CATALYST ARTICLES COMPRISING VANADIUM-BASED CATALYST AND MOLECULAR SIEVE-BASED CATALYST

Abstract

The present invention relates to a catalytic article for purifying exhaust gas containing nitrogen oxides, the catalytic article comprising a first region containing a vanadium-based SCR catalyst, a second region containing a metal-promoted molecular sieve catalyst, and a third region containing a vanadium-based SCR catalyst, at least a portion of the second region being located downstream of at least a portion of the first region and upstream of at least a portion of the third region in a flow direction of the exhaust gas, with the proviso that no portion of the second region is located upstream of the first region or downstream of the third region. The present invention also relates to a method and system for treating exhaust gas containing nitrogen oxides by selective catalytic reduction using the catalytic article.

Description

[Technical field]

[0001] The present invention relates to catalytic articles including vanadium-based catalysts and metal-promoted molecular sieve catalysts, and methods for treating exhaust gases containing nitrogen oxides by selective catalytic reduction. [Background technology]

[0002] Nitrogen oxides (NOx) are common air pollutants and are generally found in exhaust gases from mobile sources such as automobiles and stationary sources such as power plants. The control of NOx emissions has always been one of the most important topics, for example in the automotive manufacturing sector, due to the adverse environmental effects of NOx on ecosystems, humans, animals and plants.

[0003] In order to reduce NOx in exhaust gas, various treatment methods, such as catalytic reduction of nitrogen oxides, have been used. One typical catalytic reduction method is selective catalytic reduction using ammonia (NH3) or ammonia precursor as a reducing agent in the presence of atmospheric oxygen, which is also called the SCR process. The SCR process is considered superior because it can obtain a high degree of NOx reduction with a small amount of reducing agent. Typically, nitrogen oxides and the reducing agent NH3 react according to the following equation: 4NO+4NH3+O2→4N2+6H2O (standard SCR reaction) 2NO2+4NH3+O2→3N2+6H2O (slow SCR reaction) NO+NO2+2NH3→2N2+3H2O (fast SCR reaction).

[0004] A side reaction associated with selective catalytic reduction is the formation of lower valent nitrogen oxides, specifically nitrous oxide (N2O), from the reductants NH3 and oxygen.

[0005] For example, the NOx treatment efficiency in terms of NOx conversion and N2O formation is highly dependent on the catalyst used in the SCR process. As is known in the art, vanadium-based oxide materials and molecular sieve-based materials are two main types of catalysts useful for selective catalytic reduction of NOx. Recently, the use of two types of catalysts in combination for the SCR process has attracted more and more attention.

[0006] CN107100700B describes a selective catalytic reduction device including a catalytic unit arranged in series, a first catalytic unit, a second catalytic unit, and an optional third catalytic unit, where the first catalytic unit comprises a zeolite-based catalytic material made of Fe-zeolite or Cu-zeolite, the second catalytic unit comprises a vanadium-based catalytic material made of vanadium, titanium, and tungsten oxides, and the third catalytic unit comprises a zeolite-based catalytic material made of Fe-zeolite or Cu-zeolite. It is said that the multiple catalytic units arranged in the SCR device can reduce NOx in the exhaust gas while minimizing the amount of N2O generated during the NOx conversion process.

[0007] WO 2019 / 001942(A1) describes an exhaust gas aftertreatment device comprising a first SCR catalyst comprising a copper-containing zeolite material, an ammonia slip catalyst disposed downstream of the first SCR catalyst, a particulate filter, a second SCR catalyst having a vanadium-containing SCR material disposed upstream of the first SCR catalyst, an oxidation catalyst disposed downstream of the ammonia slip catalyst and upstream of the particulate filter, and a layer of copper-containing zeolite material applied to a surface of the ammonia slip catalyst having at least one precious metal.

[0008] WO 2018 / 1150454 A1 describes a catalytic device for purifying exhaust gases containing nitrogen oxides by selective catalytic reduction (SCR), the catalytic device comprising at least two catalytic zones, a first zone containing vanadium oxide and cerium oxide and a second zone containing an iron-containing molecular sieve. By combining vanadium oxide with cerium oxide in a catalytic device also having a catalytic zone with an iron-containing molecular sieve, it is said that the efficiency of SCR can be significantly improved and the formation of N2O is significantly suppressed.

[0009] The NOx treatment efficiency of SCR catalysts under some specific operating conditions still needs to be improved. The inventors have found that during the operation of some models of vehicles, frequent temperature rise and fall periods may occur, along with insufficient NH3 loading and / or high NO2 / NOx ratios of over 50% at the inlet of the SCR catalyst. Fluctuating conditions may adversely affect NOx conversion, which is a non-negligible problem in the treatment of automobile exhaust gas.

[0010] It would be desirable to develop SCR catalysts that have improved NOx reduction efficiency under varying conditions. Summary of the Invention

[0011] It is an object of the present invention to provide a catalyst article that performs well under varying conditions during operation of several models of vehicles, including, for example, temperature gradients, exhaust gas space velocity, NH3 dosage, and NO2 / NOx ratios at the inlet of the SCR catalyst.

[0012] Surprisingly, it has now been found that this objective is achieved by a catalyst article which includes a region of a metal promoted molecular sieve catalyst and two regions of a vanadium based SCR catalyst.

[0013] Thus, in one aspect, the present invention provides a catalytic article for purifying an exhaust gas containing nitrogen oxides, the catalytic article comprising: a first region containing a vanadium-based SCR catalyst; a second region containing a metal promoted molecular sieve catalyst; and a third region containing a vanadium-based SCR catalyst; During the ceremony At least a part of the second region is located downstream of at least a part of the first region and upstream of at least a part of the third region in the flow direction of the exhaust gas. The catalyst article relates to a catalyst article in which no portion of the second region is located upstream of the first region or downstream of the third region.

[0014] In another aspect, the invention relates to a method for treating an exhaust gas containing nitrogen oxides by selective catalytic reduction, the method comprising contacting the exhaust gas with a catalytic article described herein in the presence of a reducing agent.

[0015] In a further aspect, the present invention relates to a treatment system for exhaust gases, particularly from an internal combustion engine, the treatment system comprising a reductant source, a catalyst article as described herein, and optionally one or more of a diesel oxidation catalyst (DOC), a three-way catalyst (TWC), a four-way catalyst (FWC), an uncatalyzed or catalyzed soot filter (CSF), an ammonia oxidation catalyst (AMOx), a NOx trap, a NOx absorption catalyst, a hydrocarbon trap catalyst, a sensor, and a mixer.

[0016] The present inventors have found that catalytic articles according to the present invention are particularly useful for reducing NOx in exhaust gases from automotive engines experiencing varying process conditions. [Brief description of the drawings]

[0017] [Figure 1] 9 shows a schematic diagram of cyclic condition changes in an SCR performance test according to Example 9.1. [Diagram 2] 9 shows a schematic diagram of cyclic condition changes in an SCR performance test according to Example 9.2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention is described in detail below. It should be understood that the present invention may be embodied in many different ways and should not be construed as being limited to the embodiments set forth herein.

[0019] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. The terms "comprise," "comprising," and the like are used interchangeably with "contain," "containing," and the like, and are to be interpreted in an open, non-restrictive manner; that is, for example, additional components or elements may be present. The phrases "consists of" or "consists essentially of" or cognates may be subsumed within "comprises" or cognates.

[0020] The term "catalytic article" as used herein is intended to mean only an item of a particular shape having a catalytic function, not necessarily unitary, in other words, the catalytic article may be unitary or may consist of two or more separable bodies.

[0021] The term "region" as used herein is intended merely to mean that each particular catalyst present in either the washcoat or extrudate extends a particular length in the direction of exhaust gas flow. The terms "first region," "second region," and "third region" by themselves are not intended to indicate that the regions are immediately adjacent to one another or in any other particular spatial arrangement.

[0022] According to a first aspect, the present invention relates to a catalytic article for purifying an exhaust gas containing nitrogen oxides, the catalytic article comprising: a first region containing a vanadium-based SCR catalyst; a second region containing a metal promoted molecular sieve catalyst; and a third region containing a vanadium-based SCR catalyst; During the ceremony At least a part of the second region is located downstream of at least a part of the first region and upstream of at least a part of the third region in the flow direction of the exhaust gas. The catalyst article relates to a catalyst article in which no portion of the second region is located upstream of the first region or downstream of the third region.

[0023] In particular, the present invention relates to a catalytic article for purifying an exhaust gas containing nitrogen oxides, the catalytic article comprising: a first region containing a vanadium-based SCR catalyst; a second region containing a metal promoted molecular sieve catalyst; and a third region containing a vanadium-based SCR catalyst; The second region is located downstream of at least a portion of the first region and upstream of at least a portion of the third region, providing a catalytic article.

[0024] More specifically, the present invention relates to a catalytic article for purifying an exhaust gas containing nitrogen oxides, the catalytic article comprising: a first region containing a vanadium-based SCR catalyst; a second region containing a metal promoted molecular sieve catalyst; and a third region containing a vanadium-based SCR catalyst; The second region is provided in a catalyst article located completely downstream of the first region and completely upstream of the third region.

[0025] The first region contains a vanadium-based SCR catalyst. Vanadium-based SCR catalyst refers to any material that contains vanadium, typically in the form of an oxide, as the primary active species for selective catalytic reduction of NOx. Materials containing vanadium that are useful for selective catalytic reduction of NOx are well known in the art. There is no particular limitation on the vanadium-based SCR catalysts that are useful for the first and third regions.

[0026] Vanadium-based SCR catalysts generally contain or consist of vanadium oxide (e.g., VO) as the primary active species and, optionally, at least one oxide of another metal (or element) as a promoter, supported on carrier particles.

[0027] Metals (or elements) useful as promoters may include, but are not limited to, boron (B), aluminum (Al), bismuth (Bi), silicon (Si), tin (Sn), lead (Pb), antimony (Sb), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), cerium (Ce), yttrium (Y), niobium (Nb), molybdenum (Mo), and tungsten (W). In particular, vanadium-based SCR catalysts contain vanadium oxide and, optionally, at least one oxide of an element selected from silicon (Si), antimony (Sb), molybdenum (Mo), and tungsten (W).

[0028] In some embodiments according to the invention, the vanadium-based SCR catalyst contains or consists of vanadium oxide and at least one oxide of an element selected from silicon (Si), antimony (Sb), molybdenum (Mo) and tungsten (W) on particles of a support. For example, the vanadium-based SCR catalyst contains or consists of oxides of V, Sb and Si on particles of a support.

[0029] It is understood that the vanadium oxide and, if present, at least one oxide of another metal (or element) may be present in the form of a respective oxide or a composite oxide of vanadium and the other metal (or element), or a combination thereof.

[0030] Materials useful as supports may include, but are not limited to, molecular sieves and one or more oxides of metals selected from the group consisting of Ti, Si, W, Al, Ce, Zr, Mg, Ca, Ba, Y, La, Pr, Nb, Mo, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sn, and Bi. Preferably, the support may be one or more selected from titania (preferably the species containing the anatase form), silica, alumina, zirconia, and any dopant-stabilized forms thereof.

[0031] The support may be included in the vanadium-based SCR catalyst in each of the first and third regions in an amount of at least 40 wt%, at least 50 wt%, or at least 60 wt%, e.g., at least 65 wt%, at least 70 wt%, and at least 75 wt%, based on the total weight of the vanadium-based SCR catalyst. The amount of support may be up to 95 wt%, up to 90 wt%, or up to 80 wt%, based on the total weight of the vanadium-based SCR catalyst.

[0032] The vanadium-based SCR catalyst in each of the first and third regions may contain vanadium, calculated as V2O5, in an amount of 0.1-20 wt%, 1-15 wt%, 2-10 wt%, or 2-7 wt%, based on the total weight of the vanadium-based SCR catalyst. It is understood that the vanadium content of the vanadium-based SCR catalyst in the two regions may be the same or different.

[0033] Each of the at least one oxide of another metal (or element) as a promoter, when present, may be contained in the vanadium-based SCR catalyst in each of the first and third regions in an amount of 0.1 to 30 wt %, 1 to 15 wt %, or 2 to 8 wt %, based on the total weight of the vanadium-based SCR catalyst.

[0034] In certain exemplary embodiments, the vanadium-based SCR catalyst in each of the first and third regions comprises: (a) 1 to 15 percent by weight of vanadium oxide, calculated as V2O5. (b) 1 to 25 percent by weight of antimony oxide, calculated as Sb2O3; (c) 1 to 10% by weight of SiO2; (d) optionally, 1 to 10 weight percent tungsten oxide, calculated as WO; (e) containing or consisting of 65 to 95% by weight of a TiO2 support; Each is based on the total weight of the vanadium-based SCR catalyst.

[0035] In some exemplary embodiments, the vanadium-based SCR catalyst comprises: (a) 2 to 10 percent by weight of vanadium oxide, calculated as V2O5. (b) 1 to 15 percent by weight of antimony oxide, calculated as Sb2O3; (c) 2 to 10% by weight of SiO2; (d) optionally, 2 to 8 weight percent tungsten oxide, calculated as WO; (e) containing or consisting of 70 to 90% by weight of a TiO2 carrier; Each is based on the total weight of the vanadium-based SCR catalyst.

[0036] In some further exemplary embodiments, the vanadium-based SCR catalyst comprises: (a) 2 to 7 percent by weight of vanadium oxide, calculated as V2O5; (b) 2 to 8 percent by weight of antimony oxide, calculated as Sb2O3; (c) 2-8 wt.% SiO2; (e) containing or consisting of 80 to 90% by weight of a TiO2 carrier; Each is based on the total weight of the vanadium-based SCR catalyst.

[0037] The total weight of the vanadium-based SCR catalyst in each case described herein is 100% by weight.

[0038] The vanadium-based SCR catalysts in the first and third regions may be the same or different in terms of composition, it being understood that the vanadium-based SCR catalysts in the first and third regions may differ from each other in active composition, support species and / or particle size characteristics, or any other aspect.

[0039] In some embodiments according to the present invention, the vanadium-based SCR catalyst in the first zone and the third zone are the same.

[0040] The first and third regions may also each independently contain other components in addition to the vanadium-based SCR catalyst, which may be non-catalytically active components, e.g., processing aids useful in preparing the catalyst article, such as lubricants and binders, etc. The other components may also be catalytically active, e.g., active species other than the vanadium-based SCR catalyst and metal-promoted molecular sieve catalyst described herein.

[0041] The second region contains a metal promoted molecular sieve catalyst. As used herein, "metal promoted molecular sieve catalyst" is intended to mean that the metal promoted molecular sieve has the necessary SCR activity for NOx reduction.

[0042] Molecular sieves generally refer to framework materials based on an extensive three-dimensional network of oxygen ions containing tetrahedral sites and having a substantially uniform pore distribution. Molecular sieves suitable for the purposes of the present invention may be microporous or mesoporous. Typically, molecular sieves having an average pore size of less than 2 nm are classified as "microporous" and molecular sieves having an average pore size of 2-50 nm are classified as "mesoporous". The pore size is defined by the size of the rings.

[0043] In particular, the molecular sieve is a zeolite. The term "zeolite" has its usual meaning in the art and typically refers to a crystalline material (typically an aluminosilicate) with a spatial network structure in which there is an open-system three-dimensional framework structure composed of corner-sharing TO4 tetrahedra, where T is a tetravalent element (typically Si) or a trivalent element (typically Al). Anionic framework charge-balancing cations are loosely associated with framework oxygens, and the remaining pore volume is filled with water molecules. Non-framework cations are generally exchangeable and water molecules are removable.

[0044] For the purposes of the present invention, suitable molecular sieves include ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFV, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AVL, AWO, AWW, BCT , BEA, BEC, BIK, BOF, BOG, BOZ, BPH, BRE, BSV, CAN, CAS, CDO, CFI, CGF, CGS, CHA, -CHI, -CLO, CON, CSV, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EEI, EMT, EON, EPI, ERI, ESV, ETR, EUO, * -EWT, EZT, FAR, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFO, IFR, -IFU, IFW, IFY, IHW, IMF, IRN, IRR, -IRY, ISV, ITE, ITG, ITH, * -ITN, ITR, ITT, -ITV, ITW, IWR, IWS, IWV, IWW, JBW, JNT, JOZ, JRY, JSN, JSR, JST, JSW, KFI, LAU, LEV , LIO, -LIT, LOS, LOV, LTA, LTF, LTJ, LTL, LTN, MAR, MAZ, MEI, MEL, MEP, MER, MFI, MFS, MON, MOR, MOZ, *MRE, MSE, MSO, MTF, MTN, MTT, MTW, MVY, MWF, MWW, NAB, NAT, NES, NON, NPO, NPT, NSI, OBW, OFF, OKO, OSI, OSO, OWE, -PAR, PAU, PCR, PHI, PON, PO S, PSI, PUN, RHO, -RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAF, SAO, SAS, SAT, SAV, SBE, SBN, SBS, SBT, SEW, SFE, SFF, SFG, SFH, SFN, SFO, SFS, * SFV, SFW, SGT, SIV, SOD, SOF, SOS, SSF, * -SSO, SSY, STF, STI, * Zeolites having a framework type selected from the group consisting of STO, STT, STW, -SVR, SVV, SZR, TER, THO, TOL, TON, TSC, TUN, UEI, UFI, UOS, UOV, UOZ, USI, UTL, UWY, VET, VFI, VNI, VSV, WEI, -WEN, YUG and ZON, and any combination thereof, may be mentioned, but are not limited to these.

[0045] In particular, molecular sieves useful in the second region include zeolites having a framework type selected from the group consisting of AEI, AEL, AFI, AFT, AFO, AFX, AFR, ATO, BEA, CHA, DDR, EAB, EMT, ERI, EUO, FAU, FER, GME, HEU, JSR, KFI, LEV, LTA, LTL, LTN, MAZ, MEL, MFI, MOR, MOZ, MSO, MTW, MWW, OFF, RTH, SAS, SAT, SAV, SBS, SBT, SFW, SSF, SZR, TON, TSC, and WEN.

[0046] In some embodiments, molecular sieves useful for the second region include zeolites having a framework type selected from the group of AEI, BEA (e.g., beta), CHA (e.g., chabazite, SSZ-13), AFT, AFX, FAU (e.g., zeolite Y), MOR, MFI (e.g., ZSM-5), MOR (e.g., mordenite), and MEL, of which AEI, BEA, and CHA are particularly preferred.

[0047] In some other embodiments, the molecular sieve useful for the second region may be selected from small pore zeolites. The term "small pore zeolite" refers to a zeolite having a pore opening smaller than about 5 angstroms (Å). The small pore zeolite may be a small pore 8-ring zeolite. The term "8-ring zeolite" refers to a zeolite having an 8-ring pore opening. Some 8-ring zeolites may have double 6-ring (d6r) secondary structural units in which cage-like structures are formed resulting from the linkage of double 6-ring structural units with 4-rings. Examples of small pore 8-ring zeolites include framework 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.

[0048] In some particular embodiments, small pore zeolites useful in the second region include zeolites having a framework type selected from the group consisting of AEI, AFT, AFX, CHA, EAB, ERI, KFI, LEV, SAS, SAT, and SAV. Small pore zeolites having a framework type selected from the group consisting of AEI, AFT, AFX, and CHA may be specifically mentioned.

[0049] It is understood that when a zeolite is referred to herein with reference to a framework type code generally accepted by the International Zeolite Association (IZA), it is intended to include not only the standard materials but also any isotype framework material that has SCR catalytic activity. A list of standard and isotype framework materials for each framework code is available in the IZA database (http: / / www.iza-structure.org / databases / ).

[0050] Zeolites useful as molecular sieves in metal-promoted molecular sieve catalysts, such as zeolites having any of the framework types described above, suitably have a SiO2 / Al2O3 molar ratio (SAR) in the range of from 5:1 to 150:1, preferably from 5:1 to 50:1, especially from 10:1 to 30:1.

[0051] Molecular sieves have a high surface area, e.g. at least 300 m, measured according to DIN 66131. 2 / g, at least 400m 2 / g, at least 550m 2 / g or at least 650m 2 / g, e.g. 400~750m 2 / g or 500~750m 2 / g. Alternatively, or in addition, the molecular sieve may have an average crystallite size, as determined by SEM, of 10 nm to 10 μm, 50 nm to 5 μm, 0.1 to 2 μm, or 0.1 to 0.5 μm.

[0052] The molecular sieve in the second region is metal promoted, which means that a metal capable of improving the catalytic activity of the molecular sieve is incorporated in and / or on the molecular sieve. The metal, also called promoter metal, is present in the molecular sieve as a non-framework element. In other words, the promoter metal does not participate in the construction of the molecular sieve framework. The promoter metal may be present in the molecular sieve and / or on at least a portion of the molecular sieve surface, preferably in the form of an ionic species.

[0053] The promoter metal may be any metal known to be useful for improving the catalytic performance of zeolites in selective catalytic reduction (SCR) of NOx applications. In general, the promoter metal may be selected from precious metals such as Au and Ag, platinum group metals such as Ru, Rh, Pd, In and Pt, base metals such as Cr, Zr, Nb, Mo, Fe, Mn, W, V, Ti, Co, Ni, Cu, Zn, Sb, Sn and Bi, alkaline earth metals such as Ca and Mg, and any combination thereof. The promoter metal is preferably Fe or Cu or a combination thereof.

[0054] In some exemplary embodiments, the metal-promoted molecular sieve catalyst useful in the second zone is a Cu and / or Fe promoted zeolite having an AEI, BEA, CHA, AFT, AFX, FAU, FER, KFI, MOR, MFI, MOR or MEL framework type. In some further exemplary embodiments, the metal-promoted molecular sieve catalyst is a Cu and / or Fe promoted zeolite having an AEI, BEA or CHA framework type.

[0055] The promoter metal may be present in the metal-promoted molecular sieve catalyst in an amount ranging from 0.1 to 20 wt%, 0.5 to 15 wt%, 1 to 10 wt%, or 4 to 10 wt%, on an oxide basis, based on the total weight of the metal-promoted molecular sieve. In some exemplary embodiments in which Cu or Fe is used as the promoter metal, the promoter metal is preferably present in an amount of 0.5 to 15 wt%, or 1 to 15 wt%, or 1 to 10 wt%, on an oxide basis, based on the total weight of the metal-promoted molecular sieve.

[0056] The second zone may contain one or more metal promoted molecular sieve catalysts, in other words only one metal promoted molecular sieve catalyst or a combination of two or more metal promoted molecular sieve catalysts may be used in the second zone.

[0057] The second region may contain, in addition to the metal promoted molecular sieve catalyst, other components, particularly non-catalytically active components, such as processing aids, such as binders, useful in the preparation of the catalyst article.

[0058] The first region containing the vanadium-based catalyst, the second region containing the metal-promoted molecular sieve catalyst, and the third region containing the vanadium-based SCR catalyst may, independently of one another, be present in the SCR catalyst article according to the present invention in the form of an extrudate or in the form of a washcoat on a substrate.

[0059] The term "extrudate" generally refers to a shaped body formed by extrusion. The extrudate may have any suitable structure capable of passing an exhaust gas flow, preferably a honeycomb structure. The honeycomb structure may have flow channels as described below for the monolithic flow-through and wall-flow structures. When any of the first, second and third regions are present in the form of an extrudate, the extrudate may be formed from the respective catalyst and optionally at least one processing aid, such as a binder and a lubricant, by any conventional means.

[0060] The term "substrate" generally refers to a structure suitable for withstanding the conditions encountered in the exhaust stream and upon which the catalytic material is supported, typically in the form of a washcoat.

[0061] Typically, the substrate may be a monolithic flow-through structure having a plurality of fine parallel gas flow passages extending from an inlet face to an outlet face of the substrate, the passages being open to fluid flow therethrough. The passages, which are essentially straight-line paths from the fluid inlet to the fluid outlet, are defined by walls to which a catalytic material is applied as a washcoat such that gas flowing through the passages comes into contact with the catalytic material. The flow passages in the monolith substrate are thin-walled channels and can be of any suitable cross-sectional shape and size, such as trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical, circular, etc. Such structures may contain 60 to 900 or more flow passages (or "cells") per square inch of cross section. For example, the substrate may have 50 to 600 cells per square inch ("cpsi") or 200 to 450 cpsi. The wall thickness of the flow-through substrate may vary in a typical range of 2 mils to 0.1 inches.

[0062] The substrate may also be a monolithic wall-flow structure having a plurality of fine parallel gas flow passages extending from the inlet face along the outlet face of the substrate, the passages being alternately blocked at both ends. The passages are defined by walls to which a catalytic material is applied as a washcoat such that gas flowing through the passages contacts the catalytic material. This configuration requires that the gas flow through the porous walls of the wall-flow substrate to reach the outlet face. The wall-flow substrate may have a maximum pressure of 700 cpsi, for example, 100 to 400 cpsi. The flow passages in the monolith substrate are thin-walled channels, which may be of any suitable cross-sectional shape and size, such as trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical, circular, etc. The wall thickness of the wall-flow substrate may vary in a typical range of 2 mils to 0.1 inches.

[0063] The term "washcoat" has its ordinary meaning in the art and refers to a thin, adherent coating of catalyst or other material applied to a substrate. Washcoats are generally formed by preparing a slurry containing the desired materials and, optionally, processing aids such as binders having a particular solids content (e.g., 15-60% by weight), then coating the slurry on the substrate, drying, and baking to provide a washcoat layer. Washcoats are generally formed at a concentration of 0.5-10 g / in 3 , preferably 1 to 7 g / in 3 is supported on the substrate in an amount of

[0064] The substrate is usually inert and is conventionally made, for example, from a ceramic or metallic material, and is referred to herein as an "inert substrate." Alternatively, it can be considered that the substrate may be active. In that case, the substrate may consist of an extrudate containing, for example, a vanadium-based catalyst, a metal-promoted molecular sieve catalyst, or other catalytically active species. For example, any of the first, second, and third regions may be present in the form of an extrudate that constitutes a substrate consisting of any of the other regions in the form of a washcoat.

[0065] In some exemplary embodiments of the SCR catalyst article according to the present invention, the first region containing the vanadium-based catalyst, the second region containing the metal-promoted molecular sieve catalyst, and the third region containing the vanadium-based SCR catalyst are present as washcoats on one or more inert substrates.

[0066] In some specific exemplary embodiments, the first, second and third regions are supported separately on two or more inert substrates.For example, the first, second and third regions may be supported separately on exactly two or three inert substrates.When using two or more inert substrates, the substrates may be made of the same or different materials.

[0067] When two inactive substrates are used, the first and second regions or the second and third regions are supported on one substrate, and the remaining region is supported on the other substrate, or the first and part of the second region are supported on one substrate, and the remaining second and third regions are supported on the other substrate. The two regions on the same substrate may be applied to the substrate by sequentially wash-coating the respective slurries. In this case, the two regions on the same substrate may be disposed adjacent to each other or overlapping each other.

[0068] In certain other exemplary embodiments of the SCR catalyst article according to the invention, the first region containing the vanadium-based catalyst is present as an extrudate, and the second region containing the metal-promoted molecular sieve catalyst and the third region containing the vanadium-based SCR catalyst are present as washcoats on one or more inert substrates, or the first and second regions are present as washcoats on one or more inert substrates, and the third region is present as an extrudate.

[0069] In some further exemplary embodiments of the SCR catalyst article according to the invention, the first region is present as an extrudate, the second region is present on the extrudate as a washcoat extending from the outlet side to the inlet side of the extrudate for less than the entire length of the extrudate, and the third region is present as a washcoat on a single inert substrate or as a separate extrudate.

[0070] Alternatively, the third region is present as an extrudate, the second region is present on the extrudate as a washcoat extending from the inlet side to the outlet side of the extrudate for less than the entire length of the extrudate, and the first region is present as a washcoat on an inert substrate or as a separate extrudate.

[0071] Alternatively, the first and third regions are both present as extrudates and the second region is present on the extrudate of the first region as a washcoat extending from the outlet side to the inlet side of the extrudate for less than the full length of the extrudate, and / or on the extrudate of the third region as a washcoat extending from the inlet side to the outlet side of the extrudate for less than the full length of the extrudate of the third region.

[0072] As used herein, "less than the full length of the extrudate" refers to 90% or less of the full length of the extrudate, e.g., 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less.

[0073] The first region, the second region and the third region may each be included in the SCR catalyst article according to the present invention in any suitable proportion ranging from 0.5 to 90 volume % based on the total volume of the catalyst article.

[0074] In some embodiments, the second region containing a metal-promoted molecular sieve catalyst may be present in the SCR catalyst article of the present invention in an amount ranging from 0.5 to 80 volume %, preferably from 1 to 75 volume %, more preferably from 5 to 65 volume %, for example from 10 to 60 volume % or from 15 to 50 volume %, based on the total volume of the catalyst article.

[0075] The first and third regions containing the vanadium-based SCR catalyst may be contained, independently of each other, in the SCR catalyst article according to the present invention in an amount of 10 to 60 volume %, preferably 15 to 55 volume %, and more preferably 25 to 50 volume %, based on the total volume of the catalyst article.

[0076] In some exemplary embodiments, the SCR catalyst article according to the present invention comprises: - 10-60 vol. % of a first region containing a vanadium-based SCR catalyst; - 5-65 vol. % of a second region containing a metal promoted molecular sieve catalyst; and - 10-60 vol. % of a third region containing a vanadium-based SCR catalyst; Each is relative to the total volume of the catalyst article.

[0077] In certain other exemplary embodiments, the SCR catalyst article according to the present invention comprises: - 15-55 vol. % of a first region containing a vanadium-based SCR catalyst; - 10-60 vol. % of a second region containing a metal promoted molecular sieve catalyst; and - 15-55 vol. % of a third region containing a vanadium-based SCR catalyst; Each is relative to the total volume of the catalyst article.

[0078] In a further exemplary embodiment, the SCR catalyst article according to the present invention comprises: - 25-50 vol. % of a first region containing a vanadium-based SCR catalyst; - 15-50 vol. % of a second region containing a metal promoted molecular sieve catalyst; and - 25-50 vol. % of a third region containing a vanadium-based SCR catalyst; Each is relative to the total volume of the catalyst article.

[0079] Volume percentages referred to with respect to a region refer to the volume of space that the region occupies. It is understood that when the region is present as a washcoat on a substrate, the volume percentage of the region is intended to refer to the volume of the portion of the substrate in which the region is located.

[0080] The catalytic article according to the invention may include one or more additional components having any function other than SCR, including but not limited to oxidation and storage functions. The one or more additional components may be arranged with any of the three zones. For example, an oxidation catalyst based on platinum group metals (PGM) may be arranged in the area of ​​the first zone to oxidize hydrocarbons, CO or NO, or in the area of ​​the third zone to oxidize NH3. It is also conceivable that storage components such as hydrocarbon adsorbents and NOx adsorbents may be arranged in the area of ​​the first zone. The one or more additional components may be present in any form, for example as a washcoat or co-extrusion.

[0081] The SCR catalyst articles according to the invention may be used to treat exhaust gases from stationary combustion apparatus, such as, for example, power plants and heating systems for buildings and homes, as well as mobile combustion apparatus, such as vehicle combustion engines, particularly diesel engines. The SCR catalyst articles according to the invention may be particularly effective in treating exhaust gases from internal combustion engines, such as gasoline or diesel engines, particularly heavy horsepower diesel engines.

[0082] Thus, in another aspect, the present invention relates to a method for treating an exhaust gas containing nitrogen oxides by selective catalytic reduction, comprising contacting the exhaust gas in the presence of a reducing agent with an SCR catalyst article described herein.

[0083] In some embodiments, the methods are useful for treating exhaust gases from internal combustion engines, such as gasoline or diesel engines, particularly heavy duty diesel engines.

[0084] In a further aspect, the present invention relates to a system for treating exhaust gases, particularly exhaust gases from an internal combustion engine, comprising a source of reductant and a catalytic article as described herein.

[0085] The system for treating the exhaust gas may further include one or more exhaust gas treatment elements, such as, but not limited to, a catalyst other than an SCR catalyst, such as a diesel oxidation catalyst (DOC), a three-way catalyst (TWC), a four-way catalyst (FWC), an uncatalyzed or catalyzed soot filter (CSF), an ammonia oxidation catalyst (AMOx), a NOx trap, a NOx absorption catalyst, a hydrocarbon trap catalyst, a sensor, and a mixer.

[0086] In a variation of the system for treating an exhaust gas, at least one region of the catalyst article is not closely connected to other regions, in which case one or more elements of the exhaust gas treatment system, such as catalytic components other than the SCR catalyst, a reductant source, a filter, a sensor, and a mixer, may be disposed intermediately.

[0087] The exhaust gas treatment system preferably further comprises a diesel oxidation catalyst located downstream of the engine and upstream of the SCR catalyst article according to the present invention. In some embodiments, the exhaust gas treatment system preferably comprises both a diesel oxidation catalyst and a catalyzed soot filter located upstream of the SCR catalyst article according to the present invention.

[0088] Embodiment Various embodiments are listed below, it being understood that the embodiments listed below may be combined with all aspects and other embodiments according to the scope of the present invention.

[0089] Embodiment 1. A catalytic article for purifying exhaust gas containing nitrogen oxides, the catalytic article comprising: a first region containing a vanadium-based SCR catalyst; a second region containing a metal promoted molecular sieve catalyst; and a third region containing a vanadium-based SCR catalyst; During the ceremony At least a part of the second region is located downstream of at least a part of the first region and upstream of at least a part of the third region in the flow direction of the exhaust gas. The catalyst article relates to a catalyst article in which no portion of the second region is located upstream of the first region or downstream of the third region. Embodiment 2. The catalyst article of any preceding embodiment, wherein the vanadium-based SCR catalyst in each of the first and third regions contains vanadium oxide and, optionally, at least one oxide of another element as a promoter, and wherein the catalyst is supported on particles of a carrier. Embodiment 3. The catalyst article according to the previous embodiment, wherein the other elements as promoters are selected from B, Al, Bi, Si, Sn, Pb, Sb, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ce, Y, Nb, Mo and W. Embodiment 4. The catalytic article of embodiment 2 or 3, wherein the support is selected from molecular sieves and one or more oxides of elements selected from Ti, Si, W, Al, Ce, Zr, Mg, Ca, Ba, Y, La, Pr, Nb, Mo, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sn and Bi. Embodiment 5. The catalyst article of any one of the preceding embodiments, wherein the vanadium-based SCR catalyst in the first region and the third region contains vanadium, calculated as V2O5, in an amount of 0.1-20 wt%, 1-15 wt%, 2-10 wt%, or 2-7 wt%, based on the total weight of the vanadium-based SCR catalyst, and the vanadium content of the vanadium-based SCR catalyst in the two regions is the same or different. Embodiment 6. The molecular sieves in the metal promoted molecular sieve catalyst are ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFV, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AVL, AWO, AW W, BCT, BEA, BEC, BIK, BOF, BOG, BOZ, BPH, BRE, BSV, CAN, CAS, CDO, CFI, CGF, CGS, CHA, -CHI, -CLO, CON, CSV, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EEI, EMT, EON, EPI, ERI, ESV, ETR, EUO, * -EWT, EZT, FAR, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFO, IFR, -IFU, IFW, IFY, IHW, IMF, IRN, IRR, -IRY, ISV, ITE, ITG, ITH, * -ITN, ITR, ITT, -ITV, ITW, IWR, IWS, IWV, IWW, JBW, JNT, JOZ, JRY, JSN, JSR, JST, JSW, KFI, LAU, LEV , LIO, -LIT, LOS, LOV, LTA, LTF, LTJ, LTL, LTN, MAR, MAZ, MEI, MEL, MEP, MER, MFI, MFS, MON, MOR, MOZ, *MRE, MSE, MSO, MTF, MTN, MTT, MTW, MVY, MWF, MWW, NAB, NAT, NES, NON, NPO, NPT, NSI, OBW, OFF, OKO, OSI, OSO, OWE, -PAR, PAU, PCR, PHI, PON, PO S, PSI, PUN, RHO, -RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAF, SAO, SAS, SAT, SAV, SBE, SBN, SBS, SBT, SEW, SFE, SFF, SFG, SFH, SFN, SFO, SFS, * SFV, SFW, SGT, SIV, SOD, SOF, SOS, SSF, * -SSO, SSY, STF, STI, * The catalyst article of any one of the preceding embodiments, wherein the zeolite is selected from zeolites having a framework type of STO, STT, STW, -SVR, SVV, SZR, TER, THO, TOL, TON, TSC, TUN, UEI, UFI, UOS, UOV, UOZ, USI, UTL, UWY, VET, VFI, VNI, VSV, WEI, -WEN or YUG, ZON, and any combination thereof. Embodiment 7. The catalyst article of any one of the preceding embodiments, wherein the molecular sieve in the metal-promoted molecular sieve catalyst is selected from a zeolite having a framework type of AEI, AEL, AFI, AFT, AFO, AFX, AFR, ATO, BEA, CHA, DDR, EAB, EMT, ERI, EUO, FAU, FER, GME, HEU, JSR, KFI, LEV, LTA, LTL, LTN, MAZ, MEL, MFI, MOR, MOZ, MSO, MTW, MWW, OFF, RTH, SAS, SAT, SAV, SBS, SBT, SFW, SSF, SZR, TON, TSC, or WEN. Embodiment 8. The catalyst article of any one of the preceding embodiments, wherein the molecular sieve in the metal-promoted molecular sieve catalyst is selected from zeolites having a framework type of AEI, BEA, CHA, AFT, AFX, FAU, FER, KFI, MOR, MFI, MOR or MEL, among which AEI, BEA and CHA are particularly preferred. Embodiment 9. The catalytic article of any one of the preceding embodiments, wherein the metal for promoting the molecular sieve in the second region is selected from precious metals such as Au and Ag, platinum group metals such as Ru, Rh, Pd, In and Pt, base metals such as Cr, Zr, Nb, Mo, Fe, Mn, W, V, Ti, Co, Ni, Cu, Zn, Sb, Sn and Bi, alkaline earth metals such as Ca and Mg, and any combination thereof. Embodiment 10. The catalytic article of any one of the preceding embodiments, wherein the metal for promoting the molecular sieve in the second region is Fe, Cu, or a combination thereof. Embodiment 11. The catalyst article of any one of the preceding embodiments, wherein the metal for promoting the molecular sieve in the second region is present in the metal-promoted molecular sieve catalyst in an amount ranging from 0.1 to 20 wt.%, 0.5 to 15 wt.%, or 1 to 10 wt.%, on an oxide basis, based on the total weight of the metal-promoted molecular sieve. Embodiment 12. The catalytic article of any one of the preceding embodiments, wherein the first region, the second region, and the third region, independently of one another, are present in the form of an extrudate or in the form of a washcoat on a substrate. Embodiment 13. A catalytic article according to any of the previous embodiments, wherein the extrudate and / or substrate has a honeycomb structure, such as a monolith flow-through structure or a wall-flow structure. Embodiment 14. The catalytic article of any one of the preceding embodiments, wherein the first, second, and third regions are separately supported on two or more inert substrates, preferably two or three inert substrates. Embodiment 15. A catalyst article according to any one of the preceding embodiments, wherein the second region is contained in the catalyst article in an amount of 0.5 to 80 volume %, preferably 1 to 75 volume %, more preferably 5 to 65 volume %, for example 10 to 60 volume % or 15 to 50 volume %, relative to the total volume of the catalyst article. Embodiment 16. A catalyst article according to any one of the preceding embodiments, wherein the first and third regions are independently present in the catalyst article in an amount of 10 to 60% by volume, preferably 15 to 55% by volume, and more preferably 25 to 50% by volume, based on the total volume of the catalyst article. Embodiment 17. A catalytic article according to any one of the preceding embodiments, comprising: a first region containing a vanadium-based SCR catalyst; a second region containing a metal promoted molecular sieve catalyst; and a third region containing a vanadium-based SCR catalyst; The second region is located downstream of at least a portion of the first region and upstream of at least a portion of the third region, providing a catalytic article. Embodiment 18. A catalytic article according to any one of the preceding embodiments, comprising: a first region containing a vanadium-based SCR catalyst; a second region containing a metal promoted molecular sieve catalyst; and a third region containing a vanadium-based SCR catalyst; The second region is provided in a catalyst article located completely downstream of the first region and completely upstream of the third region. Embodiment 19. A method for treating an exhaust gas containing nitrogen oxides, comprising contacting the exhaust gas with a catalytic article defined in any one of embodiments 1 to 18 in the presence of a reducing agent. Embodiment 20. The method of embodiment 19, wherein the exhaust gas is from an internal combustion engine, such as a gasoline or diesel engine, in particular a high-horsepower diesel engine. Embodiment 21. A system for treating exhaust gases, particularly from an internal combustion engine, comprising a reductant source, a catalyst article according to any one of embodiments 1 to 20, and optionally one or more of a diesel oxidation catalyst (DOC), a three-way catalyst (TWC), a four-way catalyst (FWC), an uncatalyzed or catalyzed soot filter (CSF), an ammonia oxidation catalyst (AMOx), a NOx trap, a NOx absorption catalyst, a hydrocarbon trap catalyst, a sensor, and a mixer.

[0090] The present invention is further illustrated by the following examples which set forth particularly advantageous embodiments. Although the examples are provided to illustrate the invention, they are not intended to limit the invention. EXAMPLES

[0091] Example 1 Catalyst Article Sample with V-Fe-V Catalyst Configuration 1.1 Preparation of bricks containing V-based SCR catalyst on a substrate (V-SCR bricks) 173.2 g of TiO2 in anatase form with a titanium content of 95.9 wt. % calculated as TiO2, 74.4 g of vanadyl oxalate solution with a vanadium content of 10.75 wt. % calculated as V2O5, and 12.0 g of Sb2O3 were mixed in 200 g of DI water at room temperature. The resulting suspension was stirred for 30 minutes, and then 30% aqueous ammonia was added to raise the pH of the system to 7.0. Then, 46.2 g of SiO2 sol with a SiO2 content of 30.1 wt. % was added. After stirring for 1 hour, a homogeneous slurry was obtained. A 300 cpsi flow-through honeycomb cordierite substrate with a wall thickness of 5 mil was immersed in the resulting slurry to fill it with sufficient slurry. The excess slurry was carefully blown off with an air knife, then dried with hot air at 150°C for 15 minutes, and then calcined in air at 450°C for 1 hour.

[0092] 4.5g / in 3 The process of soaking, drying and calcining was repeated until a total washcoat loading on the substrate of 0.01 wt.% was obtained. The V-based SCR catalyst has a vanadium content of 4.0 wt.%, calculated as V2O5.

[0093] 1.2 Preparation of Molecular Sieve Bricks (Fe-Zeolite Bricks) Containing Fe-Promoted Molecular Sieves on a Substrate The SiO2 to Al2O3 molar ratio is 9, the iron loading calculated as Fe2O3 is 4.8 wt%, the X-ray crystallinity is 98%, and the BET surface area is 578 m 2 / g, D 90 A Fe / Beta zeolite from Zeolyst was used, having a diameter of 13 μm, 0.07 wt% Na2O, 0.03 wt% K2O, 0.01 wt% CaO, and 0.02 wt% MgO.

[0094] 95 parts by weight of Fe / Beta zeolite and 5 parts by weight of zirconium acetate, calculated as ZrO2, were mixed in deionized water to form a slurry. The slurry had a D of approximately 10 μm as measured by a Sympatec particle size analyzer. 90 The slurry was ground to a particle size of 3.2 g / in. The ground slurry was coated onto a flow-through cordierite monolith substrate with 1 inch diameter, 300 cpsi cell density, and 5 mil wall thickness by dipping the substrate into the slurry. The excess slurry was carefully blown off with an air knife, followed by drying at 130°C and calcination at 550°C. 3 The process of soaking, drying and baking was repeated until a total washcoat loading on the substrate of .

[0095] 1.3 Preparation of test samples Two cores, 1 inch in diameter and 2 inches in length, were cut from the V-SCR brick and one core, 1 inch in diameter and 1 inch in length, was cut from the Fe-Zeolite brick. The cores were arranged in the following order: a first V-SCR core, an Fe-Zeolite core, and a second V-SCR core.

[0096] Example 2 Catalyst Article Sample with V-Fe-V Catalyst Configuration 2.1 Preparation of brick containing V-based SCR catalyst on substrate (V-SCR brick) The V-SCR brick was prepared by the same method as described in Example 1.1.

[0097] 2.2 Preparation of Fe-promoted molecular sieve bricks on a substrate (Fe-zeolite bricks) The SiO2 to Al2O3 molar ratio is 9, the iron loading calculated as Fe2O3 is 4.8 wt%, the X-ray crystallinity is 98%, and the BET surface area is 578 m 2 / g, D 90 A Fe / Beta zeolite from Zeolyst was used, having a diameter of 13 μm, 0.07 wt% Na2O, 0.03 wt% K2O, 0.01 wt% CaO, and 0.02 wt% MgO.

[0098] 90 parts by weight of Fe / Beta, 5 parts by weight of iron nitrate calculated as Fe2O3, and 5 parts by weight of zirconium acetate calculated as ZrO2 were mixed in deionized water to form a slurry. The slurry was then measured with a Sympatec particle size analyzer to have a D of about 10 μm. 90 The slurry was ground to a particle size of 3.2 g / in. The ground slurry was coated onto a flow-through cordierite monolith substrate with 1 inch diameter, 300 cpsi cell density, and 5 mil wall thickness by dipping the substrate into the slurry. The excess slurry was carefully blown off with an air knife, followed by drying at 130°C and calcination at 550°C. 3 The process of soaking, drying and baking was repeated until a total washcoat loading on the substrate of 1000 μm was achieved.

[0099] 2.3 Preparation of test samples Two cores, 1 inch in diameter and 2 inches in length, were cut from the V-SCR brick and one core, 1 inch in diameter and 1 inch in length, was cut from the Fe-Zeolite brick. The cores were arranged in the following order: a first V-SCR core, an Fe-Zeolite core, and a second V-SCR core.

[0100] Example 3 Catalyst Article Sample with V-Fe-V Catalyst Configuration V-SCR brick and Fe-zeolite brick were prepared by the same method as described in examples 1.1 and 1.2, respectively.

[0101] Two cores were cut from the V-SCR brick measuring 1 inch in diameter and 1.5 inches in length, and one core was cut from the Fe-Zeolite brick measuring 1 inch in diameter and 2 inches in length. The cores were arranged in the following order: a first V-SCR core, an Fe-Zeolite core, and a second V-SCR core.

[0102] Example 4 Catalyst article sample having V-Cu-V catalyst configuration 4.1 Preparation of brick containing V-based SCR catalyst on substrate (V-SCR brick) The V-SCR bricks were prepared by the same method as described in Example 1.1.

[0103] 4.2 Preparation of Cu-promoted molecular sieve bricks on a substrate (Cu-zeolite bricks): SiO2 to Al2O3 molar ratio of 16.5, X-ray crystallinity of 99%, BET surface area of ​​520m 2 / g, D 90 CHA zeolite from Tosoh was used, with a diameter of 6 μm, Na2O≦0.01 wt % and a tap density of 0.7 g / mL.

[0104] 90 parts by weight of CHA type zeolite, 5 parts by weight of copper oxide CuO, and 5 parts by weight of zirconium acetate calculated as ZrO2 were mixed in deionized water to form a slurry. The slurry was then measured with a Sympatec particle size analyzer to have a D of about 5 μm. 90 The slurry was ground to a particle size of 2.1 g / in. The ground slurry was coated onto a flow-through cordierite monolith substrate having a 1 inch diameter, a cell density of 300 cpsi, and a wall thickness of 5 mils by dipping the substrate into the slurry. The excess slurry was carefully blown off with an air knife, followed by drying at 130°C and calcination at 550°C. 3 The process of soaking, drying and baking was repeated until a total washcoat loading on the substrate of 1000 μm was achieved.

[0105] 4.3 Preparation of test samples Two cores were cut from the V-SCR brick, 1 inch in diameter and 2 inches in length, and one core was cut from the Cu-Zeolite brick, 1 inch in diameter and 1 inch in length. The samples were arranged in the following order: first V-SCR core, Cu-Zeolite core, and second V-SCR core.

[0106] Example 5 Catalyst article sample having V-Cu-V catalyst configuration 5.1 Preparation of brick containing V-based SCR catalyst on substrate (V-SCR brick) The V-SCR brick was prepared by the same method as described in Example 1.1.

[0107] 5.2 Preparation of Cu-promoted molecular sieve bricks on substrates (Cu-zeolite bricks) Manufactured by BASF, it has a SiO2 to Al2O3 molar ratio of 21, an X-ray crystallinity of 93%, and a BET surface area of ​​583 m 2 / g, D 90 A Cu-zeolite brick was prepared according to the method described in Example 4.2, except that an AEI zeolite with a diameter of 13 microns, Na2O≦0.01 wt % and tap density=0.4 g / mL was used.

[0108] 5.3 Preparation of test samples Two cores were cut from the V-SCR brick, 1 inch in diameter and 2 inches in length, and one core was cut from the Cu-Zeolite brick, 1 inch in diameter and 1 inch in length. The cores were arranged in the following order: a first V-SCR core, a Cu-Zeolite core, and a second V-SCR core.

[0109] Example 6 Catalyst article sample having V-Fe-Cu-V catalyst configuration V-SCR brick was prepared in the same manner as in Example 1.1, Fe-zeolite brick was prepared in the same manner as in Example 1.2, and Cu-zeolite brick was prepared in the same manner as in Example 4.2.

[0110] Two cores were cut from the V-SCR brick, 1 core was cut from the Fe-Zeolite brick, 1 core was cut from the Cu ...

[0111] Example 7 Catalyst Article Sample with V-Fe-V Catalyst Configuration V-SCR brick and Fe-zeolite brick were prepared by the same method as described in examples 1.1 and 1.2, respectively.

[0112] One core measuring 1 inch in diameter and 2.0 inch in length and one core measuring 1 inch in diameter and 2.5 inch in length were cut from the V-SCR brick, and one core measuring 1 inch in diameter and 0.5 inch in length was cut from the Fe-Zeolite brick. The cores were arranged in the following order: the 2.0 inch first V-SCR core, the Fe-Zeolite core, and the 2.5 inch second V-SCR core, with the first V-SCR core contacting the test gas first.

[0113] Example 8 Catalyst Article with V-Fe-V Catalyst Configuration It is made from Zeolyst and has a SiO2 to Al2O3 molar ratio of 41, an iron loading of 1.4 wt.% calculated as Fe2O3, an X-ray crystallinity of 100%, and a BET surface area of ​​708 m 2 / g, D 90 Test samples were prepared in the same manner as described in Example 1, except that a low Fe2O3 loading Fe / Beta zeolite was used, with Fe2O3 diameter = 5 μm and Na2O = 0.03 wt %.

[0114] Comparative Example 1 V-SCR Catalyst Article Three cores, 1 inch in diameter and 2 inch in length, 1 inch and 2 inch in length, respectively, were cut from the V-SCR brick prepared by the same method described in Example 1.1. The cores were arranged in the following order: a first V-SCR core of 2 inch, a second V-SCR core of 1 inch, and a third V-SCR core of 2 inch, such that the first V-SCR core was first in contact with the test gas.

[0115] Comparative Example 2: Catalytic article having a catalyst arrangement of Fe-VV Test samples were prepared in the same manner as described in Example 1, except that the cores were arranged in the following order: Fe-zeolite core, first V-SCR core, and second V-SCR core, such that the Fe-zeolite core was first in contact with the test gas.

[0116] Comparative Example 3 Catalyst Article with VV-Fe Catalyst Configuration Test samples were prepared in the same manner as described in Example 1, except that the cores were arranged in the following order: first V-SCR core, second V-SCR core, and Fe-zeolite core, such that the first V-SCR core was contacted with the test gas first.

[0117] Comparative Example 4 Catalyst Article with V-Fe-V Catalyst Arrangement Test samples were prepared in the same manner as described in Example 1, except that the two V-SCR cores were each 0.5 inches long and the Fe-zeolite core was 4 inches long.

[0118] Example 9 SCR performance test Example 9.1 Temperature and NO2 / NO x Testing SCR performance under ratio variations Fresh samples were placed in a laboratory fixed-bed simulator with a base feed gas of 5% CO2 by volume, 5% H2O by volume, 10% O2 by volume, 500 ppm NO x (NO2 + NO), and the balance N2. Space velocity (SV) was fixed at 120,000 / hr based on a 1" x 3" cylindrical sample. NH3 vs. NO x The ratio (NSR) of NO2 / NO2 was fixed at 1.2. x The ratio was cyclically changed from condition 1 to condition 2 and then back to condition 1 over 200 seconds per cycle (as shown in FIG. 1). In each cycle, condition 1 was maintained for 50 seconds for stabilization. NO2 / NO x The ratio was varied by adjusting the percentage of NO2 in the base feed gas, and each test consisted of four cycles. The cumulative NOx and N2O emissions after four cycles were measured for the samples, and the results are summarized in Table 1 below. Condition 1: 300℃, NO x Medium 75% NO2 Condition 2: 200℃, NO x Medium 25%NO2

[0119] [Table 1]

[0120] Surprisingly, as can be seen from the test results in Table 1, SCR catalyst samples including a metal promoted zeolite region located between two vanadium based SCR regions according to the present invention exhibit improved NOx reduction, i.e., lower NOx emissions, compared to SCR catalyst samples having catalyst configurations other than the configuration design of the present invention.

[0121] In particular, a comparison of the SCR catalyst sample of Example 1 and the samples of Comparative Examples 2 and 3 clearly shows the improvement in NOx reduction achieved by the inventive arrangement design of the vanadium-based SCR catalyst and the metal promoted zeolite catalyst, while no increase in NO formation was observed.

[0122] Example 9.2 Testing SCR performance under variations in temperature, NOx feed rate, NH3 / NOx ratio, and space velocity Fresh samples were placed in a laboratory fixed-bed simulator with a base feed gas of 5% by volume Co2, 5% by volume H2O, 10% by volume O2, NO x The temperature, space velocity (SV), and NO x Supply, and NH3 / NO x The ratio (NSR) was periodically changed from condition 1 to condition 2 and then back to condition 1 (as shown in FIG. 2). In each cycle, the change from one condition to the other was accomplished over 100 seconds, and both condition 1 and condition 2 were maintained for 50 seconds for stabilization. Each test consisted of 5 cycles. The NOx conversion calculated based on the cumulative emissions and cumulative N2O emissions after 5 cycles were measured for the samples, and the results are summarized in Table 2 below. Condition 1: 200℃, SV=80,000 / hour, NO x =500ppm, NSR=2, NO x Medium 50%NO2 Condition 2: 300℃, SV=120,000 / hour, NO x=1000ppm, NSR=0.5, NO x Medium 50%NO2

[0123] [Table 2]

[0124] It can be seen that the improved NOx reduction resulting from the catalyst design of the present invention can be achieved under complex variations in multiple conditions without observing an increase in N2O formation.

Claims

1. A catalytic article for purifying an exhaust gas containing nitrogen oxides, the catalytic article comprising: a first region containing a vanadium-based SCR catalyst, a second region containing a metal promoted molecular sieve catalyst, and - a third region containing a vanadium-based SCR catalyst, During the ceremony At least a portion of the second region is located downstream of at least a portion of the first region and upstream of at least a portion of the third region in a flow direction of the exhaust gas, A catalytic article, wherein no portion of the second region is located upstream of the first region or downstream of the third region.

2. 2. The catalytic article of claim 1, wherein the vanadium-based SCR catalyst in each of the first and third regions comprises vanadium oxide and optionally at least one oxide of another element as a promoter supported on particles of a support.

3. 3. The catalytic article of claim 2, wherein the other elements as promoters are selected from the group consisting of B, Al, Bi, Si, Sn, Pb, Sb, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ce, Y, Nb, Mo and W.

4. 4. The catalytic article of claim 2 or 3, wherein the support is selected from molecular sieves and one or more oxides of elements selected from the group consisting of Ti, Si, W, Al, Ce, Zr, Mg, Ca, Ba, Y, La, Pr, Nb, Mo, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sn and Bi.

5. The vanadium-based SCR catalyst in the first region and the third region is ２ O ５ 5. The catalyst article according to claim 1, wherein the vanadium content of the vanadium based SCR catalyst in the two regions is the same or different.

6. The molecular sieve in the metal-promoted molecular sieve catalyst is ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFV, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AVL, AWO, AWW, BCT, BEA, BEC, BIK, BOF, BOG, BOZ, BPH, BRE, BSV, CAN, CAS, CDO, CFI, CGF, CGS, CHA, -CHI, -CLO, CON, CSV, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EEI, EMT, EON, EPI, ERI, ESV, ETR, EUO, ＊ -EWT, EZT, FAR, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFO, IFR, -IFU, IFW, IFY, IHW, IMF, IRN, IRR, -IRY, ISV, ITE, ITG, ITH, ＊ -ITN, ITR, ITT, -ITV, ITW, IWR, IWS, IWV, IWW, JBW, JNT, JOZ, JRY, JSN, JSR, JST, JSW, KFI, LAU, LEV, LIO, -LIT, LOS, LOV, LTA, LTF, LTJ, LTL, LTN, MAR, MAZ, MEI, MEL, MEP, MER, MFI, MFS, MON, MOR, MOZ, ＊ MRE, MSE, MSO, MTF, MTN, MTT, MTW, MVY, MWF, MWW, NAB, NAT, NES, NON, NPO, NPT, NSI, OBW, OFF, OKO, OSI, OSO, OWE, -PAR, PAU, PCR, PHI, PON, POS, PSI, PUN, RHO, -RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAF, SAO, SAS, SAT, SAV, SBE, SBN, SBS, SBT, SEW, SFE, SFF, SFG, SFH, SFN, SFO, SFS, ＊ SFV, SFW, SGT, SIV, SOD, SOF, SOS, SSF, ＊ -SSO, SSY, STF, STI, ＊ 6. The catalyst article according to any one of claims 1 to 5, selected from zeolites having a framework type of STO, STT, STW, -SVR, SVV, SZR, TER, THO, TOL, TON, TSC, TUN, UEI, UFI, UOS, UOV, UOZ, USI, UTL, UWY, VET, VFI, VNI, VSV, WEI, -WEN, YUG or ZON and any combination thereof, among which AEI, BEA, CHA, AFT, AFX, FAU, FER, KFI, MOR, MFI, MOR, MEL or any combination thereof is preferred.

7. 7. The catalytic article of any one of claims 1 to 6, wherein the metal for promoting the molecular sieve in the second region is selected from precious metals such as Au and Ag, platinum group metals such as Ru, Rh, Pd, In and Pt, base metals such as Cr, Zr, Nb, Mo, Fe, Mn, W, V, Ti, Co, Ni, Cu, Zn, Sb, Sn and Bi, alkaline earth metals such as Ca and Mg, and any combination thereof.

8. 8. The catalytic article of claim 7, wherein the metal for promoting the molecular sieve in the second region is Fe, Cu, or a combination thereof.

9. 9. The catalyst article of any one of claims 1 to 8, wherein the metal for promoting the molecular sieve in the second region is present in the metal-promoted molecular sieve catalyst in an amount in the range of 0.1 to 20 wt%, 0.5 to 15 wt%, or 1 to 10 wt%, based on the total weight of the metal-promoted molecular sieve, on an oxide basis.

10. 10. The catalytic article of any one of claims 1 to 9, wherein the first region, the second region and the third region, independently of one another, are present in the form of an extrudate or a washcoat on a substrate.

11. 11. The catalytic article of claim 10, wherein the extrudates and / or the substrate have a honeycomb structure, such as a monolith flow-through structure or a wall-flow structure.

12. The catalytic article of any one of claims 1 to 11, wherein the first, second and third regions are separately supported on two or more inert substrates.

13. 13. The catalyst article according to any one of claims 1 to 12, wherein the second region is contained in the catalyst article in a proportion of 0.5 to 80% by volume, preferably 1 to 75% by volume, more preferably 5 to 65% by volume, for example 10 to 60% by volume or 15 to 50% by volume, based on the total volume of the catalyst article.

14. 14. The catalyst article according to claim 1, wherein the first and third regions are contained in the catalyst article, independently of one another, in a proportion of 10 to 60% by volume, preferably 15 to 55% by volume, more preferably 25 to 50% by volume, based on the total volume of the catalyst article.

15. The catalyst article comprises: a first region containing a vanadium-based SCR catalyst, a second region containing a metal promoted molecular sieve catalyst, and - a third region containing a vanadium-based SCR catalyst, The second region is located downstream of at least a portion of the first region and upstream of at least a portion of the third region. A catalytic article according to any one of claims 1 to 14.

16. The catalyst article comprises: a first region containing a vanadium-based SCR catalyst, a second region containing a metal promoted molecular sieve catalyst, and - a third region containing a vanadium-based SCR catalyst, the second region is located completely downstream of the first region and completely upstream of the third region; 16. The catalyst article of claim 15.

17. A method for treating an exhaust gas containing nitrogen oxides, said method comprising contacting the exhaust gas with a catalytic article according to any one of claims 1 to 16 in the presence of a reducing agent.

18. 18. The method of claim 17, wherein the exhaust gas is from an internal combustion engine, such as a gasoline or diesel engine.

19. 17. A system for treating exhaust gases, in particular from an internal combustion engine, said system comprising a reductant source, a catalyst article according to any one of claims 1 to 16, and optionally one or more of a diesel oxidation catalyst (DOC), a three-way catalyst (TWC), a four-way catalyst (FWC), an uncatalyzed or catalyzed soot filter (CSF), an ammonia oxidation catalyst (AMOx), a NOx trap, a NOx absorption catalyst, a hydrocarbon trap catalyst, a sensor and a mixer.

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