A denitration catalyst, a method for preparing the same, and use thereof

Abstract

The present application relates to a kind of denitration catalyst and its preparation method and use, the denitration catalyst includes layered FAU molecular sieve matrix and the composite oxide active component supported on the surface and channel of the layered FAU molecular sieve matrix, the chemical formula of the composite oxide active component is MCuO x , M is rare earth doping element, wherein, x is the molar amount of oxygen atom in composite oxide, 1≤x≤2.The denitration catalyst of the present application has higher surface acidity and redox capacity, the composite oxide MCuO x Located in the surface and channel of layered FAU molecular sieve matrix improves the sulfur dioxide poisoning resistance of catalyst, ensures that catalyst still has higher catalytic activity in high SO2 Environment, even maintains original activity, and has higher catalytic activity and nitrogen selectivity in the use temperature range of 250-400 DEG C.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental protection catalysts, and relates to a molecular sieve confined denitration catalyst as well as a preparation method and application thereof. BACKGROUND

[0002] Nitrogen oxides (NO x ) are the main source of air pollution, mainly from the combustion of fossil fuels. Excessive emissions will cause environmental and climate problems such as acid rain, photochemical smog and global warming. Traditional denitration technology uses the ammonia selective catalytic reduction (NH3-SCR) method, with V2O5-WO3 / TiO2 or its modified substances as catalysts, and the operating temperature is usually 300-400℃. However, such catalysts have low activity at 250℃, and V2O5 is toxic, which becomes a bottleneck for development. Catalysts with copper oxide (CuO) and modified copper oxide as active components have attracted widespread attention from researchers due to their good low-temperature catalytic activity, high nitrogen selectivity and environmental protection characteristics.

[0003] Currently, in practical applications, the SCR denitration catalyst used for boiler flue gas treatment will encounter the problem of catalyst deactivation caused by sulfur dioxide poisoning. This is because the coal ash produced during the boiler combustion process contains a certain amount of sulfur dioxide gas, which covers the surface of the catalyst and reacts with ammonia and copper-based active components to form ammonium sulfate and cover the surface of the catalyst, which reduces the number of active sites exposed. At the same time, this will also lead to the formation of copper sulfate which is not easy to decompose, which destroys the redox capacity of the catalyst and causes irreversible deactivation of the catalyst.

[0004] CN102416320A discloses a denitration catalyst, relating to the technical field of catalysts. The catalyst is composed of the following components in weight parts: titanium dioxide 75-85 parts; tungsten trioxide 10-12 parts; silicon dioxide 3-6 parts; vanadium pentoxide 2-3 parts; kapok pulp 3-6 parts; glass fiber 2-7 parts; stearic acid 2-3 parts; after mixing the components in weight parts, stirring uniformly, then sequentially aging, pre-extruding, secondary aging, extruding, primary drying, secondary drying, high-temperature calcination, and product finishing, the catalyst product can be packaged.

[0005] CN107737588A discloses a denitration catalyst, and the raw materials are titanium dioxide 35-45 parts, antimony oxide 2-5 parts, glass fiber 10-20 parts, vanadium pentoxide 1-3 parts, molybdenum oxide 3-6 parts, and tungsten oxide 3-6 parts by weight.

[0006] The denitration catalysts described in the above scheme are difficult to balance high-temperature and low-temperature catalytic activity, and the activity of the catalysts sharply decreases after being poisoned by sulfur dioxide, so improving the denitration performance of the denitration catalyst in the presence of sulfur dioxide is very important for saving the flue gas purification cost of the coal-fired industry and improving the waste gas treatment efficiency. SUMMARY

[0007] To solve the above technical problems, the present application aims to provide a denitration catalyst and a preparation method and use thereof, the denitration catalyst has high surface acidity and redox capacity, the composite oxide MCuO x The sulfur dioxide poisoning resistance of the catalyst is improved, the catalyst still has high catalytic activity in a high SO2 environment, even maintains the original activity, and has high catalytic activity and nitrogen selectivity in a use temperature range of 250-400 DEG C.

[0008] To achieve this purpose, the following technical scheme is adopted in the present application:

[0009] In a first aspect, the present application provides a denitration catalyst, the denitration catalyst comprises a layered FAU molecular sieve matrix and a composite oxide active component loaded on the surface and pores of the layered FAU molecular sieve matrix, the chemical formula of the composite oxide active component is MCuO x , M is a rare earth doping element, wherein x is the molar amount of oxygen atoms in the composite oxide, 1≤x≤2.

[0010] In the denitration catalyst provided by the present application, the FAU molecular sieve matrix has a layered morphology, so it has strong interlayer mass transfer capacity and can quickly diffuse NO x , NH3 and other gases to active sites, the composite oxide active component MCuO x contains M-O-Cu asymmetric oxygen vacancies, which can enhance the adsorption capacity of NO x , the introduction of rare earth elements can improve the overall redox capacity of the catalyst, and the highly dispersed MCuO x active sites anchored in the molecular sieve framework make it difficult for sulfur dioxide to chemically adsorb on the catalyst. The denitration catalyst provided by the present application has strong Bronsted acid sites and Lewis acid sites, which can increase the adsorption capacity of the catalyst for NH3 and the poisoning resistance of the catalyst to sulfur dioxide.

[0011] The following is a preferred technical scheme of the present application, but not as a limitation on the technical scheme provided by the present application, through the following preferred technical scheme, the technical purpose and beneficial effects of the present application can be better achieved and realized.

[0012] Preferably, the layered FAU molecular sieve matrix includes an X-type molecular sieve or a Y-type molecular sieve, and is preferably an X-type molecular sieve.

[0013] Preferably, the silica-to-alumina ratio of the layered FAU molecular sieve matrix is ​​(1-30):1, for example, it can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 12:1, 14:1, 16:1, 18:1, 20:1, 22:1, 24:1, 26:1, 28:1, 29:1 or 30:1, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0014] Preferably, the molar fraction of the composite oxide active component is 5-30% based on the total molar amount of silicon and composite oxide active components in the FAU molecular sieve. For example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 28%, or 30%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 10-25%.

[0015] Preferably, in the active component of the composite oxide, the molar ratio of rare earth dopant to copper is (0.05-0.2):1, for example, it can be 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.11:1, 0.12:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1, 0.16:1, 0.17:1, 0.18:1, 0.19:1 or 0.2:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] In this invention, the molar ratio of rare earth dopant elements to copper elements affects its performance. By controlling the molar ratio of rare earth dopant elements to copper elements at (0.05~0.2):1, the denitration catalyst can maintain high-temperature catalytic activity and also has excellent low-temperature activity. If the cerium content is too low, the high-temperature performance of the catalyst will decrease after 350℃. If the cerium content is too high, the low-temperature performance of the catalyst will be poor before 300℃.

[0017] Preferably, the rare earth doping element includes any one or a combination of at least two of cerium, neodymium, samarium, cobalt, europium, yttrium, dysprosium, ytterbium, lanthanum, or praseodymium. Typical but non-limiting combinations include combinations of cerium and neodymium, neodymium and samarium, cobalt and europium, dysprosium, ytterbium, and lanthanum, cerium, neodymium, samarium, cobalt, and europium, cobalt, europium, yttrium, yttrium, ytterbium, and lanthanum, and combinations of cerium, neodymium, samarium, cobalt, ytterbium, lanthanum, and praseodymium.

[0018] In a second aspect, the present invention provides a method for preparing a denitrification catalyst as described in the first aspect, the method comprising the following steps:

[0019] An aluminum source, sodium hydroxide, silicon source, rare earth dopant source, copper source, and water are mixed and stirred, and then subjected to a hydrothermal reaction to obtain a first product. The first product is then mixed with an ammonium nitrate solution for ion exchange to obtain a second product. The second product is then calcined to obtain the denitrification catalyst.

[0020] The denitrification catalyst provided by this invention is simple and easy to operate. It involves adding molecular sieve raw materials and active component raw materials together for a hydrothermal reaction, followed by ion exchange to obtain the denitrification catalyst. Because the FAU molecular sieve structure has a stable topological structure and low crystal formation energy, it can successfully crystallize at a relatively low temperature after the addition of sodium hydroxide. Therefore, compared with conventional preparation methods in the prior art (such as the synthesis of Cu-SSZ-13, Cu-SAPO-34, and Cu-ZSM-5 molecular sieve catalysts), this method eliminates the step of adding an organic template agent and does not require a hydrothermal process of more than 12 hours, saving preparation time and cost.

[0021] Preferably, the silicon source includes sodium silicate.

[0022] Preferably, the aluminum source includes sodium aluminate.

[0023] Preferably, the rare earth doping element source includes any one or a combination of at least two of cerium nitrate hexahydrate, neodymium nitrate, samarium nitrate, cobalt nitrate, europium nitrate, yttrium nitrate, dysprosium nitrate, ytterbium nitrate, lanthanum nitrate, or praseodymium nitrate. Typical but non-limiting combinations include combinations of cerium nitrate hexahydrate and neodymium nitrate, combinations of neodymium nitrate and samarium nitrate, combinations of samarium nitrate and cobalt nitrate, combinations of cobalt nitrate, europium nitrate, and yttrium nitrate, combinations of cerium nitrate hexahydrate, neodymium nitrate, and samarium nitrate, combinations of cerium nitrate hexahydrate, neodymium nitrate, samarium nitrate, cobalt nitrate, and europium nitrate, combinations of cobalt nitrate, europium nitrate, yttrium nitrate, dysprosium nitrate, ytterbium nitrate, and lanthanum nitrate, and combinations of cerium nitrate hexahydrate, neodymium nitrate, samarium nitrate, cobalt nitrate, europium nitrate, yttrium nitrate, dysprosium nitrate, lanthanum nitrate, and praseodymium nitrate.

[0024] Preferably, the copper source includes copper nitrate.

[0025] Preferably, the molar ratio of sodium hydroxide to aluminum in the aluminum source is 1:(5-10), for example, it can be 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the stirring time is 1-2 hours, for example, it can be 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours or 2 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, the stirred mixture is allowed to stand before the hydrothermal reaction.

[0028] Preferably, the settling time is 6-10 hours, for example, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] Preferably, the hydrothermal reaction time is 4-8 hours, for example, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] In the preparation method of this invention, controlling the settling time and hydrothermal time within a reasonable range results in a catalyst with superior activity and resistance to SO2 poisoning. Settling time and hydrothermal time affect the crystallinity of the molecular sieve in the catalyst; excessively short settling or hydrothermal times will lead to incomplete growth of the molecular sieve framework, preventing successful anchoring of MCuO. x The catalytic performance of the active components decreases under NH3-SCR conditions regardless of the presence or absence of SO2. If the standing time or hydrothermal time is too long, the rare earth dopant source and copper source will dissolve and accumulate on the surface of the molecular sieve, and will not be able to disperse and anchor in the channels, thus affecting the catalytic performance of NH3-SCR and the ability to resist SO2 poisoning.

[0031] Preferably, the hydrothermal reaction temperature is 100-120℃, for example, it can be 100℃, 102℃, 104℃, 106℃, 108℃, 110℃, 112℃, 114℃, 116℃, 118℃ or 120℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0032] Preferably, the concentration of the ammonium nitrate solution is 1-4 mol / L, for example, it can be 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L or 4 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, the mass ratio of the first product to the ammonium nitrate solution is 1:(15-30), for example, it can be 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:28, 1:29 or 1:30, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Preferably, the temperature of the ion exchange is 60-100℃, for example, it can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0035] Preferably, the ion exchange time is 8-15 hours, for example, it can be 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours or 15 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, the ion exchange is repeated 1 to 3 times, for example, once, twice or three times, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] Preferably, the drying temperature is 70-90℃, for example, it can be 70℃, 75℃, 80℃, 85℃ or 90℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0038] Preferably, the drying time is 8-16 hours, for example, it can be 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours or 16 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] Preferably, the roasting temperature is 400-600℃, for example, it can be 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, 580℃ or 600℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0040] In the preparation method of the denitrification catalyst provided by this invention, the catalyst with better activity and resistance to SO2 poisoning is obtained by controlling the calcination temperature within the range of 400-600℃. If the calcination temperature is too high, it will cause the molecular sieve framework to collapse and cover MCuO. xThe active sites prevent the active components from being exposed and coming into contact with reactants such as NO and NH3, resulting in a decrease in catalyst performance; while too low a calcination temperature will lead to a decrease in the crystallinity of the molecular sieve and incomplete framework growth, which will significantly reduce the NH3-SCR catalytic performance of the catalyst in the presence of SO2.

[0041] Preferably, the heating rate of the calcination is 1-10℃ / min, for example, it can be 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0042] Preferably, the roasting time is 3-10 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] Thirdly, the present invention provides the use of the denitrification catalyst as described in the first aspect, said denitrification catalyst being used for the selective catalytic reduction of nitrogen oxides by ammonia.

[0044] Preferably, the operating temperature of the catalyst is 100-550℃, for example, it can be 100℃, 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, 500℃ or 550℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 150-400℃.

[0045] The denitrification catalyst provided by this invention can cover an ultra-wide temperature range of 100-550℃ for the selective catalytic reduction of nitrogen oxides by ammonia, and at the same time, the catalyst has excellent resistance to sulfur dioxide poisoning.

[0046] Thirdly, the present invention provides a denitrification reactor, the denitrification reactor comprising the denitrification catalyst as described in the first aspect.

[0047] Fourthly, the present invention provides a denitrification reaction apparatus, the denitrification apparatus comprising the denitrification reactor described in the third aspect;

[0048] The denitrification reaction device is used for mobile source gas denitrification devices and / or stationary source gas denitrification devices.

[0049] Preferably, the mobile source gas denitrification device includes any one of a diesel engine, a gas turbine, or an aircraft engine.

[0050] Preferably, the stationary source gas denitrification device includes an industrial kiln and / or a roasting kiln.

[0051] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0052] Compared with the prior art, the present invention has at least the following beneficial effects:

[0053] (1) In the denitrification catalyst provided by this invention, the FAU molecular sieve matrix has a layered morphology, thus possessing strong interlayer mass transfer capability, and is able to denitrify NO. x Gases such as NH3 rapidly diffuse to the active sites, and the active component of the composite oxide, MCuO, is rapidly absorbed. x The presence of MO-Cu asymmetric oxygen vacancies can enhance NO production. x The adsorption capacity of rare earth elements can be improved by enhancing the overall redox capacity of the catalyst. Simultaneously, the highly dispersed MCuO anchored within the molecular sieve framework further enhances this effect. x The active sites make it difficult for sulfur dioxide to be chemically adsorbed on the catalyst. The denitrification catalyst provided by this invention has strong Bronsted and Lewis acidic sites, which can increase the catalyst's adsorption capacity for NH3 and its resistance to sulfur dioxide poisoning.

[0054] (2) The denitrification catalyst provided by this invention is simple and easy to operate. It is prepared by adding molecular sieve raw materials and active component raw materials together for hydrothermal reaction, followed by ion exchange. Since the molecular sieve topology of FAU structure is stable and the crystal formation energy is low, it can be successfully crystallized at a low temperature after adding sodium hydroxide. Therefore, compared with conventional preparation methods in the prior art (such as the synthesis of Cu-SSZ-13, Cu-SAPO-34 and Cu-ZSM-5 molecular sieve catalysts), the step of adding organic template agent is eliminated, and the hydrothermal process of more than 12 hours is not required, thus saving preparation time and cost.

[0055] (3) The denitrification catalyst provided by the present invention is used for the selective catalytic reduction of nitrogen oxides by ammonia and can cover an ultra-wide temperature range of 100-550℃. At the same time, the catalyst has excellent resistance to sulfur dioxide poisoning. Attached Figure Description

[0056] Figure 1 This is a TEM image of the denitrification catalyst described in Example 1 of the present invention. Detailed Implementation

[0057] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0058] In the following examples, unless otherwise specified, all reagents and consumables were purchased from conventional reagent manufacturers in the art; unless otherwise specified, the experimental methods and techniques used are conventional methods and techniques in the art.

[0059] Example 1

[0060] This embodiment provides a denitrification catalyst, which includes an X-type molecular sieve matrix and a composite oxide active component CeCuO supported on the surface of the X-type molecular sieve matrix. 1.11 The silicon-to-aluminum ratio of the X-type molecular sieve matrix is ​​1.86:1.

[0061] Based on the total molar amount of silicon and composite oxide active components in the FAU molecular sieve, the molar fraction of the composite oxide active components is 10%; the molar ratio of rare earth dopant Ce to copper in the composite oxide active components is 0.11:1.

[0062] The preparation method of the denitration catalyst provided in this embodiment includes the following steps:

[0063] (1) Add 1.216g sodium aluminate and 0.08g sodium hydroxide to 9.5mL of deionized water, stir evenly, then add 3.370g anhydrous sodium silicate and 8mL of deionized water, then add 0.473g copper nitrate and 0.123g cerium nitrate hexahydrate, mix and stir for 1h, let stand for 8h, and then perform hydrothermal reaction at 100℃ for 6h to obtain the first product.

[0064] (2) The first product was added to 25 mL of 2 mol / L ammonium nitrate solution and stirred at 80 °C for 12 h; then a new 25 mL of 2 mol / L ammonium nitrate solution was added and stirred at 80 °C for 12 h again to obtain the second product.

[0065] (3) After drying the second product at 80°C for 12 hours, it was placed in a muffle furnace and calcined at 500°C for 4 hours at a heating rate of 5°C / min to obtain the denitrification catalyst.

[0066] TEM image of the prepared denitration catalyst is shown below Figure 1 As shown in the figure, the X-type molecular sieve has a plate-like morphology with a diameter of approximately 300 nm. Furthermore, no obvious CeCuO was observed in the figure. 1.11 The presence of particles indicates that the active component may be highly dispersed within the pores of the molecular sieve.

[0067] Example 2

[0068] This embodiment provides a denitrification catalyst, which includes an X-type molecular sieve matrix and a composite oxide active component NdCuO supported on the surface of the X-type molecular sieve matrix. 1.11 The silicon-to-aluminum ratio of the X-type molecular sieve matrix is ​​1.86:1.

[0069] Based on the total molar amount of silicon and composite oxide active components in the FAU molecular sieve, the molar fraction of the composite oxide active components is 5%; the molar ratio of rare earth dopant Nd to copper in the composite oxide active components is 0.11:1.

[0070] The preparation method of the denitration catalyst provided in this embodiment includes the following steps:

[0071] (1) Add 1.216g sodium aluminate and 0.03g sodium hydroxide to 9.5mL of deionized water, stir evenly, then add 3.370g anhydrous sodium silicate and 8mL of deionized water, then add 0.237g copper nitrate and 0.062g neodymium nitrate hexahydrate, mix and stir for 1h, let stand for 8h, and then perform hydrothermal reaction at 100℃ for 6h to obtain the first product.

[0072] (2) Add the first product to 25 mL of 1 mol / L ammonium nitrate solution and stir at 70 °C for 15 h; repeat this step twice, replacing the ammonium nitrate solution before each ion exchange, and obtain the second product after a total of 3 ion exchanges.

[0073] (3) The second product was dried at 70°C for 16 hours and then placed in a muffle furnace and calcined at 400°C for 8 hours at a heating rate of 2°C / min to obtain the denitrification catalyst.

[0074] Example 3

[0075] This embodiment provides a denitrification catalyst, which includes a Y-type molecular sieve matrix and a composite oxide active component CeCuO supported on the surface of the Y-type molecular sieve matrix. 1.2 The silicon-to-aluminum ratio of the Y-type molecular sieve matrix is ​​3.32:1.

[0076] Based on the total molar amount of silicon and composite oxide active components in the FAU molecular sieve, the molar fraction of the composite oxide active components is 28%; the molar ratio of rare earth dopant Ce to copper in the composite oxide active components is 0.2:1.

[0077] The preparation method of the denitration catalyst provided in this embodiment includes the following steps:

[0078] (1) Add 0.608g sodium aluminate and 0.12g sodium hydroxide to 9.5mL of deionized water, stir evenly, then add 3.370g anhydrous sodium silicate and 8mL of deionized water, then add 1.208g copper nitrate and 0.559g cerium nitrate hexahydrate, mix and stir for 1h, let stand for 8h, and then perform hydrothermal reaction at 100℃ for 6h to obtain the first product.

[0079] (2) The first product was added to 25 mL of 4 mol / L ammonium nitrate solution and stirred at 90 °C for 10 h; then the solution was replaced with a new 25 mL of 4 mol / L ammonium nitrate solution and stirred at 90 °C for 10 h again to obtain the second product.

[0080] (3) The second product was dried at 90°C for 10 hours and then placed in a muffle furnace and calcined at 600°C for 4 hours at a heating rate of 10°C / min to obtain the denitrification catalyst.

[0081] Example 4

[0082] This embodiment provides a denitrification catalyst, which differs from Example 1 only in that the Ce:Cu ratio is 0.02:1 when preparing the denitrification catalyst, while the other conditions and parameters are exactly the same as in Example 1.

[0083] Example 5

[0084] This embodiment provides a denitrification catalyst, which differs from Example 1 only in that the Ce:Cu ratio is 0.3:1 when preparing the denitrification catalyst, while the other conditions and parameters are exactly the same as in Example 1.

[0085] Example 6

[0086] This embodiment provides a denitrification catalyst, which differs from Example 1 only in that the standing time is 4 hours when preparing the denitrification catalyst, while the other conditions and parameters are exactly the same as in Example 1.

[0087] Example 7

[0088] This embodiment provides a denitrification catalyst, which differs from Example 1 only in that the hydrothermal time for preparing the denitrification catalyst is 3 hours, while the other conditions and parameters are exactly the same as in Example 1.

[0089] Example 8

[0090] This embodiment provides a denitrification catalyst, which differs from Example 1 only in that the standing time is 20 hours when preparing the denitrification catalyst, while the other conditions and parameters are exactly the same as in Example 1.

[0091] Example 9

[0092] This embodiment provides a denitrification catalyst, which differs from Example 1 only in that the hydrothermal time for preparing the denitrification catalyst is 24 hours, while the other conditions and parameters are exactly the same as in Example 1.

[0093] Example 10

[0094] This embodiment provides a denitrification catalyst, which differs from Example 1 only in that the calcination temperature is 300°C during the preparation of the denitrification catalyst, while the other conditions and parameters are exactly the same as in Example 1.

[0095] Example 11

[0096] This embodiment provides a denitrification catalyst, which differs from Example 1 only in that the calcination temperature is 700°C during the preparation of the denitrification catalyst, while the other conditions and parameters are exactly the same as in Example 1.

[0097] Comparative Example 1

[0098] This comparative example provides a denitration catalyst, which differs from Example 1 only in that cerium nitrate hexahydrate is not added during the preparation of this denitration catalyst, while the other conditions and parameters are exactly the same as in Example 1.

[0099] Comparative Example 2

[0100] This comparative example provides a denitration catalyst, which differs from Example 1 only in that copper nitrate is replaced with an equimolar amount of iron nitrate when preparing the denitration catalyst, while the other conditions and parameters are exactly the same as in Example 1.

[0101] Comparative Example 3

[0102] The preparation method of the denitration catalyst provided in this comparative example includes the following steps:

[0103] (1) Add 0.473g of copper nitrate and 0.123g of cerium nitrate hexahydrate (Ce:Cu = 0.11:1) to 2.406g of titanium dioxide powder;

[0104] (2) The powder was stirred and dried at 80°C, and then placed in a muffle furnace and calcined at 500°C for 4 hours at a heating rate of 5°C / min.

[0105] Performance testing:

[0106] The catalysts prepared using the above-described examples and comparative examples were used to conduct denitrification activity experiments on simulated flue gas. The simulated flue gas contained 500 ppm NH3, 500 ppm NO, 5% O2, and 250 ppm SO2, with nitrogen as the balance gas. The NO content of the catalyst was tested under the above conditions at different temperatures and with or without the introduction of 250 ppm SO2. x Conversion rate, the test results are shown in Table 1:

[0107] Table 1

[0108]

[0109]

[0110] The test results show that:

[0111] (1) As can be seen from Examples 1-3, the FAU molecular sieve matrix has a layered morphology and strong interlayer mass transfer capability, which can transfer NO x Gases such as NH3 rapidly diffuse to the active sites, and the active component of the composite oxide, MCuO, is rapidly absorbed. x The presence of MO-Cu asymmetric oxygen vacancies can enhance NO production. x The adsorption capacity of rare earth elements can be improved by enhancing the overall redox capacity of the catalyst. Simultaneously, the highly dispersed MCuO anchored within the molecular sieve framework further enhances this effect. x The active sites make it difficult for sulfur dioxide to be chemically adsorbed on the catalyst. The denitrification catalyst provided by this invention has strong Bronsted and Lewis acidic sites, which can increase the catalyst's adsorption capacity for NH3 and its resistance to sulfur dioxide poisoning.

[0112] (2) By comparing Example 1 with Examples 4-5, it can be seen that the molar ratio of rare earth dopant elements and copper elements in the denitration catalyst of the present invention affects the catalytic activity and the ability to resist SO2 poisoning. When the molar ratio of rare earth dopant elements and copper elements is controlled at (0.05~0.2):1, the denitration catalyst can maintain high-temperature catalytic activity and also has excellent low-temperature activity. If the proportion of rare earth dopant elements is too low, the high-temperature performance of the catalyst will decrease after 300℃. If the proportion of rare earth dopant elements is too high, the low-temperature performance of the catalyst before 300℃ will be poor.

[0113] (3) A comparison between Example 1 and Examples 6-9 shows that in the denitrification catalyst of the present invention, if the settling time and hydrothermal time are too short, it will affect the crystallinity of the molecular sieve in the catalyst, resulting in incomplete framework growth and failure to successfully anchor MCuO. x The catalytic performance of the active components decreases under NH3-SCR conditions regardless of the presence or absence of SO2. Excessive standing time and hydrothermal time will cause the cerium and copper sources to dissolve and accumulate on the surface of the molecular sieve, making them unable to disperse and anchor in the channels, thus affecting the catalytic performance and anti-poisoning ability of NH3-SCR.

[0114] (4) A comparison between Example 1 and Examples 10-11 shows that in the denitrification catalyst of the present invention, if the calcination temperature is too high, it will cause the molecular sieve framework to collapse and cover MCuO. xThe active sites prevent the active components from being exposed and coming into contact with reactants such as NO and NH3, resulting in a decrease in catalyst performance; while too low a calcination temperature will lead to a decrease in the crystallinity of the molecular sieve and incomplete framework growth, which will significantly reduce the NH3-SCR catalytic performance of the catalyst in the presence of SO2.

[0115] (5) As can be seen from Example 1 and Comparative Examples 1-2, rare earth elements play an important role in resisting poisoning and enhancing performance at medium and high temperatures. After replacing rare earth elements with other elements such as iron, the catalyst prepared and then passing SO2 gas through it showed a decrease in NO. x The conversion rate decreased significantly, the redox ability of the catalyst decreased, and the activity at medium and high temperatures also decreased.

[0116] (6) As can be seen from Example 1 and Comparative Example 3, when using traditional titanium dioxide as a support, the NO content of the prepared catalyst after passing SO2 gas through it is significantly reduced. x The conversion rate dropped significantly because the active component could not be uniformly dispersed on the support, leading to the chemical adsorption of sulfur dioxide on the catalyst and causing SO2 poisoning. However, the layered FAU molecular sieve matrix described in this invention has strong interlayer mass transfer capabilities, and the highly dispersed MCuO anchored within the molecular sieve framework... x The active sites make it difficult for sulfur dioxide to be chemically adsorbed on the catalyst, thus enabling NO to be... x Gases such as NH3 rapidly diffuse to the active sites, thereby achieving degradation.

[0117] In summary, this invention utilizes FAU molecular sieves with a layered structure as the catalyst matrix, leveraging their strong interlayer mass transfer capabilities to effectively convert NO... x Gases such as NH3 rapidly diffuse to the active sites, forming the composite oxide MCuO. x As the active component of the catalyst, it contains MO-Cu asymmetric oxygen vacancies, which can enhance NO. x The adsorption capacity of rare earth elements can be improved by enhancing the overall redox capacity of the catalyst. Simultaneously, the highly dispersed MCuO anchored within the molecular sieve framework further enhances this effect. x The active site of the catalyst exhibits excellent resistance to sulfur dioxide poisoning over an ultra-wide temperature range of 100-550℃.

[0118] The applicant declares that the above description is only a specific embodiment 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 conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A denitrification catalyst, characterized in that, The denitrification catalyst comprises a layered FAU molecular sieve matrix and a composite oxide active component supported on the surface and within the pores of the layered FAU molecular sieve matrix. The chemical formula of the composite oxide active component is MCuO. x M is a rare earth dopant element, where x is the molar amount of oxygen atoms in the composite oxide, 1≤x≤2; The denitrification catalyst is prepared by the following method, the method comprising: An aluminum source, sodium hydroxide source, silicon source, rare earth dopant source, copper source, and water are mixed and stirred, and then a hydrothermal reaction is carried out to obtain a first product; the first product is mixed with an ammonium nitrate solution for ion exchange to obtain a second product; the second product is dried and calcined to obtain the denitrification catalyst. The rare earth doping elements include any one or a combination of at least two of cerium, neodymium, samarium, europium, yttrium, dysprosium, ytterbium, lanthanum, or praseodymium.

2. The denitrification catalyst according to claim 1, characterized in that, The layered FAU molecular sieve matrix includes X-type molecular sieves or Y-type molecular sieves.

3. The denitrification catalyst according to claim 2, characterized in that, The layered FAU molecular sieve matrix is ​​an X-type molecular sieve.

4. The denitrification catalyst according to claim 1, characterized in that, The silicon-to-aluminum ratio of the layered FAU molecular sieve matrix is ​​(1-30):

1.

5. The denitrification catalyst according to claim 1, characterized in that, Based on the total molar amount of silicon and composite oxide active components in the FAU molecular sieve, the molar fraction of the composite oxide active components is 5-30%.

6. The denitrification catalyst according to claim 5, characterized in that, Based on the total molar amount of silicon and composite oxide active components in the FAU molecular sieve, the molar fraction of the composite oxide active components is 10-25%.

7. The denitrification catalyst according to claim 1, characterized in that, In the active component of the composite oxide, the molar ratio of rare earth dopant to copper is (0.05-0.2):

1.

8. A method for preparing a denitrification catalyst as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: An aluminum source, sodium hydroxide source, silicon source, rare earth dopant source, copper source, and water are mixed and stirred, and then subjected to a hydrothermal reaction to obtain a first product. The first product is then mixed with an ammonium nitrate solution for ion exchange to obtain a second product. The second product is then dried and calcined to obtain the denitrification catalyst.

9. The preparation method according to claim 8, characterized in that, The silicon source includes sodium silicate.

10. The preparation method according to claim 8, characterized in that, The aluminum source includes sodium aluminate.

11. The preparation method according to claim 8, characterized in that, The rare earth doping element source includes any one or a combination of at least two of cerium nitrate hexahydrate, neodymium nitrate, samarium nitrate, europium nitrate, yttrium nitrate, dysprosium nitrate, ytterbium nitrate, lanthanum nitrate, or praseodymium nitrate.

12. The preparation method according to claim 8, characterized in that, The copper source includes copper nitrate.

13. The preparation method according to claim 8, characterized in that, The molar ratio of sodium hydroxide to aluminum in the aluminum source is 1:(5-10).

14. The preparation method according to claim 8, characterized in that, The stirring time is 1-2 hours.

15. The preparation method according to claim 8, characterized in that, Before the hydrothermal reaction, the stirred mixture is allowed to stand.

16. The preparation method according to claim 15, characterized in that, The settling time is 6-10 hours.

17. The preparation method according to claim 8, characterized in that, The hydrothermal reaction time is 4-8 hours.

18. The preparation method according to claim 8, characterized in that, The hydrothermal reaction temperature is 100-120℃.

19. The preparation method according to claim 8, characterized in that, The concentration of the ammonium nitrate solution is 1-4 mol / L.

20. The preparation method according to claim 8, characterized in that, The mass ratio of the first product to the ammonium nitrate solution is 1:(15-30).

21. The preparation method according to claim 8, characterized in that, The ion exchange temperature is 60-100℃.

22. The preparation method according to claim 8, characterized in that, The ion exchange time is 8-15 hours.

23. The preparation method according to claim 8, characterized in that, The ion exchange is repeated 1-3 times.

24. The preparation method according to claim 8, characterized in that, The drying temperature is 70-90℃.

25. The preparation method according to claim 8, characterized in that, The drying time is 8-16 hours.

26. The preparation method according to claim 8, characterized in that, The roasting temperature is 400-600℃.

27. The preparation method according to claim 8, characterized in that, The heating rate during roasting is 1-10℃ / min.

28. The preparation method according to claim 8, characterized in that, The roasting time is 3-10 hours.

29. Use of a denitrification catalyst as described in any one of claims 1-7, characterized in that, The denitrification catalyst is used for the selective catalytic reduction of nitrogen oxides by ammonia.

30. The use of the denitrification catalyst according to claim 29, characterized in that, The catalyst operates at a temperature of 100-550℃.

31. The use of the denitrification catalyst according to claim 29, characterized in that, The catalyst operates at a temperature of 150-400℃.

32. A denitrification reactor, characterized in that, The denitrification reactor includes the denitrification catalyst as described in any one of claims 1-7.

33. A denitrification device, characterized in that, The denitrification device includes the denitrification reactor as described in claim 32; The denitrification device includes a mobile source gas denitrification device and / or a stationary source gas denitrification device.

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