Metal element modified alcohol-SCR (selective catalytic reduction) catalyst as well as preparation method and application thereof

Abstract

The invention provides a metal element modified alcohol-SCR catalyst as well as a preparation method and application thereof. The metal element modified alcohol-SCR catalyst comprises an aluminum-rich molecular sieve and a metal element loaded on the surface of the aluminum-rich molecular sieve, the metal elements comprise Bi and rare earth elements; the aluminum-rich molecular sieve comprises an H-Beta molecular sieve and / or an H-ZSM-5 molecular sieve; the silica-alumina ratio of the H-Beta molecular sieve is 3 to 14; the silica-alumina ratio of the H-ZSM-5 molecular sieve is 5 to 30. The aluminum-rich molecular sieve is selected as a matrix of the metal element modified alcohol-SCR catalyst, and the metal element is used for modifying the metal element to optimize the structure and surface properties of the metal element modified alcohol-SCR catalyst, so that a temperature window for catalyzing an alcohol-SCR reaction is improved, and the catalytic activity of the alcohol-SCR reaction and the nitrogen oxide conversion efficiency are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of catalytic technology, and relates to a catalyst for removing nitrogen oxides, in particular to an alcohol-SCR catalyst modified with metal elements and a preparation method and application thereof. Background Art

[0002] In the context of current environmental protection, the reduction of nitrogen oxides (NO x ) is of crucial importance. Selective catalytic reduction (SCR) technology, as an efficient method for NO x removal, has been widely applied in many fields. Among them, alcohol-SCR catalysts have become one of the important research directions in SCR technology due to their unique reaction characteristics. Traditional alcohol SCR catalysts face many challenges in practical applications, and the problem of narrow temperature window is particularly prominent. Most existing alcohol SCR catalysts can only exhibit high catalytic activity and selectivity within a specific and relatively narrow temperature range. Once the reaction temperature deviates from this range, the catalytic performance will drop sharply.

[0003] Based on the problems existing in the prior art, it is of great significance to develop an alcohol-SCR catalyst with a wide temperature window, low preparation cost and excellent catalytic performance. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide an alcohol-SCR catalyst modified with metal elements and a preparation method and application thereof. The present invention selects aluminosilicate zeolite as the matrix of the alcohol-SCR catalyst modified with metal elements and modifies it with metal elements to optimize its structure and surface properties, thereby improving the temperature window of the catalytic alcohol-SCR reaction and enhancing the catalytic activity and nitrogen oxide conversion efficiency of the alcohol-SCR reaction.

[0005] To achieve the purpose of this invention, the following technical solutions are adopted:

[0006] In the first aspect, the present invention provides an alcohol-SCR catalyst modified with metal elements, and the alcohol-SCR catalyst modified with metal elements includes aluminosilicate zeolite and metal elements supported on the surface of the aluminosilicate zeolite;

[0007] The metal elements include Bi and rare earth elements;

[0008] The aluminosilicate zeolite includes H-Beta zeolite and / or H-ZSM-5 zeolite;

[0009] The silicon-aluminum ratio of the H-Beta zeolite is 3-14; the silicon-aluminum ratio of the H-ZSM-5 zeolite is 5-30.

[0010] The present invention identifies the types and silicon-aluminum ratios of aluminum-rich molecular sieves, and selects H-Beta molecular sieves with a silicon-aluminum ratio of 3-14 and / or H-ZSM-5 molecular sieves with a silicon-aluminum ratio of 5-30 as the matrix of the metal element-modified alcohol-SCR catalyst. The aluminum-rich molecular sieve has the characteristic of abundant Al sites. The Si-O(H)-Al sites and adjacent extra-framework aluminum (EFAl) species cooperate, and without the need to additionally load active components, it can catalyze the conversion of nitrogen oxides into N2. The present invention modifies the aluminum-rich molecular sieve with metal elements. Bi can improve the temperature window of the catalyst, and rare earth elements can greatly improve the catalytic performance of the aluminum-rich molecular sieve. The two act synergistically to jointly optimize the structure and surface properties of the aluminum-rich molecular sieve, thereby improving the temperature window of the catalytic alcohol-SCR reaction and significantly enhancing the catalytic activity and nitrogen oxide conversion efficiency of the alcohol-SCR reaction.

[0011] Preferably, the mass ratio of Bi to the aluminum-rich molecular sieve is (0.5-10):100.

[0012] Preferably, the mass percentage of the rare earth element to the aluminum-rich molecular sieve is (0-10):100.

[0013] Preferably, the specific surface area of the aluminum-rich molecular sieve is 300m 2 / g - 800m 2 / g.

[0014] Preferably, the rare earth element includes any one or a combination of at least two of lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, erbium, ytterbium or yttrium, and is preferably lanthanum and / or samarium.

[0015] In a second aspect, the present invention provides a preparation method of the metal element-modified alcohol-SCR catalyst as described in the first aspect, and the preparation method includes:

[0016] Mix the aluminum-rich molecular sieve with a metal compound to prepare a precursor of the metal element-modified alcohol-SCR catalyst; calcine the precursor of the metal element-modified alcohol-SCR catalyst to obtain the metal element-modified alcohol-SCR catalyst;

[0017] The metal compound includes a Bi compound and a rare earth compound.

[0018] Preferably, the Bi compound includes any one or a combination of at least two of Bi(NO3)3, BiCl3, Bi2(SO4)3 or NaBiO3.

[0019] Preferably, the rare earth compound includes any one or a combination of at least two of oxides, nitrates, acetates or chlorides of rare earth elements.

[0020] Preferably, the method for preparing the metal element-modified alcohol-SCR catalyst precursor includes any one of liquid-phase mixing impregnation method, equal-volume impregnation method, liquid-phase ion exchange method, or solid-state grinding method, and preferably the liquid-phase mixing impregnation method.

[0021] Preferably, the liquid-phase mixing impregnation method includes:

[0022] Impregnate the aluminum-rich molecular sieve in an aqueous solution of a metal compound, stir in a water bath, then perform rotary evaporation and drying to obtain the metal element-modified alcohol-SCR catalyst precursor.

[0023] Preferably, the solid-liquid ratio of the aluminum-rich molecular sieve to the aqueous solution of the metal compound is 0.001 g / mL - 0.5 g / mL, and preferably 0.01 g / mL - 0.1 g / mL.

[0024] Preferably, the temperature of the water bath stirring is 25°C - 80°C, and the time of the water bath stirring is 0.5 h - 8 h.

[0025] Preferably, the temperature of the rotary evaporation is 25°C - 80°C.

[0026] Preferably, the temperature of the drying is 60°C - 100°C.

[0027] Preferably, the temperature of the calcination is 300°C - 800°C, and preferably 400°C - 600°C.

[0028] Preferably, the time of the calcination is 1 h - 10 h, and preferably 3 h - 6 h.

[0029] In the third aspect, the present invention provides an application of the metal element-modified alcohol-SCR catalyst as described in the first aspect, and the metal element-modified alcohol-SCR catalyst is applied to the field of nitrogen oxide removal.

[0030] The metal element-modified alcohol-SCR catalyst is applied to the scenario of removing NOx with alcohols as reducing agents, including but not limited to the tail gas treatment of automobiles, ships, non-road mobile sources, or stationary sources. When the metal element-modified alcohol-SCR catalyst is applied to nitrogen oxide removal, the alcohol used as a reducing agent only needs to be a compound with reducing ability at the temperature of the reduction treatment of the waste gas, without special limitation. It is preferably an alcohol with 6 or fewer carbon atoms, such as methanol, ethanol, propanol, isopropanol, etc., and more preferably methanol or ethanol.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention selects aluminosilicate zeolite as the matrix of the metal element-modified alcohol-SCR catalyst, and modifies it with metal elements to optimize its structure and surface properties, thereby improving the temperature window for catalyzing the alcohol-SCR reaction and enhancing the catalytic activity of the alcohol-SCR reaction and the conversion efficiency of nitrogen oxides.

[0033] (2) The present invention identifies the types and silica-alumina ratios of aluminosilicate zeolites, and selects H-Beta zeolite with a silica-alumina ratio of 3-14 or H-ZSM-5 zeolite with a silica-alumina ratio of 5-30 as the matrix of the metal element-modified alcohol-SCR catalyst. The aluminosilicate zeolite has the characteristic of abundant Al sites, and the Si-O(H)-Al sites and adjacent extra-framework aluminum (EFAl) species cooperate, and can catalyze the conversion of nitrogen oxides into N2 without additional loading of active components.

[0034] (3) The preparation method of the metal element-modified alcohol-SCR catalyst provided by the present invention is simple and easy to implement, has a low preparation cost, and is easy to realize industrial application. Description of the Drawings

[0035] Figure 1 are the activity test results of the metal element-modified alcohol-SCR catalysts provided in Example 1, Example 6, Comparative Example 1 and Comparative Example 2 at different temperatures. Detailed Embodiments

[0036] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the term "including" and any variations thereof in this application are intended to cover non-exclusive inclusion.

[0038] The object of the present invention is to provide a metal element-modified alcohol-SCR catalyst and its preparation method and application.

[0039] In a specific embodiment, the present invention provides a metal element-modified alcohol-SCR catalyst, and the metal element-modified alcohol-SCR catalyst includes an aluminosilicate zeolite and a metal element supported on the surface of the aluminosilicate zeolite;

[0040] The metal element includes Bi and rare earth elements;

[0041] The aluminosilicate zeolite includes H-Beta zeolite and / or H-ZSM-5 zeolite;

[0042] The silica-alumina ratio of the H-Beta molecular sieve is 3-14; the silica-alumina ratio of the H-ZSM-5 molecular sieve is 5-30.

[0043] In the present invention, the silica-alumina ratio of the aluminosilicate molecular sieve refers to the molar ratio of Si atoms to Al atoms. The silica-alumina ratio of the H-Beta molecular sieve is 3-14, for example, it can be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable; the silica-alumina ratio of the H-ZSM-5 molecular sieve is 5-30, for example, it can be 5, 10, 15, 20, 25 or 30, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0044] In the present invention, the type and silica-alumina ratio of the aluminosilicate molecular sieve are identified, and the H-Beta molecular sieve with a silica-alumina ratio of 3-14 and / or the H-ZSM-5 molecular sieve with a silica-alumina ratio of 5-30 are selected as the matrix of the metal element-modified alcohol-SCR catalyst. The aluminosilicate molecular sieve has the characteristic of abundant Al sites. The Si-O(H)-Al sites and adjacent extra-framework aluminum (EFAl) species cooperate, and without additional loading of active components, it can catalyze the conversion of nitrogen oxides into N2. In the present invention, the aluminosilicate molecular sieve is modified with metal elements. Bi can improve the temperature window of the catalyst, and rare earth elements can greatly improve the catalytic performance of the Beta molecular sieve. The two act synergistically to jointly optimize the structure and surface properties of the aluminosilicate molecular sieve, thereby improving the temperature window of the catalytic alcohol-SCR reaction and significantly enhancing the catalytic activity and nitrogen oxide conversion efficiency of the alcohol-SCR reaction.

[0045] In the metal element-modified alcohol-SCR catalyst provided by the present invention, the Bi element is used to adjust the active temperature window. The increase in the loading amount of Bi can lower the active temperature window. However, if the loading amount of Bi is too much, the excessive oxidation will lead to a significant decrease in the performance at high temperatures. If the loading amount of Bi is too little, there are not enough metal active sites to drive the reduction of the active temperature window.

[0046] In some embodiments, the mass ratio of Bi to the aluminosilicate molecular sieve is (0.5-10):100, for example, it can be 0.5:100, 1:100, 2:100, 3, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100 or 10:100, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable, and preferably (0.5-4):100.

[0047] In the metal element-modified alcohol-SCR catalyst provided by the present invention, rare earth elements are used to improve the catalytic performance of the molecular sieve support. An increase in the loading amount of rare earth elements helps to improve the activity. However, if the loading amount of rare earth elements is too high, the excessive enhancement of oxidizing property will lead to a significant decrease in the performance at high temperature. If the loading amount of rare earth elements is too low, there are not enough metal active sites to promote the activation of reaction species, and the effect of good activity improvement cannot be achieved.

[0048] In some embodiments, the mass percentage of the rare earth element to the aluminum-rich molecular sieve is (0-10):100. For example, it can be 0, 0.5:100, 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100 or 10:100, including but not limited to the listed values. Other unlisted values within the numerical range are equally applicable. Preferably, it is (1-4):100.

[0049] In some embodiments, the specific surface area of the aluminum-rich molecular sieve is 300 m 2 / g - 800 m 2 / g. For example, it can be 300 m 2 / g, 350 m 2 / g, 400 m 2 / g, 450 m 2 / g, 500 m 2 / g, 550 m 2 / g, 600 m 2 / g, 650 m 2 / g, 700 m 2 / g, 750 m 2 / g or 800 m 2 / g, including but not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0050] In some embodiments, the rare earth element includes any one or a combination of at least two of lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, erbium, ytterbium or yttrium. Typical but non-limiting combinations include the combination of lanthanum and cerium, the combination of praseodymium and neodymium, the combination of samarium and gadolinium, or the combination of erbium and yttrium. Preferably, it is lanthanum and / or samarium.

[0051] In another specific embodiment, the present invention provides a preparation method of a metal element-modified alcohol-SCR catalyst as described in the above specific embodiment. The preparation method includes:

[0052] Mixing the aluminum-rich molecular sieve with a metal compound to prepare a precursor of the metal element-modified alcohol-SCR catalyst; calcining the precursor of the metal element-modified alcohol-SCR catalyst to obtain the metal element-modified alcohol-SCR catalyst;

[0053] The metal compound includes a Bi compound and a rare earth compound.

[0054] In some embodiments, the Bi compound includes any one or a combination of at least two of Bi(NO3)3, BiCl3, Bi2(SO4)3, or NaBiO3. Typical but non-limiting combinations include the combination of Bi(NO3)3 and BiCl3, the combination of BiCl3 and Bi2(SO4)3, the combination of Bi2(SO4)3 and NaBiO3, or the combination of NaBiO3 and Bi(NO3)3.

[0055] In some embodiments, the rare earth compound includes any one or a combination of at least two of oxides, nitrates, acetates, or chlorides of rare earth elements. Typical but non-limiting combinations include the combination of oxides and nitrates of rare earth elements, the combination of acetates and chlorides, the combination of nitrates and acetates, or the combination of chlorides and oxides.

[0056] In some embodiments, when the metal compound includes both a Bi compound and a rare earth compound, the method of mixing the dealuminized zeolite with the metal compound includes simultaneously mixing the dealuminized zeolite, the Bi compound, and the rare earth compound.

[0057] In some embodiments, when the metal compound includes both a Bi compound and a rare earth compound, the method of mixing the dealuminized zeolite with the metal compound includes first mixing the dealuminized zeolite with one of the Bi compound or the rare earth compound, and then mixing with the other.

[0058] In some embodiments, the method for preparing the metal element-modified alcohol-SCR catalyst precursor includes any one of liquid-phase mixing impregnation method, equal-volume impregnation method, liquid-phase ion exchange method, or solid-state grinding method, preferably the liquid-phase mixing impregnation method.

[0059] In some embodiments, the liquid-phase mixing impregnation method includes:

[0060] Impregnating the dealuminized zeolite in an aqueous solution of the metal compound, stirring in a water bath, rotary evaporation, and drying to obtain the metal element-modified alcohol-SCR catalyst precursor.

[0061] In some embodiments, when the metal compound includes both a Bi compound and a rare earth compound, the liquid-phase mixed impregnation method includes impregnating the aluminum-rich molecular sieve in an aqueous solution of the Bi compound / rare earth compound, stirring in a water bath, rotary evaporation, and drying to obtain an aluminum-rich molecular sieve loaded with the Bi compound / rare earth compound; then impregnating the aluminum-rich molecular sieve loaded with the Bi compound / rare earth compound in an aqueous solution of the rare earth compound / Bi compound, stirring in a water bath, rotary evaporation, and drying to obtain the precursor of the metal element-modified alcohol-SCR catalyst.

[0062] In some embodiments, the equal-volume impregnation method includes:

[0063] Dripping an aqueous solution of a metal compound into an aluminum-rich support, stirring evenly, and drying to obtain the precursor of the metal element-modified alcohol-SCR catalyst.

[0064] In some embodiments, the liquid-phase ion exchange method includes:

[0065] Impregnating the aluminum-rich molecular sieve in an aqueous solution of a metal compound, stirring in a water bath, filtering, rinsing with deionized water, and drying to obtain the precursor of the metal element-modified alcohol-SCR catalyst.

[0066] In some embodiments, the solid-state grinding method includes:

[0067] Performing solid-state grinding and mixing of the aluminum-rich molecular sieve and a metal compound to obtain the precursor of the metal element-modified alcohol-SCR catalyst.

[0068] In some embodiments, in the liquid-phase mixed impregnation method and / or the liquid-phase ion exchange method, the solid-liquid ratio of the aluminum-rich molecular sieve to the aqueous solution of the metal compound is independently 0.001 g / mL - 0.5 g / mL, for example, it can be 0.001 g / mL, 0.005 g / mL, 0.01 g / mL, 0.02 g / mL, 0.03 g / mL, 0.04 g / mL, 0.05 g / mL, 0.06 g / mL, 0.07 g / mL, 0.08 g / mL, 0.09 g / mL, 0.1 g / mL, 0.2 g / mL, 0.4 g / mL, or 0.5 g / mL, including but not limited to the recited values, and other unrecited values within the numerical range are equally applicable, and preferably 0.01 g / mL - 0.1 g / mL.

[0069] In some embodiments, in the liquid-phase mixing impregnation method and / or the liquid-phase ion exchange method, the temperature of the water bath stirring is independently 25°C - 80°C, for example, it can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable; the time of the water bath stirring is 0.5h - 8h, for example, it can be 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h or 8h, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0070] In some embodiments, the temperature of the rotary evaporation is 25°C - 80°C, for example, it can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0071] In some embodiments, in the liquid-phase mixing impregnation method, the equal-volume impregnation method or the liquid-phase ion exchange method, the drying temperature is independently 60°C - 100°C, for example, it can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0072] In the present invention, the time for drying the metal element-modified alcohol-SCR catalyst precursor is not particularly limited, aiming to completely volatilize the residual solvent.

[0073] In some embodiments, the calcination temperature is 300°C - 800°C, for example, it can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C or 800°C, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable, and preferably 400°C - 600°C.

[0074] In some embodiments, the calcination time is 1h - 10h, for example, it can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable, and preferably 3h - 6h.

[0075] In another specific embodiment, the present invention is the application of the metal element-modified alcohol-SCR catalyst as described in the above specific embodiment, and the metal element-modified alcohol-SCR catalyst is applied to the field of nitrogen oxide removal.

[0076] Example 1

[0077] This embodiment provides an alcohol-SCR catalyst modified with metal elements. The alcohol-SCR catalyst modified with metal elements includes an H-Beta molecular sieve with a specific surface area of 500 m 2 / g and a Si / Al ratio of 5, as well as Bi and Sm supported on the surface of the H-Beta molecular sieve. Among them, the mass ratio of Bi and Sm to the H-Beta molecular sieve is 2:100, that is, the total mass ratio of Bi and Sm to the H-Beta molecular sieve is 4:100.

[0078] The preparation method of the alcohol-SCR catalyst modified with metal elements includes:

[0079] According to the mass ratio of Bi and Sm to the H-Beta molecular sieve of 2:100 and a solid solution ratio of 0.01 g / mL, the H-Beta molecular sieve with a Si / Al ratio of 5 is impregnated in an aqueous solution of Bi(NO3)3·5H2O and Sm(NO3)3·6H2O, stirred in a water bath at 40 °C for 5 h, rotary evaporated at 60 °C, and then dried at 100 °C to obtain the precursor of the alcohol-SCR catalyst modified with metal elements; the precursor of the alcohol-SCR catalyst modified with metal elements is calcined at 550 °C for 4 h to prepare the alcohol-SCR catalyst modified with metal elements.

[0080] Example 2

[0081] This embodiment provides an alcohol-SCR catalyst modified with metal elements. The alcohol-SCR catalyst modified with metal elements includes an H-Beta molecular sieve with a specific surface area of 800 m 2 / g and a Si / Al ratio of 3, as well as Bi, Sm, and La supported on the surface of the H-Beta molecular sieve. Among them, the mass ratio of Bi to the H-Beta molecular sieve is 4:100, the mass ratio of Sm to the H-Beta molecular sieve is 1:100, and the mass ratio of La to the H-Beta molecular sieve is 3:100, that is, the total mass ratio of Bi, Sm, and La to the H-Beta molecular sieve is 8:100.

[0082] The preparation method of the alcohol-SCR catalyst modified with metal elements includes:

[0083] According to the mass ratio of Bi to H-Beta molecular sieve being 4:100, the mass ratio of Sm to H-Beta molecular sieve being 1:100, and the mass ratio of La to H-Beta molecular sieve being 3:100, with a solid solution ratio of 0.08 g / mL, the H-Beta molecular sieve with Si / Al of 3 was impregnated in an aqueous solution of Bi(NO3)3·5H2O, Sm(NO3)3·6H2O, and La(NO3)3·6H2O, stirred in a water bath at 25 °C for 8 h, rotary evaporated at 25 °C, and then dried at 60 °C to obtain the precursor of the metal element-modified alcohol-SCR catalyst; at 400 °C, the precursor of the metal element-modified alcohol-SCR catalyst was calcined for 6 h to prepare the metal element-modified alcohol-SCR catalyst.

[0084] Example 3

[0085] This example provides a metal element-modified alcohol-SCR catalyst. The metal element-modified alcohol-SCR catalyst includes an H-Beta molecular sieve with a specific surface area of 300 m 2 / g and Si / Al of 14, as well as Bi and Y supported on the surface of the H-Beta molecular sieve. Among them, the mass ratio of Bi to the H-Beta molecular sieve is 1:100, and the mass ratio of Y to the H-Beta molecular sieve is 3:100, that is, the total mass ratio of Bi and Y to the H-Beta molecular sieve is 4:100.

[0086] The preparation method of the metal element-modified alcohol-SCR catalyst includes:

[0087] According to the mass ratio of Bi to the H-Beta molecular sieve being 1:100 and the mass ratio of Y to the H-Beta molecular sieve being 3:100, the H-ZSM-5 molecular sieve with Si / Al of 14 was subjected to solid-state grinding with Bi(NO3)3·5H2O and Y(NO3)3·6H2O to obtain the precursor of the metal element-modified alcohol-SCR catalyst; at 300 °C, the precursor of the metal element-modified alcohol-SCR catalyst was calcined for 10 h to prepare the metal element-modified alcohol-SCR catalyst.

[0088] Example 4

[0089] This example provides a metal element-modified alcohol-SCR catalyst. The metal element-modified alcohol-SCR catalyst includes an H-Beta molecular sieve with a specific surface area of 450 m 2H-ZSM-5 zeolite with a specific surface area of 600 m² / g and a Si / Al ratio of 14, as well as Bi and Pr supported on the surface of the ZSM-5 zeolite, where the mass ratio of Bi to the ZSM-5 zeolite is 0.5:100, and the mass ratio of Pr to the ZSM-5 zeolite is 1:100, that is, the total mass ratio of Bi and Pr to the ZSM-5 zeolite is 1.5:100.

[0090] The preparation method of the metal element modified alcohol-SCR catalyst includes:

[0091] According to the mass ratio of Bi to the ZSM-5 zeolite being 0.5:100 and the mass ratio of Pr to the ZSM-5 zeolite being 1:100, solid-state grinding is carried out on the H-ZSM-5 zeolite with a Si / Al ratio of 14 and Bi(NO₃)₃·5H₂O and Pr(NO₃)₃·6H₂O to obtain the precursor of the metal element modified alcohol-SCR catalyst; at 600 °C, the precursor of the metal element modified alcohol-SCR catalyst is calcined for 3 h to prepare the metal element modified alcohol-SCR catalyst.

[0092] Example 5

[0093] This example provides a metal element modified alcohol-SCR catalyst. The metal element modified alcohol-SCR catalyst includes H-ZSM-5 zeolite with a specific surface area of 600 m² 2 / g and a Si / Al ratio of 5, as well as Bi and La supported on the surface of the H-ZSM-5 zeolite, where the mass ratio of Bi to the H-ZSM-5 zeolite is 8:100, and the mass ratio of La to the H-ZSM-5 zeolite is 10:100, that is, the total mass ratio of Bi, Sm, and La to the H-ZSM-5 zeolite is 18:100.

[0094] The preparation method of the metal element modified alcohol-SCR catalyst includes:

[0095] According to the mass ratio of Bi to the H-ZSM-5 zeolite being 8:100, the mass ratio of La to the H-ZSM-5 zeolite being 10:100, and the solid solution ratio being 0.2 g / mL, the H-ZSM-5 zeolite with a Si / Al ratio of 3 is impregnated in an aqueous solution of Bi(NO₃)₃·5H₂O, Sm(NO₃)₃·6H₂O, and La(NO₃)₃·6H₂O, stirred in a water bath at 25 °C for 8 h, rotary evaporated at 25 °C, and then dried at 60 °C to obtain the precursor of the metal element modified alcohol-SCR catalyst; at 450 °C, the precursor of the metal element modified alcohol-SCR catalyst is calcined for 5 h to prepare the metal element modified alcohol-SCR catalyst.

[0096] Example 6

[0097] This embodiment provides an alcohol-SCR catalyst modified with metal elements. The alcohol-SCR catalyst modified with metal elements includes an H-ZSM-5 molecular sieve with a specific surface area of 600 m 2 / g and a Si / Al ratio of 30, and Bi supported on the surface of the H-ZSM-5 molecular sieve. Among them, the mass ratio of Bi to the H-ZSM-5 molecular sieve is 10:100.

[0098] The preparation method of the alcohol-SCR catalyst modified with metal elements includes:

[0099] According to the mass ratio of Bi to the H-ZSM-5 molecular sieve being 10:100 and the solid solution ratio being 0.005 g / mL, the H-ZSM-5 molecular sieve with a Si / Al ratio of 30 is impregnated in an aqueous solution of Bi(NO3)3·5H2O, stirred in a water bath at 25°C for 8 h, rotary evaporated at 25°C, and then dried at 60°C to obtain the precursor of the alcohol-SCR catalyst modified with metal elements; at 800°C, the precursor of the alcohol-SCR catalyst modified with metal elements is calcined for 1 h to prepare the alcohol-SCR catalyst modified with metal elements.

[0100] Example 7

[0101] This embodiment provides an alcohol-SCR catalyst modified with metal elements. The alcohol-SCR catalyst modified with metal elements is the same as that in Example 1 except that the mass ratios of Bi and Sm to the H-Beta molecular sieve are both 0.1:100, that is, the total mass ratio of Bi and Sm to the H-Beta molecular sieve is 0.2:100.

[0102] The preparation method of the alcohol-SCR catalyst modified with metal elements is the same as that in Example 1 except that according to the mass ratios of Bi and Sm to the H-Beta molecular sieve being both 0.1:100, the H-Beta molecular sieve with a Si / Al ratio of 5 is impregnated in an aqueous solution of Bi(NO3)3·5H2O and Sm(NO3)3·6H2O.

[0103] Example 8

[0104] This embodiment provides an alcohol-SCR catalyst modified with metal elements. The alcohol-SCR catalyst modified with metal elements is the same as that in Example 1 except that the mass ratios of Bi and Sm to the H-Beta molecular sieve are both 11:100, that is, the total mass ratio of Bi and Sm to the H-Beta molecular sieve is 22:100.

[0105] The preparation method of the metal element modified alcohol-SCR catalyst is the same as that of Example 1 except that the H-Beta zeolite with Si / Al of 5 is impregnated in the aqueous solutions of Bi(NO3)3·5H2O and Sm(NO3)3·6H2O according to the mass ratio of Bi and Sm to the H-Beta zeolite both being 11:100.

[0106] Example 9

[0107] This example provides a metal element modified alcohol-SCR catalyst. The difference between the metal element modified alcohol-SCR catalyst and that of Example 1 is that during the preparation process, the temperature for calcining the precursor of the metal element modified alcohol-SCR catalyst is 250 °C, and the rest are the same as those of Example 1.

[0108] Example 10

[0109] This example provides a metal element modified alcohol-SCR catalyst. The difference between the metal element modified alcohol-SCR catalyst and that of Example 1 is that during the preparation process, the temperature for calcining the precursor of the metal element modified alcohol-SCR catalyst is 900 °C, and the rest are the same as those of Example 1.

[0110] Comparative Example 1

[0111] This comparative example provides a metal element modified alcohol-SCR catalyst, which is an H-Beta zeolite with a specific surface area of 500 m 2 / g and Si / Al of 5.

[0112] Comparative Example 2

[0113] This comparative example provides a metal element modified alcohol-SCR catalyst, which is the same as that of Example 1 except that Bi is not loaded.

[0114] The preparation method of the metal element modified alcohol-SCR catalyst is the same as that of Example 1 except that the H-Beta zeolite with Si / Al of 5 is impregnated in the aqueous solution of Sm(NO3)3·6H2O according to the mass ratio of Sm to the H-Beta zeolite being 2:100 and the solid solution ratio being 0.01 g / mL.

[0115] Comparative Example 3

[0116] This comparative example provides a metal element modified alcohol-SCR catalyst, which is the same as that of Example 1 except that the Si / Al of the H-Beta zeolite is 20.

[0117] The preparation method of the metal element modified alcohol-SCR catalyst is the same as that of Example 1, except that the H-Beta zeolite with Si / Al of 20 is impregnated in the aqueous solution of Bi(NO3)3·5H2O and Sm(NO3)3·6H2O.

[0118] Comparative Example 4

[0119] This comparative example provides a metal element modified alcohol-SCR catalyst, which is the same as Example 4 except that the Si / Al of the H-ZSM-5 zeolite is 40.

[0120] The preparation method of the metal element modified alcohol-SCR catalyst is the same as that of Example 1, except that the H-ZSM-5 zeolite with Si / Al of 40 is subjected to solid-state grinding with Bi(NO3)3·5H2O and Pr(NO3)3·6H2O.

[0121] Performance test:

[0122] The present invention tests the activities of the metal element modified alcohol-SCR catalysts provided in all the above examples and comparative examples at different temperatures, detects the component composition in the tail gas by a Fourier transform infrared spectrometer, and calculates the conversion efficiency of NO x . Among them, the reaction space velocity is 30000 h -1 , and the test gas composition is: [NO]=1000 ppm, [CH3OH]=2000 ppm, [O2]=10%, [H2O]=5%, and the balance gas is N2. The test results are shown in Table 1.

[0123] Figure 1 It is the activity test results of the metal element modified alcohol-SCR catalysts provided in Example 1, Example 6, Comparative Example 1 and Comparative Example 2 at different temperatures.

[0124] Table 1

[0125]

[0126]

[0127] According to the test results of Examples 1 to 9 and Comparative Example 1, after using Bi and rare earth elements defined in the present application to jointly modify the aluminum-rich zeolite, the obtained metal element modified alcohol-SCR catalyst exhibits excellent denitrification performance, the temperature window for catalyzing the alcohol-SCR reaction is improved, and the conversion efficiency of NO x is significantly improved.

[0128] According to the test results of Example 1 and Comparative Example 2, if only rare earth elements are used to modify the aluminum-rich molecular sieve, the structure and surface of the aluminum-rich molecular sieve cannot be effectively optimized, and the temperature window for catalyzing the alcohol-SCR reaction cannot be improved.

[0129] According to the test results of Example 1 and Comparative Example 3, as well as Example 4 and Comparative Example 4, if the Si / Al of the molecular sieve serving as the matrix of the alcohol-SCR catalyst modified with metal elements does not meet the scope of this application, the denitration performance will decrease significantly.

[0130] The applicant declares that the above description is only a specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. An alcohol-SCR catalyst modified by a metal element, characterized in that, The metal element-modified alcohol-SCR catalyst includes an aluminum-rich molecular sieve and a metal element supported on the surface of the aluminum-rich molecular sieve; The metal element includes Bi and rare earth elements; The aluminum-rich molecular sieve includes H-Beta molecular sieve and / or H-ZSM-5 molecular sieve; The silicon-aluminum ratio of the H-Beta molecular sieve is 3-14; the silicon-aluminum ratio of the H-ZSM-5 molecular sieve is 5-30.

2. The metal element-modified alcohol-SCR catalyst according to claim 1, wherein The mass ratio of Bi to the aluminum-rich molecular sieve is (0.5-10):100; and / or, the mass percentage of the rare earth element to the aluminum-rich molecular sieve is (0-10):100; And / or, the specific surface area of the aluminum-rich molecular sieve is 300 m 2 / g - 800 m 2 / g.

3. The metal element-modified alcohol-SCR catalyst according to claim 1 or 2, characterized in that, The rare earth element includes any one or a combination of at least two of lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, erbium, ytterbium or yttrium.

4. A method for preparing a metal element-modified alcohol-SCR catalyst according to any one of claims 1-3, characterized in that, The preparation method includes: Mixing the aluminum-rich molecular sieve with a metal compound to prepare a precursor of the metal element-modified alcohol-SCR catalyst; calcining the precursor of the metal element-modified alcohol-SCR catalyst to obtain the metal element-modified alcohol-SCR catalyst; The metal compound includes a Bi compound and a rare earth compound.

5. The preparation method according to claim 4, characterized in that, The Bi compound includes any one or a combination of at least two of Bi(NO3)3, BiCl3, Bi2(SO4)3 or NaBiO3; and / or, the rare earth compound includes any one or a combination of at least two of oxides, nitrates, acetates or chlorides of rare earth elements.

6. The preparation method according to claim 4 or 5, characterized in that The method for preparing the precursor of the metal element-modified alcohol-SCR catalyst includes any one of liquid-phase mixing impregnation method, equal-volume impregnation method, liquid-phase ion exchange method or solid-state grinding method, preferably the liquid-phase mixing impregnation method.

7. The preparation method according to claim 6, wherein The liquid-phase mixing impregnation method includes: Impregnating the aluminum-rich molecular sieve in an aqueous solution of a metal compound, stirring in a water bath, rotary evaporating, and drying to obtain the precursor of the metal element-modified alcohol-SCR catalyst; and / or, the solid-liquid ratio of the aluminum-rich molecular sieve to the aqueous solution of the metal compound is 0.001g / mL-0.5g / mL; and / or, the temperature of the water bath stirring is 25°C-80°C, and the time of the water bath stirring is 0.5h-8h; and / or, the temperature of the rotary evaporation is 25°C-80°C; and / or, the drying temperature is 60°C-100°C.

8. The preparation method according to any one of claims 4-7, characterized in that, The calcination temperature is 300°C-800°C; and / or, the calcination time is 1h-10h.

9. The preparation method according to claim 8, characterized in that, The calcination temperature is 400°C-600°C; and / or, the calcination time is 3h-6h.

10. Use of the metal element-modified alcohol-SCR catalyst according to any one of claims 1-3, characterized in that, The metal element-modified alcohol-SCR catalyst is applied to the field of nitrogen oxide removal.

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