsorption characteristics of zeolite with the adsorption characteristics of the zeolite mixture according to the present invention.

Claims (19)

Flowing an engine exhaust stream over a combination of molecular sieve absorbing hydrocarbons over water to provide a primary exhaust stream; Flowing the primary effluent gas stream over the catalyst to convert any residual hydrocarbons and contaminants contained in the primary effluent gas stream to a harmless product and providing a treated effluent stream; And discharging the treated effluent stream to the atmosphere, the method comprising the steps of: The combination of molecular sieves has (1) pores not greater than 8-membered rings, and (a) the oxide of the primary tetravalent element versus (b) the trivalent element, the pentavalent element, Wherein the molar ratio of the oxides of the second quaternary elements or the oxides of the second quaternary elements differing from the elements is at least 10, and (2) at least 10 pores of the same size as the 10 membered rings (A) an oxide of a primary quadrivalent element, (b) a quaternary quadrivalent element different from the trivalent element, or a quaternary quadrivalent element, or an oxide of a mixture thereof, of at least 10, ≪ / RTI > of at least about < RTI ID = 0.0 > 33. ≪ / RTI > The method according to claim 1, Wherein the oxides (1) (a) and (2) (a) are silicon oxides and the oxides (1) , Indium oxide, zinc oxide, magnesium oxide, cobalt oxide, and mixtures thereof. ≪ Desc / Clms Page number 20 > 3. The method of claim 2, Wherein the oxides (1) (b) and (2) (b) are aluminum oxides. delete delete delete 3. The method of claim 2, Process for treating a cold starting engine exhaust gas stream comprising hydrocarbons and contaminants, characterized in that the molecular sieve (1), molecular sieve (2) or both comprise a metal selected from Cu, Ag, Au or mixtures thereof . 3. The method of claim 2, Wherein the engine is an internal combustion engine. ≪ Desc / Clms Page number 20 > 9. The method of claim 8, Wherein the internal combustion engine is an automotive engine. ≪ Desc / Clms Page number 20 > 3. The method according to claim 1 or 2, Wherein the engine uses hydrocarbonaceous fuel as the fuel. ≪ Desc / Clms Page number 19 > 3. The method according to claim 1 or 2, Wherein the surface of the molecular sieve is deposited with a metal selected from the group consisting of platinum, palladium, rhodium, ruthenium, and mixtures thereof. 12. The method of claim 11, Wherein the metal is a mixture of platinum, palladium, or platinum and palladium. ≪ Desc / Clms Page number 20 > delete delete delete delete delete delete delete

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