SCR catalyst composition and SCR catalyst article containing the catalyst composition

Abstract

The present invention discloses a catalyst composition for the selective catalytic reduction of nitrogen oxides, comprising at least one oxide of vanadium in an amount of 2.0 to 4.0 wt. % based on the total weight of the catalyst composition, calculated as V2O5, at least one oxide of tungsten in an amount of 2.5 to 7.2 wt. % based on the total weight of the catalyst composition, calculated as WO3, at least one oxide of antimony in an amount of 0.6 to 3.4 wt. % based on the total weight of the catalyst composition, calculated as Sb2O5, at least one oxide of zirconium in an amount of 0 to 1.0 wt. % based on the total weight of the catalyst, calculated as ZrO2, and at least one oxide of titanium in an amount of 84.6 to 94.9 wt. % based on the total weight of the catalyst, wherein the weight percentages of the vanadium, tungsten, antimony, titanium, and optionally zirconium oxides, calculated as V2O5, WO3, Sb2O5, TiO2, and optionally ZrO2, respectively, total 100 wt. %. Additionally, an SCR catalyst article is disclosed, to which the SCR catalyst composition of the present invention is applied in the form of a coating. Suitable catalyst supports are corrugated substrates and cordierite monoliths. The SCR catalyst articles can be used in methods for reducing nitrogen oxides in the exhaust gases of lean-burn internal combustion engines, and they can also be included in exhaust gas purification systems for treating diesel exhaust gases.

Description

[Technical Field]

[0001] The present invention relates to an SCR catalyst composition comprising an oxide of titanium, vanadium, tungsten, antimony, and optionally zirconium. Furthermore, an SCR catalyst article comprising the catalyst composition is disclosed. The SCR catalyst composition and the SCR catalyst article comprising the SCR catalyst composition according to the present invention can be used for purifying the exhaust of lean combustion engines, particularly diesel engines. [Background technology]

[0002] Exhaust gases from vehicles, primarily those with lean-running combustion engines, specifically contain particulate matter, as well as primary emissions of carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides. Due to their relatively high oxygen content (up to 15% by volume), carbon monoxide and hydrocarbons can be relatively easily neutralized by oxidation. However, reducing nitrogen oxides to nitrogen is far more difficult.

[0003] Nitrogen oxides (NOx) are produced from exhaust gases in the presence of oxygen. x A known method for removing nitrogen oxides is selective catalytic reduction (SCR) with ammonia on a suitable catalyst. In this method, nitrogen oxides to be removed from the exhaust gas are converted to nitrogen and water using ammonia. Nitric oxide (NO) and nitrogen dioxide (NO2) are then converted to NO. x It can be summarized as follows.

[0004] Selective catalytic reduction (SCR) is carried out in the presence of an SCR catalyst according to the reaction scheme shown below. 4NO + 4NH3 + O2 → 4N2 + 6H2O (1) NO + NO2 + 2NH3 → 2N2 + 3H2O (2) 6NO2 + 8NH3 → 7N2 + 12H2O (3) 2NO2 + 4NH3 + O2 → 3N2 + 6H2O (4)

[0005] Reactions 1 and 2 are the main reactions, and each NO is converted x One mole of ammonia is consumed per mole. Reactions 3 and 4 are NO x The reaction occurs in gases, mostly present as NO2. Catalysts are used to initiate the reaction at temperatures between 150 and 480°C. The most common types of SCR catalysts are based on molecular sieves accelerated by vanadium oxide or transition metals on a titanium dioxide (TiO2) support system. In the latter case, copper and / or iron-accelerated zeolites are used in most cases. Reaction 1 is known as the "standard SCR reaction," reaction 2 as the "fast SCR reaction," and reactions 3 and 4 as the "NO2 SCR reaction." Ammonia used as a reducing agent can be produced as a secondary emission in the exhaust system, or it can be made available in the exhaust gas system by hydrolysis through the injection of a precursor capable of forming ammonia, such as urea, ammonium carbamate, or ammonium formate. To implement the last modified SCR method mentioned, a reducing agent supply source, an injection device for quantitatively delivering the reducing agent into the exhaust gas as needed, and an SCR catalyst placed in the exhaust gas flow path are required.

[0006] For example, mixed oxides, particularly those based on vanadium oxides such as titanium dioxide and / or vanadium pentoxide, and which may contain other oxides such as silicon, molybdenum, manganese, and tungsten, can be used as SCR catalysts. These catalysts are described in detail in the literature; see, for example, International Publication 89 / 03366(A1), European Patent Publication 0345695(A2), European Patent Publication 0385164(A2), International Publication 2011 / 013006(A2), and U.S. Patent Application Publication 2013 / 205743(A1).

[0007] International Publication No. 2011 / 011101(A1) discloses a catalyst for the selective catalytic reduction of nitrogen oxides. The catalyst comprises a metal oxide support, vanadium, an active substance, antimony, and a promoter that acts as a catalyst for the reduction of nitrogen oxides and simultaneously promotes higher sulfur poisoning resistance and low-temperature catalytic activity. The amount of antimony in the catalyst is preferably 0.5 to 7 wt% (weight%), and the amount of vanadium is preferably 1 to 3 wt%. According to International Publication No. 2011 / 011101(A1), mixed metal oxide catalysts containing tungsten oxide improve sulfur poisoning resistance at low temperatures, but the use of tungsten oxide significantly increases the price of the catalyst, which should be avoided for economic reasons. As a result, the catalyst according to this invention does not contain tungsten. However, the mixed metal oxide catalyst according to International Publication No. 2011 / 011101(A1) includes a support, such as titanium oxide, silicates, zirconia, alumina, and mixtures thereof. Preferably, the carrier (also synonymously called TiO2) is TiO2.

[0008] International Publication No. 2011 / 127505(A1) discloses a composition comprising a vanadate represented by the formula XVO4 / S, where XVO4 represents a Bi-, Sb-, Ga- and / or Al-vanadate, optionally in a mixture of one or more rare-earth metal-vanadates, or a mixture of one or more transition metal-vanadates, or a mixture of one or more transition metal-vanadates and one or more rare-earth metal-vanadates, and S is optionally a support comprising TiO2 combined with a dopant, and a method for preparing such a catalyst composition. When XVO4 is SbVO4, it is synthesized by mixing a solution of SbCl3 containing 63.9 wt% Sb2O3 with a solution containing NH4VO3. The solid obtained after calcination was identified by XRD. The support material is preferably commercially available TiO2 / WO3 / SiO2. The amounts of TiO2, WO3, and SiO2 in the support material are not indicated.

[0009] International Publication No. 2017 / 101449(A1) describes the support TiO2 and VSbO4 and V determined by X-ray diffraction (XRD) analysis using CuKα rays. 0.92 S 0.92 Disclosed are a catalyst composition for the selective catalytic reduction of nitrogen oxides, comprising a composite oxide containing vanadium and antimony having a rutile-type structure different from O4, and optionally one or more oxides selected from the group consisting of silicon oxides, vanadium oxides, and antimony oxides; a method for preparing the catalyst composition; a catalyst composition obtained / can be obtained by the method; and the use of the catalyst composition for the selective catalytic reduction of nitrogen oxides. The support material must contain TiO2, but may further consist of TiO2, SiO2, and WO3, or TiO2 and ZrO2. Vanadium and antimony exist in the form of a composite oxide containing a rutile structure. Vanadium is present in the catalyst in an amount of 0.5 to 6% by weight, calculated as elemental V, and antimony is present in an amount of 0.8 to 16% by weight, calculated as elemental Sb. TiO2 is preferably present in the form of anatase. The titanium content is preferably in the range of 50 to 97.5% by weight, calculated as TiO2, and the silicon content (if present) is preferably in the range of 0.2 to 9.5% by weight, calculated as elemental Si. International Publication No. 2017 / 101449(A1) does not mention the amounts of WO3 and ZrO2 (if they are present). It explicitly states that either a) TiO2, SiO2, and WO3, or b) TiO2 and ZrO2 can be the support material, but it does not explicitly state that all four oxides, namely TiO2, SiO2, WO3, and ZrO2, should be present in the catalyst composition.

[0010] Chinese Patent Publication No. 107262086(A) relates to a selective catalytic reduction (SCR) denitrification catalyst, and more particularly to an SCR denitrification catalyst, preparation method, and applications for promoting the decomposition of ammonium bisulfate by low-temperature flue gas. The SCR denitrification catalyst uses a composite oxide composed of titanium oxide and a transition metal oxide as a support, with vanadium oxide as the active component and tungsten oxide as a co-catalyst, and the molar ratio of the transition metal element to the titanium element in the catalyst is (0.1~0.5):1, and the transition metal oxide includes one or more of MnO2, Fe2O3, CeO2, ZrO2, Al2O3, SnO2, Nb2O5, and Sb2O5. An SCR denitrification catalyst for promoting the low-temperature decomposition of ammonium bisulfate is prepared by adding an appropriate amount of transition metal oxide to the catalyst, and this catalyst promotes the decomposition of ammonium bisulfate at temperatures below 350°C. In summary, the catalyst according to Chinese Patent Publication No. 107262086(A) comprises titanium, vanadium, and tungsten oxides, and may also include transition metal oxides selected from zirconium dioxide and antimony pentoxide. The molar ratio of one or more transition metal elements, for example, the molar ratio of ZrO2 and Sb2O5 to TiO2, is 0.1 to 0.5:1.

[0011] International Publication No. 2018 / 018406(A1) discloses catalysts for NOx removal, more specifically supported catalysts, monolithic selective catalytic reduction (SCR) catalysts, methods for preparing the same, and methods for NOx removal. The supported catalyst comprises a support and a catalytically active component supported on the support, which comprises vanadium, antimony, and at least one further component selected from the group of oxides of silicon, aluminum, and zirconium, preferably at least one of silica and / or alumina. The support material can be selected from TiO2, or TiO2 and SiO2, or TiO2 and WO3, or TiO2, SiO2 and WO3. The support is preferably TiO2 and is present in an amount of 50 to 97.5% by weight. Calculated as V2O5 and Sb2O5 respectively, the V content is preferably in the range of 1 to 10% by weight, and the Sb content is preferably in the range of 1 to 20% by weight. ZrO2 and SiO2 may be present in amounts of 0.5 to 20% by weight. None of the examples shown in International Publication No. 2018 / 018406(A1) contain all six elements Ti, W, V, Sb, and Zr. Examples 9 and 10 contain Ti, Si, W, V, and Sb, but do not contain Zr. Only Examples 9 and 10 contain WO3, and their WO3 content is very high (9% and 10% by weight, respectively). All other examples disclosed in International Publication No. 2018 / 018406(A1) contain only some of these five elements. Many examples contain antimony oxide, but the amount varies. According to the comparison of SCR activity performed in International Publication No. 2018 / 018406(A1), a low antimony oxide content of about 2% by weight shows significantly lower NOx conversion than catalysts containing higher amounts of antimony oxide, i.e., 7 to about 16% by weight. In International Publication No. 2018 / 018406(A1), antimony oxide is calculated as Sb2O3.

[0012] U.S. Patent Application Publication 2016 / 0288094(A1) discloses a catalyst comprising at least two catalytically active layers A and B. Layer A is applied directly to a support, and layer B is applied to layer A to cover layer A at least partially or over its entire length. Thus, layer B comes into contact with the exhaust gas before layer A. The support may be a throughput honeycomb or a wall flow filter. Both layers A and B contain a support oxide selected from titanium dioxide, zirconium dioxide, or aluminum oxide, preferably titanium dioxide. Layer A contains vanadium pentoxide and tungsten trioxide as catalytically active metal oxides, and optionally also contains silicon dioxide and / or antimony pentoxide. Layer B contains vanadium pentoxide, tungsten trioxide, and silicon dioxide, and optionally also contains antimony pentoxide. The total weight of layer A is greater than the total weight of layer B, and the proportion of vanadium pentoxide in layer A is greater than the proportion of vanadium pentoxide in layer B. If layer A contains silicon dioxide, its proportion in layer A is smaller than that in layer B. All catalysts in the examples have a high proportion of tungsten pentoxide, approximately 7-10% by weight, in both layers A and B.

[0013] In "SO2resistant antimony prompted V2O5 / TiO2catalyst for NH3-SCR of Nox at low temparatures" by HH Phil, MP Reddy, PA Kumar, LK Ju and JS Hyo, Applied Catal B 2008, 78, 301~308, the effect of promoters on the sulfur resistance of V2O5 / TiO2 SCR catalysts was investigated. The promoters were selected from Se, Sb, Cu, S, B, Bi, Pb and P. Selenium showed the best NOx conversion rate at 150~400 °C, but was excluded because selenium has a high vapor pressure. Among the remaining promoters, a 2 wt% Sb loading on V2O5 / TiO2 showed the best NOx conversion rate, combined with high resistance to SO2. A catalyst with 2 wt% Sb on V2O5 / TiO2 was compared with a commercial catalyst containing 10 wt% W on V2O5 / TiO2. Both catalysts showed comparable NOx conversion rates and SO2 resistance, but activity measurements carried out with both catalysts, i.e., measurements in an atmosphere containing SO2, NO x , NH3, O2 and H2O also revealed the formation of a significant amount of ammonium sulfate salt. When tungsten was used as a promoter, the percentage of tungsten had to be increased to an amount of about 5~10 wt% in order to achieve sulfur poisoning resistance at low temperatures. Since the amount of tungsten increases the cost of the catalyst, the aim of this study was to find a promoter that could replace tungsten and to improve sulfur poisoning at low temperatures.

Summary of the Invention

Problems to be Solved by the Invention

[0014] Since the internal combustion engine of an automobile operates in a transient operation cycle, the SCR catalyst also needs to have good selectivity and ensure the highest possible nitrogen oxide conversion rate even under widely varying operating conditions. Therefore, it is also necessary to ensure complete and selective conversion of the resulting nitrogen oxides, both at low temperatures, as well as at high temperatures, for example when occurring at full throttle.

[0015] However, in the prior art up to now, it has not been possible to simultaneously optimize the vanadium SCR catalyst with respect to, on the one hand, low-temperature activity (T < 250 °C) and thermal stability, and on the other hand, the activity of the fresh catalyst and the aged catalyst. Improvement of low-temperature activity is always associated with a lack of thermal stability, and vice versa, and the same necessary changes also apply to the activity of the fresh catalyst versus the aged catalyst.

[0016] However, the market demand for this type of catalyst is increasing. Therefore, an object of the present invention is to provide a vanadium-containing catalyst composition for the selective catalytic reduction of nitrogen oxides, which exhibits good low-temperature activity, at the same time exhibits better thermal stability, and also exhibits good catalyst performance in both fresh and aged states. Another object of the present invention is to provide a SCR catalyst article comprising the SCR catalyst composition.

Means for Solving the Problems

[0017] Technical Solution The object of providing a vanadium-containing catalyst composition for the selective catalytic reduction of nitrogen oxides, which is distinguished by good low-temperature activity and at the same time higher high-temperature selectivity, and also exhibits good catalyst performance in both fresh and aged states, is - at least one vanadium oxide in an amount of 2.0 to 4.0% by weight based on the total weight of the catalyst composition calculated as V2O5, - at least one tungsten oxide in an amount of 2.5 to 7.2% by weight based on the total weight of the catalyst composition calculated as WO3, - at least one antimony oxide in an amount of 0.6 to 3.4% by weight based on the total weight of the catalyst composition calculated as Sb2O5, - at least one zirconium oxide in an amount of 0 to 1.0% by weight based on the total weight of the catalyst calculated as ZrO2, -and consists of at least one titanium oxide in an amount of 84.6 to 94.9% by weight based on the total weight of the catalyst, calculated as TiO2. This is achieved by a catalyst composition in which the weight percentages of vanadium, tungsten, antimony, titanium, and zirconium oxides, calculated as V2O5, WO3, Sb2O5, TiO2, and optionally ZrO2, total 100% by weight.

[0018] Surprisingly, we found that the novel catalyst composition exhibited good activity at both low and high temperatures, and also showed better thermal stability in both its fresh and aged states.

[0019] The catalyst composition for the selective catalytic reduction of nitrogen oxides according to the present invention, which exhibits good low-temperature activity while simultaneously showing higher high-temperature selectivity and good catalytic performance in both fresh and aged states, and an SCR catalyst article containing the SCR catalyst composition are described below, and the present invention encompasses all embodiments shown below, individually and in combination with each other.

[0020] A "catalyst composition" is a substance or mixture of substances that can convert one or more components of exhaust gas or waste gas into one or more other components. Therefore, a "catalyst composition" is catalytically active. An example of such a catalyst composition is, for example, an oxidation catalyst composition that can convert volatile organic compounds and carbon monoxide into carbon dioxide, or ammonia into nitrogen oxides. Another example of such a catalyst is, for example, a selective reduction catalyst (SCR catalyst) composition that can convert nitrogen oxides into nitrogen and water. In the context of the present invention, an SCR catalyst is a catalyst comprising a carrier substrate and an SCR catalyst composition. The SCR catalyst composition according to the present invention comprises, as defined above, at least one catalytically active metal oxide of each of vanadium, tungsten, antimony, and titanium, and optionally zirconium.

[0021] A "catalyst substrate," also simply called a "carrier substrate," is a support on which a catalyst composition is attached to form the final catalyst. Thus, the carrier substrate is a carrier for the catalytically active composition.

[0022] A suspension or dispersion is a heterogeneous mixture containing solid particles and a solvent. The solid particles do not dissolve but remain suspended throughout the entire volume of solvent, free-floating in the medium. If the solid particles have an average particle size of 1 μm or less, the mixture is called a dispersion; if the average particle size is greater than 1 μm, the mixture is called a suspension. As used in the context of this invention, the term "mixture" refers to a material composed of two or more different substances that are physically combined, in which each component retains its own chemical properties and structure. Despite the fact that there is no chemical change in its components, the physical properties of the mixture, such as its melting point, may differ from those of the individual components.

[0023] A "wash coat" is a suspension or dispersion of solid particles that can be applied to a catalyst substrate. This suspension or dispersion is often called a "wash coat slurry." The slurry is applied to a carrier substrate and then dried. It is also possible to continuously apply two or more wash coats to a carrier substrate. Those skilled in the art know that it is possible to apply two or more wash coats to a single carrier substrate by "layering" or "zoning," and that layering and zoning can also be combined. In the case of layering, the wash coats are applied one after another to the carrier substrate. The wash coat applied first and therefore in direct contact with the carrier substrate is the "lower layer," and the wash coat applied last is the "upper layer." In the case of zoning, the first wash coat is applied to the carrier substrate from the first side A toward the other side B, but not along the entire length of the carrier substrate, but only to the endpoint between sides A and B. Then, the second wash coat is applied to the carrier starting from side B and extending to the endpoint between sides B and A. The endpoints of the first and second wash coats do not need to be the same; if they are the same, both wash coat zones are adjacent to each other. However, if the endpoints of the two wash coat zones located between sides A and B of the carrier substrate are not the same, there may be a gap between the first wash coat zone and the second wash coat zone, or they may overlap. As described above, layering and zoning can also be combined, for example, if one wash coat is applied over the entire length of the carrier substrate and the other wash coat is applied only from one side to the endpoint between both sides. A washcoat in the sense of the present invention comprises a solvent, usually water, and particles of at least one titanium oxide. Furthermore, the washcoat may optionally include a binder and / or additives. Suitable binders are, for example, alumina, silica, non-zeolite silica-alumina, and naturally occurring clays. Suitable additives are, for example, polyacrylates, amines, citrates, tartarates, and rheological modifiers such as starch and cellulose. Such binders and additives are known to those skilled in the art and can be used in the context of the present invention without departing from the claims. The wash coat can be applied to the carrier substrate in one or more steps. In one embodiment of the present invention, the washcoat slurry comprises a solvent, usually water, and particles of at least one titanium oxide. This washcoat is applied to a substrate and dried. Subsequently, each of the at least one oxide of vanadium, tungsten, antimony, and optionally zirconium, or their precursors, is applied to the dried and calcined washcoat by impregnating the dried and calcined washcoat with a precursor of each of the at least one oxide of vanadium, tungsten, antimony, and optionally zirconium. Each of the at least one oxide of vanadium, tungsten, antimony, and zirconium can be applied in the form of its oxide precursor, or all of them can be applied in the form of the oxide, or some of the oxides can be applied in the form of their oxide precursor and some in the form of the oxide. The precursor is a compound containing the intended oxide metal of vanadium, tungsten, antimony, or zirconium, such as a salt, which can be converted to the final oxide by, for example, heat treatment. In another embodiment of the present invention, the washcoat slurry comprises a solvent, usually water, and each of the following: at least one oxide of titanium, and at least one oxide of vanadium, tungsten, antimony, and optionally zirconium, and / or a precursor of at least one oxide of vanadium, tungsten, antimony, and optionally zirconium. If a precursor of at least one oxide of vanadium, tungsten, antimony, and optionally zirconium is used, it is subsequently converted to a catalytically active metal oxide as described above. Furthermore, at least one titanium oxide, as well as some of the oxides and / or precursors thereof of vanadium, tungsten, antimony, and optionally zirconium, can be applied to the catalyst substrate in the form of a washcoat slurry, while other oxides of vanadium, tungsten, antimony, and optionally zirconium can be subsequently applied to the dried and calcined washcoat, for example, by impregnation as described above. In the context of the present invention, “coating” is the SCR catalyst composition according to the present invention attached to the catalyst substrate. The immobilization of the SCR catalyst composition can be carried out according to the embodiments described above. Thus, the coating comprises, as described above, oxides of titanium, vanadium, tungsten, antimony, and optionally zirconium. In embodiments of the present invention in which the washcoat comprises all metal oxides or their precursors in the catalyst composition, the washcoat is applied to a carrier substrate and then dried, for example, at room temperature. Subsequently, the coated carrier substrate is calcined, for example, at a temperature of 500-600°C. This method of applying the washcoat to the substrate is hereafter referred to as the "one-pot method." It is feasible for both corrugated and cordierite substrates. In embodiments of the present invention in which the wash coat comprises some but not all of the metal oxides or their precursors in the catalyst composition, the wash coat is applied to a carrier substrate and then dried, for example, at room temperature. Subsequently, the coated carrier substrate is calcined, for example, at a temperature of 500-600°C. Then, other oxides or their precursors are applied to the dried wash coat, for example, by impregnation, and then a drying step is performed, preferably at room temperature. Next, the coated carrier substrate is heated to a temperature of 450-600°C. If metal oxide precursors are used, this heating step decomposes the precursors into the corresponding metal oxides. Methods for applying, drying, and calcining wash coats, and for decomposing metal oxide precursors into corresponding metal oxides, are known to those skilled in the art and can be applied in the context of the present invention without departing from the claims.

[0024] Optionally, the catalyst support material may be mixed with each of at least one oxide or precursor thereof of titanium, vanadium, tungsten, antimony, and optionally zirconium, and then extruded. It is also possible to extrude only the catalyst support material and at least one titanium oxide, and then apply the other oxides or their precursors thereafter. Furthermore, it is possible to extrude a portion of the catalyst support material, at least one titanium oxide, and the other oxides or their precursors, and then apply the other oxides or their precursors thereafter. Such extrusion methods are known to those skilled in the art and can be applied in the context of the present invention without departing from the claims.

[0025] "Catalyst article" or "brick" includes a catalyst substrate and a coating attached thereto. In the context of the present invention, "SCR catalyst load" refers to the concentration of the SCR catalyst composition, given in grams of each component per liter of catalyst substrate. "SCR catalyst articles" are used to remove NO from exhaust gas or waste gas. x This catalyst article is suitable for the removal of [unspecified substance].

[0026] As used in the context of the present invention, a “system” for purifying exhaust gases comprises two or more consecutive catalyst articles, each individual catalyst article designed to remove specific components of the exhaust gas, for example, volatile organic compounds (VOCs), hydrocarbons (HCs), and carbon monoxide in the case of an oxidation catalyst, or nitrogen oxides in the case of an SCR catalyst, or particulate matter in the case of a particulate filter, or excess ammonia in the case of an ammonia slip catalyst (ASC). These catalyst articles are well known.

[0027] "Upstream" and "downstream" are terms used in relation to the normal flow direction of exhaust gases in the exhaust pipeline. "Zone or catalyst article 1 or catalyst article 2 located upstream of a zone" means that zone or catalyst article 1 is located closer to the exhaust gas source than zone or catalyst article 2, i.e., closer to the combustion source, such as the motor. The direction of flow is from the exhaust gas source, i.e., from the combustion source to the exhaust pipe. Therefore, with respect to this flow direction, the exhaust gases enter each zone or catalyst article at its inlet end and exit each zone or catalyst article at its outlet end.

[0028] At least one titanium oxide is present in an amount of 84.6–94.9% by weight, depending on the amount of vanadium, tungsten, antimony, and optionally zirconium oxides. This means that vanadium, tungsten, antimony, and optionally zirconium oxides are present in the above range, with the remainder being titanium oxide, and the total amount of all oxides being 100% by weight. The at least one titanium oxide is titanium dioxide (TiO2). It is well known that TiO2 exists in several phases, particularly anatase, rutile, and brookite. A preferred titanium dioxide contains at least 95% by weight, preferably at least 98% by weight, and more preferably at least 99.5% by weight of anatase. The remainder to make a total of 100% by weight is preferably represented by rutile and / or brookite, more preferably rutile.

[0029] At least one vanadium oxide is present in an amount of 2.0 to 4.0% by weight, preferably 2.4 to 3.4% by weight, and more preferably 2.4 to 2.8% by weight. In one embodiment, the at least one vanadium oxide is vanadium pentoxide (V2O5).

[0030] At least one tungsten oxide is present in an amount of 2.5 to 7.2% by weight, preferably 2.5 to 7.0% by weight, more preferably 3.0 to 5.5% by weight, and most preferably 3.5 to 5.0% by weight. In one embodiment, the at least one tungsten oxide is tungsten trioxide (WO3).

[0031] At least one antimony oxide is present in an amount of 0.6 to 3.4% by weight, preferably 1.5 to 2.5% by weight. In one embodiment, the at least one antimony oxide is present in the form of antimony pentoxide (Sb2O5).

[0032] The catalyst composition according to the present invention contains at least one zirconium oxide in an amount of 0 to 1.0% by weight. This means that there is either no zirconium oxide present, corresponding to an amount of 0% by weight of at least one zirconium oxide, or at least one zirconium oxide is present in an amount greater than 0% by weight and up to 1.0% by weight. When used in the present invention, the term "optionally zirconium" also includes embodiments in which no zirconium oxide is present, and embodiments in which at least one zirconium oxide is present in an amount greater than 0 to 1.0% by weight. In embodiments containing zirconium, zirconium is present in an amount greater than 0 to 1.0% by weight, preferably 0.01 to 1.0% by weight, more preferably 0.2 to 1.0% by weight, and even more preferably 0.4 to 0.7% by weight. In one embodiment, at least one zirconium oxide is zirconium dioxide (ZrO2). The preferred amounts of titanium, tungsten, vanadium, and antimony oxides are the same as those shown above for zirconium-free catalysts, and the same applies to the preferred oxide properties of these elements.

[0033] Those skilled in the art know that vanadium, tungsten, antimony, and zirconium each form several oxides, each having a different oxidation state. Examples of vanadium oxides include V2O3, VO2, and V2O5. Examples of tungsten oxides include WO2 and WO3. Examples of antimony oxides include Sb2O3, Sb2O4, and Sb2O5. Zrconium oxides include, for example, ZrO2.

[0034] Those skilled in the art know that oxides of these metals can coexist in various oxidation states, and that some metals, particularly vanadium, form a broad family of oxides. However, in the context of the present invention, the amounts of vanadium, tungsten, antimony, and zirconium oxides are calculated in the form of oxides V2O5, WO3, Sb2O5, and Zr2O. Those skilled in the art know how to determine the amounts of the corresponding metals, vanadium, tungsten, antimony, and zirconium, in a catalyst composition, and how to convert them to the amounts of V2O5, WO3, Sb2O5, and ZrO2.

[0035] In one embodiment of the present invention, a catalyst composition for the selective catalytic reduction of nitrogen oxides, -Calculated as V2O5, based on the total weight of the catalyst composition, at least one vanadium oxide in an amount of 2.0 to 4.0% by weight, -Calculated as WO3, based on the total weight of the catalyst composition, an amount of at least one tungsten oxide in an amount of 2.5 to 7.2% by weight, -Calculated as Sb2O5, based on the total weight of the catalyst composition, an amount of at least one antimony oxide of 0.6 to 3.4% by weight, -and consists of at least one titanium oxide in an amount of 85.6 to 94.9% by weight based on the total weight of the catalyst, calculated as TiO2. When calculated using V2O5, WO3, Sb2O5, and TiO2 respectively, the total weight percentage of vanadium, tungsten, antimony, and titanium oxides is 100% by weight.

[0036] In another embodiment of the present invention, a catalyst composition for the selective catalytic reduction of nitrogen oxides, -Calculated as V2O5, based on the total weight of the catalyst composition, at least one vanadium oxide in an amount of 2.0 to 4.0% by weight, -Calculated as WO3, based on the total weight of the catalyst composition, an amount of at least one tungsten oxide in an amount of 2.5 to 7.2% by weight, -Calculated as Sb2O5, based on the total weight of the catalyst composition, an amount of at least one antimony oxide of 0.6 to 3.4% by weight, -Calculated as ZrO2, based on the total weight of the catalyst, an amount of at least one zirconium oxide of 0.2 to 1.0 wt%, -and consists of at least one titanium oxide in an amount of 84.6 to 94.7% by weight based on the total weight of the catalyst, calculated as TiO2. When calculated using V2O5, WO3, Sb2O5, TiO2, and ZrO2 respectively, the total weight percentage of vanadium, tungsten, antimony, titanium, and zirconium oxides is 100% by weight.

[0037] The SCR catalyst article according to the present invention includes a catalyst substrate on which the SCR catalyst composition according to the present invention is attached in the form of a coating.

[0038] The catalyst substrate is selected from corrugated substrates and cordierite monoliths.

[0039] A suitable cordierite monolith may be a wall flow filter or a flow-through substrate. The wall flow filter or flow-through substrate may exist in the form of a honeycomb structure.

[0040] In one embodiment, the carrier substrate is a corrugated substrate, which is also referred to hereafter as a “corrugated substrate monolith.” Such corrugated substrate monoliths are known to those skilled in the art. They are disclosed, for example, in International Publication No. 2010 / 066345(A1). The corrugated substrate preferably has a wall density of at least 50 g / l but not exceeding 300 g / l, and a porosity of at least 50%. The monolith substrate is a high silica content glass paper or an E-glass fiber paper. Optionally, the paper has a layer of diatomaceous earth and / or a layer of titania. Diatomaceous earth is a naturally occurring soft siliceous sedimentary rock that is readily crushed into a pure white to off-white powder. Siliceous rocks are sedimentary rocks having silica (SiO2) as their main component.

[0041] A catalyst article in which the catalyst composition is applied to a corrugated substrate has the advantage that the catalyst layer, i.e., the layer formed by applying the catalyst composition to the support substrate, does not peel off from the monolithic substrate during the starting and stopping of a combustion engine or gas turbine. At the same time, this catalyst has been shown to have improved catalytic activity.

[0042] The catalyst material is applied to a monolithic substrate having the form of a flat or corrugated sheet. The substrate is made from a sheet of E-glass fiber or a sheet of glass having a high silicon content. Optionally, the sheet may include a layer of TiO2, a layer of diatomaceous earth, or a layer containing both TiO2 and diatomaceous earth.

[0043] High-silicon content glass contains 94-95% by weight of SiO2, 4-5% by weight of Al2O3, and some Na2O, and these fibers have a fiber diameter of 8-10 μm and a density of 2,000-2,200 g / l. One example is commercially available SILEX staple fiber.

[0044] E glass contains 52-56% by weight of SiO2, 12-16% by weight of Al2O3, 5-10% by weight of B2O3, 0-1.5% by weight of TiO2, 0-5% by weight of MgO, 16-25% by weight of CaO, 0-2% by weight of K2O / Na2O, and 0-0.8% by weight of Fe2O3.

[0045] Preferably, the substrate material is selected such that the density of the substrate is at least 50 g / l but no more than 300 g / l of the material, and the porosity of the substrate wall is at least 50 volume% of the material.

[0046] The porosity of the monolithic substrate is obtained by pores having a depth of 50 μm to 200 μm and a diameter of 1 μm to 30 μm.

[0047] The preferred amounts of titanium, vanadium, tungsten, antimony, and optionally zirconium oxides are the same as those shown above for catalyst compositions containing or not containing zirconium, and the same applies to the preferred oxide properties of these elements.

[0048] The fixation of the SCR catalyst composition onto the catalyst substrate in the form of a coating is performed by applying the wash coat defined above onto the catalyst substrate.

[0049] The wash coat comprises at least a solvent, preferably water, and particles of at least one titanium oxide. The at least one titanium oxide is preferably TiO2 and contains at least 95% by weight, preferably at least 98% by weight, and more preferably at least 99.5% by weight of anatase. The remainder to make a total of 100% by weight is preferably represented by rutile and / or brookite, more preferably rutile. In one embodiment, the wash coat further comprises a binder, such as alumina, silica, non-zeolite silica-alumina, or natural clay. In another embodiment, the wash coat further comprises additives, such as polyacrylates, amines, citrates, tartarates, and rheological modifiers such as starch and cellulose. In yet another embodiment, the wash coat further contains additives but does not contain a binder. If the coating contains at least one oxide of zirconium, zirconium dioxide or its precursor can be added to the wash coat. It is also possible to add a binder and / or additive and / or at least one oxide or precursor of zirconium to the wash coat.

[0050] In one embodiment, the wash coat comprises water, titanium dioxide, and optionally a binder and / or additive and / or at least one oxide or precursor of zirconium.

[0051] In another embodiment, the wash coat comprises water, titanium dioxide, each of at least one oxide of vanadium, tungsten, antimony, and optionally zirconium and / or a precursor of at least one oxide of vanadium, tungsten, antimony, and optionally zirconium, and optionally a binder and / or additives. In yet another embodiment, the wash coat comprises water, titanium dioxide, some oxides and / or precursors thereof of vanadium, tungsten, antimony, and optionally zirconium, and a binder and / or additives.

[0052] The wash coat is applied to the catalyst substrate in a direction perpendicular to the surfaces A and B of the catalyst substrate. It can be applied from top to bottom, preferably by applying the wash coat under pressure from the top to the bottom. Alternatively, the wash coat can be applied from bottom to top, preferably by immersing it from the bottom to the top under reduced pressure. The application of the wash coat from top to bottom and from bottom to top is known to those skilled in the art and this knowledge can be applied in the context of the present invention without departing from the scope of the claims.

[0053] The dry washcoat and its pH value can be conveniently adjusted to obtain the desired coating load. In embodiments of the present invention, the pH value of the washcoat is adjusted to be different from the isoelectric point (IEP) of the particles suspended or dispersed in the washcoat. The isoelectric point is the pH value at which the particles have no net charge. Adjustment to a pH value that is more acidic than the IEP can be done by adding an acid, such as nitric acid. Adjustment to a pH value that is more basic than the IEP can be done by adding a base, such as ammonia or an amine. Methods for adjusting the dry washcoat and its pH value are known to those skilled in the art and can be applied without departing from the scope of the claims.

[0054] Optionally, the wash coat may be ground, for example, in a bead mill before being applied to the catalyst substrate. Preferably, the particles contained in the wash coat are ground to a D90 particle size of ≤2 μm.

[0055] Next, the wash coat is applied to the catalyst substrate and then dried and calcined, for example, by drying at room temperature followed by calcination at 500-600°C.

[0056] If the washcoat does not contain all of the oxides of vanadium, tungsten, antimony, and optionally zirconium, these oxides that have not yet been applied can be applied in a subsequent step, for example, by impregnating the washcoat with these oxides and / or their precursors. Impregnation can be carried out, for example, by immersing the washcoated catalyst substrate in an aqueous solution of the precursors. The precursors of vanadium, tungsten, antimony, and zirconium oxides are preferably used in the form of aqueous solutions thereof.

[0057] Suitable precursor salts of vanadium are ammonium metavanadate and vanadium oxalates and tartrates. A preferred precursor salt of tungsten is ammonium metatungstate. Suitable precursor salts of antimony include antimony sulfate, antimony acetate, antimony tartrate, antimony glycolate, and antimony acetylacetonate. Suitable precursors for zirconium are zirconium(IV) chloride, zirconyl(IV) nitrate, and zirconyl(IV) sulfate. When using an antimony precursor other than antimony tartrate, it is preferable to add tartaric acid to the aqueous solution of the antimony precursor. Preferably, the tartaric acid and antimony precursor are used in a molar ratio of 2:1 to 8:1.

[0058] In one embodiment of the present invention, the catalyst substrate is a corrugated substrate, and the washcoat consists of water, titanium dioxide, and optionally a binder and / or additive and / or at least one oxide or precursor of zirconium. When the catalyst composition according to the present invention contains zirconium, it is most preferable to add a zirconium precursor to the washcoat. After applying the washcoat, the washed corrugated substrate is subsequently impregnated with aqueous solutions of vanadium, tungsten, and antimony precursors. The application of the washcoat, drying and calcination, and decomposition of the metal oxide precursors into the corresponding metal oxides are carried out as described above.

[0059] In another embodiment of the present invention, the catalyst substrate is a corrugated substrate, and the wash coat comprises titanium dioxide, vanadium, tungsten, antimony oxides and / or vanadium, tungsten, and antimony precursors, and optionally a binder and / or additives and / or at least one oxide or precursor of zirconium. Here again, the application of the wash coat, drying and calcination, and the decomposition of the metal oxide precursors into the corresponding metal oxides are carried out as described above. This method of applying the wash coat is the “one-pot method” as defined above.

[0060] In yet another embodiment of the present invention, the catalyst substrate is a cordierite substrate as described above, and the wash coat comprises titanium dioxide, an oxide of vanadium, tungsten, or antimony, and optionally a binder and / or additive and / or at least one oxide or precursor of zirconium.

[0061] When a corrugated substrate is coated with a wash coat containing the catalyst composition according to the present invention, the concentration is preferably 250 to 550 g / l, more preferably 350 to 450 g / l. When a cordierite substrate is coated with a wash coat containing the catalyst composition according to the present invention, the concentration is preferably 100 to 500 g / l, more preferably 150 to 400 g / l.

[0062] The catalyst article according to the present invention is particularly suitable for the reduction of nitrogen oxides in the exhaust gas of lean-burn internal combustion engines, especially diesel engines. Therefore, the present invention also relates to a method for reducing nitrogen oxides in the exhaust gas of a lean-burn internal combustion engine, comprising the following steps: - A step of adding a reducing agent to the exhaust gas containing nitrogen oxides, The present invention relates to a method comprising the step of passing a mixture obtained from exhaust gas containing nitrogen oxides and a reducing agent through a catalyst article according to the present invention.

[0063] As a reducing agent, ammonia is particularly considered, and especially advantageously, not ammonia itself, but an ammonia precursor—particularly urea—is added to the exhaust gas containing nitrogen oxides.

[0064] In particular, the catalyst according to the present invention is used, for example, as a component of an exhaust gas purification system that includes an oxidation catalyst and a diesel particulate filter located on the inlet side, in addition to the catalyst article according to the present invention. In this case, the catalyst article according to the present invention may also exist as a coating on the diesel particulate filter.

[0065] Therefore, the present invention also relates to an exhaust gas purification system for treating diesel exhaust gas, wherein in the direction of exhaust gas flow, - Oxidation catalyst, - Diesel particulate filters, and -Catalyst article according to the present invention, or - Oxidation catalyst, and -The present invention relates to an exhaust gas purification system, which includes a diesel particulate filter on which the catalyst composition according to the present invention is present as a coating.

[0066] Oxidation catalysts suitable for the exhaust gas purification system according to the present invention, particularly platinum, palladium, or platinum and palladium supported on aluminum oxide, and diesel particulate filters are known to those skilled in the art and are commercially available.

[0067] The exhaust gas purification system according to the present invention generally includes a device for quantitatively delivering a reducing agent positioned upstream of the catalyst according to the present invention. The injection device can be freely selected by those skilled in the art. Such devices are known to those skilled in the art and can be applied in the context of the present invention without departing from the scope of the claims. The reducing agent injected into the exhaust gas flow via the injection device may be ammonia itself or in the form of a compound formed from ammonia under ambient conditions. Examples of suitable compounds include aqueous solutions of urea or ammonium formate, and solid ammonium carbamate. Typically, the reducing agent or its precursor is supported together with the injection device and held in a container connected to the injection device. [Brief explanation of the drawing]

[0068] [Figure 1] This shows the conversion of NOx in fresh and aged states at 200°C as a function of the amount of V2O5 by weight in a catalyst composition containing 3.6 wt% WO3 and 1.6 wt% Sb2O5, compared to a catalyst containing 2.7 wt% V2O5, 4.0 wt% WO3 and 0 wt% Sb2O5. [Figure 2] This shows the formation of N2O in a catalyst composition containing 3.6 wt% WO3 and 1.6 wt% Sb2O5 as a function of the amount of V2O5 by weight in both fresh and aged states at 550°C, compared to a catalyst containing 2.7 wt% V2O5, 4.0 wt% WO3, and 0 wt% Sb2O5. [Figure 3] This shows the conversion of NOx in fresh and aged states at 200°C as a function of the amount of WO3 in a catalyst composition containing 2.4 wt% V2O5 and 1.6 wt% Sb2O5, compared to a catalyst containing 2.7 wt% V2O5 and 0 wt% Sb2O5. [Figure 4]This shows the formation of N2O in the fresh and aged states at 550°C as a function of the amount of WO3 in a catalyst composition containing 2.4 wt% V2O5 and 1.6 wt% Sb2O5, compared to a catalyst containing 2.7 wt% V2O5 and 0 wt% Sb2O5. [Figure 5] The transformation of NOx as a function of the amount of Sb2O5 for a fresh catalyst composition is shown. [Figure 6] This shows the transformation of NOx as a function of the amount of Sb2O5 in the catalyst composition after aging. [Figure 7] This shows the conversion of NOx and formation of N2O at 550°C for a sample containing 0% by weight of ZrO2. [Figure 8] This shows the conversion of NOx and formation of N2O at 550°C for samples prepared using the one-pot method. [Modes for carrying out the invention]

[0069] Embodiment Embodiment 1: Preparation of an SCR catalyst article having a corrugated catalyst substrate SCR catalyst articles according to the present invention were prepared. A corrugated substrate was used as a catalyst substrate, and the SCR catalyst composition according to the present invention and several comparative catalyst compositions were attached to it.

[0070] Preparation of catalyst articles with corrugated catalyst substrate An aqueous slurry containing TiO2 (anatase) and ZrO(NO3)2 and having a dry matter content of 57 - 59 wt% was applied onto a corrugated substrate of 260 cpsi, where "cpsi" represents "cells per square inch". Subsequently, the substrate was calcined at 580 °C. Subsequently, an impregnation solution was prepared by mixing various amounts of A grams of an aqueous solution containing vanadyl oxalate (7.15% V), B grams of an aqueous solution of ammonium metatungstate (39.36% W), C grams of deionized water, D grams of tartaric acid, and E grams of antimony acetate (Sb(OAc)3) (see Table 1). Then, the substrate was immersed in the impregnation solution for 20 seconds, dried, and then heat-treated at 450 °C to obtain the catalyst loadings of %V2O5, %WO3, %Sb2O5, %ZrO2 based on the total weight of the catalyst composition as shown in Table 1.

[0071]

Table 1

[0072] Note that Examples 1, 4, 7, 8, and 9 in Table 1 are comparative examples because they either do not contain tungsten or antimony, or contain neither tungsten nor antimony.

[0073] Embodiment 2: NOx Conversion and N2O Formation of an SCR Catalyst Article with a Corrugated Catalyst Substrate The NOx conversion and N2O formation of the examples according to Embodiment 1 were tested in the fresh state and after aging under the following conditions.

[0074] NOx (250 ppm), NH3 (300 ppm), H2O (4%), O2 (12%), at GSVH = 100,000 -1 , 100% with N2. The NOx conversion was measured at 200, 250, 300, 350, 400, 450, 500 °C and 550 °C.

[0075] Aging was carried out at 550 °C for 100 hours, with H2O = (10%), at GSVH = 10,000 -1 and.

[0076] All percentages shown above refer to volume percentages.

[0077] GHSV is the space velocity of gas per unit time.

[0078] Entrance and exit numbers x Based on concentration, NO x The conversion is calculated as follows:

[0079]

number

[0080] During the ceremony, X:NO x Conversion % NOx in NO at the inlet end of the SCR catalyst article x concentration NOx out NO at the outlet end of the SCR catalyst article x concentration NO at both the entrance and exit ends x Concentration can be expressed in moles or mass. NO x The N2O concentration was measured by FTIR.

[0081] The results of NOx conversion and N2O formation for fresh and aged examples are shown in Tables 2 and 3.

[0082] X(T) is NO at temperature T in °C. x This shows the conversion. The formation of N2O was measured at 550°C.

[0083] [Table 2]

[0084] [Table 3]

[0085] Embodiment 3: NO as a function of the amount of V2O5 x Conversion and formation of N2O Figure 1 shows the conversion of NOx in the fresh and aged states at 200°C as a function of the amount of V2O5 in weight percent in a catalyst composition containing 3.6 wt% WO3 and 1.6 wt% Sb2O5. For comparison, a catalyst containing 2.7 wt% V2O5, 4.0 wt% WO3 and 0 wt% Sb2O5 is also shown. All amounts shown for each oxide are relative to the total amount of the catalyst composition. The remainder up to 100 wt% is represented by TiO2.

[0086] The aging of the catalyst composition and the measurement of NOx conversion were performed as described above.

[0087] Table 4 shows the catalyst compositions and NOx conversion.

[0088] The results are shown in Figure 1.

[0089] [Table 4]

[0090] Figure 2 shows the formation of N2O in the fresh and aged states at 550°C as a function of the amount of V2O5 in weight percent in a catalyst composition containing 3.6 wt% WO3 and 1.6 wt% Sb2O5. For comparison, a catalyst containing 2.7 wt% V2O5, 4.0 wt% WO3 and 0 wt% Sb2O5 is also shown. All amounts shown for each oxide are relative to the total amount of the catalyst composition. The remainder up to 100 wt% is represented by TiO2.

[0091] The aging of the catalyst composition and the formation of N2O were measured as described above.

[0092] Table 5 lists the catalyst compositions and the formation of N2O.

[0093] The results are shown in Figure 2.

[0094] [Table 5]

[0095] Embodiment 3: NO as a function of the quantity of WO3 x Conversion and formation of N2O NO in fresh and aged states at 200°C as a function of the amount of WO3 in weight % in a catalyst composition containing 2.4 wt% V2O5 and 1.6 wt% Sb2O5 x The conversion is shown in Figure 1. For comparison, catalysts containing 2.7 wt% V2O5, 0 wt% Sb2O5, and various amounts of WO3 are also shown. All amounts shown for each oxide are relative to the total amount of the catalyst composition. The remainder up to 100 wt% is represented by TiO2.

[0096] The aging of the catalyst composition and the measurement of NOx conversion were performed as described above.

[0097] Table 6 shows the catalyst compositions and NOx conversion.

[0098] The results are shown in Figure 3.

[0099] [Table 6]

[0100] Figure 4 shows the formation of N2O in the fresh and aged states at 550°C as a function of the amount of WO3 in weight percent in a catalyst composition containing 2.4 wt% V2O5 and 1.6 wt% Sb2O5. For comparison, catalysts containing 2.7 wt% V2O5, 0 wt% Sb2O5 and various amounts of WO3 are also shown. All amounts shown for each oxide are relative to the total amount of the catalyst composition. The remainder up to 100 wt% is represented by TiO2.

[0101] The aging of the catalyst composition and the formation of N2O were measured as described above.

[0102] Table 7 lists the catalyst compositions and the formation of N2O.

[0103] The results are shown in Figure 4.

[0104] [Table 7]

[0105] Embodiment 4: NO as a function of the amount of Sb2O5 x Conversion and formation of N2O Examples 2 and 26, which contain antimony, exhibit higher stability and better freshness performance than Examples 8 and 9, which do not contain antimony.

[0106] Example 9 demonstrates that the performance in the fresh state can be compensated for by increasing the tungsten content in a formulation that does not contain antimony. However, thermal stability cannot be obtained without adding antimony.

[0107] Table 8 shows NO as a function of the amount of Sb2O5 for fresh catalyst compositions. x This shows the conversion of NO and the formation of N2O. x The result of the conversion is shown in Figure 5.

[0108] Table 9 shows NO as a function of the amount of Sb2O5 for the catalyst composition after aging. x This shows the conversion of NO and the formation of N2O. x The result of the conversion is shown in Figure 6.

[0109] [Table 8]

[0110] [Table 9]

[0111] The above embodiment demonstrates that the addition of antimony improves the thermal stability of the catalyst composition. When antimony is present in the catalyst composition, the amounts of vanadium and tungsten required to obtain denitrification activity are smaller than those required for catalysts containing only vanadium and tungsten but without antimony.

[0112] In contrast to prior art, as can be seen from Figure 2, WO3 is shown to be necessary to obtain good fresh performance of the catalyst composition.

[0113] Embodiment 5: NO of a sample containing 0% ZrO2 x Conversion and formation of N2O An aqueous slurry containing TiO2 (anatase) with a dry content of 55% was applied to a corrugated substrate at 260 cpsi. Next, the zirconium-free substrate was calcined at 580°C. Subsequently, an impregnation solution was prepared by mixing 215 grams of an aqueous solution containing vanadyl oxalate (7.15% V), 72 grams of an aqueous solution of ammonium metatungstate (39.36% W), 151 grams of deionized water, 59 grams of tartaric acid, and 28 grams of antimony acetate. The substrate was then immersed in the impregnation solution for 20 seconds, dried, and then heat-treated at 450°C to obtain catalyst loadings of 3.1%, 4.0%, and 1.7% of %V2O5, %WO3, and %Sb2O5, respectively, based on the total weight of the catalyst composition. The sample labeled 27 was then used. NOx (250ppm), NH3 (300ppm), H2O (4%), O2 (12%), GSVH=100000 hours -1 The measurement was performed with N2 as 100%. NOx conversion was measured at 200, 250, 300, 350, 400, 450, 500°C and 550°C.

[0114] Aging was performed at 550°C for 100 hours, with H2O = (10%) and GSVH = 10000 hours. -1 I went there.

[0115] The results are shown in Figure 7 and Table 10.

[0116] [Table 10]

[0117] Embodiment 6: Conversion of NOx and formation of N2O in a sample prepared by the one-pot method An aqueous slurry containing TiO2 (anatase), VO2, Sb2 (glycolate)3, and WO3, with a dry matter content of 55%, was applied to a corrugated substrate at 260 cpsi and then calcined at 580°C to obtain catalyst loadings of 3.2%, 4.0%, and 2.0% of %V2O5, %WO3, and %Sb2O5, respectively, based on the total weight of the catalyst composition. The sample labeled 28 was then processed. NOx (250ppm), NH3 (300ppm), H2O (4%), O2 (12%), GSVH=100000 hours -1 The measurement was performed with N2 as 100%. NOx conversion was measured at 200, 250, 300, 350, 400, 450, 500°C and 550°C.

[0118] Aging was performed at 550°C for 100 hours, with H2O = (10%) and GSVH = 10000 hours. -1 I went there.

[0119] The results are shown in Figure 8 and Table 11.

[0120] [Table 11]

[0121] Embodiment 7: Sample prepared on a cordierite substrate using the one-pot method An aqueous slurry containing TiO2 (anatase), VO2, WO3, and Sb2O5, with a dry content of 55%, was applied to a cordierite substrate at 300 cpsi and then calcined at 580°C to obtain catalyst loadings of 3.2%, 4.0%, and 2.0% of %V2O5, %WO3, and %Sb2O5, respectively, based on the total weight of the catalyst composition.

[0122] The sample labeled 29, NOx (250ppm), NH3 (300ppm), H2O (4%), O2 (12%), GSVH=100000 hours -1 The measurement was performed with N2 as 100%. NOx conversion was measured at 200, 250, 300, 350, 400, 450, 500°C and 550°C.

[0123] Aging was performed at 550°C for 100 hours, with H2O = (10%) and GSVH = 10000 hours. -1 I went there.

[0124] The conversion of NOx and the formation of N2O are equivalent to those in Embodiment 6.

Claims

1. A catalyst composition for the selective catalytic reduction of nitrogen oxides, -V ２ O ５ Based on the total weight of the catalyst composition, the amount of at least one vanadium oxide is calculated to be 2.0 to 4.0% by weight. - WO ３ Based on the total weight of the catalyst composition, the amount of at least one tungsten oxide is calculated to be 2.5 to 7.2% by weight. -Sb ２ O ５ Based on the total weight of the catalyst composition, the amount of at least one antimony oxide is calculated to be 0.6 to 3.4% by weight. -ZrO ２ Based on the total weight of the catalyst, the amount of at least one zirconium oxide is calculated to be 0.2 to 1.0% by weight. - and TiO ２ Based on the total weight of the catalyst, the amount of at least one titanium oxide is calculated to be 84.6 to 94.7% by weight. V ２ O ５ , WO ３ , Sb ２ O ５ , TiO ２ and ZrO ２ A catalyst composition in which the weight ratios of vanadium, tungsten, antimony, titanium and zirconium oxides are calculated respectively so that the total is 100% by weight.

2. The at least one titanium oxide is titanium dioxide (TiO2). ２ The catalyst composition according to claim 1, wherein it comprises at least 95% by weight of anatase.

3. An SCR catalyst article comprising a catalyst substrate to which the SCR catalyst composition according to any one of claims 1 to 2 is attached in the form of a coating.

4. The SCR catalyst article according to claim 3, wherein the catalyst substrate is selected from a corrugated substrate and a cordierite monolith.

5. The SCR catalyst article according to claim 4, wherein the catalyst substrate is a cordierite monolith selected from wall flow filters and flow-through substrates.

6. A method for reducing nitrogen oxides in the exhaust gas of a lean-burn internal combustion engine, - A step of adding a reducing agent to the exhaust gas containing nitrogen oxides, A method comprising the step of passing an exhaust gas mixture obtained, which contains exhaust gas containing nitrogen oxides and a reducing agent, through a catalyst article according to any one of claims 3 to 5.

7. An exhaust gas purification system for treating diesel exhaust gases, - Oxidation catalyst, - Diesel particulate filters, and - Catalyst article according to any one of claims 3 to 5 or - Oxidation catalyst, and - An exhaust gas purification system comprising a diesel particulate filter, wherein the catalytic composition described in any one of claims 1 to 2 is present thereon as a coating.

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