Catalyst composition added with a copper trap component for reducing NOx

Abstract

This disclosure is a x A catalyst composition for the conversion, and a wall flow filter substrate containing such a catalyst composition, are provided. A particular catalyst composition comprises a zeolite having a Cu / Al ratio of 0.1 to 0.5 and sufficient Cu exchanged onto cation sites to obtain a CuO loading of 1 to 15 wt. %, and a D of about 0.5 to 20 microns at a concentration of about 1 to 20 wt. %. 90 and a copper trap component (e.g., alumina) comprising a plurality of particles having a particle size. The zeolite and copper trap component can be in the same washcoat layer or in different washcoat layers (such that the copper trap component acts as a "pre-coating" on the wall flow filter substrate).

Description

Technical Field

[0001] The present invention relates to a zeolite-containing SCR catalyst composition added with a washcoat component capable of trapping mobile copper, a method for preparing and using such a catalyst composition for lean emission control applications, and a catalyst article and system using such a catalyst composition.

Background Art

[0002] Over the years, harmful components of nitrogen oxides (NO x ) have caused air pollution. NO x is contained in exhaust gases from internal combustion engines (e.g., automobiles and trucks), combustion facilities (e.g., power plants heated by natural gas, oil, coal), and nitric acid production plants.

[0003] NO x To treat NO-containing gas mixtures and reduce air pollution, various treatment methods have been used. One type of treatment involves the catalytic reduction of nitrogen oxides. There are two processes: (1) a non-selective reduction process in which carbon monoxide, hydrogen, or a low molecular weight hydrocarbon is used as a reducing agent, and (2) a selective reduction process in which ammonia or an ammonia precursor is used as a reducing agent. In the selective reduction process, a high degree of nitrogen oxide removal can be achieved with a small amount of reducing agent.

[0004] The selective reduction process is referred to as the SCR (Selective Catalytic Reduction) process. The SCR process uses the catalytic reduction of nitrogen oxides with a reducing agent (e.g., ammonia) in the presence of atmospheric oxygen, mainly resulting in the formation of nitrogen and steam as follows: 4NO + 4NH3 + O2 → 4N 2+ 6H2O (standard SCR reaction) 2NO2 + 4NH3 + O2 → 3N2 + 6H2O (slow SCR reaction) NO + NO2 + 2NH3 → 2N2 + 3H2O (fast SCR reaction)

[0005] The catalyst used in the SCR process should ideally be able to maintain good catalytic activity under hydrothermal conditions over a wide range of operating temperature conditions, for example, from 200 °C to 600 °C or higher. The SCR catalyst used in exhaust gas control applications is exposed to high-temperature hydrothermal conditions during the regeneration of the soot filter, which is a component of the exhaust gas treatment system used for particle removal.

[0006] Molecular sieves such as zeolites have been used for the selective catalytic reduction (SCR) of nitrogen oxides with reducing agents such as ammonia, urea, or hydrocarbons in the presence of oxygen. Zeolites are crystalline materials with uniform pore diameters in the range of about 3 to about 10 angstroms, depending on the type of zeolite and the type and amount of cations contained in the zeolite lattice. Zeolites having 8-ring pore openings and double 6-ring secondary building units, specifically those having a cage-like structure, have been studied in recent years for use as SCR catalysts. A particular type of zeolite having these properties is chabazite (CHA), which is a small-pore zeolite having 8-membered ring pore openings (about 3.8 angstroms) accessible from three-dimensional porosity. The cage-like structure results from connecting double 6-ring building units by 4-rings.

[0007] Metal-promoted zeolite catalysts, particularly those containing iron-promoted and copper-promoted zeolite catalysts, are known for the selective catalytic reduction of nitrogen oxides by ammonia. For example, iron-promoted zeolite beta has been an effective commercial catalyst for the selective reduction of nitrogen oxides by ammonia, as described, for example, in U.S. Patent No. 4,961,917. It is always desirable to improve the performance of the catalyst, and thus it would be beneficial to provide an SCR catalyst (and in particular, an SCR on filter substrate, i.e., SCRoF) with improved low-temperature and / or high-temperature performance. SUMMARY OF THE INVENTION

[0008] The present disclosure provides a catalyst composition comprising a copper trap component (e.g., alumina) and one or more zeolites (e.g., one or more metal-promoted zeolites). The present disclosure further provides a catalyst article and system comprising such a catalyst article, the catalyst article comprising a reference catalyst composition disposed on a substrate, e.g., a filter substrate (providing a selective catalytic reduction catalyst on a filter, i.e., SCRoF). Advantageously, in some such embodiments, the catalyst composition (and related articles and systems) exhibit beneficial properties such as improved NO x conversion compared to equivalent catalyst compositions without the copper trap component. Without intending to be limited by theory, it is believed that the addition of alumina may result in a modification of the microporosity of the resulting catalyst composition. Such microporosity can be explained, for example, by the zeolite surface area (ZSA) of the catalyst composition. The specific microporosity of a given catalyst composition, particularly in its calcined and aged form, can affect the activity of the composition. Advantageously, in various embodiments, the disclosed compositions exhibit a relatively low SCR activity loss upon aging.

[0009] In one aspect, the present disclosure provides a catalyst article comprising a wall-flow filter substrate and a catalyst composition coated on the wall-flow filter substrate, the catalyst composition comprising a zeolite having sufficient Cu exchanged at the cation sites of the zeolite such that the zeolite has a Cu / Al ratio of 0.1 to 0.5 and a CuO loading of 1 to 15 wt%, and a copper trap component in an amount of about 1 to about 20 wt% based on the weight of the Cu-exchanged zeolite, the copper trap component comprising a plurality of particles having a D 90 particle size of about 0.5 to 20 microns.

[0010] In some embodiments, the catalyst composition is in the form of a first washcoat containing zeolite and a second washcoat containing a copper trap component, the second washcoat is disposed directly on at least a portion of the wall flow filter substrate, and the first washcoat is disposed directly on at least a portion of the second washcoat. In some embodiments, the catalyst composition is in the form of a washcoat containing a physical blend of zeolite and a copper trap component, and the washcoat is disposed directly on at least a portion of the wall flow filter substrate. In further such embodiments, the first washcoat further contains a second copper trap component, which may be the same as or different from the copper trap component of the second washcoat.

[0011] Such catalyst articles may exhibit enhanced activity at low and / or high temperatures. For example, in some embodiments, the disclosed catalyst articles exhibit enhanced NO x conversion at 200 °C compared to a catalyst composition that does not contain a copper trap component. In some embodiments, the disclosed catalyst articles exhibit enhanced NO x conversion at 600 °C compared to a catalyst composition that does not contain a copper trap component.

[0012] The configuration and form of the copper trap component can be varied. In some embodiments, it includes a material selected from the group consisting of alumina, silica, zirconia, niobium, molybdenum, and combinations thereof. In certain embodiments, the copper trap component includes alumina. Such alumina can be selected, for example, from the group consisting of boehmite, gamma alumina, silica alumina, stabilized alumina, and combinations thereof. In one particular embodiment, the copper trap component includes gamma alumina. In some embodiments, the copper trap component includes a plurality of particles having a D 90 particle size of about 0.5 to 5 microns. In some embodiments, the copper trap component includes a plurality of particles having a D 90 particle size of about 0.5 to 3 microns.

[0013] The composition and form of the zeolite in the disclosed composition can be varied. In some embodiments, the zeolite has an average particle size of from about 0.01 to about 5 microns. In some embodiments, the zeolite can have an "8-ring" framework structure selected from AEI, AFT, AFV, AFX, AVL, CHA, DDR, EAB, EEI, ERI, IFY, IRN, KFI, LEV, LTA, LTN, MER, MWF, NPT, PAU, RHO, RTE, RTH, SAS, SAT, SAV, SFW, TSC, UFI, and combinations and twins thereof. In certain embodiments, the zeolite has a framework structure selected from AEI, AFT, CHA, LTA, and combinations and twins thereof. In a particular embodiment, the zeolite has a CHA framework structure. In other embodiments, the zeolite can have a "10-ring" framework structure selected from the group consisting of AEL, AFO, AHT, BOF, BOZ, CGF, CGS, CHI, DAC, EUO, FER, HEU, IMF, ITH, ITR, JRY, JSR, JST, LAU, LOV, MEL, MFI, MFS, MRE, MTT, MVY, MWW, NAB, NAT, NES, OBW, PAR, PCR, PON, PUN, RRO, RSN, SFF, SFG, STF, STI, STT, STW, SVR, SZR, TER, TON, TUN, UOS, VSV, WEI, WEN, and combinations and twins thereof. Such framework structures can be selected, for example, from FER, MEL, MFI, STT, and combinations and twins thereof.In further embodiments, the zeolite can have a "12-ring" framework structure selected from the group consisting of AFI, AFR, AFS, AFY, ASV, ATO, ATS, BEA, BEC, BOG, BPH, BSV, CAN, CON, CZP, DFO, EMT, EON, EZT, FAU, GME, GON, IFR, ISV, ITG, IWR, IWS, IWV, IWW, JSR, LTF, LTL, MAZ, MEI, MOR, MOZ, MSE, MTW, NPO, OFF, OKO, OSI, RON, RWY, SAF, SAO, SBE, SBS, SBT, SEW, SFE, SFO, SFS, SFV, SOF, SOS, STO, SSF, SSY, USI, UWY, VET, and combinations and intergrowths thereof. For example, the zeolite in certain embodiments has a framework structure selected from AFI, BEA, FAU, MAZ, MOR, OFF, and combinations and intergrowths thereof.

[0014] Compositions containing zeolites of two or more different framework structures can, in certain embodiments, be provided as combinations or intergrowths having the same or different ring numbers (e.g., including two 8-ring framework structures, two 10-ring framework structures, two 12-ring framework structures, an 8-ring and a 10-ring framework structure, an 8-ring and a 12-ring framework structure, or a 10-ring and a 12-ring framework structure). In certain embodiments, the zeolite has a framework structure including an intergrowth of CHA and GME or AEI and GME.

[0015] The amount of each component in the disclosed catalyst composition can, in some embodiments, be provided as follows. In some embodiments, the copper trap component is present in an amount of about 2 to about 20 wt% based on the weight of the Cu-exchanged zeolite. In some embodiments, the zeolite in the catalyst composition is present in an amount of about 0.5 g / in 3 ~ about 5.0 g / in 3 . In further embodiments, the zeolite is present in the catalyst composition in an amount of about 1 g / in 3 ~ about 5.0 g / in 3 .

[0016] In some embodiments, a first portion of the second washcoat is disposed within the walls of the substrate, and a second portion of the second washcoat is disposed on the walls of the substrate. In some embodiments, the second washcoat is disposed within the walls of the substrate. In some embodiments, the first washcoat is disposed on the walls of the substrate.

[0017] In another aspect of the present disclosure, there is provided an exhaust gas treatment system comprising a catalyst article as disclosed hereinabove in fluid communication with an internal combustion engine downstream of a urea injector. Such an exhaust gas treatment system can include a variety of other additional components. For example, in some embodiments, the system further comprises a component selected from the group consisting of a diesel oxidation catalyst, a particulate filter, an ammonia oxidation catalyst, a lean NO x trap, and any combination thereof. The internal combustion engine is, in some embodiments, a diesel engine.

[0018] In a further aspect of the present disclosure, a method of preparing an SCRoF with enhanced low temperature and high temperature NO x conversion, comprising coating a first washcoat comprising a copper trap component comprising a plurality of particles having a D 90 particle size of about 0.5 to 20 microns on at least a portion of a wall flow filter substrate to obtain a pre-coated wall flow filter substrate, and coating the pre-coated wall flow filter substrate with a second washcoat, the second washcoat comprising a zeolite having sufficient Cu exchanged at the cation sites of the zeolite such that the zeolite has a Cu / Al ratio of 0.1 to 0.5 and a CuO loading of 1 to 15 wt%, coating, and firing the coated wall flow filter substrate to obtain an SCRoF. In yet another aspect, enhanced low temperature and high temperature NO xA method of preparing SCRoF with conversion, comprising coating a washcoat containing a mixture of a copper trap component and zeolite on a wall flow filter substrate, wherein the copper trap component comprises a plurality of particles having a D particle size of about 0.5 to 20 microns, and the zeolite component is coated such that the zeolite contains sufficient Cu exchanged at the cation sites of the zeolite to have a Cu / Al ratio of 0.1 to 0.5 and a CuO loading of 1 to 15 wt%, and firing the coated wall flow filter substrate to obtain SCRoF. In some such embodiments, the copper trap component is alumina. The step of coating with the copper trap component can be carried out, in some embodiments, to provide an alumina precoating of about 0.05 g / in to about 0.5 g / in of alumina on the wall flow filter substrate. 90 The step of coating with the copper trap component can be carried out, in some embodiments, to provide an alumina precoating of about 0.05 g / in to about 0.5 g / in of alumina on the wall flow filter substrate. 3 ~ about 0.5 g / in 3 of alumina on the wall flow filter substrate.

Brief Description of the Drawings

[0019] To provide an understanding of embodiments of the present invention, reference is made to the accompanying drawings, which are not necessarily drawn to scale, and reference numerals refer to components of exemplary embodiments of the present invention. The drawings are merely examples and should not be construed as limiting the present invention.

[0020]

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DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, the present disclosure will be described more fully hereinafter with reference to exemplary embodiments. These exemplary embodiments are described so that the present disclosure is thorough and complete and fully conveys the scope of the present disclosure to those skilled in the art. In fact, the present disclosure can be implemented in many different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will meet applicable legal requirements. As used herein and in the appended claims, the singular forms "a", "an", "the" include plural referents unless the context clearly dictates otherwise.

[0022] The present disclosure generally relates to NO from engines such as diesel engines xProvided is a catalyst composition suitable for at least partial conversion of an effluent, e.g., an SCR catalyst composition. The catalyst composition generally includes one or more metal-promoted molecular sieves (e.g., zeolites) and can be prepared and coated onto a substrate using a washcoat technique as more fully described below. Certain embodiments described herein provide a catalytic wall flow filter, i.e., a selective catalytic reduction on filter (SCRoF) article, using a catalyst composition such as a coating on a wall flow filter substrate. The catalyst compositions disclosed herein can provide effective high temperature and / or low temperature performance depending on the particular physical properties of the catalyst composition, and in particular embodiments, depending on the porosity (and in particular microporosity) of the catalyst composition. The disclosed compositions include a copper trap agent such as alumina and, in some embodiments, exhibit improved NO x conversion (at high and / or low temperatures) and / or reduced N2O formation as compared to equivalent compositions without such added copper trap agent.

[0023] One aspect of the present disclosure is the recognition that ion-exchanged copper within a zeolite structure is mobile under high-temperature hydrothermal conditions. Without being restricted to a particular mechanism, it is thought that when copper exits the zeolite lattice, it forms small CuO clusters that become active towards NH3 oxidation and the loss of SCR activity. Furthermore, when copper is removed from the zeolite ion-exchange sites, the structure becomes unstable under hydrothermal conditions, resulting in dealumination, loss of the crystallinity and surface area of the zeolite, and thus loss of SCR activity. To minimize the formation of small CuO clusters, the present invention recognizes that mobile CuO can be trapped, immobilized, or isolated as cupric oxide by a suitable metal oxide, i.e., the above-mentioned "copper trap agent", to form an ABxOy structure (A = Cu and B = a second metal). Metal oxides known to form ternary metal oxides are Y2O3, CeO2, TiO2, ZrO2, V2O5, Nb2O5, Ta2O5, Cr2O3, Nb2O5, WO3, Mn2O3, Fe2O3, CO2O3, Al2O3, Ga2O3, SiO2, and Bi2O3. Accordingly, the present application mainly focuses on including alumina as providing this function, but it is understood that the principles, compositions, and methods disclosed herein are also applicable to the metal oxides referenced above.

[0024] Catalyst compositions generally exhibit some degree of porosity that can be described as being in the form of macroporosity (pores with diameters greater than 50 nm), and / or mesoporosity (pores with diameters between 2 nm and 50 nm), and / or microporosity (pores with diameters of about 2 nm or less) according to the IUPAC definition of pore size. Macroporosity and mesoporosity are known to be important considerations for mass transfer, and microporosity affects access to the catalyst sites and thus the catalytic activity. As described herein, including alumina in a metal-promoted molecular sieve-containing catalyst composition can result in a composition washcoat having a significantly higher zeolite surface area (ZSA) compared to the corresponding composition washcoat without alumina, especially after particularly severe aging (e.g., aging at 800 °C or higher). Further, as described herein, including alumina in a washcoat layer adjacent to a composition washcoat containing a metal-promoted molecular sieve-containing catalyst composition can similarly exhibit improved NO x conversion and / or reduced N2O formation.

[0025] This disclosure describes a change in the alumina content of the catalyst composition, which has been found to result in a change in the microporosity of the catalyst composition (defined by m 2 / g of ZSA). By changing the alumina content, and thus by changing the ZSA of the catalyst composition (especially in the aged form), different catalytic activities were observed. Specifically, catalysts with added alumina, which exhibit higher ZSA values, are shown herein to have improved SCR performance, i.e., increased NO x conversion and / or reduced N2O formation.

[0026] As used herein, "ZSA" is "zeolite surface area" and is compared between objects of equal size in weight or volume, m 2 / g, m 2 / in 3 or simply m 2It can be represented by. ZSA mainly refers to the surface area associated with the micropores of zeolites (usually with a diameter of about 2 nm or less). "ZSA" specifically refers to the name of the "zeolite" surface area, but this term is generally intended to be more widely applicable to the molecular sieve surface area. Methods for evaluating ZSA are disclosed throughout this specification.

[0027] Catalyst composition The catalyst compositions disclosed herein generally include a molecular sieve and a copper trap component, such as alumina. The molecular sieve and the copper trap component can be contained within the same washcoat layer, or can be contained within separate washcoat layers that together "catalyst composition" for the purposes of this disclosure. Advantageously, the present disclosure relates particularly to a layered structure, wherein the catalyst composition includes a copper trap component-containing "precoat" on a substrate, and a molecular sieve-containing coating is disposed on at least a portion of the precoat. It should be noted that the present disclosure refers to a "copper trap component" as being present in the catalyst composition. It should be understood that this nomenclature is relevant, for example, when the molecular sieve is copper-promoted. However, the types of "copper trap components" referred to hereinafter in this specification do not necessarily require copper promotion of the zeolite, and the "copper trap components" can be useful and relevant when the molecular sieve is promoted with another type of metal, such as iron.

[0028] Regarding the molecular sieve component of the disclosed catalyst composition, the molecular sieve generally includes a metal-promoted (e.g., Cu-promoted, Fe-promoted, or Cu / Fe-promoted) molecular sieve. In a particularly preferred embodiment, the molecular sieve is copper-promoted. As used herein, the expression "molecular sieve" refers to framework materials such as zeolites and other framework materials (e.g., isomorphously substituted materials), which can be used as catalysts, for example, in particulate form, in combination with one or more promoter metals. Molecular sieves generally contain tetrahedral sites and have a substantially uniform pore distribution and are materials based on oxygen ions with a wide three-dimensional network structure having an average pore diameter of 20 Å or less. The pore diameter is defined by the ring diameter. As used herein, the term "zeolite" refers to specific examples of molecular sieves that further contain silicon and aluminum atoms. According to one or more embodiments, defining molecular sieves by their structure type is intended to include both molecular sieves having that structure type and all isotype framework materials such as SAPO, AlPO, and MeAPO materials having the same structure type.

[0029] In more specific embodiments, by referring to an aluminosilicate zeolite structure type, the material is limited to a molecular sieve that does not deliberately contain phosphorus or other metals substituted into the framework. However, for clarity, 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 understood to be crystalline materials and aluminosilicates having an open three-dimensional framework structure composed of corner-sharing TO4 tetrahedra (where T is Al or Si). Zeolites generally contain a molar ratio of silica to alumina (SAR) of 2 or more. The zeolite for use in the disclosed catalyst compositions is not particularly limited with respect to the SAR value, although specific SAR values associated with the zeolite can, in some embodiments, affect the SCR performance of the catalyst composition into which it is incorporated (e.g., after aging). In some embodiments, the SAR value of the zeolite is from about 5 to about 100 or from about 5 to about 50. In some embodiments, the SAR is from 5 to 20, and in other embodiments, the SAR is from 20 to 50.

[0030] The cations that balance the charge of the anionic framework are loosely associated with the oxygen of the framework, and the remaining pore volume can potentially be filled with water molecules. The non-framework cations are generally exchangeable, and the water molecules are removable. Zeolites are crystalline materials having a fairly uniform pore diameter in the range of about 3 to 10 angstroms, depending on the type of zeolite and the type and amount of cations contained in the zeolite lattice.

[0031] Molecular sieves can be classified by the framework topology for structure identification. Typically, any structural type of zeolite can be used, for example, the structural types of ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, 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, MEL, MEP, MER, MFI, MFS, MON, 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, SOS, SSY, STF, STI, STT, TER, THO, TON, TSC, UEI, UFI, UOZ, USI, UTL, VET, VFI, VNI, VSV, WIE, WEN, YUG, ZON, or combinations thereof. In certain embodiments, the structural type is selected from AEI, AFT, AFV, AFX, AVL, CHA, DDR, EAB, EEI, ERI, IFY, IRN, KFI, LEV, LTA, LTN, MER, MWF, NPT, PAU, RHO, RTE, RTH, SAS, SAT, SAV, SFW, TSC, UFI, and combinations thereof. Existing twins of these materials, including but not limited to, AEI - CHA, are also intended to be included herein.

[0032] Zeolites consist of secondary building units (SBUs) and composite building units (CBUs) and occur in many different framework structures. The secondary building units contain up to 16 tetrahedral atoms and are not chiral. The composite building units do not necessarily need to be achiral and are not necessarily used in the construction of the entire framework. For example, the group of zeolites has single 4-ring (s4r) composite building units within their framework structures. In the 4-ring, the "4" indicates the positions of the tetrahedral silicon and aluminum atoms, and the oxygen atoms are located between the tetrahedral atoms. Other composite building units include, for example, single 6-ring (s6r) units, double 4-ring (d4r) units, and double 6-ring (d6r) units. The d4r unit is brought about by bonding two s4r units. The d6r unit is brought about by bonding two s6r units. The d6r unit has 12 tetrahedral atoms. Zeolite framework types with d6r secondary building units 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. In one or more particular embodiments of the present disclosure, the molecular sieve of the catalyst composition has a CHA framework type. In a particular embodiment, the molecular sieve has a CHA framework type and is selected from the group consisting of 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, and ZYT-6.

[0033] In certain embodiments, the zeolite of the disclosed catalyst composition comprises small pore zeolites. Small pore molecular sieves contain channels defined by up to eight tetrahedral atoms. The expression "8-ring" zeolite refers to 8-ring pore openings, and in some cases, the "8-ring" zeolite may have a double six-ring secondary building unit and may have a cage-type structure resulting from the connection of double six-ring structural units by 4-rings. Exemplary small pore molecular sieves include framework types ACO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, ATT, CDO, CHA, DDR, DFT, EAB, EDI, EPI, ERI, GIS, GOO, IHW, ITE, ITW, LEV, KFI, MER, MON, NSI, OWE, PAU, PHI, RHO, RTH, SAT, SAV, SIV, THO, TSC, UEI, UFI, VNI, YUG, ZON, and mixtures or intergrowths thereof. For example, in certain embodiments, the zeolite comprises small pore zeolites having a framework type selected from the group consisting of CHA, LEV, AEI, AFT, AFX, ERI, SFW, KFI, DDR, ITE, and mixtures or intergrowths thereof.

[0034] In certain embodiments, the zeolite of the disclosed catalyst composition comprises medium pore zeolites. Medium pore zeolites contain channels defined by 10-membered rings. Exemplary medium pore molecular sieves include framework types AEL, AFO, AHT, BOF, BOZ, CGF, CGS, CHI, DAC, EUO, FER, HEU, IMF, ITH, ITR, JRY, JSR, JST, LAU, LOV, MEL, MFI, MFS, MRE, MTT, MVY, MWW, NAB, NAT, NES, OBW, PAR, PCR, PON, PUN, RRO, RSN, SFF, SFG, STF, STI, STT, STW, SVR, SZR, TER, TON, TUN, UOS, VSV, WEI, WEN, and mixtures or intergrowths thereof. For example, in certain embodiments, the zeolite comprises medium pore zeolites having a framework type selected from the group consisting of FER, MEL, MFI, STT, and mixtures or intergrowths thereof.

[0035] In certain embodiments, the zeolite of the disclosed catalyst composition comprises a large pore zeolite. The large pore molecular sieve contains channels defined by 12-membered rings. Exemplary large pore molecular sieves include framework types AFI, AFR, AFS, AFY, ASV, ATO, ATS, BEA, BEC, BOG, BPH, BSV, CAN, CON, CZP, DFO, EMT, EON, EZT, FAU, GME, GON, IFR, ISV, ITG, IWR, IWS, IWV, IWW, JSR, LTF, LTL, MAZ, MEI, MOR, MOZ, MSE, MTW, NPO, OFF, OKO, OSI, RON, RWY, SAF, SAO, SBE, SBS, SBT, SEW, SFE, SFO, SFS, SFV, SOF, SOS, STO, SSF, SSY, USI, UWY, VET, and mixtures or intergrowths thereof. For example, in certain embodiments, the zeolite comprises a large pore zeolite having a framework type selected from BEA, FAU, MOR, and mixtures or intergrowths thereof.

[0036] As mentioned above herein, the disclosed catalyst compositions generally comprise a metal-promoted molecular sieve (e.g., zeolite). As used herein, "promoted" refers to a molecular sieve that contains one or more components intentionally added, as opposed to containing impurities that may be inherent to the molecular sieve. Thus, a promoter is a component that is intentionally added to enhance the activity of a catalyst as compared to a catalyst that does not have the intentionally added promoter. In one or more embodiments according to the present disclosure, suitable metals are exchanged within the molecular sieve to promote the SCR of nitrogen oxides. Copper can be a particularly useful metal for exchange since it is involved in the conversion of nitrogen oxides. Thus, in certain embodiments, catalyst compositions are prepared that include a copper-promoted molecular sieve (e.g., zeolite), such as Cu-CHA. However, the present invention is not intended to be limited thereto, and catalyst compositions that include other metal-promoted molecular sieves are also encompassed herein.

[0037] The promoter metal can generally be selected from the group consisting of alkali metals, alkaline earth metals, Group IIIB, Group IVB, Group VB, Group VIB, Group VIIB, Group VIIIB, Group IB, Group IIB transition metals, Group IIIA elements, Group IVA elements, lanthanides, actinides, and combinations thereof. Specific promoter metals that can be used to prepare the metal-promoted molecular sieve include, in various embodiments, copper (Cu), cobalt (Co), nickel (Ni), lanthanum (La), manganese (Mn), iron (Fe), vanadium (V), silver (Ag), cerium (Ce), neodymium (Nd), praseodymium (Pr), titanium (Ti), chromium (Cr), zinc (Zn), tin (Sn), niobium (Nb), molybdenum (Mo), hafnium (Hf), yttrium (Y), tungsten (W), and combinations thereof, but are not limited thereto. Such combinations of metals, such as copper and iron, can be used to obtain a mixed Cu-Fe promoted molecular sieve, such as Cu-Fe-CHA. In certain embodiments, the promoter metal associated with the disclosed zeolite component comprises copper (e.g., as CuO), iron (e.g., as Fe2O3), or manganese (e.g., as MnO2).

[0038] The promoter metal content of the metal-promoted molecular sieve, calculated as an oxide, is in one or more embodiments at least about 0.1 wt% based on the total weight of the calcined molecular sieve (including the promoter) and reported as free of volatiles. In certain embodiments, the promoter metal of the zeolite component comprises Cu, and the Cu content calculated as CuO is in each case in the range of about 0.1 wt% to about 20 wt%, including about 0.5 wt% to about 17 wt%, about 2 wt% to about 15 wt%, or about 2 wt% to about 10 wt%, based on the total weight of the calcined molecular sieve reported as free of volatiles. In some embodiments, the zeolite component (including the promoter metal) can be defined by the ratio of the promoter metal to aluminum in the promoted zeolite. For example, in some embodiments, the molar ratio of promoter metal to aluminum is about 0.1 to about 0.5 (e.g., the Cu / Al ratio is about 0.1 to about 0.5).

[0039] The copper trap component of the disclosed catalyst compositions can be of various types. In a preferred embodiment, the copper trap component is alumina or silica-alumina. In the following description, the focus is on alumina as the copper trap component, but it should be understood that the features and parameters discussed below herein are not intended to be limited thereto and are applicable to other "copper trap components" as well. Alumina can be, for example, boehmite, gamma alumina, delta / theta alumina, transitional or stabilized alumina, doped alumina (e.g., silica-doped alumina), or combinations thereof. In certain embodiments, the alumina component in the disclosed composition is in the form of "gamma alumina" or "activated alumina", which typically exhibits a BET surface area in excess of 60 square meters per gram ("m 2 / g"), often up to about 200 m 2 / g or more. "BET surface area" has its ordinary meaning associated with the Brunauer, Emmett, Teller method for determining surface area by N2 adsorption. In one or more embodiments, the BET surface area is about 100 to about 150 m2 is in the range of / g. Such activated alumina is usually a mixture of the gamma and delta phases of alumina, but may also contain significant amounts of eta, kappa, and theta alumina phases. Useful commercially available aluminas include high surface area aluminas such as high bulk density gamma alumina, and macroporous gamma aluminas with low or medium bulk density. Generally, the alumina component of the disclosed catalyst compositions is not binder alumina. Binder alumina is typically in the form of soluble alumina (e.g., Al(NO3)3, or colloidal alumina with a particle size D typically in the range of 5 to 50 nm) 90 in the form of dispersible colloidal alumina having. On the other hand, in the alumina component of the disclosed catalyst compositions, the disclosed alumina is generally non-dispersible and has an aggregate size D 10 > 0.1 micron.

[0040] Typically, the alumina component of the disclosed catalyst compositions is substantially free of any associated active metal. "Substantially free of" means "little or none" or "not intentionally added", and also means containing only trace amounts and / or unintended amounts. For example, in certain embodiments, "substantially free of" means less than 2 wt% (wt%), less than 1.5 wt%, less than 1.0 wt%, less than 0.5 wt%, 0.25 wt%, less than 0.01 wt% of the metal associated with the alumina component, based on the weight of the total composition shown. Thus, it is advantageous that the alumina component is not intentionally added to act as a support for any metal species (e.g., active metals), and in some such embodiments, the alumina component is referred to herein as an "alumina-free" component (i.e., substantially free of active metal species).

[0041] In some embodiments, the alumina is present in particulate form, which in some embodiments can be on the order of 20 micrometers in size. The alumina can have, for example, a D of about 0.5 micron to about 20 microns 90It can have a particle size distribution. The particle size refers to primary particles. The particle size can be measured by a laser light scattering method, for example, according to ASTM method D4464, using a dispersion system or dry powder. D 90 The particle size distribution, when measured with a scanning electron microscope (SEM) or transmission electron microscope (TEM) for sub-micron sized particles and a particle size analyzer for micron sized particles, indicates that 90% (number) of the particles have a Feret diameter less than a specific size.

[0042] The relative amounts of the promoted zeolite and alumina components in the disclosed catalyst composition can be various. In some embodiments, the alumina component is present in an amount of about 1 to 50 weight percent of the catalyst composition, for example, about 1 to about 20 weight percent of the catalyst composition, about 5 to about 15 weight percent of the catalyst composition, or about 5 to about 10 weight percent of the catalyst. Exemplary alumina contents in the disclosed catalyst composition are at least about 1 weight percent, at least about 5 weight percent, at least about 10 weight percent, at least about 12 weight percent, or at least about 15 weight percent based on the total weight of the catalyst composition.

[0043] In some embodiments, the amount of the promoted zeolite in the catalyst composition can be decreased compared to an equivalent catalyst composition containing only the promoted zeolite without the alumina component disclosed herein, while at the same time having equivalent or better catalytic activity (e.g., equivalent or increased NO xachieve conversion and / or equivalent or reduced N2O production). Thus, in some embodiments, as the amount of alumina in the disclosed compositions increases, it may be possible to reduce the amount of the metal-promoted zeolite component. For example, by increasing the amount of alumina in the catalyst composition, the amount of zeolite can be directly reduced by the same amount. In other words, in some embodiments, a portion of the promoted zeolite in the comparative catalyst composition is replaced by an alumina component as disclosed herein, and the resulting catalyst composition can exhibit equivalent or better SCR activity. However, in other embodiments, alumina is added such that the promoted zeolites of the inventive and comparative compositions are provided in equivalent amounts. In such embodiments, by increasing the amount of alumina in the catalyst composition (while maintaining the same amount of promoted zeolite), a catalyst composition having equivalent or better SCR activity can be provided.

[0044] In some embodiments, the disclosed catalyst compositions comprise a mixture of a promoted zeolite and an alumina component. In some embodiments, the disclosed catalyst compositions comprise separate formulations, one formulation comprising an active SCR catalyst component (e.g., a promoted zeolite) and a second formulation comprising an alumina component. For example, in one particular embodiment, the formulation comprising the alumina component is present as a "precoating" on at least a portion of the substrate, and the formulation comprising the promoted zeolite is applied thereto to obtain the desired catalyst composition. "Precoating" means that a first washcoat containing alumina is applied directly to the substrate (with one or more additional washcoats, including a washcoat containing the promoted zeolite, applied to at least a portion of the "precoat").

[0045] substrate According to one or more embodiments, the substrate (to which the disclosed catalyst composition is applied to obtain a catalyst article, e.g., an SCR catalyst article such as SCRoF) can be constructed from any material typically used to prepare automotive catalysts and is typically composed of a metallic or ceramic honeycomb structure. As used herein, the term "substrate" refers to a monolithic material to which the catalyst material is typically applied in the form of a washcoat. The substrate typically provides a plurality of walls to which an SCR washcoat composition (e.g., including the metal-promoted molecular sieves disclosed above herein) is applied and adhered, thereby acting as a carrier for the catalyst composition.

[0046] Exemplary metal substrates include heat-resistant metals and metal alloys such as titanium and stainless steel and other alloys in which iron is a substantial or major component. Such alloys may contain one or more of nickel, chromium, and / or aluminum, and the total amount of these metals may advantageously include at least 15 wt% of the alloy, e.g., 10 - 25 wt% chromium, 3 - 8 wt% aluminum, and up to 20 wt% nickel. The alloys may also contain one or more other metals in minor or trace amounts, such as manganese, copper, vanadium, and titanium. The surface of the metal substrate can be oxidized at a high temperature, e.g., 1000 °C or higher, to form an oxide layer on the surface of the substrate, improving the corrosion resistance of the alloy and facilitating the adhesion of the washcoat layer to the metal surface. Ceramic materials used to construct the substrate can include any suitable refractory material, e.g., cordierite, mullite, cordierite-α alumina, silicon carbide, aluminum titanate, silicon nitride, zircon mullite, spodumene, alumina-silica magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, α alumina, and aluminosilicate, etc.

[0047] Any suitable substrate can be used, such as a monolithic flow-through substrate having a plurality of fine and parallel gas flow paths extending from an inlet to an outlet face of the substrate so that the passageway is open to fluid flow. The passageway, which is an essentially straight path from inlet to outlet, is defined by walls coated with the catalyst material as a washcoat such that the gas flowing through the passageway contacts the catalyst material. The flow paths of the monolithic substrate are thin-walled channels that can be of any suitable cross-sectional shape, such as trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical, and circular. Such structures can contain from about 60 to about 1200 or more gas inlet openings (i.e., "cells") per square inch of cross-section (cpsi), more typically from about 300 to 600 cpsi. The wall thickness of the flow-through substrate can vary and a typical range is from 0.002 to 0.01 inches. A representative commercially available flow-through substrate is a cordierite substrate having a wall thickness of 4 - 6 mils at 400 cpsi or 3 - 4 mils at 600 cpsi. However, it will be understood that the present invention is not limited to a particular substrate type, material, or geometric shape.

[0048] Figures 1 and 2 show a typical wall-flow filter substrate 10 (also called a wall-flow filter) having a plurality of passageways 12. The passageways are formed by and surrounded tubularly by the inner wall 13 of the filter substrate. FIG. 1 shows the exterior of an embodiment of a wall-flow filter substrate having an inlet end 14 and an outlet end 16. The passageways are alternately blocked at the inlet end by an inlet plug 18 and at the outlet end by an outlet plug 20 to form a checkerboard pattern that is reversed at the inlet end 14 and the outlet end 16 of the substrate.

[0049] Figure 2 shows a cross-sectional view of an embodiment of a plurality of porous walls extending longitudinally from an inlet end to an outlet end of a wall flow filter substrate. A partial cross-sectional view of an embodiment of a plurality of porous walls 13 extending longitudinally from an inlet end 14 to an outlet end 16 and forming a plurality of parallel passages 12 is shown. A gas flow 22 (shown as an arrow) enters through an open end with the plug removed from the inlet passage 24, stops at a closed end by the outlet plug 20, diffuses through the porous wall 13, and forms a passage to the outlet passage 26. The gas flow 22 exits the filter by flowing through an open end with the plug removed from the outlet passage 26 and stops at a closed end by the inlet plug 18. The gas is prevented from flowing back from the outlet passage to the inlet end of the filter by the inlet plug 18 and from re-entering the inlet passage from the outlet end by the outlet plug 20. Thus, the amount of passages is an inlet passage that is open at the inlet end and closed at the outlet end, and the amount of passages is an outlet passage that is closed at the inlet end and open at the outlet end, where the outlet passage is a passage different from the inlet passage.

[0050] Such monolithic substrates can contain up to about 700 or more cpsi, such as about 100 - 400 cpsi, more typically about 200 - about 300 cpsi. The cross-sectional shape of the cells can vary as described above. The wall flow substrate typically has a wall thickness of 0.008 - 0.02 inches. Representative commercially available wall flow substrates are constructed from porous cordierite, examples of which have a wall thickness of 200 cpsi and 10 mils, or 300 cpsi and 8 mils, and a wall porosity of 45 - 65%. Other ceramic materials such as aluminum titanate, silicon carbide, and silicon nitride are also used as wall flow filter substrates. However, it will be understood that the present disclosure is not limited to a particular substrate type, material, or shape. It should be noted that when the substrate is a wall flow substrate, the catalyst composition can penetrate into the pore structure of the porous wall (i.e., partially or completely block the pore openings) in addition to being disposed on the surface of the wall.

[0051] The wall flow filter article substrate is, for example, about 50 cm 3, approximately 100 cm 3 , approximately 200 cm 3 , approximately 300 cm 3 , approximately 400 cm 3 , approximately 500 cm 3 , approximately 600 cm 3 , approximately 700 cm 3 , approximately 800 cm 3 , approximately 900 cm 3 , or approximately 1000 cm 3 to approximately 1500 cm 3 , approximately 2000 cm 3 , approximately 2500 cm 3 , approximately 3000 cm 3 , approximately 3500 cm 3 , approximately 4000 cm 3 , approximately 4500 cm 3 , or approximately 5000 cm 3 may have a volume up to. In some embodiments, the wall flow filter article substrate may have a volume of 2.0 L, 2.5 L, 5.0 L, 10 L, 20 L, or 30 L, and it should be understood that all volumes between any two of these exemplary values are also contemplated by the present invention. The wall flow filter substrate typically has a wall thickness of from about 200 microns to about 500 microns, for example, from about 200 microns to about 300 microns.

[0052] The walls of the wall-flow filter are porous and generally have a wall porosity of at least about 50% or at least about 60% before the placement of the functional coating, and an average pore diameter of at least about 5 microns. For example, the wall-flow filter article substrates in some embodiments will have a porosity of 50% or more, 60% or more, 65% or more, or 70% or more. For example, the wall-flow filter article substrate will have a wall porosity of from about 50%, about 60%, or about 65% to about 70% and an average pore diameter of from about 10 microns, about 20 microns, or about 25 microns to about 30 microns before the placement of the catalyst coating. The terms "wall porosity" and "substrate porosity" have the same meaning and are interchangeable. Porosity is the ratio of the void volume (or pore volume) to the total volume of the substrate. The pore diameter can be determined according to the ISO15901-2 (static volume) procedure for nitrogen pore diameter analysis. The nitrogen pore diameter can be measured with a Micromeritics TRISTAR3000 series instrument. The nitrogen pore diameter can be determined using BJH (Barrett-Joyner-Halenda) calculations and 33 desorption points. Useful wall-flow filters have a high porosity and allow for a high loading of the catalyst composition without imposing excessive backpressure during operation.

[0053] In certain embodiments, there is provided a wall-flow filter comprising a catalyst composition comprising a copper trap component (e.g., alumina) as disclosed herein. Such coated filters, generally referred to as SCRoF (i.e., selective catalytic reduction catalyst (SCR) on a filter), in some embodiments exhibit enhanced NO x conversion with respect to coated filters comprising a catalyst composition to which no copper trap component (e.g., alumina) has been added.

[0054] In one embodiment, the catalyst composition is provided such that alumina is mixed with the other components of the catalyst composition. In such embodiments, SCRoF can advantageously increase the high-temperature NO x conversion as compared to SCRoF comprising a catalyst composition that does not contain alumina.

[0055] In one embodiment, alumina is provided as a first washcoat, also referred to herein as a "precoating" (disposed directly on / adjacent to the substrate), and a filter is provided in which a zeolite-containing washcoat is coated on at least a portion of the alumina precoating. The loading of this alumina coating can form a layer or sublayer within the microstructure of the filter wall or near the surface of the wall. The loading of the alumina washcoat can vary from about 0.05 g / in 3 of alumina, such as about 0.15 g / in 3 to about 0.5 g / in 3 of alumina. In some embodiments, the thickness of the layer may be difficult to accurately characterize, for example, due to the microstructure of the filter. The alumina in the first washcoat can have a particle size having a D 90 of about 0.5 to about 20 μm. Such SCRoF exhibits improved low-temperature SCR activity in some embodiments compared to catalyst compositions that do not contain alumina (e.g., containing other components of the same type / amount).

[0056] Method for preparing SCR composition According to the present disclosure, the SCR catalyst composition is generally prepared by providing a metal-promoted molecular sieve material. Molecular sieves having a CHA structure can be prepared according to various techniques known in the art, such as U.S. Patent No. 4,544,538 by Zones, U.S. Patent No. 6,709,644 by Zones, and U.S. Patent No. 8,883,119 by Bull et al. (each of which is incorporated herein by reference in its entirety). Methods for preparing other types of molecular sieves are known in the art and can be readily used to provide the desired zeolite framework for inclusion within the disclosed compositions.

[0057] To prepare a metal-promoted molecular sieve according to various embodiments of the present invention, a metal (e.g., copper) is ion-exchanged into the molecular sieve. Such metals are generally ion-exchanged into an alkali metal or NH4 molecular sieve (e.g., as disclosed in Bleken, F et al., Topics in Catalysis 2009, 52, 218-228, which is incorporated herein by reference, by methods known in the art into an alkali metal molecular sieve for NH4 + ion exchange).

[0058] The preparation of the metal-promoted molecular sieve typically involves an ion-exchange process between the molecular sieve in particulate form and a metal precursor solution. For example, a copper salt may be used to supply copper. When copper acetate is used to provide copper, the copper concentration of the liquid copper solution used in the copper ion exchange is, in certain embodiments, in the range of about 0.01 to about 0.4 moles, more specifically in the range of about 0.05 to about 0.3, even more specifically in the range of about 0.1 to about 0.25 moles, even more specifically in the range of about 0.125 to about 0.25 moles, even more specifically in the range of about 0.15 to about 0.225 moles, and even more specifically approximately about 0.2. In certain embodiments, a metal such as copper is ion-exchanged into an alkali metal or NH4 + -chabazite to form Cu-chabazite.

[0059] To further promote the SCR of nitrogen oxides, in some embodiments, the molecular sieve can be promoted with two or more metals (e.g., copper in combination with one or more other metals). When two or more metals are included in the metal ion-promoted molecular sieve material, the plurality of metal precursors (e.g., copper and iron precursors) can be ion-exchanged in a plurality of exchange steps, either simultaneously or separately. In certain embodiments, the second metal can be exchanged into the molecular sieve material that has been first promoted with the first metal (e.g., the second metal can be exchanged into the copper-promoted molecular sieve material). The second molecular sieve material can be of various types and, in some embodiments, can be iron or an alkaline earth metal or an alkali metal.

[0060] Coating process of the substrate As mentioned above, the catalyst composition is prepared and coated onto a substrate. This method can include mixing the catalyst composition (or one or more components of the catalyst composition) disclosed generally herein with a solvent (e.g., water) to form a slurry for coating the catalyst substrate. As mentioned above, the metal-promoted zeolite component and the alumina component can be prepared in the same slurry or in separate slurries, i.e., each providing one washcoat or independent washcoats on the substrate. In some embodiments, one slurry is provided containing a copper trap component (e.g., alumina), and a second slurry is provided containing the metal-promoted zeolite component and optionally an additional alumina component (which can be the same as or different from the alumina component of the first slurry).

[0061] In addition to the catalyst component(s) (i.e., the metal-promoted molecular sieve and / or the copper trap component) in a given washcoat slurry, the slurry may optionally contain various additional components. Typical additional components include, for example, but are not limited to, one or more binders and additives for controlling the pH and viscosity of the slurry. Specific additional components include binders (e.g., typically in an amount of about 0.1 to about 10 weight percent based on the weight of the washcoat, silica, titania, zirconia, or combinations thereof), associative thickeners, and / or surfactants (including anionic, cationic, nonionic, or amphoteric surfactants) and zirconium acetate.

[0062] In some embodiments, the slurry can be milled to enhance the mixing of the particles and the formation of a homogeneous material. Milling can be accomplished with a ball mill, a continuous mill, or other similar equipment, and the solids content of the slurry can be, for example, about 20 to 60 weight percent, more specifically, about 30 to 40 weight percent. In one embodiment, the milled slurry is characterized by a D 90 particle size of about 5 to about 50 microns (e.g., about 5 to about 20 microns, or about 10 to about 20 microns).

[0063] Next, a washcoat technique known in the art is used to coat the slurry onto the catalyst substrate. As used herein, "washcoat" has its ordinary meaning in the art of thin, adherent coating techniques for materials (e.g., catalyst materials) applied to a "substrate", e.g., a honeycomb flow-through monolith substrate or a filter substrate that is porous enough to allow passage of the gas stream being treated. As used herein and as described in Heck, Ronald and Farrauto, Robert, Catalytic Air Pollution Control, New York: Wiley-Interscience, 2002, pp. 18-19, the washcoat layer comprises compositionally distinct layers of materials disposed on the surface of the monolithic substrate or underlying washcoat layer. The substrate can contain one or more washcoat layers, and each washcoat layer can have a unique chemical catalytic function.

[0064] A washcoat is generally formed by preparing a slurry containing a specific solids content (e.g., 30 - 60 wt%) of a catalyst material (here, a metal-promoted zeolite component, an alumina component, or both) in a liquid vehicle, which is then coated onto one or more substrates and dried to provide a washcoat layer. To coat a wall flow substrate with the catalyst material of one or more embodiments, the substrate can be vertically immersed into a portion of the catalyst slurry such that the upper part of the substrate is positioned just above the surface of the slurry. In this way, the slurry contacts the inlet face of each honeycomb wall but is prevented from contacting the outlet face of each wall. The sample is left in the slurry for about 30 seconds. The substrate is removed from the slurry, and the excess slurry is removed from the wall flow substrate by first draining it from the channels, then blowing compressed air (in the direction of slurry penetration), and then applying a vacuum from the direction of slurry penetration. By using this technique, the catalyst slurry penetrates the walls of the substrate, but the pores are not blocked to the extent that excessive backpressure is generated in the finished substrate. As used herein, the term "penetrate" when used to describe the dispersion of the catalyst slurry on the substrate means that the catalyst composition is dispersed throughout the walls of the substrate.

[0065] Thereafter, the coated substrate is dried at a high temperature (e.g., 100 - 150 °C) for a certain period (e.g., 10 minutes - 3 hours) and then calcined by heating, for example, at 400 - 600 °C typically for about 10 minutes - about 3 hours. After drying and calcination, the final washcoat coating layer can be considered to be essentially solvent-free.

[0066] After calcination, the catalyst loading can be determined by calculating the difference between the coated weight and the uncoated weight of the substrate. As will be apparent to those skilled in the art, the catalyst loading can be adjusted by changing the rheology of the slurry. Further, the coating / drying / calcination process can be repeated as necessary to build up the coating to the desired loading level or thickness.

[0067] Aging can be carried out under various conditions and, as used herein, "aging" is understood to encompass a range of conditions (e.g., temperature, time, and atmosphere). Exemplary aging protocols include exposing a fired coated substrate to a temperature of about 750° C. for about 5 hours in 10% steam or to a temperature of about 800° C. for about 16 hours in 10% steam. However, these protocols are not intended to be limiting, and the temperature can be lower or higher (e.g., including, but not limited to, temperatures of 400° C. or higher, such as 400° C. to 1000° C., 600° C. to 950° C., or 650° C. to about 800° C.), the time can be shorter or longer (e.g., including, but not limited to, times of about 1 hour to about 100 hours, or about 2 hours to about 50 hours), and the atmosphere can be adjusted (e.g., to have different amounts of steam and / or other components present therein).

[0068] Catalyst article The resulting catalyst article (providing a substrate coated with one or more washcoat layers and coated with a catalyst composition) can have various configurations. In some embodiments, as referred to herein, all components of the disclosed catalyst composition (including the metal-promoted zeolite component and the copper trap component) are contained within a single catalyst composition washcoat layer (i.e., a mixture), which is provided as one or more layers on the substrate. In some embodiments, a catalyst article is provided wherein the catalyst composition coated on the substrate includes separate washcoat layers, with at least one washcoat layer including the metal-promoted zeolite component and at least one (separate) washcoat layer including an alumina component. For example, in one particular embodiment, a first catalyst composition washcoat layer including the alumina component is in direct contact with the substrate, and a second catalyst composition washcoat layer including the metal-promoted zeolite component is present directly on at least a portion of the first catalyst composition washcoat layer. In this particular embodiment, one exemplary catalyst article has a weight of 0.2 to 2.0 g / in 3It includes a substrate having an alumina-containing washcoat layer disposed directly on its surface under a load, and a metal-promoted zeolite-containing washcoat layer disposed on the alumina-containing washcoat layer.

[0069] The washcoat(s) can be applied such that different coating layers can be in direct contact with the substrate. Alternatively, one or more "undercoats" may be present such that at least a portion of the catalyst composition washcoat layer(s) is not in direct contact with the substrate (but rather in contact with the undercoat). One or more "overcoats" may also be present such that at least a portion of the coating layer(s) is not directly exposed to the gas stream or the atmosphere (but rather in contact with the overcoat).

[0070] The different catalyst composition washcoat layers may be in direct contact with each other without an "intermediate" overlapping zone. Alternatively, the different catalyst composition washcoat layers may have a "gap" between two zones and may not be in direct contact. In the case of an "undercoat" or an "overcoat", the gap between different layers is called an "intermediate layer". The undercoat is a layer "below" the catalyst composition washcoat layer, the overcoat is a layer "above" the catalyst composition washcoat layer, and the intermediate layer is a layer "between" two catalyst composition washcoat layers. The intermediate layer(s), undercoat(s), and overcoat(s) may contain one or more functional compositions or may not contain a functional composition.

[0071] The catalyst coating can include two or more thin adhesion layers, layers adhered to each other, and a coating adhered to the substrate. The entire coating includes individual "coating layers". The catalyst coating can advantageously be "zoned", including zoned catalyst layers. This can also be said to be "laterally zoned". For example, the layer can extend from the inlet end to the outlet end and can extend up to about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, or about 90% of the length of the substrate. Another layer can extend from the outlet end to the inlet end and can extend up to about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, or about 90% of the length of the substrate. Different coating layers may be adjacent to each other and may not overlap each other. Alternatively, different layers may overlap a part of each other to provide a third "intermediate" zone. The intermediate zone can extend, for example, from about 5% to about 80% of the length of the substrate, for example, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60, or about 70%.

[0072] Each of the different layers can extend over the entire length of the substrate or each can extend over a part of the length of the substrate and can partially or entirely overlap or underlay each other. Each of the different layers can extend from either the inlet end or the outlet end.

[0073] Different catalyst compositions can be present in each separate coating layer. For example, one coating layer can include an SCR catalyst composition as disclosed herein (the coating layer includes both a metal-promoted zeolite and an alumina component), and the second layer can include another type of catalyst composition for providing a different catalytic function. As another example, two coatings can be provided to provide the catalyst compositions disclosed herein (including one layer containing a metal-promoted zeolite and a second layer containing alumina), and different catalytic functions can be provided including a third coating containing another type of catalyst composition. Thus, the discussion regarding different layers can correspond to any of these layers. The catalyst coating can include one, two, or three or more coating layers. One or more coating layers together include a catalyst composition.

[0074] The zones of the present disclosure are defined by the relationship of the coating layers. For different coating layers, several possible zoning configurations exist. For example, an upstream zone and a downstream zone can exist, an upstream zone, an intermediate zone, and a downstream zone can exist, four different zones, etc. can exist. When two layers are adjacent and do not overlap, an upstream zone and a downstream zone exist. When two layers overlap to some extent, upstream, downstream, and intermediate zones exist. For example, when a coating layer extends over the entire length of a substrate, a different coating layer extends a specific length from the outlet end, and a portion of the first coating layer is overlaid, upstream and downstream zones exist. The catalyst coating can include two or more identical layers.

[0075] A resulting catalyst article that includes a catalyst composition as disclosed herein on a substrate can advantageously exhibit good SCR activity in some embodiments. Without intending to be limited by theory, the enhanced SCR activity associated with the disclosed catalyst articles may, in some embodiments, be attributed to the improved hydrothermal stability of the zeolite component. In this regard, catalyst articles that include metal-promoted zeolites generally undergo significant deactivation upon aging (e.g., 16 hours at 800 °C), as indicated by low NO x conversion. Surprisingly, catalyst articles that include a catalyst composition as disclosed herein (including both a metal-promoted zeolite component and an alumina component) have been found to maintain high activity (i.e., NO x conversion) under such aging conditions. Indeed, this high activity has been demonstrated in various embodiments, including across a test window of 200 °C to 600 °C, for use at both high and low temperatures in some embodiments.

[0076] In certain embodiments, the disclosed catalyst articles more advantageously exhibit a reduction in N2O formation at low and / or high temperatures. For example, in the fresh state, certain alumina-containing samples exhibit lower peak N2O formation at both low and high temperatures relative to zeolite-only benchmarks. After aging, all alumina-containing samples exhibit lower N2O formation at high temperatures.

[0077] Without intending to be limited by theory, in some embodiments, such improvements (i.e., increased NO x conversion and / or reduced N2O formation) may be related to a higher zeolite surface area (ZSA) of the washcoat(s), particularly after calcination and aging. Thus, in certain embodiments, it is believed that the activity of the catalyst may be affected by the ZSA of the washcoat(s) that include the catalyst composition. ZSA is typically expressed in m 2 / g, m 2 / in 3 2, or m2 Provided in units of, it provides the measured value of the surface area of the micropores (pores with a diameter of 2 nm or less). The method of testing ZSA is described in detail in U.S. Provisional Patent Application No. 62 / 517,243 by Petrovic et al. on June 9, 2017, the entire content of which is incorporated herein by reference. Briefly, such a method includes analyzing the nitrogen partial pressure point to obtain the BET surface area and calculating ZSA from the BET surface area, so as to test ZSA without removing the coating from the substrate and without pulverizing the substrate before analysis. Such an effect of ZSA is observed especially after severe aging (for example, aging at 800 °C for 16 hours). It has been demonstrated that for severely aged catalyst articles containing the catalyst compositions disclosed herein, higher NOx conversion (at low and / or high temperatures) can correlate with higher ZSA.

[0078] The aforementioned effects related to the inclusion of alumina in the disclosed metal-promoted zeolite-containing catalyst compositions / articles apply to both the catalyst compositions / articles in which the components are mixed and the catalyst compositions / articles in which the components are in separate washcoat layers (for example, there is an alumina component in the first washcoat layer on the substrate and a metal-promoted zeolite in the second washcoat layer of the first washcoat layer).

[0079] Exhaust treatment system The selective reduction of nitrogen oxides using the catalyst compositions according to the present disclosure is generally carried out in the presence of ammonia or urea. In particular, an SCR system containing the catalyst compositions prepared according to the methods described herein can be integrated into the exhaust gas treatment system of a vehicle. An exemplary SCR system can include the following components. The SCR catalyst compositions described herein; a urea storage tank; a urea pump; a urea dosing system; a urea injector / nozzle; and respective control units.

[0080] In some aspects, the present disclosure also relates to removing nitrogen oxides (NO xIt can be related to a method for selectively reducing x The term "nitrogen oxides", or NO

[0081] In some embodiments, the catalyst composition described herein is at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99% NO x conversion over a temperature range of about 150 °C to about 650 °C, about 200 °C to about 600 °C, about 300 °C to about 600 °C, about 300 °C to about 550 °C, about 300 to about 500 °C, or about 350 °C to about 450 °C. In certain embodiments, the catalyst composition is at least about 70% NO x conversion at 200 °C (e.g., when the catalyst composition is about 120 m 2 / g or more of ZSA or in the form of fired fresh and / or aged cores of about 1.3 in 3 cores, having a total ZSA greater than about 1300 m 2 ).

[0082] The present invention also provides an exhaust treatment system incorporating the SCR composition described herein. The SCR composition of the present invention is typically used in an integrated exhaust treatment system that includes one or more additional components for treating diesel exhaust gas emissions. Thus, terms such as "exhaust stream", "engine exhaust stream", "exhaust gas stream" refer to engine effluent, as well as effluent upstream or downstream of one or more other catalyst system components described herein. Such additional catalyst components include, but are not limited to, diesel oxidation catalysts (DOCs), catalytic soot filters (CSFs), lean NO x traps (LNTs), and NH3 control catalysts.

[0083] Figure 3 shows one exemplary embodiment of an engine system that includes an emissions treatment system, a urea injector, and other engine components. The SCRoF catalyst 150 disclosed herein can be placed directly downstream of the engine or downstream of another catalyst component shown here as an optional component 147. The optional additional catalyst 143 can be placed downstream of the SCRoF catalyst 150 and can include an AMOx catalyst, another SCR catalyst, and / or a catalyst for oxidizing hydrocarbons and carbon monoxide. Additional oxidation catalysts can be included depending on the desired levels of ammonia, carbon monoxide, and hydrocarbon removal. Exhaust gas containing gaseous pollutants (unburned hydrocarbons, carbon monoxide, NO x (including), and particulate matter) is carried from the engine 141 through the connector 142 to the various components shown in Figure 3, and the exhaust gas is discharged from the system through the tailpipe 144. It is understood that other components can be included upstream or downstream of the SCRoF 150 in addition to those shown in Figure 3.

[0084] The system shown in Figure 3 further shows the injection of a reducing agent, such as urea, which can be sprayed as a spray into the exhaust stream through a nozzle (not shown). The urea water shown in one line 148 can function as an ammonia precursor that can be mixed with air on another line 149 within the mixing station 146. The valve 145 can be used to meter the exact amount of urea water that is converted to ammonia in the exhaust stream. The exhaust stream with ammonia added is carried to the SCRoF catalyst 150 for the SCR reaction. The injector shown is an example of one type of system that can be used, and other variations are within the scope of the present disclosure.

[0085] Experiment Aspects of the present invention are further illustrated by the following examples, which are presented to illustrate specific aspects of the invention and should not be construed as limiting the invention.

[0086] Examples: To form the SCRoF catalyst products, various coating methods and various alumina materials were investigated. Specifically, the alumina materials evaluated in this study were dispersive boehmite alumina, gamma alumina, and silica-doped gamma alumina. Table 1 below shows the design and coating of the evaluated samples.

[0087] SCRoF samples were prepared by washcoating the catalyst slurry onto the wall flow filter substrate. The catalyst slurry was composed of either one or two components such that zeolite and alumina were coated continuously or as a mixture onto the filter. CU-CHA was typically D 90 <ground to 5 μm (90% of the particles are less than 5 μm), and the alumina component was D 90 <ground to either 3 (for precoat) or 5 μm (as a mixture with zeolite). Sample 70-1 was a Cu-CHA single-component composition (without alumina) and was used as a reference. Samples 70-4 and 70-5 were prepared by first coating alumina and then coating Cu-CHA. In the case of sample 70-6, the Cu-CHA-containing washcoat also contained a small amount of alumina-based material. Samples 70-7 to 70-10 were created by coating a mixture of Cu-CHA and alumina. The zeolite-containing washcoat (main coat in Table 1) was coated onto the filter substrate twice using the same slurry, first from the inlet and then from the outlet, with firing (450 °C / 1 h) in between to obtain the target washcoat loading.

[0088] The substrate used in this example had a porosity of 63%, an average pore diameter of 23 μm, and 300 cells / in 2It is a SiC flow-through filter segment (34 mm x 34 mm x 153 mm) with a cell density of and a wall thickness of 0.3 mm. Table 1 shows the washcoat compositions and designs of Sample 70-1 and Samples 70-4 to 70-10. γ-Al2O3 (A), γ-Al2O3 (B), and γ-Al2O3 (C) in Table 1 represent alumina materials obtained from different suppliers.

Table 1

[0089] Figure 4 shows the cold flow ΔP measurement values of the samples in Table 1 at a flow rate of 35 ft 3 / min. As shown in the graph, the ΔP of most of the coated samples was equivalent.

[0090] The samples were evaluated for NH3 storage capacity in fresh form and then subjected to aging (5 hours at 850 °C with 10% steam) and NH3 storage capacity was evaluated again. NH3 storage capacity was measured by NH3 adsorption-desorption experiments. The NH3 adsorption amount was carried out at 200 °C in the SCR feed, which was composed of GHSV = 60,000 h -1 with 500 ppm NO, 500 ppm NH3, 10% O2, 5% CO2, 5% H2O, and the balance N2. The NH3 desorption experiment consisted of two parts: isothermal purge with an inert gas stream (5% CO2, 5% H2O and the balance N2) at 200 °C (1 h) and temperature programmed desorption (TPD) up to 550 °C with the same flow. The cumulative NH3 desorption was used as the NH3 storage capacity. The NH3 storage capacities of all fresh and aged samples are summarized in Figure 5. In Table 2, the NH3 storage capacity is further classified into the parts of isothermal desorption (weakly bound NH3) and TPD (strongly retained NH3), and the differences between fresh and aged samples.

[0091] The data indicates that for the fresh sample, the total amount of NH3 desorbed from the reference sample is 1.18 g / L, and all other samples, namely samples 4, 5, and 10 with slightly higher values (1.22 - 1.24 g / L), were within + / - 10% of the reference. For the aged samples, the total amount of desorbed NH3 is significantly less than that of the corresponding fresh samples. Interestingly, the NH3 desorbed in the isothermal part is higher for the aged samples than for the corresponding fresh samples. Although not intended to be limited by theory, it is thought that the amount of weakly acidic sites increased after aging, while the amount of strongly acidic sites decreased.

[0092] Among the aged samples, sample 70 - 5 showed the highest total NH3 capacity (1.0 g / L), which was much higher than that of the zeolite-only reference (0.74 g / L). Sample 70 - 5 also showed at least a decrease in NH3 capacity after aging at 850 °C / 5 h. Figure 6 specifically compares the NH3 TPD profiles for samples 70 - 1 (control / reference) and 70 - 5. Similar NH3 desorption profiles were found for the fresh samples. However, for the aged samples, the NH3 desorption intensity on sample 70 - 5 was significantly higher than that of sample 70 - 1.

Table 2

[0093] NO conversion for fresh SCRoF samples and aged SCRoF samples x was measured from 200 to 600 °C under steady-state reaction conditions. The reaction was carried out in N2 at GHSV = 60,000 h-1 -1 using a feed consisting of 500 ppm NH3, 500 ppm NO, 10% O2, 5% H2O, and 5% CO2. For clarity, the NO x conversion at 200 °C and 600 °C is plotted as a bar graph (Figures 7 and 9).

[0094] At 200 °C, the NOx The conversion is nearly the same (about 80%). However, all the aged samples show higher NO x conversion than the reference (sample 70-1) at 200 °C, and among them, samples 70-5, 70-4, and 70-10 are quite high (by 20%, 9%, and 8% respectively). Sample 70-5 is the most active catalyst at 200 °C.

[0095] Figure 8 shows the correlation between the steady-state NO x conversion at 200 °C and the cumulative NH3 desorption at 200 °C for the aged SCRoF samples. As shown, the NO x conversion is linearly correlated with the NH3 capacity. Large differences in activity and NH3 capacity were observed on the aged catalysts. Although not intended to be limited by theory, the fundamental reason behind this correlation is thought to be that the NH3 storage capacity is a measure of the number of active sites (exchange copper sites) of the catalyst aged at 850 °C. Notably, the fact that significant differences were found for the aged samples (having the same amount of Cu-CHA) from the perspective of NO x conversion and NH3 adsorption capacity. Again, although not intended to be limited by theory, this suggests that different amounts of active copper sites remain in the zeolite after aging at 850 °C as a result of including alumina.

[0096] As shown in Figure 9, at 600 °C, the fresh NO x conversion of all the alumina-added samples is higher than the reference, and some exceed 10%. This is a surprising observation since the alumina additive was not expected to be effective without high-temperature treatment. After aging at 850 °C, the difference in activity becomes more prominent. Pre-coating the filter with alumina is not significant for NO x conversion at 600 °C, but it appears that mixing zeolite and alumina clearly increases the high-temperature NO x conversion. Mixing alumina and zeolite leads to a clear increase in NO xThe increase in conversion is in the range of 7 - 14%, and sample 70 - 9 is the best. Samples 5, 6, and 7 all contain the additive of γ - Al2O3(A), but different effects can be shown depending on the coating method.

[0097] As a conclusion, this example found that for the aged samples, when alumina and zeolite are mixed, slightly higher NO x conversion is brought about at 200 °C (samples 70 - 7 to 70 - 10). The pre - coating of 0.15 g / in 3 of γ - Al2O3(A) increased the NO x conversion significantly (sample 70 - 5). For the aged samples, when alumina and zeolite are mixed, the NO x conversion becomes significantly higher at 600 °C (samples 70 - 6 to 70 - 10). These findings are summarized in Figure 10.

[0098] N2O is a by - product of the SCR process and typically appears as low - temperature peaks and high - temperature peaks. The low - temperature peak typically appears between 200 - 250 °C for fresh samples and 200 - 300 °C for aged samples. The high - temperature peak appears between 450 - 550 °C for fresh samples and 500 - 600 °C for aged samples. Table 3 shows the peak N2O formation for fresh and aged samples. For both fresh and aged catalysts, the alumina - containing catalysts show lower peak N2O formation at high temperatures compared to the zeolite - only reference. For some fresh catalysts, the low - temperature peak N2O formation is lower than the reference.

Table 3

[0099] The invention disclosed in this specification is described by specific embodiments and means of their use, but many modifications and changes can be made by those skilled in the art without departing from the scope of the disclosure described in the claims. Further, various aspects of this disclosure can be used in applications other than those specifically described herein.

Claims

1. A catalyst article for use as a selective catalytic reduction (SCR) catalyst article, comprising: A wall flow filter substrate; A catalyst composition coated on the wall flow filter substrate, the catalyst composition comprising: Zeolite having sufficient Cu exchanged at the cation sites of the zeolite to have a Cu / Al ratio of 0.1 to 0.5 and a CuO loading of 1 to 15 wt%; About 1 to about 20 wt% of a copper trap component based on the weight of the Cu-exchanged zeolite; The copper trap component comprises a plurality of particles having a D ９０ particle size of about 0.5 to 20 microns, and The catalyst composition is in the form of a washcoat comprising a physical blend of the zeolite and the copper trap component; The washcoat is disposed directly on at least a portion of the wall flow filter substrate. A catalyst article.

2. The catalyst composition is in the form of a first washcoat comprising the zeolite and a second washcoat comprising the copper trap component; The second washcoat is disposed directly on at least a portion of the wall flow filter substrate, and the first washcoat is disposed directly on at least a portion of the second washcoat. The catalyst article according to claim 1.

3. The first washcoat further comprises a second copper trap component, and the second copper trap component may be the same as or different from the copper trap component of the second washcoat. The catalyst article according to claim 2.

4. The copper trap component comprises a material selected from the group consisting of alumina, silica, zirconia, niobium, molybdenum, and combinations thereof. The catalyst article according to any one of claims 1 to 3.

5. The catalyst article according to claim 4, wherein the copper trap component contains alumina.

6. The catalyst article according to claim 5, wherein the alumina is selected from the group consisting of boehmite, gamma alumina, silica alumina, stabilized alumina, and combinations thereof.

7. The catalyst article according to claim 6, wherein the alumina contains gamma alumina.

8. The copper trap component contains a plurality of particles having a D ９０ particle size of about 0.5 to 5 microns, and the catalyst article according to any one of claims 1 to 7.

9. The copper trap component contains a plurality of particles having a D ９０ particle size of about 0.5 to 3 microns, and the catalyst article according to any one of claims 1 to 7.

10. The zeolite has an average particle size of about 0.01 to about 5 microns, and the catalyst article according to any one of claims 1 to 9.

11. The zeolite has an "8-ring" framework structure selected from the group consisting of AEI, AFT, AFV, AFX, AVL, CHA, DDR, EAB, EEI, ERI, IFY, IRN, KFI, LEV, LTA, LTN, MER, MWF, NPT, PAU, RHO, RTE, RTH, SAS, SAT, SAV, SFW, TSC, UFI, and combinations and twins thereof, and the catalyst article according to any one of claims 1 to 10.

12. The zeolite has a framework structure selected from AEI, AFT, CHA, LTA, and combinations and twins thereof, and the catalyst article according to claim 11.

13. The zeolite has a CHA framework structure, and the catalyst article according to claim 11.

14. The catalyst article according to any one of claims 1 to 10, wherein the zeolite has a "10-ring" framework structure selected from the group consisting of AEL, AFO, AHT, BOF, BOZ, CGF, CGS, CHI, DAC, EUO, FER, HEU, IMF, ITH, ITR, JRY, JSR, JST, LAU, LOV, MEL, MFI, MFS, MRE, MTT, MVY, MWW, NAB, NAT, NES, OBW, PAR, PCR, PON, PUN, RRO, RSN, SFF, SFG, STF, STI, STT, STW, SVR, SZR, TER, TON, TUN, UOS, VSV, WEI, WEN, and combinations and twins thereof.

15. The catalyst article according to claim 14, wherein the zeolite has a framework structure selected from FER, MEL, MFI, STT, and combinations and twins thereof.

16. The catalyst article according to any one of claims 1 to 10, wherein the zeolite has a "12-ring" framework structure selected from the group consisting of AFI, AFR, AFS, AFY, ASV, ATO, ATS, BEA, BEC, BOG, BPH, BSV, CAN, CON, CZP, DFO, EMT, EON, EZT, FAU, GME, GON, IFR, ISV, ITG, IWR, IWS, IWV, IWW, JSR, LTF, LTL, MAZ, MEI, MOR, MOZ, MSE, MTW, NPO, OFF, OKO, OSI, RON, RWY, SAF, SAO, SBE, SBS, SBT, SEW, SFE, SFO, SFS, SFV, SOF, SOS, STO, SSF, SSY, USI, UWY, VET, and combinations and twins thereof.

17. The catalyst article according to claim 16, wherein the zeolite has a framework structure selected from AFI, BEA, FAU, MAZ, MOR, OFF, and combinations and twins thereof.

18. The catalyst article according to any one of claims 1 to 10, wherein the zeolite has a framework structure including a twin crystal of CHA and GME or AEI and GME.

19. The catalyst article of any one of claims 1 to 18, wherein the copper trap component is present in an amount of about 2 to about 20 wt %, based on the weight of the Cu-exchanged zeolite.

20. The zeolite is about 0.5 g / in ３ ~ about 5.0 g / in ３ The catalytic article of any one of claims 1 to 19, wherein the catalyst is present in an amount of from about 100 to about 1000.

21. The zeolite has a density of about 1 g / in ３ ~ about 5.0 g / in ３ 21. The catalytic article of claim 20, wherein the catalyst is present in an amount of

22. 22. The catalytic article of claim 2 and any one of claims 3 to 21 that directly or indirectly derives from claim 2, wherein a first portion of the second washcoat is disposed within a wall of the substrate and a second portion of the second washcoat is disposed on a wall of the substrate.

23. The catalytic article of claim 2 and any one of claims 3 to 21 that directly or indirectly derives from claim 2, wherein the second washcoat is disposed within a wall of the substrate.

24. 24. The catalytic article of claim 22 or 23, wherein the first washcoat is disposed on a wall of the substrate.

25. 25. An exhaust gas treatment system comprising the catalytic article of any one of claims 1 to 24 downstream of a urea injector and in fluid communication with an internal combustion engine.

26. 26. The exhaust gas treatment system of claim 25, further comprising a component selected from the group consisting of a diesel oxidation catalyst, a soot filter, an ammonia oxidation catalyst, a lean NOx trap, and any combination thereof.

27. 27. The exhaust gas treatment system of claim 25 or 26, wherein the internal combustion engine is a diesel engine.

28. A method for preparing an SCRoF with enhanced low-temperature and high-temperature NOx conversion, comprising: Coating a wall-flow filter substrate with a washcoat containing a mixture of a copper trap component and a zeolite, wherein the copper trap component comprises a plurality of particles having a D ９０ particle size of about 0.5 to 20 microns, coating, wherein the zeolite component contains sufficient Cu exchanged at the cation sites of the zeolite such that the zeolite has a Cu / Al ratio of 0.1 to 0.5 and a CuO loading of 1 to 15 wt%; firing the coated wall-flow filter substrate to obtain the SCRoF. **Claim 29** The method according to claim 28, wherein the copper trap component is alumina. **Claim 30** The method according to claim 28 or 29, wherein the SCRoF comprises an alumina loading of about 0.05 g / in ３ to about 0.5 g / in ３ of alumina on the wall-flow filter substrate.

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