Catalytic systems including antimony-containing catalysts

Abstract

A catalyst system for purifying exhaust gases, comprising one or more antimony-containing regions comprising an antimony-containing catalyst, in particular an antimony-containing SCR catalyst, and one or more antimony trapping regions optionally comprising a metal-promoted molecular sieve, wherein at least one of the antimony trapping regions is located downstream of the one or more antimony-containing regions in the flow direction of the exhaust gas, and also a method for the treatment of exhaust gases containing nitrogen oxides.

Description

[Technical field]

[0001] The present invention relates to a catalyst system including an antimony-containing catalyst and a method for the treatment of exhaust gases containing nitrogen oxides. [Background technology]

[0002] Antimony-containing catalysts are known to be useful in many fields, such as the production of polyester materials, the ammoxidation of alkanes and alkenes, the alkoxylation of organic compounds, and the treatment of engine exhaust. Antimony species can function either as activators or promoters and can have different chemical compositions depending on the specific application. In recent decades, concerns regarding the volatility of antimony species at high temperatures have become an issue that limits the available market for antimony-containing catalysts in certain applications, such as engine exhaust treatment.

[0003] Engine exhaust, particularly diesel engine exhaust, contains gaseous emissions such as carbon monoxide (CO), unburned hydrocarbons (HC), and nitrogen oxides (NOx), as well as condensed phase materials (liquids and solids) commonly referred to as particulate matter (PM). Engine exhaust must be treated in the engine exhaust system before being released into the air. Engine exhaust systems generally contain catalysts for the reduction of NOx, for example by selective catalytic reduction (SCR).

[0004] Antimony species have been reported as a good candidate for effectively improving the SCR performance of vanadium-based oxide SCR catalysts. US Patent No. 2009 / 143225 (A1) describes an SCR catalyst containing vanadium oxide and antimony as active materials, and proves that antimony is effective in promoting the reduction of nitrogen oxides (NOx) at low temperatures and increasing sulfur poisoning resistance. Vanadium-based oxide SCR catalysts containing antimony species are also described, for example, in Korean Patent No. 101065242 (B1), US Patent No. 8975206 (B2), and International Publication No. 2017101449 (A1).

[0005] Despite the good promotion effect of antimony on vanadium-based oxide SCR catalysts, the application of vanadium-based oxide SCR catalysts containing antimony species in engine exhaust systems is limited due to concerns about the volatility of antimony species at high temperatures that may contact the SCR catalyst in the high-temperature exhaust gas flow. Several means have been proposed that are useful for reducing antimony evaporation from SCR catalysts. For example, WO2021055299(A1) describes vanadium-based oxide catalysts containing antimony species, and demonstrates that the presence of tungsten species in the catalyst can significantly suppress the evaporation of antimony species at high temperatures.

[0006] It would be desirable to provide an alternative or more effective approach to reducing the release of antimony into the environment from antimony-containing catalysts. Summary of the Invention

[0007] It is an object of the present invention to provide a catalyst system, including an antimony-containing catalyst, that produces desirably low amounts of antimony emissions into the environment.

[0008] Surprisingly, this object has been achieved by a catalyst system comprising one or more antimony-containing regions and one or more regions containing a molecular sieve for capturing antimony.

[0009] Thus, in one aspect, the present invention provides a catalyst system for purifying exhaust gases, comprising: one or more antimony-containing regions comprising an antimony-containing catalyst, in particular an antimony-containing SCR catalyst; - one or more antimony capture regions, optionally comprising a metal promoted molecular sieve; The present invention relates to a catalyst system in which at least one of the antimony trapping regions is located downstream of one or more antimony-containing regions in the exhaust gas flow direction.

[0010] In another aspect, the present invention relates to a method for the treatment of exhaust gases containing nitrogen oxides comprising contacting the exhaust gas with a catalyst system as described herein in the presence of a reducing agent.

[0011] In a further aspect, the present invention relates to a system for the treatment of exhaust gases, particularly from an internal combustion engine, comprising a reductant source, a catalyst system as described herein, and optionally one or more of a diesel oxidation catalyst (DOC), a three-way conversion catalyst (TWC), a four-way conversion catalyst (FWC), an uncatalyzed or catalyzed soot filter (CSF), an ammonia oxidation catalyst (AMOx), a NOx trap, a NOx absorber catalyst, a hydrocarbon trap catalyst, a sensor, and a mixer.

[0012] It has been found by the inventors that the release of antimony from an antimony-containing catalyst to the environment can be effectively suppressed by placing an antimony capture zone downstream that includes a molecular sieve. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will be described in detail herein below. It should be understood that the present invention can be embodied in many different ways and should not be construed as being limited to the embodiments set forth herein.

[0014] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Terms such as "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 included within "comprises" or cognates.

[0015] As used herein, the term "region" is intended simply to mean a portion of a catalyst system that includes a particular material and extends a particular length in the exhaust gas flow direction.

[0016] Any references herein to "upstream" and "downstream" will be understood to be relative to the direction of flow of the fluid, for example the direction of exhaust gas flow.

[0017] According to a first aspect, the present invention provides a catalytic system for purifying exhaust gases, comprising: one or more antimony-containing regions comprising an antimony-containing catalyst; - one or more antimony capture regions, optionally comprising a metal promoted molecular sieve; A catalyst system is provided in which at least one of the antimony trapping regions is located downstream of the one or more antimony-containing regions in the exhaust gas flow direction.

[0018] The antimony-containing region may include any antimony-containing catalyst useful for purifying exhaust gases. In particular, the antimony-containing region includes an antimony-containing SCR catalyst.

[0019] Antimony-containing catalysts can be those vanadium-based SCR catalysts that contain an antimony promoter. Antimony-containing catalysts thus contain vanadium as the primary active species for selective catalytic reduction of NOx, and antimony as a promoter, each typically present in the form of its respective oxide and / or their composite oxides.

[0020] The antimony-containing catalyst may optionally include at least one additional metal or metalloid. The additional metal or metalloid may include, but is not limited to, boron (B), aluminum (Al), bismuth (Bi), silicon (Si), tin (Sn), lead (Pb), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), cerium (Ce), yttrium (Y), niobium (Nb), molybdenum (Mo), barium (Ba), samarium (Sm), erbium (Er), and tungsten (W). In particular, the additional metal or metalloid may be selected from silicon (Si), molybdenum (Mo), and tungsten (W). It will be understood that the at least one metal or metalloid may be present in the form of its respective oxide, or a complex oxide thereof with vanadium, antimony, or other additional metals or metalloids, or a combination thereof.

[0021] In some embodiments, the antimony-containing catalyst contains or consists of antimony oxide, vanadium oxide, and optionally at least one oxide of a metal or metalloid selected from silicon (Si), molybdenum (Mo), and tungsten (W) on a particle of support. For example, the antimony-containing catalyst contains or consists of vanadium (V), antimony (Sb), and silicon (Si) oxides on a particle of support.

[0022] Materials useful as supports may include, but are not limited to, molecular sieves and 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 anatase), silica, alumina, zirconia, and any dopant stabilized form thereof.

[0023] The antimony-containing catalyst may contain antimony in an amount of 1-30 wt%, 1-25 wt%, 1-15 wt%, 2-12 wt%, or 2-8 wt%, calculated as Sb2O3, based on the total weight of the antimony-containing catalyst.

[0024] The antimony-containing catalyst may contain vanadium in an amount of 0.1-20 wt.%, 1-15 wt.%, 2-10 wt.%, or 2-7 wt.%, calculated as V2O5, based on the total weight of the antimony-containing catalyst.

[0025] Each of the at least one additional metal or metalloid, when present, may be contained in the antimony-containing catalyst in an amount of 0.1 to 30 wt. %, 1 to 15 wt. %, or 2 to 10 wt. %, calculated as the respective oxide, based on the total weight of the antimony-containing catalyst.

[0026] The support may be present in the antimony-containing catalyst in an amount of at least 40%, at least 50%, at least 65%, at least 70%, or at least 75% by weight based on the total weight of the antimony-containing catalyst. The amount of support may be up to 95%, or up to 90% by weight based on the total weight of the antimony-containing catalyst.

[0027] In some exemplary embodiments, the antimony-containing catalyst comprises: (a) 1 to 25 weight percent antimony oxide, calculated as Sb2O3; (b) 1 to 15 weight percent vanadium oxide, calculated as V2O5; (c) 1 to 15 wt. % SiO2; (d) optionally, 1 to 10 weight percent tungsten oxide, calculated as WO; (e) 65 to 95% by weight of a TiO2 support; and Each is based on the total weight of the antimony-containing catalyst.

[0028] In some exemplary embodiments, the antimony-containing catalyst comprises: (a) 1 to 15 weight percent antimony oxide, calculated as Sb2O3; (b) 2 to 10 weight percent vanadium oxide, calculated as V2O5; (c) 2 to 10% by weight of SiO2; (d) optionally, 2 to 10 weight percent tungsten oxide, calculated as WO; (e) 70 to 90% by weight of a TiO2 support; and Each is based on the total weight of the antimony-containing catalyst.

[0029] In some further exemplary embodiments, the antimony-containing catalyst comprises: (a) 2 to 12% by weight, preferably 2 to 8% by weight, of antimony oxide, calculated as Sb2O3; (b) 2 to 7 percent by weight of vanadium oxide, calculated as V2O5; (c) 2 to 10% by weight of SiO2; (e) 75 to 90% by weight of a TiO2 support; and Each is based on the total weight of the antimony-containing catalyst.

[0030] The total weight of the antimony-containing catalyst in each case as described herein is 100% by weight.

[0031] It will be understood that the antimony-containing catalyst in each of the antimony-containing regions, when two or more such regions are present, may have the same or different composition from one another.

[0032] Antimony-containing catalysts should be between 50 and 3,000 g / ft2, calculated as Sb2O3, based on the area of ​​each antimony-containing catalyst. 3 of antimony, preferably 200 to 2,200 g / ft 3 of antimony, more preferably 350 to 2,000 g / ft 3 of antimony.

[0033] The antimony-containing region may also contain one or more components in addition to the antimony-containing catalyst, which may be non-catalytically active components, such as processing aids useful in the preparation of the catalyst article, such as lubricants and binders. Other components may also be catalytically active, such as active species other than the antimony-containing catalyst.

[0034] Surprisingly, the present inventors have found that molecular sieves are useful for trapping antimony species. Accordingly, one or more regions containing molecular sieves are disposed in the catalyst system to trap antimony. These regions are referred to herein as antimony trapping regions.

[0035] The antimony capture zone optionally comprises a metal-promoted molecular sieve. In this specification, the term "metal-promoted" in the context of a molecular sieve is intended to mean that a metal is incorporated in and / or on the molecular sieve that can improve any performance of the molecular sieve. The metal, also referred to as 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.

[0036] 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 ring size.

[0037] 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) having a spatial network with an open 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.

[0038] For the purposes of the present invention, suitable molecular sieves 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, 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, *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.

[0039] In particular, molecular sieves useful in the antimony capture region include zeolites having a framework type selected from the group 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.

[0040] In some embodiments, molecular sieves useful for the antimony capture 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, with AEI, BEA, and CHA being particularly preferred.

[0041] In some other embodiments, molecular sieves useful for the antimony capture 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-six ring (d6r) secondary structural units in which a cage-like structure is formed resulting from the joining of double-six ring structural units with 4-rings. Exemplary 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.

[0042] In some particular embodiments, small pore zeolites useful for the antimony capture 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.

[0043] It will be 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 reference material but also any framework isotype that has SCR catalytic activity. A list of reference materials and framework isotypes for each framework type code is available from the IZA database (http: / / www.iza-structure.org / databases / ).

[0044] Aluminosilicate zeolites useful as molecular sieves in the antimony capture region, such as those having any of the framework types as described hereinabove, 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 40:1.

[0045] Molecular sieves have a high surface area, e.g., at least 300 m, as determined 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 450-750m 2 The BET surface area can be expressed as 1 / g.

[0046] In some embodiments, the molecular sieve in the antimony capture zone is selected from metal promoted molecular sieves. 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, Al, 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.

[0047] In some exemplary embodiments, the antimony capture region may comprise a Cu- and / or Fe-promoted zeolite having an AEI, BEA, CHA, AFT, AFX, FAU, FER, KFI, MOR, MFI, MOR, or MEL framework type, particularly a Cu- and / or Fe-promoted zeolite having an AEI, BEA, or CHA framework.

[0048] The promoter metal may be present in the metal-promoted molecular sieve in an amount of 0.1-20 wt%, 0.5-15 wt%, 1-10 wt%, or 4-10 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 0.5-15 wt%, or 1-15 wt%, or 1-10 wt%, on an oxide basis, based on the total weight of the metal-promoted molecular sieve.

[0049] The antimony capture zones may each contain one or more metal-promoted molecular sieves, in other words, only one metal-promoted molecular sieve or a combination of two or more metal-promoted molecular sieves may be used in a single antimony capture zone.

[0050] Molecular sieves are available in a range of 2,500 to 6,500 g / ft2 based on their antimony capture area. 3 , preferably 3,000 to 5,500 g / ft 3 It should be understood that the amount of molecular sieve refers to the amount of metal promoted molecular sieve when a metal promoted molecular sieve is used.

[0051] Optionally, the antimony capture region may include one or more functional components, such as a precious metal-based catalyst useful for treating exhaust gases.

[0052] In some embodiments, at least one of the antimony capture regions comprises a precious metal-based catalyst. Thus, such region comprises a first component of an optionally metal-promoted molecular sieve and a second component of a precious metal-based catalyst.

[0053] The precious metal-based catalyst may contain one or more precious metals supported on particles of a support. Suitable precious metals are in particular the platinum group metals, such as Ru, Rh, Pd, In, and Pt, preferably Pt and Pd.

[0054] The support for the precious metal may be any material suitable for receiving and supporting the precious metal, such as a molecular sieve, an oxide of a metal 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, Sm, Eu, Hf, and Bi. In particular, the support for the precious metal may be selected from high surface area alumina, ceria, zirconia, lanthana, baria, yttria, neodymia, praseodymia, titania, europia, samaria, hafnia, and any composite or combination thereof.

[0055] Each of the one or more precious metals may be present in an amount ranging from 0.01 to 20 g / ft2 based on the respective antimony capture area. 3 , preferably 0.5 to 10 g / ft 3 may be present in an amount of

[0056] The first component of the optionally metal-promoted molecular sieve and the second component of the noble metal-based catalyst may be present in the antimony capture zone in any possible form, for example as a mixture thereof or in separate forms. Alternatively, the first and second components may be combined, for example by supporting the noble metal on the optionally metal-promoted molecular sieve.

[0057] In some embodiments, at least one of the antimony capture regions is layered with a layer containing a molecular sieve and a layer containing a precious group metal-based catalyst. The arrangement of these layers is not particularly limited. The layer containing the molecular sieve can be placed on top of the layer containing the precious group metal-based catalyst, and vice versa.

[0058] The antimony capture region may include at least one additional component, such as a processing aid, which may be catalytically active or inactive.

[0059] The one or more antimony-containing regions and the one or more antimony trapping regions may, independently of one another, be present in the catalyst system according to the invention in the form of an extrudate or in the form of a washcoat on a substrate.

[0060] The term "extrudate" generally refers to a shaped body formed by extrusion. The extrudate may have any suitable structure for passing gas flow, preferably a honeycomb structure. The honeycomb structure may have flow channels as described herein below for the monolithic flow-through and wall-flow structures. When any of the 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.

[0061] The term "substrate" generally refers to a structure suitable for withstanding the conditions encountered in the exhaust stream, upon which the catalytic material is supported, typically in the form of a washcoat.

[0062] 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 such that the passages are open to fluid flow therethrough. The passages, which are essentially straight-line paths from their fluid inlets to their fluid outlets, 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. The flow passages of the monolithic substrate are thin-walled channels and may 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, with typical ranges being 2 mils to 0.1 inches.

[0063] 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, with alternating passages being blocked at opposite 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 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, e.g., 100-400 cpsi. The flow passages of the monolithic substrate are thin-walled channels and 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 with a typical range of 2 mils to 0.1 inches.

[0064] The term "washcoat" has its ordinary meaning in the art and refers to a thin, adherent coating of catalytic 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 firing to provide a washcoat layer. Washcoats are generally formed in the form of one or more layers at a concentration of 0.1-10 g / in. 3 , e.g. 0.5~7g / in 3 is loaded onto the substrate in an amount of

[0065] The substrate is usually inert and is conventionally made, for example, from a ceramic or metallic material, and will be referred to herein as an "inert substrate." It is contemplated that the substrate may alternatively be active, in which case the substrate may consist, for example, of extrudates containing molecular sieve catalyst or other catalytically active species.

[0066] In some exemplary embodiments of the catalyst system according to the present invention, the one or more antimony-containing regions and the one or more antimony-trapping regions are present as washcoats on one or more strips of inert substrate, and in particular, at least one of the antimony-containing regions and at least one of the antimony-trapping regions are separately supported on two or more strips of inert substrate.

[0067] In some specific exemplary embodiments, the catalyst system according to the present invention includes one antimony-containing region and one antimony trapping region supported as washcoats on one or two strips of substrate. In the case of one strip of substrate, the washcoat of the antimony-containing region is located upstream of the washcoat of the antimony trapping region. In the case of two strips of substrate, the antimony-containing region is supported as a washcoat on a first, upstream substrate and the antimony trapping region is supported as a washcoat on a second, downstream substrate.

[0068] In some other specific exemplary embodiments, the catalyst system according to the invention includes two antimony-containing regions and one antimony trapping region, which are supported as washcoats on one, two or three strips of substrate. In the case of one strip of substrate, the washcoats of the two antimony-containing regions are located upstream of the washcoat of the antimony trapping region. In the case of two strips of substrate, the washcoats of the two antimony-containing regions may be supported in sequence on a first upstream substrate strip, and the antimony trapping region is supported as a washcoat on a second downstream substrate strip. Alternatively, one antimony-containing region may be supported as a washcoat on a first upstream substrate strip, and the other antimony-containing region and the antimony trapping region are supported as respective washcoats on a second downstream substrate strip, and the antimony trapping region is located downstream of the antimony-containing region on the second downstream substrate strip. In the case of three strips of substrate, one antimony-containing region is carried on the first, upstream substrate strip, the other antimony-containing region is carried on the second, intermediate substrate strip, and the antimony trapping region is carried on the third, downstream substrate strip.

[0069] In some further specific exemplary embodiments, the catalyst system according to the invention comprises one antimony-containing region and two antimony-trapping regions, which are supported as washcoats on one, two or three strips of substrate. In the case of one strip of substrate, the washcoat of one antimony-trapping region is located downstream of both the washcoat of the antimony-containing region and the washcoat of the other antimony-trapping region, and the latter two regions can be arranged in that order or in reverse. In the case of two strips of substrate, it can be contemplated that any two of the three regions can be supported as respective washcoats on one substrate strip, and the remaining region on the other substrate strip, where one antimony-trapping region is located furthest downstream. In the case of three strips of substrate, for example, the antimony-containing region is supported on the first upstream substrate strip, one antimony-trapping region is supported on the second intermediate substrate strip, and the other antimony-trapping region is supported on the third downstream substrate strip.

[0070] Suitable designs for catalyst systems according to the invention containing more regions can be envisaged with reference to the configurations as described above.

[0071] In other exemplary embodiments of the catalyst system according to the present invention, the one or more antimony-containing regions are present as extrudates and the one or more antimony trapping regions are present as washcoats supported on one or more strips of substrate. The extrudates of the antimony-containing regions and the substrate supporting the antimony trapping regions may be arranged in any order in the direction of exhaust gas flow, provided that at least one antimony trapping region is located furthest downstream.

[0072] A catalyst system according to the present invention may include one or more antimony trapping regions and at least one housing for housing the one or more antimony trapping regions, it will be understood that one housing may house only one region or may house two or more regions.

[0073] Preferably, the catalyst system according to the present invention comprises only one housing for containing all the regions, or comprises two or more housings in fluid communication with each other. The housings preferably have a uniform shape, for example a cylindrical form. In the case of two or more housings, the housings preferably have the same shape, in particular a cylindrical form.

[0074] Each of the one or more antimony-containing regions is contained in the catalyst system in a proportion of 10 to 90 volume %, preferably 20 to 80 volume %, and more preferably 30 to 70 volume %, based on the total volume of the antimony-containing region and the antimony capture region.

[0075] Each of the one or more antimony trapping regions is contained in the catalyst system in a proportion of 10 to 90 volume %, preferably 20 to 80 volume %, and more preferably 30 to 70 volume %, based on the total volume of the antimony-containing region and the antimony trapping region.

[0076] Volume percentages referred to with respect to a region refer to the volume of space that the region occupies. It will be 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.

[0077] The catalytic article according to the present invention may include one or more components or regions that may provide additional functions, including but not limited to oxidation and storage functions. It may be contemplated that storage components, such as hydrocarbon adsorbents and NOx adsorbents, may be disposed in the area of ​​the antimony-containing region. The one or more additional components may be present in any form, such as a washcoat or co-extrusion. It may also be contemplated that there may be an intermediate region between the antimony-containing region and the antimony-trapping region that provides additional functions.

[0078] The catalyst system according to the invention may be used, for example, to treat exhaust gases from stationary combustion devices, such as power plants and heating systems in buildings and homes, as well as from mobile combustion devices, such as combustion engines in vehicles, particularly diesel engines. The catalyst system according to the invention may be particularly effective in treating exhaust gases from internal combustion engines, e.g. gasoline or diesel engines, particularly heavy duty diesel engines.

[0079] Thus, in another aspect, the present invention relates to a method for the treatment of an exhaust gas containing nitrogen oxides, comprising contacting the exhaust gas with a catalyst system as described herein in the presence of a reducing agent.

[0080] In some embodiments, the methods are useful for treating exhaust gases generated by internal combustion engines, such as gasoline or diesel engines, particularly heavy duty diesel engines.

[0081] In a further aspect, the present invention relates to a system for the treatment of exhaust gases, particularly those originating from an internal combustion engine, comprising a reductant source, a catalytic system as described herein.

[0082] The system for treating exhaust gas may further include one or more exhaust gas treatment elements. Conventional exhaust gas treatment elements include catalysts other than SCR catalysts, such as, but not limited to, diesel oxidation catalysts (DOC), three-way catalysts (TWC), four-way catalysts (FWC), uncatalyzed or catalyzed soot filters (CSF), ammonia oxidation catalysts (AMOx), NOx traps, NOx absorber catalysts, hydrocarbon trap catalysts, sensors, and mixers.

[0083] In a variant of the system for the treatment of exhaust gases, at least one region of the catalyst system is not closely connected to the other regions, in which case one or more elements of the exhaust gas treatment system, such as a catalyst component other than the SCR catalyst, a reductant source, a filter, a sensor, and / or a mixer, may be located intermediately.

[0084] The exhaust gas treatment system preferably further comprises a diesel oxidation catalyst located downstream of the engine and upstream of the catalyst system 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 catalyst system according to the present invention.

[0085] Embodiment Various embodiments are listed below. It will be understood that the embodiments listed below can be combined with all aspects and other embodiments in accordance with the scope of the present invention.

[0086] Embodiment 1. A catalyst system for purifying exhaust gas, comprising: one or more antimony-containing regions comprising an antimony-containing catalyst, in particular an antimony-containing SCR catalyst; - one or more antimony capture regions, optionally comprising a metal promoted molecular sieve; A catalyst system, wherein at least one of the one or more antimony trapping regions is located downstream of the one or more antimony-containing regions in a flow direction of the exhaust gas.

[0087] Embodiment 2. The catalyst system of embodiment 1, wherein the antimony-containing catalyst contains antimony oxide, vanadium oxide, and optionally at least one oxide of another metal or metalloid, supported on particles of a support.

[0088] Embodiment 3. The catalyst system of embodiment 2, wherein the support in the antimony-containing catalyst is selected from molecular sieves and 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.

[0089] Embodiment 4. The catalyst system of embodiment 2 or 3, wherein the other metal or metalloid is 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, Er, Ba, Sm, and W.

[0090] Embodiment 5. The catalyst system of any one of embodiments 1-4, wherein at least one of the one or more antimony capture regions comprises a precious metal-based catalyst.

[0091] Embodiment 6. The catalyst system of embodiment 5, wherein the noble metal-based catalyst contains one or more noble metals, preferably platinum group metals, more preferably Pt, supported on particles of a support.

[0092] Embodiment 7. The catalyst system according to embodiment 6, wherein the support in the noble metal-based catalyst is selected from the group consisting of molecular sieves and 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, Sm, Eu, Hf, and Bi.

[0093] Embodiment 8. A catalyst system according to any one of embodiments 5 to 7, wherein at least one of the one or more antimony capture regions is layered with a layer comprising a molecular sieve and a layer comprising a precious metal-based catalyst.

[0094] Embodiment 9. Each of the one or more precious metals is 0.01 to 20 g / ft based on each antimony capture area. 3 , preferably 0.5 to 10 g / ft 3 The catalyst system of any one of embodiments 5 to 8, wherein the catalyst system is present in an amount of

[0095] In Embodiment 10, the molecular sieve in one or more antimony capture regions 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, *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.

[0096] Embodiment 11. The catalyst system of any one of embodiments 1 to 10, wherein the molecular sieve is metal promoted, the metal being 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, Al, Ti, Co, Ni, Cu, Zn, Sb, Sn, and Bi, alkaline earth metals such as Ca and Mg, and any combination thereof.

[0097] Embodiment 12. The catalyst system of embodiment 11, wherein the molecular sieve is metal promoted, and the metal is Fe, Cu, or a combination thereof.

[0098] Embodiment 13. A catalyst system according to any one of embodiments 1 to 12, wherein the molecular sieve in the one or more antimony capture zones is selected from aluminosilicate zeolites having a SiO2 / Al2O3 molar ratio (SAR) in the range of 5:1 to 150:1, preferably 5:1 to 50:1, in particular 10:1 to 40:1.

[0099] Embodiment 14. A catalyst system according to any one of embodiments 1 to 13, wherein the one or more antimony capture regions and the one or more antimony-containing regions are present, independently of one another, in the form of an extrudate or in the form of a washcoat on a substrate.

[0100] Embodiment 15. The catalyst system of any one of embodiments 1 to 14, wherein at least one of the one or more antimony capture regions and at least one of the one or more antimony-containing regions are separately supported on two or more strips of an inert substrate.

[0101] Embodiment 16. A catalyst system according to embodiment 14 or 15, wherein the extrudate and / or the substrate has a honeycomb structure, such as a monolithic flow-through structure or a wall-flow structure.

[0102] Embodiment 17. A catalyst system according to any one of embodiments 1 to 16, wherein each of the one or more antimony-containing regions is contained in the catalyst system in a proportion of 10 to 90% by volume, preferably 20 to 80% by volume, and more preferably 30 to 70% by volume, based on the total volume of the antimony-containing region and the antimony capture region.

[0103] Embodiment 18. A catalyst system according to any one of embodiments 1 to 17, wherein each of the one or more antimony trapping regions is contained in the catalyst system in an amount of 10 to 90 volume %, preferably 20 to 80 volume %, and more preferably 30 to 70 volume %, based on the total volume of the antimony-containing region and the antimony trapping region.

[0104] Embodiment 19. A method for the treatment of an exhaust gas containing nitrogen oxides, comprising contacting the exhaust gas with a catalyst system according to any one of embodiments 1 to 18 in the presence of a reducing agent.

[0105] Embodiment 20. The method of embodiment 19, wherein the exhaust gas originates from an internal combustion engine, such as a gasoline or diesel engine.

[0106] Embodiment 21. A system, particularly for the treatment of exhaust gases generated from an internal combustion engine, comprising a reductant source, a catalyst system according to any one of embodiments 1 to 18, 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 absorber catalyst, a hydrocarbon trap catalyst, a sensor, and a mixer.

[0107] The present invention will be further illustrated by the following examples which set forth particularly advantageous embodiments. The examples are provided to illustrate the invention, but they are not intended to limit the invention. EXAMPLES

[0108] Example 1 Example 1.1 Preparation of Strips Containing Antimony-Containing Catalyst on a Substrate 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 another 30% aqueous ammonia solution 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, followed by drying with hot air at 150°C for 15 minutes, and then calcined in air at 450°C for 1 hour.

[0109] 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 achieved. The antimony-containing catalyst has a vanadium content of 4.0 wt.%, calculated as V2O5.

[0110] Example 1.2 Preparation of antimony capture strips containing an upper layer of Cu-promoted CHA zeolite and an underlayer of Pt-based catalyst on a substrate i) Preparation of the lower layer A solution of bis(ethanolammonium)hexahydroxoplatinum(IV) with a Pt content of 17.6 wt% was mixed with deionized water to form a homogenous mixture, which was impregnated into 510 g of Al2O3 powder and stirred for 30 minutes. The resulting slurry was coated onto a 300 cpsi flow-through cordierite monolith substrate with a wall thickness of 5 mils by immersing the substrate in the slurry. The excess slurry loading was carefully blown off with an air knife, followed by drying at 130°C and calcination at 450°C. After cooling to room temperature, the Pt loading was 2 g / ft 3 At 0.5g / in 3 The process of soaking, drying, and baking was repeated until a total washcoat loading on the substrate of 0.01 g was achieved.

[0111] ii) Preparation of the upper layer SiO2 to Al2O3 molar ratio of 31, 600m 2 / g BET surface area, D of 16 μm 90 An H-formed CHA zeolite with 0.07 wt. % Na2O and a tap density of 0.37 g / mL was used.

[0112] 92 parts by weight of CHA zeolite, 3 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 determine a D of 5 μm. 90 The milled slurry was coated onto the coated substrate of step i) above 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. The powder had a particle size of 2.1 g / in 3 The process of soaking, drying, and baking was repeated until a total washcoat loading on the substrate of 0.01 g was achieved.

[0113] Example 2 Example 2.1 Preparation of Strips Containing Antimony-Containing Catalyst on a Substrate The strips were prepared by the same process as described in Example 1.1.

[0114] Example 2.2 Preparation of antimony capture strips containing an upper layer of Cu-promoted CHA zeolite and an underlayer of Pt-based catalyst on a substrate i) Preparation of the lower layer The underlayer of antimony capture strips was prepared by the same process as described in Example 1.

[0115] ii) Preparation of the upper layer SiO2 to Al2O3 molar ratio of 11, 450m 2 / g BET surface area, D of 13 μm 90 An H-formed CHA zeolite with 0.12 wt. % Na2O and a tap density of 0.6 g / mL was used.

[0116] 91 parts by weight of CHA zeolite, 4 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 determine a D of 5 μm. 90 The milled slurry was coated onto the coated substrate obtained in step i) above 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. The powder had a particle size of 2.1 g / in 3 The process of soaking, drying, and baking was repeated until a total washcoat loading on the substrate of 0.01 g was achieved.

[0117] Example 3 Example 3.1 Preparation of Strips Containing Antimony-Containing Catalyst on a Substrate The strips were prepared by the same process as described in Example 1.1.

[0118] Example 3.2 Preparation of strips containing an upper layer of Cu-promoted CHA zeolite and an underlayer of Pt-based catalyst on a substrate i) Preparation of the lower layer The underlayer of antimony capture strips was prepared by the same process as described in Example 1.

[0119] ii) Preparation of the upper layer SiO2 to Al2O3 molar ratio of 11, 450m 2 / g BET surface area, D of 13 μm 90 An H-formed CHA zeolite with 0.12 wt. % Na2O and a tap density of 0.6 g / mL was used.

[0120] 87 parts by weight of CHA zeolite, 8 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 determine a D of 5 μm. 90 The milled slurry was coated onto the coated substrate obtained in step i) above 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. The powder had a particle size of 2.1 g / in 3 The process of soaking, drying, and baking was repeated until a total washcoat loading on the substrate of 0.01 g was achieved.

[0121] Example 4 Example 4.1 Preparation of Strips Containing Antimony-Containing Catalyst on a Substrate The strips were prepared by the same process as described in Example 1.1.

[0122] Example 4.2 Preparation of strips containing an upper layer of Fe-promoted β zeolite and an underlayer of Pt-based catalyst on a substrate i) Preparation of the lower layer The underlayer of antimony capture strips was prepared by the same process as described in Example 1.

[0123] ii) Preparation of the upper layer SiO2 to Al2O3 molar ratio of 40, iron loading of 1.4 wt. % calculated as Fe2O3, 100% X-ray crystallinity, 708 m 2BET surface area in g / m, D 90 A Fe / β zeolite with pore size = 5 microns and Na2O = 0.03 wt % was used.

[0124] 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 was then measured with a Sympatec particle size analyzer to determine a D of 5 μm. 90 The milled slurry was coated onto the coated substrate obtained in step i) above 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. The powder had a particle size of 2.1 g / in 3 The process of soaking, drying, and baking was repeated until a total washcoat loading on the substrate of 0.01 g was achieved.

[0125] Example 5 Example 5.1 Preparation of Strips Containing Antimony-Containing Catalyst on a Substrate The strips were prepared by the same process as described in Example 1.1.

[0126] Example 5.2 Preparation of strips containing an upper layer of Fe-promoted β zeolite and an underlayer of Pt-based catalyst on a substrate i) Preparation of the lower layer The underlayer of antimony capture strips was prepared by the same process as described in Example 1.

[0127] ii) Preparation of the upper layer SiO2 to Al2O3 molar ratio of 40, iron loading of 1.4 wt. % calculated as Fe2O3, 100% X-ray crystallinity, 708 m 2 BET surface area in g / m, D 90 A Fe / β zeolite with pore size = 5 microns and Na2O = 0.03 wt % was used.

[0128] 94 parts by weight of Fe / β zeolite, 1 part 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 5 μm. 90 The milled slurry was coated onto the coated substrate obtained in step i) above 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. The powder had a particle size of 2.1 g / in 3 The process of soaking, drying, and baking was repeated until a total washcoat loading on the substrate of 0.01 g was achieved.

[0129] Example 6 Example 6.1 Preparation of Strips Containing Antimony-Containing Catalyst on a Substrate The strips were prepared by the same process as described in Example 1.1.

[0130] Example 6.2 Preparation of strips containing an upper layer of Fe-promoted β zeolite and an underlayer of Pt-based catalyst on a substrate i) Preparation of the lower layer The underlayer of antimony capture strips was prepared by the same process as described in Example 1.

[0131] ii) Preparation of the upper layer SiO2 to Al2O3 molar ratio of 9, iron loading of 4.8 wt. % calculated as Fe2O3, X-ray crystallinity of 98%, 578 m 2 BET surface area in g / m, D 90 An Fe / β zeolite with .DELTA.=13 μm, 0.07 wt. % Na2O, 0.03 wt. % K2O, 0.01 wt. % CaO, and 0.02 wt. % MgO was used.

[0132] 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 was then measured with a Sympatec particle size analyzer to determine a D of 5 μm. 90The milled slurry was coated onto the coated substrate obtained in step i) above 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. The powder had a particle size of 2.1 g / in 3 The process of soaking, drying, and baking was repeated until a total washcoat loading on the substrate of 0.01 g was achieved.

[0133] Example 7 Example 7.1 Preparation of Strips Containing Antimony-Containing Catalyst on a Substrate The bricks were prepared by the same process as described in Example 1.1.

[0134] Example 7.2 Preparation of strips containing an upper layer of Fe-promoted β zeolite and an underlayer of Pt-based catalyst on a substrate i) Preparation of the lower layer The underlayer of antimony capture strips was prepared by the same process as described in Example 1.

[0135] ii) Preparation of the upper layer SiO2 to Al2O3 molar ratio of 150, X-ray crystallinity of 90%, 568m 2 BET surface area in g / m, D 90 An H-forming beta zeolite with a particle size of 15 μm and a loose bulk density of 0.3 g / L was used.

[0136] 91 parts by weight of beta zeolite, 4 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 5 μm. 90 The milled slurry was coated onto the coated substrate obtained in step i) above 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. The powder had a particle size of 2.1 g / in 3The process of soaking, drying, and baking was repeated until a total washcoat loading on the substrate of 0.01 g was achieved.

[0137] Example 8 Measurement of Sb release Preparation of test samples Samples representing the antimony-containing regions were prepared by cutting cores having a 1 inch diameter and a 2 inch length from each strip containing an antimony-containing catalyst as prepared in the above examples.

[0138] Samples representing the antimony capture area were prepared by cutting cores having a 1 inch diameter and 1 inch length from each antimony capture strip as prepared in the above examples.

[0139] Measurement process In an experimental fixed-bed simulator (quartz glass tube with an inner diameter of 1.2 inches), one sample representing the antimony-containing region and one sample of the antimony-trapping region were consecutively placed from upstream to downstream in the gas flow direction, using ceramic fiber paper as a mat material to wrap around the samples. 8 g of γ-alumina granules (Alfa Aesar, bimodal) were packed after the samples as an adsorbent. After placement, the simulator was purged with N2 gas with 5 vol.% O2 and heated to a temperature as shown in Table 1. Then, a gas consisting of 5 vol.% H2O, 5 vol.% O2, 500 vppm NO, 500 vppm NH3, and the balance N2 was supplied to the simulator at a total flow rate of 7.5 L / min for 18 hours for heat treatment.

[0140] For comparison, tests were also performed in which the sample representing the antimony trapping region was replaced with gamma alumina granules.

[0141] After cooling, the gamma-alumina granules were removed from the reactor and analyzed for antimony content according to the following procedure, which indicates the release of antimony from the preceding sample: i) grinding the gamma alumina granules into a fine powder; ii) dissolving the powder from i) in a mineral acid consisting of 12 parts by volume of 16N HNO3, 4.0 parts by volume of 28N HF, and 0.8 parts by volume of 12N HCl by pressure digestion until a clear solution is observed; iii) Determining the antimony content using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES).

[0142] The test results are summarized in Table 1 below.

[0143] [Table 1]

[0144] Example 9 Catalyst performance test A cylindrical sample from Example 1.1 having a diameter of 1 inch and a length of 2 inches was hydrothermally aged at 550° C. for 200 hours in 10% by volume water / air.

[0145] A cylindrical sample having a diameter of 1 inch and a length of 1 inch from Example 1.2 was hydrothermally aged at 650° C. for 50 hours in 10% by volume water / air.

[0146] In a laboratory fixed bed simulator, the aged sample from Example 1.1 was placed upstream followed by the aged sample from Example 1.2 to measure the SCR catalyst performance. The base feed gas consisted of 5 vol.% H2O, 10 vol.% O2, 1000 ppm NO, and the balance N2. The volumetric space velocity (SV) was fixed at 60,000 / hr based on a 1"x3" cylindrical sample, and the ratio of NH3 to NO (NSR) was fixed at 1.0. The NO conversion at 200°C was 67%.

Claims

1. A catalytic system for purifying exhaust gases, comprising: one or more antimony-containing regions comprising an antimony-containing catalyst, in particular an antimony-containing SCR catalyst; one or more antimony capture regions, optionally comprising metal-promoted molecular sieves; A catalyst system wherein at least one of the one or more antimony trapping regions is located downstream of the one or more antimony-containing regions in the direction of exhaust gas flow.

2. 10. The catalyst system of claim 1, wherein the antimony-containing catalyst comprises antimony oxide, vanadium oxide, and optionally at least one oxide of another metal or metalloid supported on particles of a support.

3. 3. The catalyst system of claim 2, wherein the support in the antimony-containing catalyst is selected from molecular sieves and 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.

4. 4. The catalyst system of claim 2 or 3, wherein the other metal or metalloid is 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, Er, Ba, Sm, and W.

5. 3. The catalyst system of claim 1 or 2, wherein at least one of the one or more antimony capture regions comprises a precious metal-based catalyst.

6. 6. The catalyst system of claim 5, wherein the noble metal-based catalyst comprises one or more noble metals, preferably platinum group metals, more preferably Pt, supported on particles of a support.

7. 7. The catalyst system of claim 6, wherein the support in the noble metal-based catalyst is selected from molecular sieves and 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, Sm, Eu, Hf, and Bi.

8. 6. The catalyst system of claim 5, wherein at least one of the one or more antimony capture regions is layered with a layer comprising the molecular sieve and a layer comprising the noble metal-based catalyst.

9. Each of the one or more precious metals is from 0.01 to 20 g / ft based on each antimony capture area. ３ , preferably 0.5 to 10 g / ft ３ 6. The catalyst system of claim 5, wherein the catalyst system is present in an amount of

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3. The catalyst system according to claim 1 or 2, wherein the zeolite is selected from aluminosilicate zeolites having a framework type of AEI, BEA, CHA, AFT, AFX, FAU, FER, KFI, MOR, MFI, MOR, MEL, or any combination thereof, among which AEI, BEA, CHA, AFT, AFX, FAU, FER, KFI, MOR, MFI, MOR, MEL, or any combination thereof is preferred.

11. 3. The catalyst system of claim 1, wherein the molecular sieve is metal promoted, and the metal is selected from noble 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, Al, Ti, Co, Ni, Cu, Zn, Sb, Sn, and Bi, alkaline earth metals such as Ca and Mg, and any combination thereof.

12. 12. The catalyst system of claim 11, wherein the molecular sieve is metal promoted, and the metal is Fe, Cu, or a combination thereof.

13. The molecular sieve in the one or more antimony capture zones has a SiO:O ratio in the range of 5:1 to 150:1, preferably 5:1 to 50:1, especially 10:1 to 40:

1. ２ / Al ２ O ３ 3. The catalytic system according to claim 1 or 2, wherein the catalyst is selected from aluminosilicate zeolites having a molar ratio (SAR).

14. 3. The catalyst system of claim 1, wherein the one or more antimony capture regions and the one or more antimony-containing regions are present, independently of one another, in the form of an extrudate or a washcoat on a substrate.

15. 3. The catalyst system of claim 1, wherein at least one of the one or more antimony capture regions and at least one of the one or more antimony-containing regions are separately supported on two or more strips of inert substrate.

16. 15. The catalyst system of claim 14, wherein the extrudates and / or the substrate have a honeycomb structure, such as a monolithic flow-through structure or a wall-flow structure.

17. 3. The catalyst system according to claim 1, wherein each of the one or more antimony-containing regions is contained in the catalyst system in a proportion of 10 to 90% by volume, preferably 20 to 80% by volume, and more preferably 30 to 70% by volume, based on the total volume of the antimony-containing region and the antimony capture region.

18. 3. The catalyst system according to claim 1, wherein each of the one or more antimony trapping regions is contained in the catalyst system in a proportion of 10 to 90% by volume, preferably 20 to 80% by volume, more preferably 30 to 70% by volume, based on the total volume of the antimony-containing region and the antimony trapping region.

19. 10. A method for the treatment of exhaust gases containing nitrogen oxides, comprising contacting said exhaust gases with the catalyst system of claim 1 or 2 in the presence of a reducing agent.

20. 20. The method of claim 19, wherein the exhaust gas originates from an internal combustion engine, such as a gasoline or diesel engine.

21. 3. A system, particularly for the treatment of exhaust gases originating from an internal combustion engine, comprising a reductant source, a catalyst system according to claim 1 or 2, 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 absorber catalyst, a hydrocarbon trap catalyst, a sensor and a mixer.