Layered catalyst article

Abstract

The present invention relates to a catalyst article for treating exhaust gases, comprising: - a substrate having an inlet end and an outlet end defining an axial length; - a first coating layer extending in part or over the entire axial length of the substrate, comprising a first catalyst containing a vanadium component; - a second coating layer extending in part or over the entire axial length of the substrate, comprising a second catalyst containing a noble metal component; and - a third coating layer comprising or consisting of an inorganic oxide selected from rare earth metal oxides such as titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; lanthanum oxide and cerium oxide; any combination thereof; or composite oxides thereof, extending in part or over the entire axial length of the substrate, and positioned as an intermediate layer between the first and second coating layers over part or over the entire axial length of the substrate. The present invention also relates to a method and system for treating exhaust gases containing nitrogen oxides with a catalyst article.

Description

[Technical Field]

[0001] The present invention relates to a layered catalyst article for treating exhaust gases containing nitrogen oxides, comprising a layer containing a vanadium-based catalyst and a layer containing a noble metal-based catalyst. The present invention also relates to a method and system for treating exhaust gases containing nitrogen oxides. [Background technology]

[0002] Engine exhaust consists substantially of particulate matter and gaseous pollutants such as unburned hydrocarbons (hydrocarbons, HC), carbon monoxide (CO), and nitrogen oxides (NOx). Engine exhaust must be treated in the engine exhaust system before being released into the air. Controlling NOx emissions is always one of the most important topics, especially regarding the treatment of diesel engine exhaust, due to the adverse environmental impact of NOx on ecosystems, humans, animals, and plants.

[0003] Various treatment processes, such as catalytic reduction of nitrogen oxides, are used to reduce NOx in exhaust gases. One typical catalytic reduction process is selective catalytic reduction, also known as the SCR process, which uses ammonia (NH3) or an ammonia precursor as a reducing agent in the presence of atmospheric oxygen. The SCR process is considered superior because it can achieve 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] In the SCR process, a stoichiometrically excess reducing agent NH3 or its precursor is typically injected into the exhaust flow to reduce NOx at the highest possible conversion rate. Excess ammonia can escape from the vehicle's tailpipe. Another potential scenario for ammonia escaping from the tailpipe is that a significant amount of ammonia retained on the surface of the SCR catalyst during the low-temperature phase of a typical operating cycle desorbs from the SCR catalyst as the operating temperature rises. When the release of ammonia into the air, also known as ammonia slip, occurs, several problems arise. Ammonia slip is harmful to human health and the environment. Ammonia can cause significant eye and throat irritation above 100 ppm and significant skin irritation above 400 ppm, and the IDLH value of ammonia in air is known to be 500 ppm. In addition, ammonia is caustic, especially in its aqueous form. Condensation of ammonia and water in the low-temperature region of the exhaust line downstream of the exhaust treatment catalyst results in a corrosive mixture that damages the exhaust line. Ammonia should be removed before it enters the tailpipe. Ammonia oxidation (AMOx) catalysts (also known as ammonia slip catalysts, ASCs) placed downstream of an SCR catalyst are generally used to convert slipped ammonia into N2.

[0005] Ammonia oxidation (AMOx) catalysts are known, and these contain noble metal active species for oxidizing ammonia, and usually also contain SCR active species. Zeolites are widely used as known SCR active species, but vanadium-based species are rarely used due to the significant poisoning effect of vanadium species on noble metals.

[0006] U.S. Patent Application Publication No. 2014 / 0212350(A1) describes a catalyst article for treating exhaust gases, comprising: (a) a first catalyst layer having a plurality of continuous sublayers, each sublayer containing vanadium oxide on a first refractory metal oxide support; (b) a second catalyst layer disposed on a second refractory metal oxide support containing one or more noble metals; and (c) a substrate on which the first and second catalyst layers are located and / or within the substrate. The catalyst article in the embodiments of this patent application contains vanadium and tungsten oxide in the first catalyst layer.

[0007] U.S. Patent Application Publication No. 2014 / 0178273(A1) describes a treatment apparatus configured to receive exhaust flow from a power source, comprising: a first layer having a selective catalytic reduction layer; a second layer located downstream of the first layer and containing an oxidation catalyst support; a substrate layer located adjacent to the second layer; and an additive located between the first and second layers, wherein the additive acts to substantially prevent the migration of components of the second layer to the first layer when the exhaust flow is treated by the oxidation catalyst support. The SCR catalyst material may contain a zeolite component, or may contain vanadium oxide, tungsten oxide, and / or molybdenum oxide deposited on titanium oxide.

[0008] Japanese Patent Publication No. 2019035340(A) describes an exhaust gas control system comprising an exhaust pipe through which exhaust gas from an internal combustion engine passes, and a composite catalyst device provided in the exhaust pipe, having a composite catalyst in which at least one of an SCR (Selective Catalytic Reduction) catalyst and a PGM (Platinum Group Metal) catalyst is mixed or multilayered with a copper oxide catalyst. The SCR catalyst may contain zeolite or vanadium.

[0009] It is desirable if low-cost vanadium-based SCR active species can be applied to an ammonia oxidation (AMOx) catalyst that has less poisoning effect on noble metals and thus has a desirable ammonia removal efficacy. SUMMARY OF THE INVENTION

[0010] An object of the present invention is to provide an AMOx catalyst article including a vanadium-based SCR catalyst and a noble metal-based catalyst, in which poisoning of noble metal species is reduced, and thus an improved NH3 conversion rate can be provided, particularly in the low-temperature operation stage of an exhaust treatment system.

[0011] Surprisingly, this object is achieved by a layered catalyst article comprising a layer containing a vanadium-based catalyst, a layer containing a noble metal-based catalyst, and in addition a layer of inorganic oxide particles.

[0012] Thus, in a first aspect, the present invention is a catalyst article for treating an exhaust stream, comprising: - a substrate having an inlet end and an outlet end defining an axial length; - a first coating layer extending over a part or the whole of the axial length of the substrate and containing a first catalyst containing a vanadium component; - a second coating layer extending over a part or the whole of the axial length of the substrate and containing a second catalyst containing a noble metal component; - a third coating layer extending over a part or the whole of the axial length of the substrate and containing an inorganic oxide selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or a composite oxide thereof, where the third coating layer is disposed as an intermediate layer between the first coating layer and the second coating layer over a part or the whole of the axial length of the substrate, and relates to a catalyst article.

[0013] In a second aspect, the present invention relates to a system for treating an exhaust stream, comprising a reducing agent source (e.g., NH3 or its precursor), a catalyst article as described in the first aspect of the present invention, and optionally, one or more of a diesel oxidation catalyst (DOC), a selective catalytic reduction catalyst (SCR), a three-way conversion catalyst (TWC), a four-way conversion catalyst (FWC), a non-catalytic or catalyzed soot filter (CSF), a NOx trap, a hydrocarbon trap catalyst, a sensor, and a mixer.

[0014] In a third aspect, the present invention relates to a method for treating an exhaust stream containing nitrogen oxides, comprising passing the exhaust stream through the system as described in the second aspect of the present invention in the presence of NH3 as a reducing agent.

[0015] In a fourth aspect, the present invention relates to a method for reducing the poisoning of a noble metal component in a catalyst article comprising a first coating layer containing a vanadium-based catalyst and a second coating layer containing a noble metal-based catalyst, comprising incorporating at least partially an inorganic oxide layer between the first coating layer and the second coating layer, wherein the inorganic oxide is selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or a composite oxide.

[0016] Surprisingly, it has been found by the inventors that the poisoning of the noble metal component in an AMOx catalyst article containing a vanadium-based catalyst and a noble metal-based catalyst can be effectively suppressed by a layered structure having an intermediate layer of an inorganic oxide selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide, rare earth metal oxides, any combination thereof, or a composite oxide thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] [Figure 1a] A schematic longitudinal cross-sectional view of the layered structure of the catalyst article from the inlet end to the outlet end on the substrate according to Examples 1 to 5 and Comparative Example 6 is shown. [Figure 1b] A schematic longitudinal cross-sectional view of the layered structure of the catalyst article from the inlet end to the outlet end on the substrate according to Comparative Example 7 is shown. [Figure 2a] A schematic longitudinal cross-sectional view illustrating an exemplary layered structure from the inlet end to the outlet end on a substrate, which can also be employed in the catalyst article according to the present invention, is shown. [Figure 2b] A schematic longitudinal cross-sectional view illustrating an exemplary layered structure from the inlet end to the outlet end on a substrate, which can also be employed in the catalyst article according to the present invention, is shown. [Figure 2c] A schematic longitudinal cross-sectional view illustrating an exemplary layered structure from the inlet end to the outlet end on a substrate, which can also be employed in the catalyst article according to the present invention, is shown. [Figure 3a] A schematic longitudinal cross-sectional view illustrating an exemplary layered structure from the inlet end to the outlet end on a substrate, which can also be employed in the catalyst article according to the present invention, is shown. [Figure 3b] A schematic longitudinal cross-sectional view illustrating an exemplary layered structure from the inlet end to the outlet end on a substrate, which can also be employed in the catalyst article according to the present invention, is shown. [Figure 4a] A schematic longitudinal cross-sectional view illustrating an exemplary layered structure from the inlet end to the outlet end on a substrate, which can also be employed in the catalyst article according to the present invention, is shown. [Figure 4b] A schematic longitudinal cross-sectional view illustrating an exemplary layered structure from the inlet end to the outlet end on a substrate, which can also be employed in the catalyst article according to the present invention, is shown. [Figure 5a] A schematic longitudinal cross-sectional view illustrating an exemplary layered structure from the inlet end to the outlet end on a substrate, which can also be employed in the catalyst article according to the present invention, is shown. [Figure 5b] A schematic longitudinal cross-sectional view illustrating an exemplary layered structure from the inlet end to the outlet end on a substrate, which can also be employed in the catalyst article according to the present invention, is shown. [Modes for carrying out the invention]

[0018] The present invention is described in detail below herein. 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 described herein.

[0019] In this specification, the singular forms "a," "an," and "the" refer to multiple objects unless the context clearly indicates otherwise. Terms such as "comprise" and "comprising" are used interchangeably with "contain" and "containing" and should be interpreted in a non-restrictive, open manner; that is, for example, there may be further components or elements. The expressions or cognates of "consists of" or "consists essentially of" may be encompassed by "comprises" or cognates.

[0020] As used herein, the term “region” is intended to refer simply to a portion of a catalyst article that contains the specified material and extends for a specific length in the direction of flow of the exhaust gas.

[0021] In this specification, the term "vanadium-based" in the context of catalysts is intended to refer to catalysts containing vanadium-active species such as vanadium oxide.

[0022] In this specification, the term “noble metal-based” in the context of catalysts is intended to refer to catalysts containing noble metal active species.

[0023] In this specification, any reference to “upstream” and “downstream” will be understood to refer to a position relative to the direction of flow, for example, the direction of flow of an exhaust flow.

[0024] The terms "first" and "second" themselves are not intended to impose any limitations on the arrangement or configuration of the catalyst or coating layer within the catalyst article, within the context of the catalyst or coating layer.

[0025] According to a first aspect, the present invention relates to a catalyst article for processing exhaust gas flow, - A substrate having an inlet end and an outlet end that define the axial length, - A first coating layer extending in part or over the entire axial length of the substrate, comprising a first catalyst containing a vanadium component, - A second coating layer extending in part or over the entire axial length of the substrate, comprising a second catalyst containing a precious metal component, - A third coating layer extending in part or over the axial length of a substrate, comprising an inorganic oxide selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or composite oxides thereof, A third coating layer is positioned as an intermediate layer between the first coating layer and the second coating layer, extending over part or the entire axial length of the substrate. The present invention provides a catalyst article equipped with the following features.

[0026] <First coating layer> The first catalyst in the first coating layer may be a vanadium-based SCR catalyst, which refers to any material that generally contains a vanadium component, typically in the form of an oxide, as the main active species for the selective catalytic reduction of NOx supported on the particles of the support. Materials containing vanadium components useful for the selective catalytic reduction of NOx are known in the art. The vanadium-based SCR catalyst useful for the first coating layer is not particularly limited.

[0027] Vanadium-based SCR catalysts generally contain, or consist of, a vanadium component (e.g., V2O5) as the main active species supported on a support particle, and optionally additional metal or metalloid components as accelerator components. Examples of additional metals or metalloids 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), barium (Ba), samarium (Sm), erbium (Er), and tungsten (W). In particular, vanadium-based SCR catalysts contain vanadium oxide and, optionally, at least one oxide of a metal or metalloid selected from silicon (Si), antimony (Sb), molybdenum (Mo), and tungsten (W). Additional metal or metalloid components may exist in the form of their respective oxides, composite oxides of their vanadium and / or other additional metals or metalloids, or combinations thereof.

[0028] In some embodiments of the present invention, the vanadium-based SCR catalyst contains, or comprises, a vanadium component and at least one metal or metalloid component selected from silicon (Si), antimony (Sb), molybdenum (Mo), and tungsten (W), supported on particles of a support. In particular, the vanadium-based SCR catalyst may contain a vanadium (V) component, an antimony (Sb) component, and optionally further metal or metalloid components, supported on particles of a support.

[0029] It will be understood that the vanadium component and additional metal or metalloid components (if any) in the first catalyst, supported on the particles of the support, may be in the form of any two or more composite oxides of the respective oxides, vanadium, and additional metal or metalloids, or any combination thereof.

[0030] For example, in some embodiments, the first catalyst contains vanadium oxide, antimony oxide, and optionally a vanadium-antimony composite oxide, supported on particles of a support.

[0031] In some specific embodiments, the first catalyst contains or comprises vanadium oxide, antimony oxide, silicon dioxide, and optionally any composite oxide thereof, supported on particles of a carrier.

[0032] Useful materials as supports for the vanadium component in the first catalyst and optionally additional metal or metalloid components include, but are not limited to, molecular sieves and oxides of metals or metalloids 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 forms thereof.

[0033] The first catalyst may contain a vanadium component in an amount of 0.5 to 8% by weight or 1 to 6% by weight, calculated as V2O5 based on the total weight of the first catalyst.

[0034] Additional metal or metalloid components, if present, may be included in the first catalyst in amounts of 0.1–30% by weight, 1–15% by weight, or 2–10% by weight, calculated as their respective oxides based on the total weight of the first catalyst.

[0035] The support may be contained in the first catalyst in an amount of at least 45% by weight, at least 60% by weight, at least 70% by weight, or at least 75% by weight, based on the total weight of the first catalyst. The amount of the support may be up to 95% by weight, or up to 90% by weight, based on the total weight of the first catalyst.

[0036] In some embodiments, the first catalyst may contain an antimony component in an amount of 0.5 to 16% by weight or 2 to 9% by weight, calculated as Sb2O3 based on the total weight of the first catalyst.

[0037] In some embodiments, the first catalyst is (a) Calculated as V2O5, with 0.5-8 wt% vanadium oxide, (b) Calculated as Sb2O3, with 0.5-16 wt% antimony oxide, (c) 1 to 15% by weight of SiO2, (e) Contains or consists of 70-95% by weight of TiO2. Each is based on the total weight of the first catalyst.

[0038] In some further embodiments, the first catalyst is (a) Calculated as V2O5, with 1-6 wt% vanadium oxide, (b) Calculated as Sb2O3, with 2-9 wt% antimony oxide, (c) 2-10% by weight of SiO2, (e) Contains or consists of 75-95% by weight of TiO2. Each is based on the total weight of the first catalyst.

[0039] In each of the cases described herein, the total weight of the first catalyst is 100% by weight.

[0040] The first coating layer may also contain one or more components in addition to the first catalyst, which may be non-catalytically active components, such as processing aids useful for arranging the coating layer on the substrate, such as lubricants and binders. Other components may also be catalytically active, such as active species other than the catalysts described herein.

[0041] The first coating layer may extend to part or the entire axial length of the substrate. The amount of the first catalyst coating layer supported is 0.01 to 20 g / in, based on the substrate or substrate region having or supporting the first coating layer.3 Or 0.5-8g / in 3 It may be in the range of 0.005 to 1.5 g / in, calculated as V2O5 based on the substrate or substrate region comprising or supporting the first coating layer. 3 , 0.01~1.0g / in 3 , or 0.03~0.5g / in 3 It may be present in the amount that provides the vanadium.

[0042] <Second coating layer> The second catalyst in the second coating layer may be a noble metal-based oxidation catalyst containing a noble metal component, preferably a platinum group metal component, generally supported on the particles of the support. The noble metal component may contain one or more selected from ruthenium, rhodium, iridium, palladium, platinum, silver, and gold on the particles of the support. Preferably, the noble metal component contains one or more selected from ruthenium, rhodium, iridium, palladium, and platinum, more preferably palladium and platinum, and most preferably platinum, on the particles of the support.

[0043] The precious metals may exist in any possible valence state, for example, as the respective metals or metal oxides in catalytically active forms, or as, for example, the respective metal compounds, complexes, etc., which will be understood to decompose or otherwise be converted to catalytically active forms during the calcination or use of the catalyst.

[0044] A useful material as a support for the noble metal in the second catalyst may be any material suitable for receiving and supporting the noble metal, such as molecular sieves, or oxides of metals or metalloids 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 noble metal may be selected from high-surface-area alumina, silica, titania, ceria, zirconia, lantana, barrier, yttria, neodymia, praseodymia, titania, europia, samaria, hafnia, and any composites or combinations thereof. Exemplary supports may include silica and alumina composite oxides, silica and titania composite oxides, and the like.

[0045] Optionally, the second catalyst may further contain a zeolite or non-zeolite molecular sieve catalyst component in addition to the noble metal component.

[0046] Molecular sieves refer to skeletal materials based on a broad three-dimensional network structure of oxygen ions containing substantially tetrahedral regions and having a substantially uniform pore distribution. Molecular sieves suitable for the purposes of the present invention may be microporous or mesoporous.

[0047] In particular, the molecular sieve may be a zeolite, which is optionally metal-promoted. In this specification, the term “metal-promoted” in the context of molecular sieves is intended to mean that a metal is incorporated into and / or on the zeolite, which can also improve any properties of the zeolite.

[0048] Preferably, suitable molecular sieves include, but are not limited to, aluminosilicate zeolites having a skeleton 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. More preferably, molecular sieves include zeolites having a skeleton type selected from the group consisting 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.

[0049] Where zeolite is referred to herein with reference to the framework codes generally accepted by the International Zeolite Association (IZA), it will be understood that this is intended to include not only the reference material but also any isomorphic framework material having SCR catalytic activity. A list of reference materials and isomorphic framework materials for each framework code is available from the IZA database (http: / / www.iza-structure.org / databases / ).

[0050] In some embodiments, the second catalyst contains a metal-promoted molecular sieve catalyst component. The promoting metal can be 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. The promoting metal is preferably Fe or Cu, or a combination thereof.

[0051] In some exemplary embodiments, the second catalyst contains, as a molecular sieve catalyst component, a Cu-promoted and / or Fe-promoted zeolite having a skeleton of AEI, BEA, CHA, AFT, AFX, FAU, FER, KFI, MOR, MFI, MOR, or MEL, particularly a Cu-promoted and / or Fe-promoted zeolite having a skeleton of AEI, BEA, or CHA.

[0052] The accelerator metal may be present in the metal-accelerated molecular sieve in an amount of 0.1 to 20% by weight, or 0.5 to 15% by weight, or 1 to 10% by weight, or 2 to 6% by weight, based on the oxide, based on the total weight of the metal-accelerated molecular sieve. In some exemplary embodiments where Cu or Fe is used as the accelerator metal, the accelerator metal is preferably present in an amount of 0.5 to 15% by weight, or 1 to 15% by weight, or 1 to 10% by weight, based on the oxide, based on the total weight of the metal-accelerated molecular sieve.

[0053] The noble metal component and molecular sieve catalyst component described for the second catalyst may exist in any possible form, for example, as a physical mixture thereof or in separate forms.

[0054] The second coating layer may also contain one or more components in addition to the second catalyst, which may be non-catalytically active components, such as processing aids useful for arranging the second coating layer on the substrate, such as lubricants and binders. The components may also be catalytically active, such as active species other than the catalysts described herein.

[0055] The second coating layer may extend over part or the entire axial length of the substrate. The amount of the second catalyst coating layer supported is 0.01 to 20 g / in, based on the substrate or substrate region having or supporting the second coating layer. 3 Or 0.1-5 g / in 3may be within the range of. Additionally or alternatively, based on the substrate or substrate region carrying the second coating layer, the noble metal component may be present in an amount of 0.01 to 20 g / ft 3 , preferably 0.5 to 10 g / ft 3 calculated as each noble metal.

[0056] Based on the loading amounts of these coating layers, the first coating layer and the second coating layer may be provided in a weight ratio in the range of 50:1 to 0.5:1, 30:1 to 1:1, or 20:1 to 5:1.

[0057] <The third coating layer> The inorganic oxide in the third coating layer may be selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or their composite oxides.

[0058] The specific valence states of these inorganic oxides are not particularly limited and may have any stable valence state as in each commercially available product and / or as resulting from any possible reactions during the manufacture of the catalytic article.

[0059] In some embodiments, the inorganic oxide may be selected from titania, silica, ceria, zirconia, lanthana, silicon-titanium composite oxide, tungsten-titanium composite oxide, lanthanum-zirconium composite oxide, or any combination thereof.

[0060] In some further embodiments, the inorganic oxide may be selected from zirconia, ceria, lanthanum-zirconium composite oxide, a combination of titania and silica, a combination of silica and a silicon-titanium composite, or a combination of silica and a tungsten-titanium composite oxide.

[0061] Generally, the inorganic oxide may be present in the third coating layer in the form of particles. The particles of the inorganic oxide have a particle size D in the range of 1 to 100 microns (μm). 90It may have.

[0062] Preferably, the third coating layer does not contain any vanadium-based SCR catalyst components or noble metal-based oxidation catalyst components. In some embodiments, the third coating layer consists of an inorganic oxide described herein in the context of the third coating layer.

[0063] The third coating layer is positioned as an intermediate layer between the first and second coating layers, extending over part or all of the axial length of the substrate. The amount of the third catalyst coating layer supported is 0.01 to 20 g / in, based on the substrate or substrate region having or supporting the third coating layer. 3 Preferably 0.1 to 5 g / in 3 It could be within the range.

[0064] Surprisingly, it was found that applying an inorganic oxide as an intermediate layer in the catalyst article improved the NH3 removal performance of a catalyst article comprising a vanadium-based catalyst layer and a noble metal-based catalyst layer for treating exhaust gases containing nitrogen oxides.

[0065] <Base material> As used herein, the term “substrate” generally refers to a structure suitable for withstanding the conditions encountered in an exhaust flow, on which a catalytic material is supported, typically in the form of a coating, or washcoat. The substrate may have an inlet and outlet end defining its axial length, and a plurality of fine parallel gas flow channels extending along the axial length.

[0066] The substrate is typically inert and conventionally made from, for example, ceramic or metallic materials, and is also known as an "inert substrate." Alternatively, the substrate may be active and may consist of, for example, an extruded material containing catalytically active species.

[0067] The substrate may be a monolithic flow-through structure, which has multiple fine parallel gas flow channels extending from the inlet end to the outlet end of the substrate, and as a result the channels are open to the fluid flow passing through them. The channels are essentially straight paths from their fluid inlet to fluid outlet and are defined by walls to which the catalyst material is applied as a wash coat so that the flow passing through the channels comes into contact with the catalyst material. The flow channels of the monolithic substrate are thin-walled channels, which can be any preferred cross-sectional shape and size such as trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical, or circular. Such structures can accommodate 50 to 900 or more flow channels (or "cells") per square inch of cross-section. For example, the substrate may have 50 to 600 cells / square inch ("cpsi") or 200 to 450 cpsi. The wall thickness of the flow-through substrate can vary, with a typical range being 2 mil to 0.1 inches.

[0068] The substrate may also be a monolithic wall-flow structure having multiple fine parallel gas flow channels extending along the inlet to outlet end of the substrate, with alternating channels being blocked at both ends. The channels are defined by walls to which the catalyst material is applied as a wash coat, so that the flow flowing through the channels comes into contact with the catalyst material. This configuration requires the flow to flow through the porous walls of the wall-flow substrate to reach the outlet end. The wall-flow substrate may have a maximum pressure of 700 cpsi, for example, 100 to 400 cpsi. The flow channels of the monolithic substrate are thin-walled channels and can be any preferred cross-sectional shape and size, such as trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical, or circular. The wall thickness of the wall-flow substrate can vary in a typical range of 2 mil to 0.1 inches.

[0069] The term "wash coat" has its usual meaning in the art and refers to a thin, adhesive coating of a catalytic material or other material applied to a substrate. Wash coats are generally formed by preparing a slurry containing the desired material and processing aids such as a binder having an optional specific solid content (e.g., 15-60% by weight), then applying the slurry to a substrate, drying, and firing to provide a wash coat layer. Wash coats are generally in the form of one or more layers and are typically 0.1-10 g / in 3 For example, 0.5-7 g / in 3 It is supported on the substrate in that quantity.

[0070] <Composition of catalyst articles> In the catalyst article according to the present invention, the first, second, and third coating layers may be provided in any suitable layered configuration known in the art, for example, in a conventional configuration of an AMOx catalyst article comprising a layer of SCR catalyst and a layer of oxidation catalyst, wherein the third coating layer is arranged as an intermediate layer between the first coating layer and the second coating layer over part or all of the axial length of the substrate.

[0071] Preferably, the first coating layer, i.e., the coating layer containing a vanadium component and a first catalyst, is positioned as the uppermost layer. More preferably, the first coating layer extends along the entire axial length of the substrate. The second coating layer may be positioned as the bottom layer and extends along part or all of the axial length of the substrate.

[0072] In some embodiments, both the first and second coating layers extend along the entire axial length of the substrate. Preferably, the first coating layer, i.e., a coating layer containing a first catalyst containing a vanadium component, is positioned as the uppermost layer; the second coating layer, i.e., a coating layer containing a second catalyst containing a noble metal component, is positioned as the lowermost layer; and the third coating layer, i.e., a coating layer containing an inorganic oxide as described herein, is positioned as an intermediate layer between the first and second coating layers, extending over part or all of the axial length of the substrate.

[0073] In some specific embodiments, the catalyst article according to the present invention is - A substrate having an inlet end and an outlet end that define the axial length, - A first coating layer, which is the top layer extending along the entire axial length of the substrate, contains a first catalyst containing a vanadium component. - A second coating layer, which is the bottom layer and extends along the entire axial length of the substrate, contains a second catalyst containing a precious metal component. - A third coating layer extending along the entire axial length of the substrate, comprising: titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; and inorganic oxides selected from any combination thereof or composite oxides thereof, A third coating layer is positioned as an intermediate layer between the first coating layer and the second coating layer, It is equipped with.

[0074] Figure 1a schematically shows a longitudinal cross-sectional view of the above layered structure on the substrate of the catalyst article, from the inlet end to the outlet end.

[0075] In some other specific embodiments, the catalyst article according to the present invention is - A substrate having an inlet end and an outlet end that define the axial length, - A first coating layer, which is the top layer extending along the entire axial length of the substrate, contains a first catalyst containing a vanadium component. - A second coating layer, which is the bottom layer and extends along the entire axial length of the substrate, contains a second catalyst containing a precious metal component. - A third coating layer extending in part along the axial length of the substrate, comprising an inorganic oxide selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or composite oxides thereof, A third coating layer is positioned as an intermediate layer between the first coating layer and the second coating layer, extending over a portion of the axial length of the substrate, preferably from the inlet or outlet end of the substrate toward the opposite end, and extending from the outlet end toward the opposite end of the substrate. It is equipped with.

[0076] Figures 2a and 2b schematically show exemplary longitudinal cross-sectional views of the above layered structure on the substrate of the catalyst article, from the inlet end to the outlet end.

[0077] Furthermore, the catalyst article according to the present invention is - A substrate having an inlet end and an outlet end that define the axial length, - A first coating layer, which is the top layer extending along the entire axial length of the substrate, contains a first catalyst containing a vanadium component. - A second coating layer, which is the bottom layer and extends along the entire axial length of the substrate, contains a second catalyst containing a precious metal component. - A third coating layer extending in part along the axial length of the substrate, comprising an inorganic oxide selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or composite oxides thereof, A third coating layer is positioned as an intermediate layer between the first coating layer and the second coating layer, extending over a portion of the axial length of the substrate at a distance from both the inlet and outlet ends, It may also be intended that it be equipped with such features.

[0078] Figure 2c schematically shows an exemplary longitudinal cross-sectional view of the above layered structure on the substrate of the catalyst article, from the inlet end to the outlet end.

[0079] In some other embodiments, the first coating layer extends along the entire axial length of the substrate, and the second and third coating layers extend along portions of the axial length of the substrate. Preferably, the first coating layer, i.e., a coating layer containing a first catalyst containing a vanadium component, is positioned as the uppermost layer extending along the entire axial length of the substrate; the second coating layer, i.e., a coating layer containing a second catalyst containing a noble metal component, is positioned as the bottom layer extending along a portion of the length of the substrate from the inlet or outlet end; and the third coating layer, i.e., a coating layer containing an inorganic oxide as described herein, is positioned as an intermediate layer extending along a length equal to or less than the length of the second coating layer within the region where the second coating layer is positioned.

[0080] In some specific embodiments, the catalyst article according to the present invention is - A substrate having an inlet end and an outlet end that define the axial length, - A first coating layer, which is the top layer extending along the entire axial length of the substrate, contains a first catalyst containing a vanadium component. - A second coating layer, which is the bottom layer and extends in part along the axial length of the substrate, contains a second catalyst containing a precious metal component. - A third coating layer extending in part along the axial length of the substrate, comprising an inorganic oxide selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or composite oxides thereof, The invention comprises a third coating layer, which is positioned as an intermediate layer between a first coating layer and a second coating layer, wherein both the second and third coating layers extend over the same portion of the axial length of the substrate, from the inlet or outlet end of the substrate toward the opposite end, preferably from the outlet end of the substrate toward the opposite end.

[0081] Figures 3a and 3b schematically show exemplary longitudinal cross-sectional views of the above-mentioned layered structure on the substrate of the catalyst article, from the inlet end to the outlet end.

[0082] In some other specific embodiments, the catalyst article according to the present invention is - A substrate having an inlet end and an outlet end that define the axial length, - A first coating layer, which is the top layer extending along the entire axial length of the substrate, contains a first catalyst containing a vanadium component. - A second coating layer, which is the bottom layer and extends in part along the axial length of the substrate, contains a second catalyst containing a precious metal component. - A third coating layer extending in part along the axial length of the substrate, comprising an inorganic oxide selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or composite oxides thereof, The coating comprises a third coating layer, which is positioned as an intermediate layer between a first coating layer and a second coating layer, wherein both the second and third coating layers extend from an inlet or outlet end of the substrate toward the opposite end, preferably from the outlet end of the substrate toward the opposite end, and the third coating layer extends over an axial length shorter than the axial length of the second coating layer.

[0083] Figures 4a and 4b schematically show exemplary longitudinal cross-sectional views of the above layered structure on the substrate of the catalyst article, from the inlet end to the outlet end.

[0084] Furthermore, the catalyst article according to the present invention is - A substrate having an inlet end and an outlet end that define the axial length, - A first coating layer, which is the top layer extending along the entire axial length of the substrate, contains a first catalyst containing a vanadium component. - A second coating layer, which is the bottom layer and extends in part along the axial length of the substrate, contains a second catalyst containing a precious metal component. - A third coating layer extending in part along the axial length of the substrate, comprising an inorganic oxide selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or composite oxides thereof, The coating may also include a third coating layer, which is positioned as an intermediate layer between the first coating layer and the second coating layer, wherein the second coating layer extends from the inlet or outlet end of the substrate toward the opposite end, preferably from the outlet end of the substrate toward the opposite end, and the third coating layer is positioned at a distance from both the inlet and outlet ends of the substrate and extends within the region in which the second coating layer is positioned over an axial length shorter than the axial length of the second coating layer.

[0085] Figures 5a and 5b schematically show exemplary longitudinal cross-sectional views of the above layered structure on the substrate of the catalyst article, from the inlet end to the outlet end.

[0086] The catalytic articles according to the present invention can be used to process exhaust flows from automobile internal combustion engines, particularly diesel engines. The catalytic articles according to the present invention may be particularly effective in processing exhaust flows from large diesel engines, including on-road and off-road large diesel engines.

[0087] Accordingly, in a second aspect, the present invention relates in particular to a system for processing exhaust flows from large diesel engines, including large on-road and off-road diesel engines, comprising a reducing agent source (e.g., NH3 or a precursor thereof) and a catalytic article as described in the first aspect above.

[0088] A system for treating exhaust gases may further comprise one or more conventional exhaust gas treatment elements. Conventional exhaust gas treatment elements include, but are not limited to, diesel oxidation catalysts (DOCs), selective catalytic reduction catalysts (SCRs), ternary catalytic converters (TWCs), quaternary catalytic converters (FWCs), catalytic converters (CSFs) or catalytic soot filters (CSFs), NOx traps, hydrocarbon trap catalysts, sensors, and mixers.

[0089] In some embodiments, the system for treating the exhaust flow further includes a diesel oxidation catalyst (DOC) and a selective catalytic reduction (SCR) catalyst located downstream of the engine and upstream of the catalytic articles as described in the first embodiment above. Preferably, the system for treating the exhaust flow further includes a diesel oxidation catalyst (DOC), a selective catalytic reduction (SCR) catalyst, and a catalytic soot filter (CSF) located upstream of the catalytic articles as described in the first embodiment above.

[0090] In a third aspect, the present invention relates to a method for treating an exhaust flow containing nitrogen oxides, comprising passing the exhaust flow through the system described in the second aspect in the presence of NH3 as a reducing agent.

[0091] In some embodiments, this method is useful for processing exhaust flows from diesel engines, particularly large diesel engines, such as on-road and off-road large diesel engines.

[0092] In a fourth aspect, the present invention relates to a method for reducing poisoning of a noble metal component in a catalyst article comprising a first coating layer containing a vanadium-based catalyst and a second coating layer containing a noble metal-based catalyst, the method comprising incorporating at least partially an inorganic oxide layer between the first coating layer and the second coating layer, wherein the inorganic oxide is selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or composite oxides.

[0093] 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. 1. A catalytic article for treating exhaust flow, - A substrate having an inlet end and an outlet end that define the axial length, - A first coating layer extending in part or over the entire axial length of the substrate, comprising a first catalyst containing a vanadium component, - A second coating layer extending in part or over the entire axial length of the substrate, comprising a second catalyst containing a precious metal component, - A third coating layer comprising or consisting of inorganic oxides selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or composite oxides thereof, extending in part or over the entire axial length of the substrate, A third coating layer is positioned as an intermediate layer between the first coating layer and the second coating layer, extending over part or the entire axial length of the substrate. A catalyst article comprising: 2. The catalyst article according to Embodiment 1, wherein the substrate is a flow-through substrate or a wall-flow substrate. 3. The catalyst article according to Embodiment 2, wherein the substrate is a flow-through substrate. 4. The catalyst article according to any one of embodiments 1 to 3, wherein both the first coating layer and the second coating layer extend along the entire axial length of the substrate. 5. A catalyst article according to any one of embodiments 1 to 4, wherein the first coating layer is the uppermost layer extending along the entire axial length of the substrate, and the second coating layer is the bottom layer. 6. The catalyst article according to Embodiment 5, wherein the second layer and the third coating layer extend along the entire axial length of the substrate. 7. The catalyst article according to Embodiment 5, wherein the third coating layer extends over a portion of the axial length of the substrate. 8. The catalyst article according to Embodiment 7, wherein the second coating layer extends along the entire axial length of the substrate, and the third coating layer extends along a portion of the axial length of the substrate from the exit end to the opposite end. 9. The catalyst article according to Embodiment 7, wherein both the second layer and the third coating layer extend over the same portion of the axial length of the substrate from the exit end of the substrate toward the opposite end. 10. A catalyst article according to any one of Embodiments 1 to 9, wherein the first catalyst contains a vanadium component in an amount of 0.5 to 8% by weight, calculated as V2O5 based on the total weight of the first catalyst. 11. The catalyst article according to Embodiment 10, wherein the first catalyst contains a vanadium component in an amount of 1 to 6% by weight, calculated as V2O5 based on the total weight of the first catalyst. 12. A catalyst article according to any one of Embodiments 1 to 11, wherein the first catalyst contains an antimony component. 13. The catalyst article according to Embodiment 12, wherein the first catalyst contains an antimony component in an amount of 0.5 to 16% by weight, calculated as Sb2O3 based on the total weight of the first catalyst. 14. The catalyst article according to Embodiment 13, wherein the first catalyst contains an antimony component in an amount of 2 to 9% by weight, calculated as Sb2O3 based on the total weight of the first catalyst. 15. A catalyst article according to any one of Embodiments 1 to 14, wherein the first catalyst contains vanadium oxide, antimony oxide, and optionally a composite oxide of vanadium and antimony, supported on particles of a carrier. 16. The catalyst article according to Embodiment 15, wherein the support comprises a molecular sieve and one or more oxides of metals or metalloids 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. 17. A catalyst article according to any one of Embodiments 1 to 16, wherein the precious metal component contains one or more selected from ruthenium, rhodium, iridium, palladium, and platinum, more preferably palladium and platinum, most preferably platinum, supported on particles of a carrier. 18. The catalyst article according to Embodiment 17, wherein the support in the noble metal component is one or more of the following: molecular sieves and oxides of metals or metalloids 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. 19. The catalyst article according to any one of Embodiments 1 to 18, wherein the second catalyst contains a zeolite or non-zeolite molecular sieve catalyst component in addition to the noble metal component. 20. A catalyst article according to any one of Embodiments 1 to 19, wherein the third coating layer contains or consists of an inorganic oxide selected from titania, silica, ceria, zirconia, lantana, silicon-titanium composite oxide, tungsten-titanium composite oxide, lanthanum-zirconium composite oxide, or any combination thereof. 21. The third coating layer is 0.01-20 g / in 3 Preferably 0.1 to 5 g / in 3 A catalyst article according to any one of embodiments 1 to 20, present in an amount of . 22. The first coating layer is 0.01-20 g / in 3 Preferably 0.5-8 g / in 3 A catalyst article according to any one of embodiments 1 to 21, present in an amount of . 23. The second coating layer is 0.01-20 g / in 3 Preferably 0.1 to 5 g / in 3 A catalyst article according to any one of embodiments 1 to 22, present in an amount of [amount]. 24. The amount of precious metals, when calculated as each precious metal, ranges from 0.01 to 20 g / ft. 3 Preferably 0.5-10 g / ft 3 A catalyst article according to any one of embodiments 1 to 23, present in an amount of [amount]. 25. A system for treating exhaust gas flow, comprising: a reducing agent source (e.g., NH3 or its precursor); a catalytic article described in any of Embodiments 1 to 20; and optionally one or more of the following: a diesel oxidation catalyst (DOC), a selective catalytic reduction catalyst (SCR), a ternary catalytic converter (TWC), a quaternary catalytic converter (FWC), a catalyst-free or catalytic soot filter (CSF), a NOx trap, a hydrocarbon trap catalyst, a sensor, and a mixer. 26. The system according to Embodiment 25, wherein the exhaust flow originates from an internal combustion engine, particularly a diesel engine. 27. A method for treating an exhaust stream containing nitrogen oxides, comprising passing the exhaust stream through the system described in Embodiment 25 or 26 in the presence of NH3 as a reducing agent. 28. A method for reducing poisoning of a noble metal component in a catalyst article, comprising a first coating layer containing a vanadium-based catalyst and a second coating layer containing a noble metal-based catalyst, the method comprising incorporating a layer of inorganic oxide at least partially between the first coating layer and the second coating layer, wherein the inorganic oxide is selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or composite oxides.

[0094] The present invention is further illustrated by the following embodiments, which describe particularly advantageous embodiments. The embodiments are provided to illustrate the present invention, but are not intended to limit it. [Examples]

[0095] Example 1 Step 1.1 Apply the bottom wash coat layer containing the Pt-based catalyst onto the substrate. A Cu-CHA slurry was prepared by mixing 218.7 g of Zeolyst Cu-CHA zeolite and 6.2 g of Al2O3 powder in 300 g of deionized (DI) water. The Cu-CHA zeolite had a molar ratio of 28 SiO2 to Al2O3, a weight content of 3.2% CuO, an X-ray crystallinity of 98%, and 750 m 2 BET surface area per gram, and D5 microns 90 It has.

[0096] A Pt slurry was prepared by mixing 69 g of colloidal Pt solution containing 2% by weight with 100 g of DI water to form a homogeneous mixture. This slurry was then impregnated with 207 g of 8% SiO2-doped TiO2 powder, stirred for 30 minutes, and the pH was adjusted to 4 with tartaric acid. The particle size was then measured using a Sympatec particle size analyzer. 90 It was ground down to a size of 5 microns.

[0097] Cu-CHA slurry and Pt slurry were mixed, the pH was adjusted to 5 with tartaric acid, and then stirred for 20 minutes to obtain a homogeneous slurry. The obtained slurry was coated onto a 300 cpsi flow-through cordierite monolith substrate with a wall thickness of 5 mil by immersing the substrate in the slurry. Excess slurry was carefully blown off with an air knife, followed by drying at 130°C and calcination at 550°C. After cooling to room temperature, 0.5 g / in was applied to the substrate. 3 The immersion, drying, and firing processes are repeated until a total wash coat load of 0.25 g / in is obtained, resulting in a Cu-CHA load of 0.25 g / in. 3 The Pt load is 3g / ft 3 That was the case.

[0098] Step 1.2 Apply an intermediate wash coat layer containing TiO2 particles. 150 g of anatase-type TiO2 with a titanium content of 95.9 wt% (calculated as TiO2) was added to 200 g of DI water at room temperature. The resulting suspension was stirred for 30 minutes, and then the pH was adjusted to 7.0 using a 25% aqueous ammonia solution. Next, 15 g of SiO2 sol with a SiO2 content of 40 wt% was added. After stirring for 1 hour, the particle size D 90 A homogeneous slurry with a diameter of less than 15 microns was obtained, into which the substrate having the bottom wash coat obtained from step 1.1 was immersed to load a sufficient amount of 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 baking in air at 450°C for 1 hour. 1.0 g / in on the substrate. 3 The immersion, drying, and firing processes were repeated until the total load of the intermediate wash coat layer was obtained.

[0099] Step 1.3 Apply the top wash coat layer containing the V-type catalyst. 132.8g of anatase-form TiO2 having a titanium content of 95.9 wt% calculated as TiO2, 57.1g of vanadyl oxalate solution having a vanadium content of 10.8 wt% calculated as V2O5, and 9.0g of Sb2O3 were mixed in 200g of DI water at room temperature. The resulting suspension was stirred for 30 minutes, and then 25% aqueous ammonia was added to raise the pH of the system to 7.0. Next, 25.5g of SiO2 sol having a SiO2 content of 30.1 wt% was added. After stirring for 1 hour, a homogeneous slurry for the V-system catalyst was obtained, into which a substrate having a two-layer washcoat obtained from step 1.2 was immersed to support a sufficient amount of 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. The V-type catalyst has a vanadium content of 4.0% by weight, calculated as V2O5 based on the total weight of the V-type catalyst.

[0100] 3.0g / in 3The process of immersion, drying, and firing was repeated until the total load of the top wash coat layer was obtained, thereby providing a catalyst article having the three-layer wash coat structure shown in Figure 1a.

[0101] Example 2 Step 2.1 Apply the bottom wash coat layer containing the Pt-based catalyst onto the substrate. The procedure described in step 1.1 above was repeated to provide a substrate having a bottom wash coat layer.

[0102] Step 2.2 Apply an intermediate wash coat layer containing SiO2-doped TiO2 particles. 150 g of anatase-type 5 wt% SiO2-doped TiO2, with a solid content of 95 wt% calculated as SiO2 / TiO2, was added to 200 g of DI water at room temperature. After stirring the resulting suspension for 30 minutes, the pH was adjusted to 7.0 using a 25% aqueous ammonia solution. Then, 15 g of SiO2 sol with a 40 wt% SiO2 content was added. After stirring for 1 hour, the D particles less than 15 microns were removed. 90 A homogeneous slurry with a particle size of was obtained, and the substrate having the bottom wash coat obtained from step 2.1 was immersed in it to load a sufficient amount of 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 calcining in air at 450°C for 1 hour. 1.0 g / in 3 The immersion, drying, and firing processes were repeated until the total load of the intermediate wash coat was obtained.

[0103] Step 2.3 Apply the top wash coat layer containing the V-type catalyst. The procedure described in step 1.3 above was repeated on the coated substrate obtained in step 2.2 to provide a catalyst article having a three-layer wash-coat structure as shown in Figure 1a.

[0104] Example 3 Step 3.1 Apply the bottom wash coat layer containing the Pt-based catalyst onto the substrate. The procedure described in step 1.1 above was repeated to provide a substrate having a bottom wash coat layer.

[0105] Step 3.2 Apply an intermediate wash coat layer containing WO3-doped TiO2 particles. 150 g of anatase-type 10 wt% WO3-doped TiO2, with a solid content of 96 wt% calculated as WO3 / TiO2, was added to 200 g of DI water at room temperature. The resulting suspension was stirred for 30 minutes, and then the pH was adjusted to 7.0 using a 25% aqueous ammonia solution. Next, 15 g of SiO2 sol with a 40 wt% SiO2 content was added. After stirring for 1 hour, the particle size D 90 A homogeneous slurry with a diameter of less than 15 microns was obtained, into which the substrate having the bottom wash coat obtained from step 3.1 was immersed to load a sufficient amount of 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 baking in air at 450°C for 1 hour. 1.0 g / in 3 The immersion, drying, and firing processes were repeated until the total load of the intermediate wash coat was obtained.

[0106] Step 3.3 Apply the top wash coat layer containing the V-type catalyst. The procedure described in step 1.3 above was repeated on the coated substrate obtained in step 3.2 to provide a catalyst article having a three-layer wash-coat structure as shown in Figure 1a.

[0107] Example 4 Step 4.1 Apply the bottom wash coat layer containing the Pt-based catalyst onto the substrate. The procedure described in step 1.1 above was repeated to provide a substrate having a bottom wash coat layer.

[0108] Step 4.2 Apply an intermediate wash coat layer containing CeO2 particles. 300 g of CeO2, with a solid content of 98% by weight calculated as CeO2, was added to 550 g of DI water at room temperature. After stirring the resulting suspension for 30 minutes, the particle size D 90A homogeneous slurry with a diameter of less than 15 microns was obtained, into which the substrate having the bottom wash coat obtained from step 4.1 was immersed to load a sufficient amount of 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 baking in air at 450°C for 1 hour. 1.0 g / in 3 The immersion, drying, and firing processes were repeated until the total load of the intermediate wash coat was obtained.

[0109] Step 4.3 Apply the top wash coat layer containing the V-type catalyst. The procedure described in step 1.3 above was repeated on the coated substrate obtained in step 4.2 to provide a catalyst article having a three-layer wash-coat structure as shown in Figure 1a.

[0110] Example 5 Step 5.1 Apply the bottom wash coat layer containing the Pt-based catalyst onto the substrate. The procedure described in step 1.1 above was repeated to provide a substrate having a bottom wash coat layer.

[0111] Step 5.2 Apply an intermediate wash coat layer containing ZrO2 particles. 300 g of ZrO2, with a calculated solid content of 97% by weight as ZrO2, was added to 550 g of DI water at room temperature. The resulting suspension was stirred for 30 minutes, then ground, and the particle size was determined by D 90 A homogeneous slurry with a diameter of less than 15 microns was obtained, into which the substrate having the bottom wash coat obtained from step 5.1 was immersed to load a sufficient amount of 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 baking in air at 450°C for 1 hour. 1.0 g / in 3 The immersion, drying, and firing processes were repeated until the total load of the intermediate wash coat was obtained.

[0112] Step 5.3 Apply the top wash coat layer containing the V-type catalyst. The procedure described in step 1.3 above was repeated on the coated substrate obtained in step 5.2 to provide a catalyst article having a three-layer wash-coat structure as shown in Figure 1a.

[0113] Example 6 (Comparison) Step 6.1 Apply the bottom wash coat layer containing the Pt-based catalyst onto the substrate. The procedure described in step 1.1 above was repeated to provide a substrate having a bottom wash coat layer.

[0114] Step 6.2 Apply an intermediate wash coat layer containing Al2O3 particles. 300 g of Al2O3, with a solid content of 97% by weight calculated as Al2O3, was added to 550 g of DI water at room temperature. After stirring the resulting suspension for 30 minutes, the particle size D 90 A homogeneous slurry with a diameter of less than 15 microns was obtained, into which the substrate having the bottom wash coat obtained from step 6.1 was immersed to load a sufficient amount of 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 baking in air at 450°C for 1 hour. 1.0 g / in 3 The immersion, drying, and firing processes were repeated until the total load of the intermediate wash coat was obtained.

[0115] Step 6.3 Apply the top wash coat layer containing the V-type catalyst. The procedure in step 1.3 described above was repeated on the coated substrate obtained in step 6.2 to provide a catalyst article having a three-layer wash-coat structure as shown in Figure 1a.

[0116] Example 7 (Comparison) Step 7.1 Apply the bottom wash coat layer containing the Pt-based catalyst onto the substrate. The procedure described in step 1.1 above was repeated to provide a substrate having a bottom wash coat layer.

[0117] Step 7.2 Apply the top wash coat layer containing the V-system catalyst. The procedure described in step 1.3 above was repeated on a substrate having the bottom wash coat obtained from step 7.1 to provide a catalyst article having a two-layer wash coat structure as shown in Figure 1b.

[0118] Performance testing The catalyst articles prepared in each example were subjected to hydrothermal treatment at 550°C for 100 hours in 10 volume% water / air to obtain aged catalyst articles. Cores with a diameter of 1 inch and a length of 3 inches were cut from the aged catalyst articles as test samples and placed in a fixed laboratory simulator for testing.

[0119] The supply gas contains, by volume, 500 ppm NH3, 7% H2O, 10% O2, 8% CO2, with the remainder being N2. The test was conducted over 100,000 hours. -1 The experiment was conducted at the gas space velocity and the temperatures shown in Table 1.

[0120] The results of the NH3 conversion and the test temperatures are shown in Table 1.

[0121]

number

[0122] [Table 1] * MC: Intermediate wash coat layer

[0123] As can be seen, the aged catalyst article having the intermediate layer according to the present invention had higher NH3 conversion performance than the comparative samples, i.e., the catalyst articles of Examples 6 and 7. Although not bound by any theory, the lower NH3 conversion rate of the catalyst articles of Examples 6 and 7 is thought to be due to more severe platinum poisoning by vanadium during aging.

[0124] While the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the methods and apparatus of the present invention without departing from the spirit and scope of the invention. Accordingly, the present invention is intended to include modifications and variations that fall within the scope of the appended claims and their equivalents.

Claims

1. A catalytic article for processing exhaust flow, - A substrate having an inlet end and an outlet end that define the axial length, - A first coating layer extending in part or over the entire axial length of the substrate, comprising a first catalyst containing a vanadium component, - A second coating layer extending in part or over the entire axial length of the substrate, comprising a second catalyst containing a precious metal component, - A third coating layer comprising or consisting of inorganic oxides selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or composite oxides thereof, extending in part or over the entire axial length of the substrate, A third coating layer is provided, which is arranged as an intermediate layer between the first coating layer and the second coating layer, over part or the entire axial length of the substrate, A catalyst article comprising the following features.

2. The catalyst article according to claim 1, wherein the substrate is a flow-through substrate or a wall-flow filter substrate, preferably a flow-through substrate.

3. The catalyst article according to claim 1 or 2, wherein both the first coating layer and the second coating layer extend along the entire axial length of the substrate.

4. The catalyst article according to any one of claims 1 to 3, wherein the first coating layer is the uppermost layer extending over the entire axial length of the substrate, and the second coating layer is the lowest layer.

5. The catalyst article according to claim 4, wherein the second layer and the third coating layer extend along the entire axial length of the substrate.

6. The catalyst article according to claim 4, wherein the third coating layer extends over a portion of the axial length of the substrate.

7. The catalyst article according to claim 6, wherein the second coating layer extends over the entire axial length of the substrate, and the third coating layer extends over a portion of the axial length of the substrate from the exit end to the opposite end of the substrate.

8. The catalyst article according to claim 6, wherein both the second layer and the third coating layer extend over the same portion of the axial length of the substrate from the exit end to the opposite end of the substrate.

9. The catalyst in the preceding first step, based on the total weight of the catalyst in the preceding first step, V ２ O ５ The catalyst article according to any one of claims 1 to 8, wherein the vanadium component is contained in an amount of 0.5 to 8% by weight or 1 to 6% by weight, calculated as such.

10. The first catalyst, based on the total weight of the first catalyst, Sb ２ O ３ The catalyst article according to any one of claims 1 to 9, wherein, calculated as such, it preferably contains an antimony component in an amount of 0.5 to 16% by weight or 2 to 9% by weight.

11. The catalyst article according to any one of claims 1 to 10, wherein the first catalyst contains vanadium oxide, antimony oxide, and optionally a composite oxide of vanadium and antimony, supported on particles of a carrier.

12. The catalyst article according to claim 11, wherein the carrier comprises a molecular sieve and one or more oxides of metals or metalloids 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.

13. The catalyst article according to any one of claims 1 to 12, wherein the noble metal component contains one or more selected from ruthenium, rhodium, iridium, palladium, and platinum, more preferably palladium and platinum, most preferably platinum, supported on particles of a carrier.

14. The catalyst article according to claim 13, wherein the carrier in the noble metal component is one or more of the following: molecular sieves and oxides of metals or metalloids 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.

15. The catalyst article according to any one of claims 1 to 14, wherein the second catalyst contains a zeolite or non-zeolite molecular sieve catalyst component in addition to the noble metal component.

16. The catalyst article according to any one of claims 1 to 15, wherein the third coating layer contains or consists of an inorganic oxide selected from titania, silica, ceria, zirconia, lantana, silicon-titanium composite oxide, tungsten-titanium composite oxide, lanthanum-zirconium composite oxide, or any combination thereof.

17. The third coating layer is 0.01 to 20 g / in ３ Preferably 0.1 to 5 g / in ３ A catalyst article according to any one of claims 1 to 16, present in an amount.

18. The first coating layer is 0.01 to 20 g / in ３ Preferably 0.5 to 8 g / in ３ A catalyst article according to any one of claims 1 to 17, present in an amount.

19. The second coating layer is present in an amount of 0.01 to 20 g / in ３ , preferably 0.1 to 5 g / in ３ and the catalyst article according to any one of claims 1 to 18.

20. The aforementioned precious metal components, when calculated as each precious metal, range from 0.01 to 20 g / ft. ３ Preferably 0.5 to 10 g / ft ３ A catalyst article according to any one of claims 1 to 19, present in an amount of .

21. A system for treating exhaust gas flow, comprising a reducing agent source (e.g., NH ３ A system comprising (or a precursor thereof), a catalyst article according to any one of claims 1 to 20, and optionally one or more of the following: a diesel oxidation catalyst (DOC), a selective catalytic reduction catalyst (SCR), a ternary converter (TWC), a quaternary converter (FWC), a catalyst-free or catalytic soot filter (CSF), a NOx trap, a hydrocarbon trap catalyst, a sensor, and a mixer.

22. The system according to claim 21, wherein the exhaust flow originates from an internal combustion engine, particularly a diesel engine.

23. A method for treating exhaust gases containing nitrogen oxides, wherein NH is used as a reducing agent. ３ A method comprising passing the exhaust flow through the system according to claim 21 or 22 in the presence of [the specified element].

24. A method for reducing poisoning of a noble metal component in a catalyst article, comprising a first coating layer containing a vanadium-based catalyst and a second coating layer containing a noble metal-based catalyst, the method comprising incorporating at least partially an inorganic oxide layer between the first coating layer and the second coating layer, wherein the inorganic oxide is selected from titanium oxide, silicon oxide, zirconium oxide, tungsten oxide; rare earth metal oxides such as lanthanum oxide and cerium oxide; any combination thereof, or composite oxides.

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