CATALYST, EXHAUST GAS TREATMENT SYSTEM, AND, EXHAUST GAS TREATMENT METHOD

专利摘要:
catalyst, system for treating exhaust gas, and method for treating exhaust gas. Catalysts effective for culling nox, hydrocarbons and carbon monoxide from a gasoline engine exhaust gas are described. such catalysts include a substrate having first and second materials disposed thereon, the first material effective to catalyze selective catalytic reduction of nitrogen oxides in the presence of ammonia, and the second material effective to abate hydrocarbons and carbon monoxide, the first material comprising a molecular sieve promoted with copper and/or iron at a low loading, the second material comprising at least one oxide of ni, fe, mn, co, and cu on a support selected from oxides of ce, ce-zr, zr, mn, pr and combinations thereof. systems for treating gasoline engine exhaust gas and methods for treating exhaust gas from a gasoline engine are also described.
公开号:BR112018003261B1
申请号:R112018003261-1
申请日:2016-08-18
公开日:2021-08-03
发明作者:Xiaolai Zheng；Michel Deeba；Xiaofan Yang；Qi Fu；Knut Wassermann；Makoto Nagata；Yasuharu Kanno；Hiroki Nakayama
申请人:Basf Corporation；N.E. Chemcat Corporation；
IPC主号:

专利说明:

TECHNICAL FIELD OF THE INVENTION
[001] The present invention relates in general to the field of catalysts for the treatment of gasoline exhaust gases. BACKGROUND OF THE INVENTION
[002] Exhaust gas from vehicles powered by gasoline engines is typically treated with one or more automotive three-way conversion (TWC) catalysts, which are effective to abate NOx, carbon monoxide (CO) and hydrocarbons (HC) in the exhaust of engines operated at or near stoichiometric air/fuel conditions. The exact air-to-fuel ratio that results in stoichiometric conditions varies with the relative proportions of carbon and hydrogen in the fuel. An air/fuel (A/F) ratio is the stoichiometric ratio corresponding to the complete combustion of a hydrocarbon fuel such as gasoline, carbon dioxide (CO2) and water. The symbol À is thus used to represent the result of dividing a particular A/F ratio by the stoichiometric A/F ratio for a given fuel, so that: À = 1 is a stoichiometric mixture, À > 1 is a lean fuel mixture and À <1 is a fuel-rich mixture.
[003] Gasoline engines with electronic fuel injection systems provide a constantly varying mixture of air and fuel that circulates rapidly and continuously between rich and poor exhaust gases. Exhaust gas from vehicles powered by gasoline engines is typically treated with one or more TWC catalysts, which are effective in decreasing NOx, carbon monoxide (CO) and hydrocarbon (HC) pollutants in the exhaust of engines operated in the or near stoichiometric air/fuel conditions. A typical exhaust aftertreatment system for a stoichiometric-burning gasoline engine consists of two three-way conversion catalysts (TWC), a second TWC upstream catalyst/catalyst mounted in a position close to the exhaust manifold, and to the engine compartment (the close-coupled CC position), and a second catalyst/catalyst downstream of TWC placed in a position close to the first TWC catalyst (the second close-coupled position, CC2) or below the vehicle body ( the position under chassis, UF). The first TWC catalyst heats up quickly during cold start and provides most conversions to pollutants including NOx, HC and CO. The second TWC catalyst complements the catalytic activities, particularly after the light is off. Under rich conditions, in the presence of an excess of residual reducers and a deficiency of air, a fraction of NOx is over-reduced in the tight-coupled TWC catalyst to passively generate ammonia.
[004] The emission of nitrogen oxides (NOx) must be reduced to meet the emission regulation standards. TWC catalysts typically comprise a platinum group metal (PGM) supported on an oxygen storage component and/or a refractory metal oxide support and optionally an additional platinum group metal component supported on a second refractory metal oxide support or a second oxygen storage component. TWC catalytic converters, however, are not effective in reducing NOx emissions when the gasoline engine runs poorly due to excess oxygen in the exhaust gases. Two of the most promising technologies for NOx reduction are selective catalytic urea reduction (SCR) and lean NOx collector (LNT).
[005] Urea SCR systems require a secondary fluid tank with an injection system, resulting in additional system complexity. Other concerns for urea SCR include urea infrastructure, the potential freezing of the urea solution, and the need for triggers to periodically fill the urea solution reservoir.
[006] Gasoline engines offer significant potential to improve fuel efficiency and reduce CO2 emissions. One of the exhaust architectures for gasoline applications is the passive NH3-SCR system, which involves the use of an upstream catalyst to generate ammonia (NH3) (during fuel-rich conditions) for use by a downstream NH3-SCR for reduction of NOx. There is a continuing need, from a performance and cost reduction standpoint, to use a passive NH3-SCR catalyst based on molecular sieve to replace or downsize the second tight coupling catalyst based on PGM or the second TWC under chassis. SUMMARY OF THE INVENTION
[007] A first aspect of the present invention relates to a catalyst effective to abate NOx, hydrocarbons and carbon monoxide from a stoichiometric gasoline engine exhaust gas. In a first embodiment, the catalyst comprises a substrate having a first and second material disposed thereon, wherein the first material is effective to catalyze selective catalytic reduction of nitrogen oxides in the presence of ammonia and the second material is effective to abate hydrocarbons and carbon monoxide; wherein the first material comprises a molecular sieve promoted with copper or iron in an amount of from about 0.01% to about 2% based on oxide by weight based on the weight of the molecular sieve and/or the second material comprises by the minus an oxide of a metal selected from Ni, Fe, Mn, Co and Cu on a support selected from an oxide of Ce, Ce-Zr, Zr, Mn, Pr and combinations thereof, and wherein the first material is the second material is substantially free of a platinum group metal.
[008] In a second modality, the catalyst of the first modality is modified, in which the substrate is a honeycomb substrate and in which the first material and the second material are mixed in a single layer on the substrate.
[009] In a third modality, the catalyst of the first modality is modified, in which the first material is in a first layer and the second material is in a second layer on the substrate.
[0010] In a fourth mode, the catalyst of the third mode is modified, wherein the substrate has an axial length and an upstream end and a downstream end, and wherein the first layer is disposed at the upstream end and the second layer is arranged at the downstream end.
[0011] In a fifth mode, the catalyst of the third mode is modified, wherein the substrate has an axial length and an upstream end and a downstream end, wherein the first layer is disposed at the downstream end and the second layer it is arranged at the upstream end.
[0012] In a sixth embodiment, the catalyst of the third embodiment is modified, wherein the first layer is directly on the substrate and the second layer at least partially covers the first layer.
[0013] In a seventh embodiment, the catalyst of the third mode is modified, wherein the second layer is directly on the substrate and the first layer at least partially covers the second layer.
[0014] In an eighth modality, the catalyst of the first modality is modified, wherein the substrate is a wall flow filter with inlet passages and outlet passages.
[0015] In a ninth modality, the catalyst of the eighth modality is modified, in which the first material is disposed in the inlet passages and the second material is disposed in the outlet passages.
[0016] In a tenth modality, the catalyst of the eighth modality is modified, in which the second material is disposed in the inlet passages and the first material is disposed in the outlet passages.
[0017] In an eleventh embodiment, the catalyst of the first embodiment is modified, wherein the molecular sieve is a small-pore molecular sieve with a maximum ring size of eight tetrahedral atoms and a double unit of six rings (d6r).
[0018] In a twelfth modality, the catalyst of the first modality is modified, in which the molecular sieve is selected from the group consisting of the main chain types AEI, AFT, AFX, CHA, EAB, EMT, ERI, FAU, GME , JSR, KFI, LEV LTL, LTN, MOZ, MSO, MWW, OFF, SAS, SAT, SAV, SBS, SBT, SFW, SSF, SZR, TSC and WEN.
[0019] In a thirteenth modality, the catalyst of the first modality is modified, in which the molecular sieve is selected from the group consisting of the main chain types CHA, AEI, AFX, ERI, KFI and LEV.
[0020] In a fourteenth modality, the catalyst of the first modality is modified, in which the molecular sieve is selected from the group consisting of the main chain types AEI, CHA and AFX.
[0021] In a fifteenth modality, the catalyst of the first modality is modified, wherein the molecular sieve comprises a molecular sieve of the CHA backbone type.
[0022] In a sixteenth modality, the catalyst of the fifteenth modality is modified, wherein the molecular sieve is selected from SSZ-13, SSZ-62, natural chabazite, zeolite KG, Linde D, Linde R, LZ-218, LZ-235, LZ-236, ZK-14, SAPO-34, SAPO-44, SAPO-47, ZYT-6 and Ti-SAPO-34.
[0023] In a seventeenth embodiment, the catalyst of the sixteenth embodiment is modified, wherein the molecular sieve is SSZ-13 with a silica to alumina molar ratio of about 10 to about 75.
[0024] In an eighteenth modality, the catalyst of the sixteenth modality is modified, wherein the molecular sieve is promoted with less than about 2% copper by weight on an oxide base based on the weight of the molecular sieve promoted by the metal.
[0025] In a sixteenth modality, the catalyst of the sixteenth modality is modified, wherein the molecular sieve is promoted with copper in the range of about 0.5 to about 2% by weight based on oxide based on weight of the molecular sieve promoted by the metal, and in what, in an FTP conduction cycle (FEDERAL TEST PROCEDURE; in Portuguese, Federal Test Procedure), the catalyst is effective in converting at least about 30% of nitrogen oxides into the gas exhaust by selective catalytic reduction of nitrogen oxides in the presence of ammonia at temperatures above 850 °C for more than ten hours.
[0026] In a twentieth embodiment, the catalyst of the first embodiment is modified, wherein the second material comprises at least one oxide of a metal selected from Ni, Fe, Mn, Co and Cu.
[0027] In a twenty-first modality, the catalyst of the first modality is modified, wherein the second material comprises an oxide of Ni.
[0028] In a twenty-second embodiment, the catalyst of the first embodiment is modified, wherein the second material comprises a Ni oxide deposited on a support comprising a Ce oxide.
[0029] In the twenty-third modality, the catalyst of the eighteenth modality is modified, wherein the second material comprises a Ni oxide on a support comprising a Ce oxide.
[0030] In a twenty-fourth modality, the catalyst of the twenty-third modality is modified, wherein the first material is in a first layer and the second material is in a second layer, wherein the first layer and the second layer are disposed over a substrate in a zoned configuration, and wherein the first layer covers the second layer.
[0031] In a twenty-fifth modality, the catalyst of the first modality is modified, wherein the at least one oxide of a metal selected from Ni, Fe, Mn, Co and Cu is present in an amount from about 0.1 to about 30% by weight, based on oxide based on the weight of the support.
[0032] In a twenty-sixth modality, the catalyst of the twenty-fifth modality is modified, wherein the at least one oxide of a metal selected from Ni, Fe, Mn, Co, and Cu is present in an amount of from about 2 to about 10% by weight, based on oxide based on support weight.
[0033] A second aspect of the present invention is directed to an exhaust gas treatment system. In a twenty-seventh modality, an exhaust gas treatment system comprises: a stoichiometric gasoline engine; a three-way conversion (TWC) catalyst downstream of the engine, wherein the TWC catalyst is effective to convert carbon monoxide, hydrocarbons and nitrogen oxides, and wherein the TWC catalyst comprises at least one platinum group metal selected from platinum, palladium and rhodium; and the catalyst of the first through twenty-sixth modalities is located downstream of the three-way conversion catalyst.
[0034] In a twenty-eighth mode, the exhaust gas treatment system of the twenty-seventh mode is modified, in which the TWC catalyst is located in a first coupling position just downstream of the engine and the first mode catalyst is located in a second close-coupled position immediately downstream of the TWC catalyst.
[0035] In a twenty-ninth mode, the exhaust gas treatment system of the twenty-seventh mode is modified, in which the TWC catalyst is located in a first coupling position just downstream of the engine and the first mode catalyst is located in an under chassis position downstream of the TWC catalyst.
[0036] In a thirtieth modality, the exhaust gas treatment system of the twenty-seventh modality is modified, in which the catalyst of the first modality is exposed to a rich and poor exhaust gas with a temperature greater than 800 °C.
[0037] A third aspect of the present invention is directed to an exhaust gas treatment system. In a thirty-first modality, an exhaust gas treatment system of the twenty-seventh modality comprises: a stoichiometric gasoline engine; a selective catalytic reduction (SCR) catalyst downstream of the engine, the SCR catalyst comprising copper and a second molecular sieve with a maximum ring size of eight tetrahedral atoms and a double six-ring unit (d6r) in which copper is present in an amount of from about 0.01% to about 2% by weight, based on oxide, based on the weight of the second metal produced molecular sieve, wherein the SCR is effective to catalyze the selective catalytic reduction of nitrogen oxides in the presence of ammonia under stoichiometric engine operating conditions.
[0038] In a thirty-second modality, the exhaust gas treatment system of the thirty-first modality is modified, wherein the second molecular sieve comprises a molecular sieve of the CHA backbone type.
[0039] In a thirty-third modality, the exhaust gas treatment system of the thirty-first modality is modified, in which the second molecular sieve is selected from SSZ-13, SSZ-62, chabazite, zeolite KG, Linde D, Linde R, LZ-218, LZ-235, LZ-236, ZK-14, SAPO-34, SAPO-44, SAPO-47, ZYT-6 and Ti-SAPO-34.
[0040] In a thirty-fourth modality, the exhaust gas treatment system of the thirty-third modality is modified, wherein the second molecular sieve is SSZ-13 with a silica to alumina molar ratio of from about 10 to about 75 .
[0041] In a thirty-fifth modality, the exhaust gas treatment system of the thirty-first modality is modified, wherein the exhaust gas has a temperature of at least 850 °C.
[0042] In a thirty-sixth modality, the exhaust gas treatment system of the thirty-first modality is modified, in which the molecular sieve has a surface area greater than 400 m2/g after exposure to an exhaust gas with a temperature of about 850 °C for 2 hours.
[0043] In a thirty-seventh modality, the exhaust gas treatment system of the thirty-fifth modality is modified, in which the molecular sieve has an aged surface area after exposure to exhaust gas of about 75% of an area of fresh surface, where the fresh surface area of the molecular sieve prior to exposure to the exhaust gases.
[0044] In the thirty-eighth modality, the exhaust gas treatment system of the thirty-first modality is modified, in which the at least one oxide of a metal selected from Ni, Fe, Mn, Co and Cu is present in an amount of about 0.1% to about 30% by weight, based on oxide based on the weight of the support.
[0045] In a thirty-ninth modality, the exhaust gas treatment system of the thirty-eighth modality is modified, wherein at least one oxide of a metal selected from Ni, Fe, Mn, Co and Cu is present in an amount of about 2% to about 10% by weight, based on oxide based on the weight of the support.
[0046] A fourth aspect of the present invention is directed to a method for treating exhaust gases from stoichiometric gasoline engines. In a fortieth modality, a method of treating exhaust gases from a stoichiometric gasoline engine comprises a three-way catalyst (TWC) catalyst effective to convert carbon monoxide, hydrocarbons and nitrogen oxides, wherein the TWC catalyst contains at least one platinum group metal selected from platinum, palladium and rhodium and the first catalyst through the twenty-sixth embodiment, wherein the catalyst is located downstream of a stoichiometric gasoline engine and the TWC catalyst. BRIEF DESCRIPTION OF THE DRAWINGS
[0047] Figure 1 shows a cross-sectional view of a wall flow filter substrate; Figure 2 shows a partial cross-sectional view of catalytic article systems in accordance with one or more embodiments; Figure 3 shows partial cross-sectional views of catalytic article systems in accordance with one or more embodiments; Figure 4 shows partial cross-sectional views of catalytic article systems in accordance with one or more embodiments; Figure 5 shows partial cross-sectional views of catalytic article systems in accordance with one or more embodiments; Figure 6 shows partial cross-sectional views of catalytic article systems in accordance with one or more embodiments; Figure 7 shows partial cross-sectional views of catalytic article systems in accordance with one or more embodiments; Figure 8 is a diagram of an exemplary exhaust gas system configuration used in gasoline engines in accordance with one or more embodiments of the invention; Figure 9 is a bar graph showing BET surface areas after air aging and lean/rich aging for samples prepared in accordance with the Examples; and Figure 10 is a line graph showing the NOx performance of catalyst compositions with a base metal oxide supported on different supports with varying CeO2 content. DETAILED DESCRIPTION OF THE INVENTION
[0048] Before describing various exemplary embodiments of the invention, it should be understood that the invention is not limited to the construction details or process steps set forth in the description below. The invention is capable of other modalities and of being practiced or being carried out in various ways.
[0049] Embodiments of the invention are directed to catalysts effective to lower NOx, hydrocarbons and carbon monoxide from a stoichiometric gasoline engine exhaust gas. The integration of an SCR catalyst into a TWC system is thought to improve the NOx performance of the exhaust pipe and reduce NH3 as a secondary emission. Copper and/or iron exchange molecular sieves, however, with a CuO and/or Fe2O3 loading of 2% to 4%, are not stable under lean/rich aging conditions. Without intending to be bound by theory, it is thought that the instability of the SCR component loaded with Cu and/or Fe is due to the proximity of Cu(II) and/or Fe(III) cations in the zeolitic micropores, which undergo reduction to form metallic Cu and/or metallic Fe nanoparticles under rich aging conditions at high temperature. Under poor conditions, these metallic Cu and/or metallic Fe species are oxidized to CuO and/or Fe2O3 in an agglomerated form, rather than isolated Cu and/or Fe cations in situ. As a result, the zeolite structure continuously loses Cu and/or Fe cation species and eventually collapses. Surprisingly, it has been found that catalysts comprising a relatively low Cu and/or Fe charge exhibit higher thermal stability under lean/rich aging, particularly at high temperatures (e.g. 850°C).
[0050] Thus, in accordance with the embodiments of a first aspect of the invention, there is provided a catalyst effective to decrease NOx, hydrocarbons and carbon monoxide from a stoichiometric gasoline engine exhaust gas, the catalyst comprising a substrate having a first and second material disposed thereon, the first material effective to catalyze the selective catalytic reduction of nitrogen oxides in the presence of ammonia and the second material effective to reduce hydrocarbons and carbon monoxide, the first material comprising a molecular sieve promoted with copper and/or iron in a relatively low amount of charge on an oxide basis by weight based on the weight of the first material, the second material comprising at least one oxide of Ni, Fe, Mn, Co and Cu on a selected support a from an oxide of Ce, Ce-Zr, Zr, Mn, Pr and combinations thereof, wherein the catalyst is free of a platinum group metal.
[0051] With regard to the terms used in this description, the following definitions are provided. As used in this descriptive report and the accompanying claims, the singular forms “a”, “an”, “the” and “a” include plural referents, unless the context clearly indicates otherwise. Thus, for example, reference to "a catalyst" includes a mixture of two or more catalysts and the like.
[0052] As used herein, the term "slaughter" means decrease in amount and "reduction" means a decrease in amount, caused by any means.
[0053] As used herein, the term "substantially free of a platinum group metal" means that there is no additional platinum group metal intentionally added to the catalyst containing the first and second material and, in some embodiments, there is less than about 0.01% by weight of any additional platinum group metal by weight present in the catalyst composition. In some embodiments, "substantially free of platinum group metal" includes "free of platinum group metal".
[0054] As used herein, the terms "catalyst" or "catalyst material" or "catalytic material" refer to a material that promotes a reaction.
[0055] As used herein, the term "catalytic article" refers to an element that is used to promote a desired reaction. For example, a catalytic article may comprise a wash coating containing a catalytic species, e.g., a catalyst composition, on a substrate, e.g., a honeycomb substrate.
As used herein, the terms "layer" and "layered" refer to a structure that is supported on a surface, for example, a substrate.
[0057] As used herein, the term "gasoline engine" refers to any internal combustion engine with ignition designed to run on gasoline. Recently, to improve fuel economy, gasoline engines are being designed to operate in poor conditions. Lean conditions refer to keeping the air to fuel ratio in the combustion mixtures supplied to such engines above the stoichiometric ratio so that the resulting exhaust gases are "lean", i.e. the exhaust gases are relatively high in content. of oxygen. Lean Burn Gasoline Direct Injection (GDI) engines offer fuel efficiency benefits that can contribute to a reduction in greenhouse gas emissions that combust excess air fuel. GDI engines can have lean burn conditions and stratified combustion, resulting in particulate generation. In contrast to particulates generated by lean-burn diesel engines, particulates generated by GDI engines tend to be finer and less abundant. In one or more embodiments, the engine is selected from a stoichiometric gasoline engine or a lean gasoline direct injection engine. In other specific embodiments, the gasoline engine is a stoichiometric gasoline engine.
[0058] As used herein, the term "wash coating" has its usual meaning in the art of a thin, adherent coating of a catalytic or other material applied to a supporting substrate material, such as a supporting element of the alveolar type, which is porous enough to allow the passage of the gas stream to be treated. As is understood in the art, a wash coating is obtained from a dispersion of suspended particles, which is applied to a substrate, dried and calcined to provide the porous wash coating.
[0059] As used herein, the term "stream" broadly refers to any combination of flowing gas that may contain solid or liquid particulate matter. The term “gaseous stream” or “exhaust gas stream” means a stream of gaseous constituents, such as an engine exhaust, which may contain entrained non-gaseous components such as liquid droplets, solid particles and the like. The exhaust gas stream from an engine typically further comprises combustion products, incomplete combustion products, nitrogen oxides, combustible and/or carbonaceous particulate matter (soot), and unreacted oxygen and nitrogen. first material
[0060] In one or more embodiments, an effective catalyst to abate NOx, hydrocarbons and carbon monoxide from a stoichiometric gasoline engine exhaust gas comprises a substrate with a first and second material disposed thereon, the first material effective to catalyze selective catalytic reduction of nitrogen oxides in the presence of ammonia.
[0061] As used herein, the term "selective catalytic reduction" (SCR) refers to the catalytic process of reducing nitrogen oxides to dinitrogen (N2) using a nitrogen reductant. As used herein, the terms "nitrogen oxides" or "NOx" refer to the oxides of nitrogen.
[0062] The SCR process uses the catalytic reduction of nitrogen oxides with ammonia to form nitrogen and water:

[0063] Catalysts employed in the SCR process should ideally be able to retain good catalytic activity over a wide range of use temperature conditions, for example, about 200 °C to about 600 °C or higher, under conditions hydrothermals. Hydrothermal conditions are often encountered in practice, such as during the regeneration of a soot filter, a component of the exhaust gas treatment system used for particulate removal.
[0064] In one or more modalities, within the FTP conduction cycle, the catalyst of one or more modalities including the first material and the second material is effective to convert at least about 30% nitrogen oxides in the exhaust gases by selective catalytic reduction of nitrogen oxides in the presence of ammonia after exposure to fuel cut engine aging conditions at a temperature of about 850 °C for more than 10 hours.
[0065] As used herein, the term "Federal Test Procedure (FTP) driving cycle" refers to the set of vehicle speed as a function of time points created by the United States to represent a travel cycle with a part of urban driving, including frequent stops and a part of highway driving. The FTP driving cycle is sometimes used to assess a vehicle's fuel consumption and pollutants in a normalized way so that different vehicles can be compared. The driving cycle can be performed on a chassis dynamometer, where emissions from a vehicle's tailpipe are collected and analyzed to assess emission rates. The FTP driving cycle is a transient cycle involving many speed variations typical of road driving conditions.
[0066] As used herein, the phrase "molecular sieve" refers to backbone materials such as zeolites and other backbone materials (for example, isomorphically substituted materials), which can be used in particulate form in combination with one or more promoter metals as catalysts. Molecular sieves are materials based on an extensive three-dimensional network of oxygen ions containing generally tetrahedral-like sites and with a substantially uniform pore distribution, with an average pore size not exceeding 20 Â. Pore sizes are defined by ring size. As used herein, the term "zeolite" refers to a specific example of a molecular sieve, including silicon and aluminum atoms. According to one or more embodiments, it will be recognized that, by defining molecular sieves by their main chain type, it is intended to include the main chain type and any and all isotopic main chain materials such as SAPO, ALPO and MeAPO materials with the same type of main chain as zeolite materials.
[0067] In more specific embodiments, the reference to a type of aluminosilicate zeolite backbone limits the material to molecular sieves that do not include phosphorus or other substituted metals in the backbone. However, to be clear, as used herein, "aluminosilicate zeolite" excludes aluminophosphate materials such as SAPO, ALPO and MeAPO materials, and the broader term "zeolite" is intended to include aluminosilicates and aluminophosphates. Zeolites are crystalline materials with fairly uniform pore sizes which, depending on the type of zeolite and the type and amount of cations included in the zeolite backbone, range from about 3 to 10 Angstroms in diameter. Zeolites generally comprise silica to alumina molar ratios (SAR) of 2 or more.
[0068] The term "aluminophosphates" refers to another specific example of a molecular sieve, including aluminum and phosphate atoms. Aluminophosphates are crystalline materials with fairly uniform pore sizes.
[0069] In general, molecular sieves, eg zeolites, are defined as aluminosilicates with open three-dimensional main chain structures composed of corner-sharing TO4 tetrahedra, where T is Al or Si, or optionally P. The cations that balance a anionic backbone charges are slightly associated with backbone oxygens and the remaining pore volume is filled with water molecules. Non-main chain cations are generally interchangeable, and water molecules are removable.
[0070] In one or more embodiments, the molecular sieve independently comprises SiO4/AlO4 tetrahedra that are linked by common oxygen atoms to form a three-dimensional network. In other embodiments, the molecular sieve comprises SiO4/AlO4/PO4 tetrahedra. The molecular sieve of one or more modalities can be differentiated mainly according to the geometry of the voids that are formed by the rigid network of the tetrahedrons (SiO4)/AlO4 or SiO4/AlO4/PO4. Void entries are formed from 6, 8, 10 or 12 ring atoms relative to the atoms forming the entry opening. In one or more embodiments, the molecular sieve comprises ring sizes no greater than 12, including 6, 8, 10 and 12.
[0071] According to one or more modalities, the molecular sieve can be based on the main chain topology by which structures are identified. Typically, any type of zeolite backbone can be used, such as ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, backbone types AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AWO, AWW, BCT, BEA, BEC, BIK, BOG, BPH, BRE, CAN, CAS, SCO, CFI, SGF, CGS, CHA, CHI, CLO, CON, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EMT, EON, EPI, ERI, ESV, ETR, EUO, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFR, IHW, ISV, ITE, ITH, ITW, IWR, IWW, JBW, KFI, LAU, LEV, LIO, LIT, LOS, LOV, LTA, LTL, LTN, MAR, MAZ, MEI, HONEY, MEP, MOR, MOZ, MSO, MTF, MTN, MTT, MTW, MWW, NAB, NAT, NES, NON, NPO, NSI, OBW, OFF, OSI, OSO, OWE, PAR, PAU, PHI, PON, RHO, RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAO, SAS, SAT, SAV, SBE, SBS, SBT, SFE, SFF, SFG, SFH, SFN, SFO, SGT, SOD, STT, TER, THO, TON, TSC, UEI, UFI, UOZ, USI, UTL, VET, VFI, VNI, VSV, WIE, WEN, YUG, ZON, or combinations thereof.
[0072] In one or more embodiments, the molecular sieve comprises an 8-ring small pore aluminosilicate zeolite. As used herein, the term "small pore" refers to pore openings that are smaller than about 5 Angstroms, for example on the order of ~3.8 Angstroms. The phrase "8-ring" zeolites refers to zeolites with 8-ring pore openings and six-ring double secondary building units and which have a cage-like structure resulting from the bonding of six-ring double building units by 4 rings. In one or more embodiments, the molecular sieve is a small pore molecular sieve with a maximum ring size of eight tetrahedral atoms.
[0073] Zeolites are comprised of secondary building units (SBU) and composite building units (CBU), and appear in many different main chain structures. Secondary building units contain up to 16 tetrahedral atoms and are non-chiral. Composite building units are not required to be achiral and cannot be used to build the entire main chain. For example, a group of zeolites has a single 4-ring composite building unit (s4r) in its backbone structure. In ring-4, the "4" denotes the positions of silicon and aluminum tetrahedron atoms, and the oxygen atoms are located between tetrahedral atoms. Other composite construction units include, for example, a single 6-ring unit (s6r), a double 4-ring unit (d4r) and a dual 6-ring unit (d6r). The d4r unit is created by joining two s4r units. The d6r unit is created by joining two s6r units. In a d6r unit, there are twelve tetrahedral atoms. Zeolitic backbone types that have a d6r secondary build unit include: AEI, AFT, AFX, CHA, EAB, EMT, ERI, FAU, GME, JSR, KFI, LEV, LTL, LTN, MOZ, MSO, MWW, OFF, SAS, SAT, SAV, SBS, SBT, SFW, SSF, SZR, TSC and WEN.
[0074] In one or more embodiments, the molecular sieve comprises a d6r unit. Thus, in one or more embodiments, the molecular sieve has a main chain type selected from AEI, AFT, AFX, CHA, EAB, EMT, ERI, FAU, GME, JSR, KFI, LEV, LTL, LTN, MOZ, MSO , MWW, OFF, SAS, SAT, SAV, SBS, SBT, SFW, SSF, SZR, TSC, WEN and combinations thereof. In other specific embodiments, the molecular sieve has a main chain type chosen from the group consisting of CHA, AEI, AFX, ERI, KFI, LEV and combinations thereof. In other specific embodiments, the molecular sieve has a main chain type chosen from CHA, AEI and AFX. In one or more very specific embodiments, the molecular sieve has the main chain type CHA.
CHA backbone type zeolitic molecular sieves include a natural tectosilicate mineral of a zeolite group with approximate formula: (Ca, Na2, K2, Mg)AhSí4Oi2^6H2O (eg, calcium aluminum silicate hydrated) . Three synthetic forms of CHA backbone type zeolytic molecular sieves are described in "Zeolite Molecular Sieves" by D.W. Breck, published in 1973 by John Wiley & Sons, which is hereby incorporated by reference. The three synthetic forms reported by Breck are Zeolite K-G, described in J. Chem. Soc., p. 2822 (1956), Barrer et al; Zeolite D, described in UK Patent No. 868,846 (1961); and Zeolite R, described in U.S. Patent No. 3,030,181, which is incorporated herein by reference. The synthesis of another synthetic form of the zeolitic CHA structural type, SSZ-13, is described in U.S. Patent No. 4,544,538, which is incorporated herein by reference. The synthesis of a synthetic form of a molecular sieve with the CHA main chain type, silicoaluminophosphate 34 (SAPO-34), is described in US Patent Nos. 4,440,871 and US 7,264,789, which are incorporated herein by reference title. A method of making yet another synthetic molecular sieve having the CHA backbone type, SAPO-44, is described in U.S. Patent No. 6,162,415, which is incorporated herein by reference.
[0076] In one or more embodiments, the molecular sieve can include all compositions of aluminosilicate, borosilicate, gallosilicate, MeAPSO and MeAPO. These include, but are not limited to, SSZ-13, SSZ-62, natural chabazite, zeolite K-G, Linde D, Linde R, LZ-218, LZ-235. LZ-236, ZK-14, SAPO-34, SAPO-44, SAPO-47, ZYT-6, CuSAPO-34, CuSAPO-44, Ti-SAPO-34 and CuSAPO-47. The silica to alumina ratio of an aluminosilicate molecular sieve can vary over a wide range. In one or more embodiments, the molecular sieve has a silica to alumina (SAR) molar ratio in the range of about 2 to about 300, including about 5 to about 250; about 5 to about 200; about 5 to about 100; and about 5 to about 50. In one or more specific embodiments, the molecular sieve has a silica to alumina (SAR) molar ratio in the range of about 10 to about 200, about 10 to about 100, about from 10 to about 75, about 10 to about 60, and about 10 to about 50; about 15 to about 100, about 15 to about 75, about 15 to about 60, and about 15 to about 50; about 20 to about 100, about 20 to about 75, about 20 to about 60, and about 20 to about 50.
[0077] As used herein, the term "promoted" refers to a component that is intentionally added to the molecular sieve material, as opposed to the impurities inherent in the molecular sieve. Thus, a promoter is intentionally added to increase the activity of a catalyst compared to a catalyst that does not have an intentionally added promoter. In order to promote selective catalytic reduction of nitrogen oxides in the presence of ammonia, in one or more modalities, a suitable metal(s) is independently exchanged on the molecular sieve. According to one or more modalities, the molecular sieve is promoted with copper (Cu) and/or iron (Fe). In specific modalities, the molecular sieve is promoted with copper (Cu). In other modalities, the molecular sieve is promoted with copper (Cu) and iron (Fe). In still other modalities, the molecular sieve is promoted with iron (Fe).
[0078] Surprisingly, it has been found that the low metal content of the promoter leads to catalysts that are highly stable under lean/rich aging conditions at temperatures of 800 °C and above, particularly 850 °C and above. In one or more embodiments, the metal content of the catalyst promoter, calculated as the oxide, is up to 2% by weight, based on the weight of the molecular sieve. In specific embodiments, the metal content of the promoter, calculated as the oxide, is in the range of about 0.01% by weight to about 2% by weight, including in the range of about 0.01% to about 2 %, about 0.01% to about 1.5%, about 0.01% to about 1%, about 0.5% to about 2%, about 0.1% to about 2 % by weight, about 0.1% to about 1.5% by weight, and about 0.1% to about 1% by weight, in each case based on the weight of the metal-promoted molecular sieve. In one or more embodiments, the promoter metal content is reported on a volatile free base.
[0079] Consequently, in one or more specific embodiments, the catalyst comprises a first material effective to catalyze the selective catalytic reduction of nitrogen oxides in the presence of ammonia, the first material comprising a molecular sieve promoted with copper and/or iron in a amount ranging from about 0.01% to about 2% on an oxide basis, based on the weight of the molecular sieve. In specific embodiments, the promoter metal comprises Cu and the Cu content, calculated as CuO, is less than about 2%, based on the weight of the molecular sieve promoted by the metal. Second material
[0080] In one or more embodiments, an effective catalyst to abate NOx, hydrocarbons and carbon monoxide from a stoichiometric gasoline engine exhaust gas comprises a substrate having a first and second material disposed thereon, the second material Effective for killing hydrocarbons and carbon monoxide.
[0081] In one or more embodiments, the second material comprises at least one base metal oxide on a support. As used herein, the term "base metal" generally refers to a metal that oxidizes or corrodes relatively easily when exposed to air and moisture. In one or more embodiments, the base metal comprises one or more base metal oxides selected from vanadium (V), tungsten (W), titanium (Ti), copper (Cu), iron (Fe), cobalt (Co) , nickel (Ni), chromium (Cr), manganese (Mn), neodymium (Nd), barium (Ba), cerium (Ce), lanthanum (La), praseodymium (Pr), magnesium (Mg), calcium (Ca) , zinc (Zn), niobium (Nb), zirconium (Zr), molybdenum (Mo), tin (Sn), tantalum (Ta), cerium (Ce) and strontium (Sr), or combinations thereof. In a specific modality, the second material comprises at least one oxide of nickel (Ni), iron (Fe), manganese (Mn), cobalt (Co) and copper (Cu). In other specific embodiments, the second material comprises at least one oxide of nickel (Ni), iron (Fe) and copper (Cu). In a very specific modality, the second material comprises a nickel oxide (Ni).
[0082] Overall, there are no specific restrictions regarding the amount of base metal oxide used in the second material. In one or more embodiments, the amount of base metal oxide present is from about 0.1% to about 30% by weight, including about 1% to about 20% by weight, and about 2% to about 10% by weight, based on oxide based on the weight of the support. In one or more embodiments, the amount of base metal oxide is reported in a volatile free base. In other embodiments, the amount of Ni, Fe, Mn, Co or Cu oxide is from about 0.1% to about 30% by weight, including about 1% to about 20% by weight and about 2 % to about 10% by weight, in each case based on oxide based on the weight of the support. In one or more embodiments, the second material comprises from about 1% to 20% by weight. % of at least one metal oxide of a metal selected from nickel (Ni), iron (Fe) and copper (Cu), based on oxide based on support weight. In specific embodiments, the second material comprises from about 2% to 10% by weight of at least one metal oxide of a metal selected from nickel (Ni), iron (Fe) and copper (Cu). In each case, the % by weight is an oxide basis based on the weight of the metal-containing support. In one or more specific embodiments, the second material comprises a Ni oxide, and the Ni oxide is present in an amount of about 0.1% to 30% by weight, including about 1% to 20% by weight and about 2% to 10% by weight, based on oxide based on the weight of the support.
As used herein, the terms "refractory metal oxide support" and "support" refer to the underlying material of the high surface area over which additional chemical compounds or elements are transported. The support particles have pores larger than 20 Â and a wide pore distribution. As defined herein, such refractory metal oxide supports exclude molecular sieves, specifically, zeolites. In particular embodiments, high surface area refractory metal oxide supports can be used, for example, alumina support materials, also referred to as "gamma alpha" or "activated alumina", which typically have a BET surface area in excess of 60 square meters per gram (“m2/g”), often up to about 200 m2/g or more. Such activated alumina is generally a mixture of the gamma and delta alumina phases, but may also contain substantial amounts of eta, kappa and theta alumina phases. Refractory metal oxides other than activated alumina can be used as a support for at least some of the catalytic components in a given catalyst. For example, ceria, zirconia, alpha alumina, silica, titania and other bulk materials are known for such use.
[0084] As used herein, the term "BET surface area" has its usual meaning of referring to the Brunauer, Emmett, Teller method for determining surface area by adsorption of N2. Pore diameter and volume can also be determined using N2 type BET adsorption or desorption experiments.
[0085] As used herein, the term "oxygen storage component" (OSC) refers to an entity that has a state of multiple valences and can actively react with reductants such as carbon monoxide (CO) and/or hydrogen under reducing conditions and then react with oxidants such as oxygen or nitrogen oxides under oxidative conditions. Examples of oxygen storage components include rare earth oxides, particularly ceria, lantana, praseodymia, neodymia, niobia, europia, samaria, ytterbia, yttria, zirconia and mixtures thereof, in addition to ceria.
[0086] In one or more embodiments, the second material comprises a support selected from a cerium oxide (Ce), cerium-zirconium (CeZr), manganese (Mn), praseodymium (Pr) and combinations thereof. In one or more specific embodiments, the support comprises a ceria oxide (Ce). Thus, in one or more specific embodiments, the second material comprises from about 0.1% to 30% by weight. %, including about 1% to 20% by weight and about 2% to 10% by weight of at least one oxide of nickel (Ni), iron (Fe) and copper (Cu) and the support comprises a ceria oxide (Ce); in each case the % by weight is based on oxide based on the weight of the ceria support. In one or more specific embodiments, the second material comprises a Ni oxide, the support comprises a ceria oxide (Ce), and the Ni oxide is present in an amount ranging from about 0.1% to 30% in weight, including about 1% to 20% by weight and about 2% to 10% by weight, based on oxide based on the weight of the ceria support.
As used herein, the term "platinum group metal" or "PGM" refers to one or more chemical elements defined in the Table of Periodic Elements, including platinum (Pt), palladium, rhodium, osmium, iridium and ruthenium and mixtures thereof.
[0088] As used herein, "platinum group metal component", "platinum component", "rhodium component", "palladium component", "iridium component" and the like refers to the metal compound from the platinum group, complex or the like which upon calcination or use of the catalyst decomposes or otherwise converts to a catalytically active form, generally metal or metal oxide.
[0089] According to one or more embodiments, the first material and the second material are substantially free of a platinum group metal. As used herein, the terms "substantially free of platinum group metal" or "free of platinum group metal" mean that no platinum group metal has been intentionally added to the first material or second material and that there is generally less than about 1000 ppm, including less than about 100 ppm, less than about 10 ppm, or less than about 1 ppm of platinum group metal in the first material and in the second material. It will be recognized by one of skill in the art, however, during loading/coating, trace amounts of platinum group metal may migrate from one wash-coating component to another such that trace amounts of platinum group metal may be present in the first material and/or the second material. In one or more embodiments, the catalyst comprising the substrate having the first material and the second material coated thereon is substantially free of platinum group metal. Substrate
[0090] In one or more embodiments, the first and second catalyst materials are disposed on a substrate. As used herein, the term "substrate" refers to the monolithic material onto which the catalyst material is placed, typically in the form of a wash coat. A wash coat is formed by preparing a slurry containing a specified solids content (eg, 30% to 90% by weight) of catalyst in a liquid which is then coated onto a substrate and dried to provide a coating layer by washing. As used herein, the term "wash coating" has its usual meaning in the art of a thin, sticky coating of a catalytic or other material applied to a substrate material, such as a honeycomb-type support element, which it is porous enough to allow the passage of the gas stream to be treated.
[0091] In one or more embodiments, the substrate is selected from one or more of an alveolar monolith through a particle stream or filter, and the catalytic material(s) are applied to the substrate as a coating by washing.
[0092] In one or more embodiments, the substrate is a ceramic or metal with a honeycomb structure. Any suitable substrate may be used, such as a monolithic substrate of the type having thin parallel gas flow passages extending from an inlet or outlet face of the substrate so that the passages are open to fluid flow. through them. The passages, which are essentially direct paths from your fluid inlet to your fluid outlet, are defined by walls on which the catalytic material is coated with a wash coat so that gases flowing through the passages come into contact with the catalytic material. Monolithic substrate flow passages are thin-walled channels, which can be of any suitable cross-sectional shape and size, such as trapezoidal, rectangular, square, sinusoidal, hexagonal, oval, circular, etc. Such structures can contain from about 60 to about 900 or more gas inlet openings (i.e., cells) per square inch of cross section.
[0093] A ceramic substrate can be made of any suitable refractory material, for example, cordierite, cordierite-α-alumina, silicon nitride, zircon mullite, spodumene, alumina-silica-magnesia, zircon silicate, silimanite, a silicate of magnesium, zircon, petalite, α-alumina, an aluminosilicate and the like. Substrates useful for the catalyst of embodiments of the present invention can also be metallic in nature and be composed of one or more metals or metal alloys. A metallic substrate can include any metallic substrate, such as those with openings or "perforations" in the walls of the channels. Metallic substrates can be used in various forms such as granules, corrugated sheets or monolithic form. Specific examples of metallic substrates include heat resistant metal-based alloys, especially those in which iron is a substantial or major component. Such alloys may contain one or more of nickel, chromium and aluminum, and the total of these metals may advantageously contain at least about 15% by weight of the alloy, for example about 10% to 25% by weight of chromium, about 1% to 8% by weight aluminum and about 0% to 20% by weight nickel, in each case based on the weight of the substrate.
[0094] In one or more embodiments in which the substrate is a particulate filter, the particulate filter can be selected from a particulate gasoline filter or a soot filter. As used herein, the terms "particulate filter" or "soot filter" refer to a filter designed to remove particulate matter from an exhaust gas stream such as soot. Particulate filters include, but are not limited to honey-wall flow filters, partial filtration filters, wire mesh filters, coiled fiber filters, sintered metal filters, and foam filters.
[0095] In a specific modality, the particulate filter is a catalyzed soot filter (CSF). Catalyzed CSF comprises a substrate coated with a wash coating layer containing a platinum group metal to burn off trapped soot and/or the oxidizing NO to NO2. Catalyzed CSF is coated with a platinum group metal and one or more high surface area refractory metal oxide supports (eg, alumina, silica, silica alumina, zirconia, zirconia alumina, and ceria-zirconia) for the combustion of unburned hydrocarbons and, to some degree, particulate matter.
[0096] Wall flow substrates useful for supporting catalyst material of one or more modalities have a plurality of thin, substantially parallel gas flow passages extending along the longitudinal axis of the substrate. Typically, each pass is blocked at one end of the substrate body, with alternate passes blocked at opposite end faces. Such monolithic substrates can contain up to about 900 or more flow passages (or "cells") per square inch of cross section, although much less is possible. For example, the substrate can have from about 7 to 600, more generally from about 100 to 400, cells per square inch ("cpsi"). The porous wall flow filter used in the embodiments of the invention can be catalyzed by the fact that the wall of said element has on it or contained therein a platinum group metal. Catalytic materials may be present on the inlet side of the element wall alone, the outlet side alone, both inlet and outlet sides, or the wall itself may consist of all or part of the catalytic material. In another embodiment, this invention may include the use of one or more wash coating layers of catalytic materials and combinations of one or more wash coating layers of catalytic materials on the inlet and/or outlet walls of the element.
[0097] Figure 1 illustrates a wall flow filter substrate 50 having a plurality of passages 52. The passages are tubularly enclosed by channel walls 53 of the filter substrate. The substrate has an input end 54 and an output end 56. Alternate passages are connected at the input end with input plugs 58 and at the output end with output plugs 60 to form opposing checkerboard patterns at the input end 54 and at the outlet end 56. A gas stream 62 enters through the non-disconnected channel inlet 64, is stopped by the outlet plug 60 and diffuses through the channel walls 53 (which are porous) to the outlet side 66 .Gas cannot pass back to the inlet side of the walls due to the 58 inlet plugs.
[0098] In one or more embodiments, the first and second catalyst materials are disposed on a substrate. For example, in such embodiments, the catalyst can be disposed on a substrate through the flow. In other embodiments, the catalyst may be disposed on a wall flow filter (ie, SCR over a filter). In still other embodiments, the catalyst can be disposed in a particulate filter.
[0099] In one or more embodiments, the first material and the second material are mixed in a layer on the substrate. In one or more modalities, the mixture is a homogeneous mixture. As used herein, the terms "homogeneously mixed" or "homogeneously mixed" refer to a wash coating mixture in which the first material and the second material are evenly distributed throughout the wash coating so that the wash coating washing is the same throughout.
[00100] On a substrate, designs can include zoned and layered systems. The modalities in which the first material and the second material are mixed in a single layer on the substrate are more specifically illustrated in Figure 2. Referring to Figure 2, a layered catalyst 100 shown is where the first material and the second material are mixed into a single layer 110 and deposited onto a substrate 105. The substrate 105 has an inlet end 115 and an outlet end 120 defining an axial length L1. In one or more embodiments, substrate 105 generally comprises a plurality of channels 130 of a honeycomb substrate, of which only one channel is shown in cross-section for clarity. The first material and the second material are mixed in a single layer 110 which extends from the input end 115 of the substrate 105 through the entire axial length L1 of the substrate 105 to the output end 120. The length of the first material is the second material blended into a single layer 110 is designated as length 105a in Figure 2.
[00101] In other embodiments, the first material may be arranged as a layer on top of the substrate, and the second material may be arranged as a layer on top of the first layer. In still other embodiments, the second material can be arranged as a layer on top of the substrate, and the first material can be arranged as a layer on top of the second material. The embodiments in which the first material and the second material are disposed on the substrate in two layers are more specifically illustrated in Figure 3. Referring to Figure 3, a layered catalyst 200 shown is where the first material is disposed as a first layer. 210 on a substrate 205. The second material is disposed as a second layer 212 on top of the first layer 210. The substrate 205 has an inlet end 215 and an outlet end 220 that define an axial length L2. In one or more embodiments, substrate 205 generally comprises a plurality of channels 230 of a honeycomb substrate, of which only one channel is shown in cross-section for clarity. The first layer 210 and the second layer 212 extend from the inlet end 215 of the substrate 205 through the entire axial length L2 of the substrate 205 to the outlet end 220. The length of the first layer 210 and the second layer 212 is designated as length 205a in Figure 3. It will be recognized by one skilled in the art that, in some embodiments, the location of the first material and the second material can be reversed so that the second material forms a first layer over the substrate and the first material forms a second layer disposed on top of that of the first layer.
[00102] In one or more embodiments, the first material and the second catalyst material are arranged in an axially zoned configuration on a substrate. As used herein, the term "axially zoned" refers to the location of the upstream zone and the downstream zone in relation to each other. Axially means side by side, so that the upstream zone and the downstream zone are located next to each other. As used herein, the terms "upstream" and "downstream" refer to relative directions according to the flow of a stream of exhaust gas from the engine of an engine to an exhaust pipe, with the engine in a upstream location and the exhaust pipe and any pollution abatement items such as filters and catalytic converters downstream of the engine. When a catalyst or catalyst zone is "downstream" or "upstream" of another catalyst or zone, it may be on a different substrate or brick or in a different region of the same substrate or brick. Such modalities can be more easily understood with reference to Figures 4 to 7.
[00103] Referring to Figure 4, an embodiment example of an axially zoned catalyst 300 is shown. The first material forms an upstream zone 310, which is located upstream of the second material that forms a downstream zone 312 on a common substrate 305. Substrate 305 has an inlet end 315 and an outlet end 320 that define an axial length L3. In one or more embodiments, substrate 305 generally comprises a plurality of channels 330 of a honeycomb substrate, of which only one channel is shown in cross-section for clarity. The first material forming an upstream region 310 extends from the inlet end 315 of the substrate 305 to minus the entire axial length L3 of the substrate 305. The length of the upstream region 310 is referred to as the length of the upstream region 310a in Figure 4. The second material forming the downstream zone 312 extends from the output end 320 of the substrate 305 less than the entire axial length L3 of the substrate 305. The length of the downstream zone 312 is designated as the length of downstream zone 312a in Figure 4. In one or more embodiments, as illustrated in Figure 4, the first material that forms the upstream zone 310 is directly in contact with the second material that forms the downstream zone 312. It will be recognized by a person skilled in the art that, in some embodiments, the location of the first material and the second material can be reversed, so that the second material forms an upstream zone in the substrate and the first material forms a zone downstream on the substrate.
[00104] In other embodiments, as illustrated in Figure 5, there may be gaps between the first material and the second material. Referring to Figure 5, an exemplary embodiment of an axially zoned catalyst 400 is shown. The first material forms an upstream zone 410, which is located upstream of the second material that forms a downstream zone 412 on a common substrate 405 Substrate 405 has an inlet end 415 and an outlet end 420 that define an axial length L4. In one or more embodiments, substrate 405 generally comprises a plurality of channels 430 of a honeycomb substrate, of which only one channel is shown in section for clarity. As illustrated, there is a space, g1, between the first material forming the upstream region 410 and the second material forming the downstream region 412. The first material forming an upstream region 410 extends from the inlet end 415 of substrate 405 to less than the entire axial length L4 of substrate 405. The length of upstream zone 410 is designated as upstream zone length 410a in FIG. 5. The second material forming the downstream zone 412 extends from the exit end 420 of the substrate 405 to minus the entire axial length L4 of the substrate 405. The length of the downstream zone 412 is referred to as the zone length downstream 412a in Figure 5. It will be recognized by one skilled in the art that, in some embodiments, the location of the first material and the second material can be reversed so that the second material forms an upstream zone in the substrate and the first material forms a zone downstream in the substrate.
[00105] In other embodiments, as illustrated in Figures 6-7, it will be recognized by a person skilled in the art that the first material and the second catalyst material may be at least partially superimposed. For example, referring to Figure 6, an exemplary embodiment of an axially zoned catalyst 500 is shown. In one or more embodiments, the first material forming the upstream region 510 is at least partially superimposed on the second material forming the downstream zone 512. More specifically, the first material forming the upstream zone 510 is located upstream of the second material forming the downstream zone 512 in a common substrate 505. Substrate 505 has an inlet end 515 and an end output 520 which defines an axial length L5. In one or more embodiments, substrate 505 generally comprises a plurality of channels 530 of a honeycomb substrate, of which only one channel is shown in cross-section for clarity. The first material forming the upstream region 510 extends from the inlet end 515 of the substrate 505 to minus the entire axial length L5 of the substrate 505. The length of the upstream region 510 is referred to as the length of the upstream region 510a in FIG. 6. The second material forming the downstream zone 512 extends from the exit end 520 of the substrate 505 to minus the entire axial length L5 of the substrate 505. The length of the downstream zone 512 is referred to as the zone length downstream 512a in Figure 6. As illustrated, the first material forming the upstream region 510 is at least partially overlapped the second material forming the downstream region 512. The length of the overlap, o1, may vary. It will be recognized by one skilled in the art that, in some embodiments, the location of the first material and the second material can be reversed, so that the second material forms an upstream zone on the substrate and the first material forms a downstream zone in the substrate.
[00106] In other embodiments, as illustrated in Figure 7, the second material that forms the downstream zone 612 is at least partially superimposed on the first material that forms the upstream zone 610. More specifically, referring to Figure 7, it is An exemplary embodiment of an axially zoned catalyst 600 is shown. The first material forming the upstream region 610 is located upstream of the second material forming the downstream region 612 on a common substrate 605. The substrate 605 has an inlet end 615 and an output end 620 defining an axial length L6. In one or more embodiments, substrate 605 generally comprises a plurality of channels 630 of a honeycomb substrate, of which only one channel is shown in cross section for clarity. The first material forming the upstream region 610 extends from the inlet end 615 of the substrate 605 to a length less than the entire axial length L6 of the substrate 605. The length of the upstream region 610 is referred to as the length of the upstream zone 610a in Figure 7. The second material forming the downstream zone 612 extends from the exit end 620 of substrate 605 to minus the entire axial length L6 of substrate 605. The length of downstream zone 612 is designated as the length of the downstream zone 612a in Figure 7. As illustrated, the second material forming the downstream zone 612 is at least partially superimposed on the first material forming the upstream zone 610. The length of the overlap, o2, may vary. It will be recognized by one skilled in the art that, in some embodiments, the location of the first material and the second material can be reversed, so that the second material forms an upstream zone on the substrate and the first material forms a downstream zone in the substrate.
[00107] In one or more embodiments, the catalyst is in a wall flow filter. In such embodiments, the first material can be coated in the inlet passages of the wall flow filter and the second material can be coated in the outlet passages of the wall flow filter. It will be recognized by one of skill in the art that, in some embodiments, the location of the first material and the second material can be reversed so that the second material can be coated in the wall flow filter inlet passages and the first material can be coated in the wall flow filter outlet passages. Exhaust Gas Treatment System
[00108] Another aspect of the present invention is directed to an exhaust gas treatment system. In one or more embodiments, an exhaust gas treatment system comprises a gasoline engine, particularly a stoichiometric gasoline engine, and the catalyst from one or more embodiments downstream of the engine. In one or more modes, the gasoline engine produces exhaust gas temperatures of 850°C and above. In other embodiments, the catalyst according to one or more embodiments is exposed to temperatures in excess of 800 °C and poor and rich exhaust gases.
[00109] Referring to Figure 8, the engine exhaust system of one or more modes may additionally comprise a three-way conversion catalyst (TWC) downstream of the engine and upstream of the catalyst of one or more modes. The TWC catalyst is effective in converting carbon monoxide, hydrocarbons and nitrogen oxides. Specifically, Figure 8 shows an engine 700 exhaust system comprising a TWC 720 catalyst downstream of a 710 gasoline engine through an exhaust conduit 715 and catalyst 730 in accordance with one or more embodiments of the present invention downstream of the catalytic converter TWC 720 through a 725 exhaust pipe.
[00110] In one or more embodiments, the 700 engine exhaust system further comprises an optional 740 catalyst (for example, ammonia oxidation catalyst, CO oxidation catalyst, SCR catalyst, etc.) placed downstream of the catalyst 730 in accordance with one or more embodiments of the present invention through an exhaust conduit 735. In a particular embodiment, the optional catalyst 740 is an SCR catalyst, so that an exhaust gas treatment system comprising an exhaust gas treatment system is provided. 710 gasoline engine (e.g., a stoichiometric gasoline engine), a TWC 720 catalyst downstream of the engine, the 730 catalyst according to one or more embodiments of the present invention downstream of the TWC 720 catalyst, and an SCR catalyst downstream of catalyst 730 (the SCR catalyst comprising, for example, copper and a second molecular sieve with a maximum ring size of eight tetrahedral atoms and a double six-ring unit (d6r), wherein the co bre is present in an amount of about 0.01% to about 2% by weight based on oxide based on the weight of the second molecular sieve, and wherein the SCR is effective to catalyze the selective catalytic reduction of nitrogen oxides in the presence of ammonia under stoichiometric engine operating conditions). It will be recognized by one of skill in the art that one or more of the 730 catalysts in accordance with one or more embodiments of the present invention, the TWC 720 catalyst and the optional 740 catalyst may be in a filter. In another embodiment, the engine exhaust gas treatment system further comprises a wall flow filter or a particulate filter.
[00111] In one or more embodiments, the catalyst comprising the first material and the second material is downstream of a three-way conversion catalyst (TWC). In one or more embodiments there are one or more additional catalytic materials located between the catalyst comprising the first material and the second material and the TWC catalyst. In some embodiments, the catalyst comprising the first material and the second material is immediately downstream of the TWC catalyst. As used herein, the term "immediately downstream" refers to the relative direction in accordance with the flow of an engine exhaust gas stream from an engine towards an exhaust pipe. Immediately downstream means that there is no other catalytic material between the catalyst comprising the first material and the second material and the TWC catalyst.
[00112] In one or more embodiments, an engine exhaust system comprises a three-way conversion catalyst (TWC) mounted in a position close to the engine (in a tight coupling position, CC) and a second catalyst in accordance with the present invention in a position on or near the TWC catalyst (in a second close-coupled position, CC2) or under the vehicle body (in a position under chassis, UF). In one or more modalities there are no specific requirements regarding the TWC catalyst; any TWC catalyst known in the art can be used. In one or more embodiments, the TWC catalyst comprises a platinum group metal supported on an oxygen storage component and/or a refractory metal oxide support and, optionally, an additional platinum group metal component supported on a second refractory metal oxide support or a second oxygen storage component.
[00113] Examples of suitable oxygen storage components for the TWC catalyst comprise the rare earth oxides, particularly ceria. The CSO may also comprise one or more lantana, praseodymia, neodymia, niobia, europia, samaria, ytterbia, yttria, zirconia and mixtures thereof, in addition to ceria. Rare earth oxide can be in bulk form (eg particulate). The oxygen storage component can include cerium oxide (ceria, CeO2) in a form that exhibits oxygen storage properties. Oxygen from the ceria network can react with carbon monoxide, hydrogen or hydrocarbons under rich A/F conditions. In one or more embodiments, the oxygen storage component for the TWC catalyst comprises a ceria-zirconia compound or a rare earth-stabilized ceria-zirconia.
[00114] In one or more embodiments, the refractory metal oxide supports for the TWC catalyst independently comprise a compound that is activated, stabilized or both, selected from the group consisting of alumina, zirconia, alumina-zirconia, lantana-alumina, lantana-zirconia-alumina, alumina-chromia, ceria, alumina-ceria and combinations thereof.
[00115] In one or more embodiments, the platinum group metal component of the TWC catalyst is selected from platinum, palladium, rhodium or mixtures thereof. In specific embodiments, the platinum group metal component of the TWC catalyst comprises palladium. In general, there are no specific restrictions regarding the palladium content of the TWC catalyst.
[00116] In one or more embodiments, the TWC catalyst does not comprise an additional platinum group metal other than palladium. In other embodiments, the TWC catalyst comprises an additional platinum group metal. In one or more embodiments, when present, the additional platinum group metal is selected from platinum, rhodium and mixtures thereof. In specific embodiments, the additional platinum group metal component comprises rhodium. In specific embodiments, the TWC catalyst contains a platinum group metal selected from palladium and rhodium. In general, there are no specific restrictions regarding the rhodium content of the TWC catalyst. In one or more specific embodiments, the TWC catalyst comprises a mixture of palladium and rhodium. In other embodiments, the TWC catalyst comprises a mixture of platinum, palladium and rhodium.
[00117] In a further aspect, an engine exhaust gas treatment system is provided comprising a gasoline engine, particularly a stoichiometric gasoline engine, and a selective catalytic reduction (SCR) catalyst downstream of the engine. In one or more embodiments, the SCR catalyst comprises copper and a second molecular sieve with a maximum ring size of eight tetrahedral atoms and a dual six-ring unit (d6r).
[00118] In one or more embodiments, copper is present in an amount ranging from 0.01% to 2% by weight, based on oxide, based on the weight of the molecular sieve promoted by the metal. The SCR catalyst is effective to catalyze the selective catalytic reduction of nitrogen oxides in the presence of ammonia under stoichiometric engine operating conditions. In specific embodiments, the molecular sieve comprises a main chain CHA type molecular sieve. In other specific embodiments, the molecular sieve is selected from SSZ-13, SSZ-62, chabazite, KG zeolite, Linde D, Linde R, LZ-218, LZ-235, LZ-236, ZK-14, SAPO-34, SAPO-44, SAPO-47, ZYT-6 and Ti-SAPO-34. In very specific embodiments, the molecular sieve selected from SSZ-13 has a silica to alumina molar ratio in the range of 10 and 75. In still other specific embodiments, after exposure to rich and poor exhaust gases at temperatures above 800 °C for more than 5 hours, the molecular sieve has a surface area greater than 400 m2/g.
[00119] In one or more modalities, the exhaust gas treatment system further comprises an ammonia oxidation catalyst (AMOx) downstream of the catalyst of another modality comprising the first material and the second material. The ammonia oxidation catalyst may be provided downstream of the catalyst in a further arrangement comprising the first material and the second material to remove any ammonia that has run off from the exhaust gas treatment system. In one or more embodiments, the catalyst of a further embodiment comprising the first material and the second material is on a substrate with an inlet and an outlet, and includes an ammonia oxidation catalyst (AMOx) at the outlet. In specific embodiments, the AMOx catalyst can comprise a platinum group metal such as platinum, palladium, rhodium or combinations of the mesos. In one or more embodiments, the AMOx catalyst can comprise a lower layer with PGM and an upper layer with SCR functionality.
[00120] Such AMOx catalysts are useful in exhaust gas treatment systems including an SCR catalyst. As discussed in commonly assigned US Patent No. 5,516,497, which is incorporated in its entirety herein by way of reference, a gaseous stream containing oxygen, nitrogen oxides and ammonia can be sequentially passed through the first and second catalysts, the first catalyst favoring the reduction of nitrogen oxides and the second catalyst favoring the oxidation or other decomposition of excess ammonia. Thus, the first catalyst can be the SCR catalyst, and the second catalyst can be an AMOx catalyst and/or an integrated SCR + AMOx catalyst, which optionally comprises a zeolite.
[00121] The AMOx catalyst composition(s) can be coated on a flux or wall flux filter. If a wall flux substrate is used, the resulting system can remove particulate matter along with gaseous pollutants. The wall flow filter substrate can be made from materials commonly known in the art, such as cordierite, aluminum titanate or silicon carbide. It should be understood that loading of the catalytic composition onto a wall-flow substrate will depend on substrate properties, such as porosity and wall thickness, and typically will be less than loading onto a substrate through the flow.
[00122] Without limitation, Table 1 presents various configurations of the exhaust gas treatment system of one or more modalities. It is noted that each catalyst is connected to the next catalyst through exhaust ducts, so that the engine is upstream of catalyst A which is upstream of catalyst B which is upstream of catalyst C which is upstream of catalyst D which is upstream of catalyst E (when present): Table 1
Engine exhaust treatment method
[00123] Another aspect of the present invention is directed to a method of treating the exhaust stream of a gasoline engine, particularly a stoichiometric gasoline engine. In one or more embodiments, a method for treating an exhaust gas stream from a gasoline engine engine comprises placing the catalyst in accordance with one or more embodiments comprising a first material and a second material downstream of an engine. gasoline and the engine exhaust gas stream flowing over the catalytic converter. In one or more modalities, the method further comprises placing a three-way conversion catalyst (TWC) downstream of the engine and upstream of the catalyst according to one or more modalities and directing the exhaust gas stream through the TWC catalyst and then through the catalyst according to one or more modalities.
[00124] The invention is now described with reference to the following examples. Before describing various exemplary embodiments of the invention, it should be understood that the invention is not limited to the details of the construction or process steps set forth in the description below. The invention is capable of other modalities and of being practiced or being carried out in various ways. EXAMPLES Example 1 - Comparative
[00125] 3.2% CuO Cu-SSZ-13: To a vessel equipped with a mechanical stirrer and steam heating was added a suspension of NH4+ substituted SSZ-13 with a silica to alumina ratio of 30. The contents of the vessel were heated to 60°C with stirring. A copper acetate solution was added to the reaction mixture. The solid was filtered, washed with deionized water and air dried. The resulting Cu-SSZ-13 was calcined in air at 550 °C for 6 hours. The product obtained has a copper content of 3.2% by weight, based on CuO, as determined by ICP analysis. Example 2 - Comparative
[00126] 2.4% CuO Cu-SSZ-13: Following the preparation procedure of Example 1, Cu-SSZ-13 with a copper content of 2.4% by weight, based on CuO, as determined by analysis ICP, was obtained. Example 3
[00127] 1.7% CuO Cu-SSZ-13: Following the preparation procedure of Example 1, Cu-SSZ-13 with a copper content of 1.7% by weight, based on CuO, as determined by analysis ICP, was obtained. Example 4
[00128] 1.1% CuO Cu-SSZ-13: Following the preparation procedure of Example 1, Cu-SSZ-13 with a copper content of 1.1% by weight, based on CuO, as determined by analysis ICP, was obtained . Example 5
[00129] 0.6% CuO Cu-SSZ-13: Following the preparation procedure of Example 1, Cu-SSZ-13 with a copper content of 0.6% by weight, based on CuO, as determined by analysis ICP, was obtained. Example 6
[00130] 1.7% CuO CuSAPO-34: Following the preparation procedure of Example 3 and NH4+-SAPO-34 as the precursor, CuSAPO-34 with a copper content of 1.7% by weight, based on CuO , as determined by ICP analysis, was obtained. Example 7
[00131] 5% NiO/CeO2: A nickel nitrate solution was impregnated onto a ceria powder, with a surface area of 180 m2/g, by the incipient moisture impregnation technique to achieve a 5.0% load by weight based on NiO. The resulting wet powder was dried at 120°C for 5 hours and calcined at 550°C for 2 hours.
[00132] BET surface areas: Fresh: 112 m2/g; aged in air at 850 °C for 5 hours: 41 m2/g Example 8
[00133] 5% NiO-1% CuO/CeO2: A mixed solution of nickel nitrate and copper nitrate was impregnated onto a ceria powder, with a surface area of 180 m2/g, by the incipient moisture impregnation technique to achieve a charge of 5.0% by weight based on NiO and a charge of 1.0% by weight based on CuO. The resulting wet powder was dried at 120°C for 5 hours and calcined at 550°C for 2 hours.
[00134] BET surface areas: Fresh: 112 m2/g; aged in air at 850 °C for 5 hours: 37 m2/g Example 9
[00135] 5% Fe2O3/OSC: An iron nitrate solution was impregnated onto a stabilized ceria/zirconia powder (weight ratio CeO2/ZrO2/La2O3 = 40%/50%/10%), with an area of surface of 78 m2/g, by the incipient moisture impregnation technique to achieve a load of 5.0% by weight based on Fe2O3 and a load of 1.0% by weight based on CuO. The resulting wet powder was dried at 120°C for 5 hours and calcined at 550°C for 2 hours.
[00136] BET surface areas: Fresh: 74 m2/g; aged in air at 850 °C for 5 hours: 38 m2/g Example 10
[00137] Base metal oxide powders containing oxides of iron (Fe), copper (Cu) or nickel (Ni) deposited on various supports (ZrO2, CeO2-ZrO2, mixed oxides with 30% and 65% CeO2, and CeO2 ) were prepared by conventional incipient moisture impregnation methods, using a nitrate solution of the corresponding base metal oxide (BMO) as a precursor. BMO loading was controlled to 5% by weight. The samples were aged at 900°C for 12 hours in air with 10% water.
[00138] Figure 10 shows the NO conversion of the CO-NO reaction of supported BMO powder catalysts after aging at 900°C. The samples were tested in a gas reactor model equipped with an ANELVA mass analyzer (conditions: NO 0.100%, CO 0.450%, C5H12 0.017%, H2O 1000%, NH3 0.020%, He balance gas, evaluation temperature 400°C, total flow rate 300 cm3/min, lambda 0.704, sample weight 50 mg). Nickel-based catalysts provided desired NO conversions in the presence of CeO2 enriched supports. This observation is in line with the fact that Ni in CeO2 has better Ni reduction compared to Ni in ZrO2 or Ni in CeO2-ZrO2. In contrast, Fe and Cu catalysts showed higher NO activities on supports with lower CeO2 content. Example 11
[00139] Preparation of an upstream TWC catalyst with a three-layer wash coating architecture: three wash coating slurries were prepared, a bottom wash coating, a middle wash coating and a top wash coating. The bottom wash coat was coated onto a 4.66" x 2.87" cylinder monolith substrate with a cell density of 600 cpsi (number of cells per square inch) and a wall thickness of 3.5 mil ( approximately 100 µm) with a coating load of 1.67 g/in3. The bottom wash coating contained 2.4% by weight of palladium, 36.8% by weight of a high gamma alumina surface area (BET surface area: 150 m2/g), 22.9% by weight of cerium oxide, 25.9% by weight of zirconium oxide, 3.9% by weight of barium oxide and 8.1% by weight of rare earth metal oxides as stabilizers. A middle wash coat was coated over the bottom wash coat, with a wash coat load of 1.24 g/in3 containing 0.6% by weight of rhodium, 30.0% by weight of a high area of gamma alumina surface area (BET surface area: 150 m2/g) 24.1% by weight of cerium oxide, 38.2% by weight of zirconium oxide and 7.1% by weight of rare metal oxides such as stabilizers. A topcoat was coated over the coating by washing the medium, with a coating load of 1.21 g/in3, containing 5.6% by weight palladium, 51.5% by weight of a high alumina surface area gamma (BET surface area: 150 m2/g) 11.1% by weight cerium oxide, 12.8% by weight zirconium oxide, 6.6% by weight barium oxide and 12.4% by weight weight of rare earth metal oxides as stabilizers. Example 12 - Comparative
[00140] A slurry of Comparative Example 1 was prepared by mixing 3.2% CuO Cu-SSZ-13, as described above, with deionized water. A zirconium acetate solution containing 29% ZrO2 was added to the slurry. The slurry was coated onto 4.66" x 2.87" cylinder monolith substrates, with a cell density of 600 cpsi (number of cells per square inch) and a wall thickness of 3.5 miles, to achieve a target wash coating load of 2.73 g/in3. The coated catalysts were flash dried in a flow dryer at 200 °C and calcined at 550 °C for 2 hours. Example 13
Following the coating procedure of Comparative Example 12, a monolith catalyst from Example 3 (1.7% CuO Cu-SSZ-13) was prepared. Example 14
[00142] Following the coating procedure of Comparative Example 12, a monolith catalyst from Example 6 (1.7% CuO SAPO-34) was prepared. Example 15
[00143] This example describes the preparation of a downstream TWC catalyst, free of any PGM, which comprises a two-layer wash coating architecture. The bottom coating, with a coating load of 1.58 g/in3, contained 1.20 g/in3 of NiO-1% to 5% CuO/CeO2 (Example 8), 0.30 g/in3 of Fe2O3/ 5% OSC (Example 9) and 0.08 g/in3 of ZrO2 in the form of zirconium acetate. The top coat, with a wash coat load of 2.49 g/in3, contained 2.49 g/in3 of 1.7% CuO SAPO-34 (Example 6) and 0.09 g/in3 ZrO2 in the form of zirconium acetate. The slurries were milled to reduce average particle size and then coated onto 4.66" x 2.87" cylinder monolith substrates with a cell density of 600 cpsi (number of cells per square inch) and a thickness of 3.5 mil wall, to achieve a target wash coating load of 2.73 g/in3. The coated catalysts were instantly dried in a flow dryer at 200 °C and calcined at 550 °C for 2 hours. aging and testing
[00144] The powder samples were aged in a horizontal tube oven fitted with a quartz tube. Aging was carried out at 850 °C for 5 hours under an air flow (air aging) or lean/rich cyclic conditions (lean/rich aging) in the presence of 10% steam. In the case of lean/rich aging, the aging cycle includes 5 minutes in air, 5 minutes in N2, 5 minutes in 4% H2 balanced with N2 and 5 minutes in N2; this cycle is repeated until reaching the desired aging duration.
[00145] Monolith catalysts were individually mounted in steel converter canisters and aged in a gasoline engine exhaust line under fuel-cut aging cycles. The upstream TWC catalyst from Example 11 was aged at a maximum bed temperature of 950°C for 50 hours. The PGM-free catalysts downstream of Examples 12 to 15 were aged at a maximum bed temperature of 840°C for 10 hours. The aged catalysts were tested in a 1.8L gasoline engine that operated US FTP-75 drive cycles following certified procedures and tolerances.
[00146] Figure 9 provides a comparison of BET surface areas between Comparative Example 1 and Example 3 after air aging and lean/rich aging at 850 °C for 5 hours. Example 1 contained 3.2% CuO, a typical charge for diesel applications. Example 3 contained 1.7% CuO which was significantly less than Example 1. Under air aging conditions, both examples retained a BET surface area of >550 m2/g. However, under lean/rich aging conditions, a significant deterioration in BET surface area was observed for Example 1. In contrast, Example 3 maintained a comparable surface area to the air-aged sample under lean/age conditions. rich. Table 1 summarizes the BET surface areas of Cu-SSZ-13 and CuSAPO-34 of different CuO loadings after lean/rich aging. It is clearly demonstrated that lower CuO loads, eg 0.6-1.7% by weight, are critical for high thermal stability under lean/rich aging conditions which are more relevant for TWC applications. Table 2

[00147] Table 2 provides NOx, HC and CO conversions of the downstream PGM free catalysts to mid-bed emissions during the FTP-75 tests. All emission systems contained the universal TWC upstream catalyst from Example 11 in a tight-coupled first position (CC1) and a downstream PGM-free catalyst either in a tight-coupled second position (CC2) or in an under position. chassis (UF). Systems 1-4 were tested in the CC1 + CC2 configuration. System 1 used the catalyst from Comparative Example 12 with 3.2% CuO Cu-SSZ-13 as the downstream catalyst, which gave a conversion of 16.9% NOx. In comparison, Systems 2 and 3 used the catalyst of Example 13 (formulated with 1.7% CuO Cu-SSZ-13) and Example 14 (formulated with 1.7% CuO CuSAPO-34), respectively, which improved the NOx conversion to 34.2% at 39.2%. The improvement in NOx conversion is in good agreement with the improved thermal stability of the lower CuO zeolites under lean/rich aging conditions. System 4 used the catalyst from Example 15, which was formulated with 1.7% CuO CuSAPO-34 in the bottom layer, as well as 5% NiO-1% CuO/CeO2 and 5% Fe2O3/OSC in the top coat , as the downstream catalyst . Compared to System 3, System 4 not only improved NOx conversion to 46.6%, but also increased HC and CO conversions to 18.8% and 51.3%, respectively. These performance improvements are presumably attributable to hydrocarbon vapor reforming activities and the water-gas shift reaction of the transition metals supported in ceria and ceria-zirconia materials. System 5 was tested in the CC + UF configuration, placing the catalyst downstream of Example 15 at a lower temperature position. Compared to System 4, System 5 improved NOx conversion to 67.1% with a marginal loss in HC and CO conversions. In summary, the catalyst of Example 15 is capable of simultaneously quenching NOx, HC and CO with moderate to decent conversions under TWC conditions. Table 3

[00148] In this study, a TWC system that comprises a CC catalyst with PGM and a UF catalyst without PGM works well with a conventional stoichiometric gallosine combustion engine and offers the opportunity to reduce the use of PGM in the composition of the TWC catalyst. In addition, the CC catalyst operates like a conventional TWC, but it also generates a certain amount of NH3 under rich conditions, and the generated NH3 is used as the reductant for the SCR reaction in the UF-PGM-free catalyst. The UF catalyst without the PGM also functions as a NOx catalyst.
[00149] Reference throughout this descriptive report to "a modality", "certain modalities", "one or more modalities" or "a modality" means that a particular characteristic, structure, material or characteristic described in connection with the modality is included in at least one embodiment of the invention. Thus, the appearances of phrases such as "in one or more embodiments", "in certain embodiments", "in an embodiment" or "in an embodiment" at various places throughout this specification do not necessarily refer to the same embodiment of the invention . In addition, particular features, structures, materials or characteristics may be combined in any suitable way in one or more modalities.
[00150] Although the invention has been described herein with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention include modifications and variations that are within the scope of the appended claims and their equivalents.

权利要求:
Claims (29)
[0001]
1. Effective catalyst for culling NOx, hydrocarbons and carbon monoxide from a gasoline engine exhaust gas, the catalyst characterized by the fact that it comprises: a substrate having a first and second materials disposed thereon, wherein the first material is effective for catalyzing selective catalytic reduction of nitrogen oxides in the presence of ammonia and the second material is effective for slamming down hydrocarbons and carbon monoxide; wherein: a) the first material comprises a molecular sieve promoted with copper or iron in an amount of 0.01% to 2% on an oxide basis based on the weight of the molecular sieve; and b) the second material comprises at least one oxide of a metal selected from Ni, Fe, Mn, Co and Cu on a support selected from an oxide of Ce, Ce-Zr, Zr, Mn, Pr and combinations of the same; wherein the first material and the second material are free of a platinum group metal.
[0002]
2. Catalyst according to claim 1, characterized in that the substrate is a honeycomb substrate and in which the first material and the second material are mixed in a single layer on the substrate.
[0003]
3. Catalyst according to claim 1, characterized in that the first material is in a first layer and the second material is in a second layer on the substrate.
[0004]
4. Catalyst according to claim 3, characterized in that the substrate has an axial length and an upstream end and a downstream end, and wherein the first layer is arranged at the upstream end and the second layer is arranged at the downstream end.
[0005]
5. Catalyst according to claim 3, characterized in that the substrate has an axial length and an upstream end and a downstream end, and wherein the first layer is arranged at the downstream end and the second layer is arranged at the upstream end.
[0006]
6. Catalyst according to claim 3, characterized in that the first layer is directly on the substrate and the second layer partially or fully covers the first layer.
[0007]
7. Catalyst according to claim 3, characterized in that the second layer is directly on the substrate and the first layer partially or fully covers the second layer.
[0008]
8. Catalyst according to claim 1, characterized in that the substrate is a wall flow filter having inlet passages and outlet passages.
[0009]
9. Catalyst according to claim 8, characterized in that the first material is disposed in the inlet passages and the second material is disposed in the outlet passages.
[0010]
10. Catalyst according to claim 8, characterized in that the second material is disposed in the inlet passages and the first material is disposed in the outlet passages.
[0011]
11. Catalyst according to claim 1, characterized in that the molecular sieve is a small-pore molecular sieve having a maximum ring size of eight tetrahedral atoms and a double unit of six rings (d6r).
[0012]
12. Catalyst according to claim 1, characterized in that the molecular sieve is selected from the group consisting of the main chain types AEI, AFT, AFX, CHA, EAB, EMT, ERI, FAU, GME, JSR , KFI, LEV, LTL, LTN, MOZ, MSO, MWW, OFF, SAS, SAT, SAV, SBS, SBT, SFW, SSF, SZR, TSC and WEN.
[0013]
13. Catalyst according to claim 1, characterized in that the molecular sieve is selected from the group consisting of the main chain types CHA, AEI, AFX, ERI, KFI and LEV.
[0014]
14. Catalyst according to claim 1, characterized in that the molecular sieve comprises a molecular sieve of the main chain type CHA.
[0015]
15. Catalyst according to claim 14, characterized in that the molecular sieve is selected from SSZ-13, SSZ-62, natural chabazite, KG zeolite, Linde D, Linde R, LZ-218, LZ-235 , LZ-236, ZK-14, SAPO-34, SAPO-44, SAPO-47, ZYT-6 and Ti-SAPO-34.
[0016]
16. Catalyst according to claim 15, characterized in that the molecular sieve is SSZ-13 having a silica to alumina molar ratio of 10 to 75.
[0017]
17. Catalyst according to claim 15, characterized in that the molecular sieve is promoted with copper in an amount of 0.5% to 2% by weight on an oxide basis based on the weight of the copper promoted molecular sieve , and where in an FTP drive cycle, the catalyst is effective to convert at least 30% nitrogen oxides into the exhaust gas by selective catalytic reduction of nitrogen oxides in the presence of ammonia after exposure to aging conditions of engines with cutting fuel at a temperature of 850 °C for more than ten hours.
[0018]
18. Catalyst according to claim 1, characterized in that the second material comprises at least one oxide of a metal selected from Ni, Fe, Mn, Co and Cu.
[0019]
19. Catalyst according to claim 1, characterized in that the second material comprises an oxide of Ni, deposited on a support comprising an oxide of Ce.
[0020]
20. Catalyst according to claim 19, characterized in that the first material is in a first layer and the second material is in a second layer, wherein the first layer and second layer are arranged on the substrate in a zoned configuration, and wherein the first layer covers the second layer.
[0021]
21. Catalyst according to claim 1, characterized in that the at least one oxide of a metal selected from Ni, Fe, Mn, Co and Cu is present in an amount of 0.1% to 30% in weight, on an oxide basis based on the weight of the support.
[0022]
22. Exhaust gas treatment system, characterized by the fact that it comprises: a stoichiometric gasoline engine; a three-way conversion (TWC) catalyst downstream of the engine, wherein the TWC catalyst is effective to convert carbon monoxide, hydrocarbons, and nitrogen oxides, and wherein the TWC catalyst comprises at least one selected platinum group metal from platinum, palladium and rhodium; and a second catalyst comprising the catalyst as defined in any one of claims 1 to 21 located downstream of the TWC catalyst.
[0023]
23. Exhaust gas treatment system according to claim 22, characterized in that the TWC catalyst is located in a first position with tight coupling downstream of the engine and the second catalyst is located in a second position with tight coupling immediately downstream of the TWC catalyst; or the second catalyst is located in a position under chassis downstream of the TWC catalyst.
[0024]
24. Exhaust gas treatment system according to claim 22, characterized in that the second catalyst is exposed to poor and rich exhaust gases having a temperature in excess of 800 °C.
[0025]
25. A system for treating exhaust gas according to claim 22, characterized in that it further comprises: a selective catalytic reduction (SCR) catalyst downstream of the engine, the SCR catalyst comprising copper and a second molecular sieve having a maximum ring size of eight tetrahedral atoms and a six-ring double unit (d6r), wherein copper is present in an amount of 0.01% to 2% by weight in an oxide base based on the weight of the second molecular sieve , and in which SCR is effective to catalyze the selective catalytic reduction of nitrogen oxides in the presence of ammonia under stoichiometric engine operating conditions.
[0026]
26. Exhaust gas treatment system according to claim 25, characterized in that the engine produces exhaust gas with a temperature of at least 850 °C.
[0027]
27. Exhaust gas treatment system according to claim 26, characterized by the fact that the second molecular sieve has a surface area greater than 400 m2/g after exposure to the exhaust gas for 2 hours.
[0028]
28. Exhaust gas treatment system according to claim 26, characterized by the fact that the second molecular sieve has an aged surface area after exposure to the exhaust gas for 2 hours of 75% of a fresh surface area, in that the fresh surface area is the surface area of the molecular sieve before exposure to the exhaust gas.
[0029]
29. Method for treating exhaust gas from a stoichiometric gasoline engine, characterized by the fact that it comprises: contacting the exhaust gas with a three-way catalyst (TWC) effective to convert carbon monoxide, hydrocarbons and nitrogen oxides, wherein the TWC catalyst contains a platinum group metal selected from palladium and rhodium and a second catalyst comprising the catalyst as defined in any one of claims 1 to 21, wherein the second catalyst is located downstream of the TWC catalyst.

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法律状态:
2020-03-24| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2021-05-25| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2021-08-03| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 18/08/2016, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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US201562208136P| true| 2015-08-21|2015-08-21|

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US62/208,136|2015-08-21|

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PCT/US2016/047560|WO2017034920A1|2015-08-21|2016-08-18|Exhaust gas treatment catalysts|

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