A method for preparing an SCR denitration catalyst by using molecular sieve modified stone coal vanadium extraction tailings
By modifying vanadium tailings with zeolite ZSM-5 to enhance surface area and acid sites, the catalyst addresses the limitations of commercial SCR catalysts and environmental issues, achieving efficient low-temperature NOx reduction and resource recycling.
Patent Information
- Application Number
- CN202311582877.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-24
- Publication Date
- 2025-07-15
- Estimated Expiration
- 2043-11-24
AI Technical Summary
The existing commercial SCR denitrification catalysts are insufficiently active at low temperatures and are prone to poisoning, which is difficult to meet the NOx emission requirements of industrial low-temperature flue gases. Moreover, the vanadium tailings of stone coal extracted are not effectively utilized, resulting in waste of resources and pollution.
Vanadium tailings slag extracted by ball grinding stone coal, and a molecular sieve modified vanadium slag carrier was prepared by microwave or hydrothermal method. After multiple ion exchanges and calcination, an efficient NH3-SCR denitrification catalyst was prepared, and the catalytic activity was improved using the mesoporous structure and high surface area of the molecular sieve.
It has achieved efficient denitrification at low temperatures, wide temperature zone activity, good water and sulfur resistance, and resource utilization of shi coal vanadium tailings to prepare a highly efficient SCR denitrification catalyst.
Smart Images
Figure BDA0004569021220000091 
Figure BDA0004569021220000092
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of preparation of molecular sieve catalysts, and particularly relates to a method for preparing an SCR denitration catalyst by modifying vanadium extraction tailings from stone coal with molecular sieves. Background Art
[0002] To meet the increasing energy demands of industry, non-renewable fossil fuels remain the main energy sources for industrial production, power plants, and motor vehicles. NOx is one of the main pollutants in the atmosphere and has a huge impact on human production and life, causing serious environmental problems such as the greenhouse effect, acid rain, photochemical smog, PM2.5, etc. In industry, the effective removal of NOx mainly uses NH3-SCR (selective catalytic reduction method). Commercial catalysts are mainly V2O5-WO3(MoO3) / TiO2, with an operating temperature range of 300 - 400 °C. At this temperature, ammonium sulfate deposition on the catalyst can be avoided to a certain extent. However, the denitration device is placed downstream of the desulfurization and dust removal devices and requires additional heating. Moreover, industries such as steel, glass, and cement have increasingly high requirements for controlling NOx emissions from industrial furnaces with low-temperature flue gas (120 - 260 °C), and the commercial catalyst V2O5-WO3(MoO3) / TiO2 has problems such as a narrow temperature window and easy alkali metal poisoning. Therefore, it is very necessary to develop an NH3-SCR denitration catalyst with low temperature, wide temperature, and high activity.
[0003] Stone coal vanadium ore is a unique vanadium resource in China. China ranks first in both vanadium production and consumption in the world. Stone coal is one of the main sources of vanadium, but the content of V2O5 in vanadium-bearing shale (stone coal) is generally relatively low, at 0.1% - 2.0%. Producing 1 ton of V2O5 products usually generates 120 to 150 tons of vanadium extraction tailings. Some corrosive substances and various heavy metal elements remain in the vanadium extraction tailings from stone coal. If the stone coal vanadium slag is landfilled, it will cause waste and pollution of land resources. Therefore, considering the resource utilization of vanadium extraction tailings from stone coal is the fundamental way to solve the problem. The composition of this vanadium extraction tailings is: 48% SiO2, 3% Al2O3, 0.13% V2O5. Among them, SiO2 and Al2O3 are common carriers for denitration catalysts. However, its specific surface area is only 3.24 m 2 / g. The ordered mesoporous structure of molecular sieves is beneficial to the mass transfer of reactants / products, and has a larger specific surface area, higher surface acidity, and better NO adsorption capacity. Considering surface modification of the vanadium extraction tailings with molecular sieves and then using it as a carrier for denitration catalysts, while realizing the resource utilization of vanadium extraction tailings from stone coal, an efficient and low-cost denitration catalyst can be prepared. Summary of the Invention
[0004] In view of this, one of the purposes of the present invention is to provide a method for preparing an SCR denitration catalyst by modifying vanadium extraction tailings from stone coal with molecular sieves, including the following steps:
[0005] (1) Ball mill and crush the vanadium slag tailings from stone coal to obtain vanadium slag powder;
[0006] (2) Mix the materials including water, vanadium slag powder, silicon source, aluminum source, alkali, binder and template agent to obtain a mixed material;
[0007] (3) Crystallize the mixed material to obtain a vanadium slag support modified with molecular sieve. The crystallization method includes:
[0008] Method A: Crystallize the above-mentioned mixed material by microwave method to prepare a sodium-type M-ZSM-5 vanadium slag support modified with different nSiO2 / nAl2O3 molecular sieves;
[0009] Or Method B: Crystallize the above-mentioned mixed material by hydrothermal method to prepare a sodium-type H-ZSM-5 vanadium slag support modified with different nSiO2 / nAl2O3 molecular sieves;
[0010] (4) Subject the sodium-type M-ZSM-5 vanadium slag support or H-ZSM-5 vanadium slag support modified with different nSiO2 / nAl2O3 molecular sieves to steps including washing, filtration, drying, calcination, multiple ion exchanges, secondary washing, secondary filtration, secondary drying, and secondary calcination to obtain a hydrogen-type M-ZSM-5 or H-ZSM-5 vanadium slag support modified with different nSiO2 / nAl2O3 molecular sieves;
[0011] (5) Mix the hydrogen-type M-ZSM-5 or H-ZSM-5 vanadium slag support modified with different nSiO2 / nAl2O3 molecular sieves with the precursors of active components and additives and water evenly, and then carry out drying and calcination to obtain a denitration catalyst.
[0012] Preferably, in step (1), the particle size of the vanadium slag powder is 80-200 mesh;
[0013] Preferably, in step (2), the silicon source in the mixed material is silica sol, the aluminum source is aluminum sulfate octadecahydrate, the alkali is sodium hydroxide, and the template agent is tetrapropylammonium bromide TPABr.
[0014] Preferably, the materials in step (2) are mixed in the order of water, vanadium slag powder, binder, silicon source, aluminum source, alkali, and template agent. After adding water, vanadium slag powder, and binder, stir for 30 - 60 min, and then add the silicon source, aluminum source, alkali, and template agent. After adding each of the silicon source, aluminum source, alkali, and template agent, stir for 10 - 30 min (that is, stir for 10 - 30 min each time a material is added). The material addition method, mixing order, material aging, and crystallization process will all affect the crystallinity and crystal grain size of the molecular sieve, thereby affecting the surface modification of the vanadium slag by the molecular sieve. The modification effect of the molecular sieve causes differences in the vanadium slag carrier and catalyst structure, which in turn affects the catalytic efficiency of the catalyst; if the addition order and stirring method are not followed as described, the NO conversion efficiency of the finally obtained denitration catalyst will be greatly reduced.
[0015] Preferably, in step (3), the temperature of the microwave crystallization method is 160 °C, and the crystallization time is 6 h; for the mixed materials corresponding to the sodium-type M-ZSM-5 vanadium slag carrier modified by different nSiO2 / nAl2O3 molecular sieves, the amounts of substance of the silicon source, aluminum source, alkali, and template agent are taken as n(SiO2):n(Al2O3):n(NaOH):n(TPABr) = 1:a:0.12:0.25, and the mass ratio of the vanadium slag powder to the binder is taken as m(vanadium slag powder):m(binder) = 20:1;
[0016] The temperature of the hydrothermal crystallization method is 240 °C, and the crystallization time is 48 h; for the mixed materials corresponding to the sodium-type H-ZSM-5 vanadium slag carrier modified by different nSiO2 / nAl2O3 molecular sieves, the amounts of substance of the silicon source, aluminum source, alkali, and template agent are taken as n(SiO2):n(Al2O3):n(NaOH):n(TPABr) = 1:a:0.12:0.25, and the mass ratio of the vanadium slag powder to the binder is taken as m(vanadium slag powder):m(binder) = 20:1.
[0017] Preferably, in step (3), the different nSiO2 / nAl2O3 means that the ratio X of nSiO2 to nAl2O3 is 40, 100, 160, 220, 280, or 340. Different nSiO2 / nAl2O3 also affects the catalytic efficiency of the catalyst. The catalyst prepared by the microwave crystallization method of the present invention has the best effect when X = 40, while the catalyst prepared by the hydrothermal crystallization method has the best effect when X = 220. Therefore, different crystallization methods may affect the structure of the catalyst, resulting in different catalytic effects.
[0018] Preferably, in step (4), the calcination temperature is 550 °C, and the calcination time is 6 h; the reagent used for ion exchange is 1 mol / L NH4Cl solution, the exchange temperature is 80 °C, and the number of ion exchange times is three.
[0019] Preferably, in step (5), the precursor of the active component is a 50% Mn(NO3)2 solution and ammonium metavanadate (NH4VO3), and the precursor of the promoter is cerium nitrate hexahydrate (Ce(NO3)2·6H2O).
[0020] Preferably, in step (5), the method for uniformly mixing is stirring for 2 h, the method for drying is drying at 100 °C for 12 h, and the method for calcination is calcining in a muffle furnace at 500 °C for 4 h.
[0021] The second object of the present invention is to provide a denitration catalyst prepared by any of the above methods.
[0022] Beneficial effects: The present invention uses zeolite ZSM-5 to modify the vanadium tailings from stone coal. The specific surface area of the zeolite-modified vanadium slag is increased by dozens of times compared with the original slag, which is more conducive to the uniform dispersion of the active component and the promoter on it; and the surface of the zeolite-modified vanadium slag has more acidic sites and acid amounts, which is more conducive to the adsorption of NH3 and NO on its surface, thereby further promoting the NH3-SCR reaction. Using the zeolite-modified vanadium slag as the carrier of the denitration catalyst, while realizing the resource utilization of the vanadium tailings, a highly efficient SCR denitration catalyst with excellent low-temperature activity, wide active temperature range, and good water and sulfur resistance is prepared. Specific embodiments
[0023] In any range endpoints and any values disclosed in the present invention are not limited to the exact range and / or value, and these ranges and / or values can and should be understood to include values close to these ranges and / or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.
[0024] Example 1: Preparation of denitration catalyst 1 by microwave method to obtain carrier M-ZSM-5@FZ-X
[0025] (1) Take an appropriate amount of vanadium tailings from stone coal and place them in a ball mill for crushing and grinding, and use a stainless steel sample sieve to screen out vanadium slag powder with a mesh size of 80-200.
[0026] (2) Take the corresponding amounts of excessive silica sol, aluminum sulfate octadecahydrate, sodium hydroxide, tetrapropylammonium bromide, and deionized water with n(SiO2):n(Al2O3):n(NaOH):n(TPABr):n(H2O) = 1:a:0.12:0.25:50. Add deionized water to a beaker, then add 6 g of vanadium slag powder as the matrix material, add 0.3 g of the binder polyvinylpyrrolidone, and stir for 30 min. Add the raw materials in the order of silicon source, aluminum source, alkali, and template agent and stir until evenly mixed. Stir for 10 minutes after adding each material, then age for 1.5 h. Transfer the aged mixture to a digestion tank, load the temperature probe, and place it in a microwave chemical reactor. Carry out microwave crystallization reaction at 160 °C for 6 hours to obtain a sodium-type M-ZSM-5 vanadium slag support modified with different nSiO2 / nAl2O3 zeolites.
[0027] (3) After the reaction is complete, wait for it to cool naturally to room temperature, wash and filter the product with distilled water multiple times. The filtered solid product is dried at 100 °C for 12 h. After grinding the solid product, use a muffle furnace to calcine it at 550 °C in an air atmosphere for 6 hours to remove the template agent TPABr. Then, use a 1 mol / L NH4Cl solution to carry out ion exchange on it at a solid-liquid ratio of 1:20. The exchange conditions are to exchange three times at 80 °C, 2 h each time. After exchange, wash, filter, dry, and calcine at 550 °C for 6 hours to obtain a hydrogen-type M-ZSM-5 vanadium slag support.
[0028] (5) Prepare the catalyst with the obtained hydrogen-type M-ZSM-5 vanadium slag supports modified with different silicon-aluminum ratios (denoted as M-ZSM-5@FZ-X, X = 40, 100, 160, 220, 280, or 340) at a weight ratio of M-ZSM-5@FZ-X:MnO2:CeO2:V2O5 = 86.5:10:2.5:1. That is, take the corresponding amounts of the active component precursors, 50% Mn(NO3)2 solution, ammonium metavanadate (NH4VO3) (add an appropriate amount of oxalic acid to promote the complete dissolution of ammonium metavanadate), and the promoter precursor cerium nitrate hexahydrate (Ce(NO3)2·6H2O), dissolve them completely in deionized water, then add the support M-ZSM-5@FZ-X, stir well for 2 h, dry at 100 °C for 12 h, and then calcine at 500 °C for 4 h to obtain the VMnCeOx-M-ZSM-5@FZ-X catalyst.
[0029] Example 2: Preparation of a denitration catalyst 1 by hydrothermal method to obtain the support H-ZSM-5@FZ-X
[0030] (1) Take an appropriate amount of vanadium-extracted tailings from stone coal and place them in a ball mill for crushing and grinding. Use a stainless steel sample sieve to screen out vanadium slag powder with a particle size of 80-200 mesh;
[0031] (2) Take the corresponding excessive amounts of silica sol, aluminum sulfate octadecahydrate, sodium hydroxide, tetrapropylammonium bromide, and deionized water with n(SiO2):n(Al2O3):n(NaOH):n(TPABr):n(H2O) = 1:a:0.12:0.25:50. Add deionized water into a beaker, then add 10 g of vanadium slag powder as the matrix material, add 0.5 g of the binder polyvinylpyrrolidone, and stir for 30 min. Add the raw materials in the order of silicon source, aluminum source, alkali, and template agent and stir until evenly mixed. Stir for 10 minutes after adding each material, then age for 1.5 h. Transfer the aged mixed solution to a high-pressure reactor and carry out a crystallization reaction at 240 °C for 48 hours. Obtain sodium-type H-ZSM-5 vanadium slag carriers modified with different nSiO2 / nAl2O3 molecular sieves.
[0032] (3) After the reaction is complete, wait for it to cool naturally to room temperature, wash and filter the product with distilled water multiple times. The filtered solid product is dried at 100 °C for 12 h. After grinding the solid product, use a muffle furnace to calcine it at 550 °C in an air atmosphere for 6 hours to remove the template agent TPABr, and then use a 1 mol / L NH4Cl solution to carry out ion exchange on it according to a solid-liquid ratio of 1:20. The exchange conditions are to exchange three times at 80 °C, 2 h each time. After exchange, wash, filter, dry, and calcine at 550 °C for 6 hours to obtain a hydrogen-type H-ZSM-5 vanadium slag carrier.
[0033] (5) Prepare catalysts with the weight ratio of the obtained hydrogen-type H-ZSM-5 vanadium slag carriers modified with different silicon-aluminum ratios (denoted as H-ZSM-5@FZ-X, X = 40, 100, 160, 220, 280, or 340), H-ZSM-5@FZ-X:MnO2:CeO2:V2O5 = 86.5:10:2.5:1. That is, take the corresponding amounts of the active component precursors, 50% Mn(NO3)2 solution, ammonium metavanadate (NH4VO3) (add an appropriate amount of oxalic acid to promote the complete dissolution of ammonium metavanadate), and the promoter precursor cerium nitrate hexahydrate (Ce(NO3)2·6H2O), dissolve them completely in deionized water, then add the carrier H-ZSM-5@FZ-X, stir well for 2 h, dry at 100 °C for 12 h, and then calcine at 500 °C for 4 h to obtain the VMnCeOx-H-ZSM-5@FZ-X catalyst.
[0034] Example 3: Preparation of a denitration catalyst 2 by obtaining the carrier M-ZSM-5@FZ-X using the microwave method
[0035] (1) Take an appropriate amount of vanadium-extracted tailings from stone coal and place them in a ball mill for crushing and grinding. Use a stainless-steel sample sieve to screen out vanadium slag powder with a particle size of 80 - 200 mesh;
[0036] (2) Take the corresponding excessive amounts of silica sol, aluminum sulfate octadecahydrate, sodium hydroxide, tetrapropylammonium bromide, and deionized water with n(SiO2):n(Al2O3):n(NaOH):n(TPABr):n(H2O) = 1:a:0.12:0.25:50. Add deionized water, vanadium slag, silicon source, aluminum source, sodium hydroxide, template agent, and binder into a beaker at one time, stir for 30 min, then age for 1.5 h. Transfer the aged mixture to a digestion tank, load a temperature probe, and place it in a microwave chemical reactor. Carry out microwave crystallization reaction at 160 °C for 6 hours to obtain sodium-type M-ZSM-5 vanadium slag carriers modified with different nSiO2 / nAl2O3 molecular sieves.
[0037] (3) After the reaction is complete, wait for it to cool naturally to room temperature, wash and filter the product with distilled water multiple times. The filtered solid product is dried at 100 °C for 12 h. The solid product is ground and then calcined in a muffle furnace at 550 °C in an air atmosphere for 6 hours to remove the template agent TPABr. Then, use 1 mol / L NH4Cl solution to carry out ion exchange on it according to the solid-liquid ratio of 1:20. The exchange conditions are to exchange three times at 80 °C, 2 h each time. After exchange, wash, filter, dry, and calcine at 550 °C for 6 hours to obtain hydrogen-type M-ZSM-5 vanadium slag carriers.
[0038] (5) Prepare catalysts with the weight ratio of the obtained hydrogen-type M-ZSM-5 vanadium slag carriers modified with different silicon-aluminum ratios (denoted as M-ZSM-5@FZ-X, X = 40, 100, 160, 220, 280, or 340), M-ZSM-5@FZ-X:MnO2:CeO2:V2O5 = 86.5:10:2.5:1. That is, take the corresponding amounts of active component precursors, 50% Mn(NO3)2 solution, ammonium metavanadate (NH4VO3) (add an appropriate amount of oxalic acid to promote the complete dissolution of ammonium metavanadate), and promoter precursor cerium nitrate hexahydrate (Ce(NO3)2·6H2O), dissolve them completely in deionized water, then add the carrier M-ZSM-5@FZ-X, stir well for 2 h, dry at 100 °C for 12 h, and then calcine at 500 °C for 4 h to obtain the VMnCeOx-M-ZSM-5@FZ-X catalyst.
[0039] Example 4: Preparation of denitration catalyst 2 by hydrothermal method to obtain carrier H-ZSM-5@FZ-X
[0040] (1) Take an appropriate amount of vanadium slag from stone coal vanadium extraction and place it in a ball mill for crushing and grinding. Use a stainless steel sample sieve to screen out vanadium slag powder with a particle size of 80 - 200 mesh.
[0041] (2) Take the corresponding excessive amounts of silica sol, aluminum sulfate octadecahydrate, sodium hydroxide, tetrapropylammonium bromide, and deionized water with n(SiO2):n(Al2O3):n(NaOH):n(TPABr):n(H2O) = 1:a:0.12:0.25:50. Add deionized water, vanadium slag, silicon source, aluminum source, sodium hydroxide, template agent, and binder into a beaker at one time, stir for 30 min, then age for 1.5 h. Transfer the aged mixture to an autoclave and carry out a crystallization reaction at 240 °C for 48 h. Obtain sodium-type H-ZSM-5 vanadium slag carriers modified with zeolites of different nSiO2 / nAl2O3.
[0042] (3) After the reaction is complete, wait for it to cool naturally to room temperature, wash and filter the product with distilled water multiple times. The filtered solid product is dried at 100 °C for 12 h. The solid product is ground and then calcined in a muffle furnace at 550 °C in an air atmosphere for 6 h to remove the template agent TPABr. Then, use a 1 mol / L NH4Cl solution to carry out ion exchange on it according to a solid-liquid ratio of 1:20. The exchange conditions are to exchange three times at 80 °C, 2 h each time. After exchange, wash, filter, dry, and calcine at 550 °C for 6 h to obtain a hydrogen-type H-ZSM-5 vanadium slag carrier.
[0043] (5) Prepare catalysts with the hydrogen-type H-ZSM-5 vanadium slag carriers modified with different silicon-aluminum ratios (denoted as H-ZSM-5@FZ-X, X = 40, 100, 160, 220, 280, or 340) at a weight ratio of H-ZSM-5@FZ-X:MnO2:CeO2:V2O5 = 86.5:10:2.5:1. That is, take the corresponding amounts of the active component precursors, a 50% Mn(NO3)2 solution, ammonium metavanadate (NH4VO3) (add an appropriate amount of oxalic acid to promote the complete dissolution of ammonium metavanadate), and the promoter precursor cerium nitrate hexahydrate (Ce(NO3)2·6H2O), dissolve them completely in deionized water, then add the carrier H-ZSM-5@FZ-X, stir well for 2 h, dry at 100 °C for 12 h, and then calcine at 500 °C for 4 h to obtain the VMnCeOx-H-ZSM-5@FZ-X catalyst.
[0044] Example 5: Preparation of a denitration catalyst using vanadium slag (FZ) as a carrier
[0045] (1) Take an appropriate amount of vanadium slag from stone coal vanadium extraction and place it in a ball mill for crushing and grinding. Use a stainless steel sample sieve to screen out vanadium slag powder with a particle size of 80 - 200 mesh;
[0046] (2) Prepare the catalyst in the proportion of FZ:MnO2:CeO2:V2O5 = 86.5:10:2.5:1. That is, take the corresponding amounts of the active component precursors, 50% Mn(NO3)2 solution, ammonium metavanadate (NH4VO3) (add an appropriate amount of oxalic acid to promote the complete dissolution of ammonium metavanadate), and the promoter precursor cerium nitrate hexahydrate (Ce(NO3)2·6H2O), dissolve them completely in deionized water, then add the carrier FZ, stir well for 2 h, dry at 100 °C for 12 h, and then calcine at 500 °C for 4 h to obtain the VMnCeOx@FZ catalyst.
[0047] Example 6: Vanadium slag (FZ) as a denitration catalyst
[0048] (1) Take an appropriate amount of vanadium-containing stone coal tailings and place them in a ball mill for crushing and grinding. Use a stainless steel sample sieve to screen out vanadium slag powder with a particle size of 80 - 200 mesh.
[0049] (2) Directly take FZ without loading active components and promoters as the catalyst.
[0050] Effect example:
[0051] Catalyst performance evaluation experiment: Use simulated flue gas to test the activity of the catalyst. The composition of the simulated flue gas is: NO: 500 ppm, NH3: 500 ppm, O2: 5% vol, and N2 as the balance gas. The total flue gas flow rate is 262 mL / min, and the reaction space velocity is 10000 h -1 .
[0052] Take the catalyst, put it into a fixed-bed reactor for testing, and test the denitration efficiency of the catalyst at different temperatures (50 - 400 °C). Use a flue gas analyzer to detect the NO concentration at the outlet of the reactor. The NO conversion rate is the ratio of the concentration difference between the inlet and outlet of NO to the NO concentration at the inlet. The calculation formula is as follows:
[0053]
[0054] In the formula: represents the NO concentration at the reaction inlet; represents the NO concentration at the reaction outlet.
[0055] Carry out the above catalyst performance evaluation experiments on the denitration catalysts A: VMnCeOx-M-ZSM-5@FZ-X(1, 2), B: VMnCeOx-H-ZSM-5@FZ-X(1, 2), VMnCeOx@FZ, and FZ prepared in Examples 1 - 6 respectively. Among them, the optimal active catalysts for A and B are VMnCeOx-M-ZSM-5@FZ-40 and VMnCeOx-H-ZSM-5@FZ-220 respectively. The denitration results are shown in Table 1 below:
[0056] Table 1 NO conversion rate of the catalyst of the present invention
[0057]
[0058] As can be seen from the above data, the present invention discloses a method for preparing an SCR denitration catalyst by using molecular sieve modified vanadium-extracted stone coal tailings. This method makes full use of vanadium-extracted stone coal tailings. While carrying out resource utilization of vanadium-extracted stone coal tailings, the catalyst prepared by surface modification thereof has good denitration efficiency.
[0059] The conventional technologies and the solutions not described in detail in the above embodiments are well known in the art, so they will not be elaborated here in detail. The above embodiments and / or experimental examples have described in detail the preferred embodiments of the present invention. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention. In addition, it should be noted that in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods. In addition, any combination can be made between different embodiments of the present invention as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.
Claims
1. A method for preparing an SCR denitration catalyst by using molecular sieve modified stone coal vanadium extraction tailings, which is characterized in that, It includes the following steps: (1) Ball-mill and crush the vanadium slag from stone coal to obtain vanadium slag powder; (2) Mix the materials including water, vanadium slag powder, silicon source, aluminum source, alkali, binder and template agent to obtain a mixed material; the materials are mixed in the order of water, vanadium slag powder, binder, silicon source, aluminum source, alkali, template agent. After adding water, vanadium slag powder and binder, stir for 30 - 60 min, then add silicon source, aluminum source, alkali and template agent, and stir for 10 - 30 min respectively after adding each of them; (3) Crystallize the mixed material to obtain a vanadium slag carrier modified with molecular sieve. The crystallization method includes: Method A: Crystallize the above-mentioned mixed material by microwave method to prepare a sodium-type M-ZSM-5 vanadium slag carrier modified with different nSiO2 / nAl2O3 molecular sieves; or Method B: Crystallize the above-mentioned mixed material by hydrothermal method to prepare a sodium-type H-ZSM-5 vanadium slag carrier modified with different nSiO2 / nAl2O3 molecular sieves; (4) The sodium-type M-ZSM-5 vanadium slag carrier or H-ZSM-5 vanadium slag carrier modified with different nSiO2 / nAl2O3 molecular sieves is obtained through steps including washing, filtering, drying, calcining, multiple ion exchanges, secondary washing, secondary filtering, secondary drying, and secondary calcining to obtain a hydrogen-type M-ZSM-5 or H-ZSM-5 vanadium slag carrier modified with different nSiO2 / nAl2O3 molecular sieves; (5) Mix the hydrogen-type M-ZSM-5 or H-ZSM-5 vanadium slag carrier modified with different nSiO2 / nAl2O3 molecular sieves with the precursors of active components and promoters and water evenly, then dry and calcine to obtain an SCR denitration catalyst.
2. The method according to claim 1, characterized in that, In step (1), the particle size of the vanadium slag powder is 80 - 200 mesh.
3. The method according to claim 1, characterized in that, In step (2), the silicon source in the mixed material is silica sol, the aluminum source is aluminum sulfate octadecahydrate, the alkali is sodium hydroxide, and the template agent is tetrapropylammonium bromide TPABr.
4. The method according to claim 1, characterized in that, In step (3), the temperature of the microwave method crystallization is 160 °C and the crystallization time is 6 h; for the mixed material corresponding to the sodium-type M-ZSM-5 vanadium slag carrier modified with different nSiO2 / nAl2O3 molecular sieves, the amounts of substance of silicon source, aluminum source, alkali, template agent, and water are taken as n(SiO2):n(Al2O3): n(NaOH):n(TPABr):n(H2O) = 1:a: 0.12: 0.25: 50, and the mass ratio of vanadium slag powder to binder is taken as m(vanadium slag powder):m(binder)=20:1; The temperature of the hydrothermal crystallization is 240 °C, and the crystallization time is 48 h; in the mixed material corresponding to the sodium-type H-ZSM-5 vanadium slag carrier modified by different nSiO2 / nAl2O3 molecular sieves, the amounts of substance of the silicon source, aluminum source, alkali, template agent, and water are taken according to n(SiO2):n(Al2O3): n(NaOH):n(TPABr): n(H2O) = 1:a: 0.12: 0.25: 50, and the masses of the vanadium slag powder and the binder are taken according to m(vanadium slag powder):m(binder)=20:
1.
5. The method according to claim 1, characterized in that, In step (3), the different nSiO2 / nAl2O3 are the ratios X of nSiO2 to nAl2O3 being 40, 100, 160, 220, 280, or 340.
6. The method according to claim 1, wherein In step (4), the calcination temperature is 550 °C, and the calcination time is 6 h; the reagent used for ion exchange is 1 mol / L NH4Cl solution, the exchange temperature is 80 °C, and the number of ion exchange times is three.
7. The method according to claim 1, wherein In step (5), the precursor of the active component is 50% Mn(NO3)2 solution and ammonium metavanadate (NH4VO3), and the precursor of the promoter is cerium nitrate hexahydrate (Ce(NO3)2▪6H2O).
8. The method according to claim 1, wherein In step (5), the method for uniform mixing is stirring for 2 h, the method for drying is drying at 100 °C for 12 h, and the method for calcination is calcining in a muffle furnace at 500 °C for 4 h.
9. A denitration catalyst prepared by the method according to any one of claims 1-8.