A method for preparing a thallium-resistant SCR denitrification catalyst for cement kilns and its application

Abstract

This invention relates to the field of denitrification catalyst technology, specifically to a method for preparing a thallium-resistant SCR denitrification catalyst for cement kilns and its application. The catalyst is made from raw materials such as titanium dioxide, functional additives, ammonium metavanadate-monoethanolamine aqueous solution, ammonium metatungstate, glass fiber, stearic acid, lactic acid, polyoxyethylene, carboxymethyl cellulose, and ammonia. The preparation method includes steps such as mixing, pH adjustment, aging, extrusion molding, and calcination. The SCR denitrification catalyst prepared by this invention not only has excellent denitrification performance but also good resistance to thallium poisoning, which can effectively extend the service life of the SCR denitrification catalyst to a certain extent, and has significant practical value and broad market prospects.

Description

Technical Field

[0001] This invention relates to the field of denitrification catalyst technology, specifically to a method for preparing a thallium-resistant SCR denitrification catalyst for cement kilns and its application. Background Technology

[0002] With the rapid development of my country's economy, energy consumption is increasing daily. However, in terms of energy conversion and utilization, uneven technological development and low production efficiency have led to pollution phenomena such as smoke, acid rain, the greenhouse effect, and ozone layer depletion, resulting in increasingly serious air pollution. Cement kiln flue gas has a complex composition, containing high concentrations of nitrogen oxides (NOx). x ), dust, sulfur oxides (SO) x The flue gas treatment process involves the production of thallium (Tl) and trace amounts of heavy metals (such as thallium and mercury). Thallium, being a highly toxic heavy metal, readily adsorbs onto the surface of denitrification catalysts or reacts with active components, leading to catalyst poisoning and deactivation. Developing efficient, low-temperature denitrification catalysts resistant to thallium poisoning has become an urgent need in the cement industry.

[0003] Thallium is widely distributed in pyrite and mica minerals, which are the basic components of cement raw materials. This leads to the prevalence of thallium in cement flue gas, making thallium-induced poisoning a unique pathway for the deactivation of SCR catalysts in cement kilns. Unlike other industrial flue gases, thallium oxides gradually accumulate on the catalyst surface through dust deposition, with a content of approximately 3-6%.

[0004] Molecular sieves, including SSZ-13, SAPO-34, Beta, and ZSM-5, are considered excellent support materials for NOx removal due to their abundant surface acidity and microporous structure. ZSM-5, Beta, and SSZ-13 are all silica-alumina zeolites, where aluminum replaces silicon to form a large number of Si-O(H)-Al groups. These groups can provide a large number of protons for ion exchange with alkali metal or heavy metal ions to protect the active components.

[0005] The introduction of ZSM-5 enhances the interaction between the active component and the support, allowing thallium to accumulate in the molecular sieve portion and preventing its aggregation on the TiO2 surface, thereby preventing thallium from reacting with VO at the source. x The active site is in direct contact; at the same time, VO x Due to its high affinity for TiO2, ZSM-5 is stably loaded on the TiO2 surface and will not be lost due to the addition of molecular sieves. In addition, ZSM-5 can reduce the damage of thallium to the TiO2 microcrystalline structure after capturing thallium (such as inhibiting excessive grain growth), maintain the physical stability of the catalyst, and improve the overall NH3-SCR performance in many ways.

[0006] However, existing ZSM-5 molecular sieves have limited selective capture capacity for thallium, and their structure is easily damaged in the complex high-temperature, dusty, and sulfur-containing flue gas environment of cement kilns, leading to a decrease in their protective effect. Therefore, this invention provides a method for preparing a thallium-resistant SCR denitrification catalyst for cement kilns and its application, to solve the above-mentioned technical problems. Summary of the Invention

[0007] This invention provides a method for preparing a thallium-resistant SCR denitrification catalyst for cement kilns and its application. The SCR denitrification catalyst prepared by this invention not only has excellent denitrification performance but also good resistance to thallium poisoning, which can effectively extend the service life of the SCR denitrification catalyst to a certain extent. It has significant practical value and broad market prospects.

[0008] To achieve the above objectives, the present invention provides the following technical solution: The first objective of this invention is to provide a method for preparing a thallium-resistant SCR denitrification catalyst for cement kilns, comprising the following steps: Step 1: Add 52.8-56.5 parts by weight of titanium dioxide and 5.2-7.9 parts by weight of functional additives to a mixer, mix evenly, then add deionized water and stir at 60-80℃ to form a slurry with a moisture content of 38-39%, and set aside. Step 2: Add 1-2 parts by weight of ammonium metatungstate, 0.5-1 parts by weight of stearic acid, and 0.3-0.5 parts by weight of lactic acid to the mud and mix evenly to obtain the first mixture. Step 3: Add 2-3 parts by weight of ammonia water to the first mixture, adjust the pH of the mud to 8.2-8.5, then add 10-20 parts by weight of the modification liquid, mix and stir for 50-70 minutes, then heat up and remove moisture until the moisture content of the mud in the mixer is 33-34%, to obtain the second mixture. Step 4: Add 6-6.5 parts by weight of glass fiber to the second mixture, mix for 40-60 minutes, adjust the moisture content of the mud to 30-31%, then add 0.3-0.5 parts by weight of polyethylene oxide and 0.4-0.6 parts by weight of carboxymethyl cellulose, continue stirring and adjusting until the moisture content of the mud is 25-27% and the pH value is 7.6-8.0; then age in the mixer to obtain aged mud. Step 5: The aged mud is extruded into strips and blocks through a pre-extrusion machine. After removing impurities from the mud, the honeycomb catalyst wet preform is extruded through an extrusion die. The extruded honeycomb catalyst wet preform is dried and calcined to obtain the thallium-resistant SCR denitrification catalyst.

[0009] Furthermore, the preparation method of the functional additive is as follows: Step 1: Disperse ZSM-5 molecular sieve uniformly in deionized water at a dosage ratio of 10-30 g / L, add lanthanum nitrate and manganese nitrate, mix and stir evenly, then add 15-20% by volume of ammonium molybdate solution with a concentration of 0.1-0.2 g / mL to the resulting mixture at room temperature, and adjust the pH to 9-10; after stirring at room temperature for 4-6 hours, transfer to a reaction vessel and react at 190-230℃ for 8-12 hours; after the reaction is complete, perform solid-liquid separation, water washing, vacuum drying and sintering treatment on the reaction solution in sequence to obtain the modified porous carrier; The second step involves uniformly dispersing the modified porous carrier in a 50-70 g / L zirconium oxychloride aqueous solution at a dosage ratio of 50-80 g / L. While stirring, an equal volume of ammonium dihydrogen phosphate aqueous solution with a concentration of 30-50 g / L is added. The reaction is carried out at a temperature of 140-160℃ for 6-10 hours. After the reaction is completed, the reaction solution is subjected to solid-liquid separation, washing, vacuum drying, and sintering treatment to obtain the functional additive.

[0010] Furthermore, the concentration of lanthanum nitrate in the mixture of the first step is 0.3-0.8 mol / L, and the concentration of manganese nitrate is 0.5-1.0 mol / L.

[0011] Furthermore, the vacuum drying temperature in both the first and second steps is 100-120℃, and the vacuum drying time is 4-6 hours.

[0012] Furthermore, the sintering temperature in both the first and second steps is 450-550℃, and the sintering time is 3-5h. During sintering, a hydrogen-argon mixture with a hydrogen volume percentage of 5-10% is used as the atmosphere, and the heating rate is 5-10℃ / min.

[0013] Furthermore, the modified solution in step three is prepared by mixing metavanadate, monoethanolamine and water at a mass ratio of 1:0.8-1.2:2-4 at 70-80°C until homogeneous.

[0014] Furthermore, the metavanadate is ammonium metavanadate.

[0015] Furthermore, the aging time in step four is 8-12 hours, and the aging temperature is 25-45℃.

[0016] Furthermore, in step five, the drying temperature is 90-130℃ and the drying time is 5-12h; the calcination temperature is 550-580℃ and the calcination time is 30-35h.

[0017] Another object of the present invention is to provide the application of the thallium-resistant SCR denitrification catalyst for cement kilns prepared by the above preparation method in the denitrification of industrial tail gas in cement kilns.

[0018] The roles of each raw material are as follows: 1. Titanium dioxide: TiO2, specific surface area 80-100 m² 2 / g, with a particle size distribution D50 ranging from 0.8 to 1.2 μm, its main function is as a catalyst substrate, providing a support for the uniform distribution of the active components of the catalyst and improving N2 selectivity.

[0019] 2. ZSM-5 molecular sieve: The main components are SiO2 and Al2O3. Its main function is to improve the thallium resistance of catalysts.

[0020] 3. Ammonium metavanadate solution: Ammonium metavanadate, monoethanolamine, and deionized water are mixed in a mass ratio of 1:1:3 at 75℃±5℃ to form a homogeneous solution, wherein monoethanolamine is a co-solvent for ammonium metavanadate.

[0021] 4. Glass fiber: Its main components are SiO2, Al2O3 and CaO. It plays a skeletal role in the catalyst and improves the structural strength of the catalyst.

[0022] 5. Lactic acid: an adsorbent that improves the plasticity of mud.

[0023] 6. Stearic acid: It plays a role in catalysts by releasing molds, lubricating, and reducing viscosity.

[0024] 7. Polyoxyethylene (PEO): Viscosity range 250-350 mPa·s, thickener, flocculant, lubricant, improves the plasticity of mud.

[0025] 8. Ammonium metatungstate: A catalyst activator that improves the catalyst's resistance to sintering, enhances its thermal stability, and improves its resistance to arsenic and alkali metal poisoning.

[0026] Compared with the prior art, the beneficial effects of the present invention are: 1. The functional additive prepared in this invention uses ZSM-5 molecular sieve as the matrix material and modifies it with lanthanum and manganese oxides. The prepared functional additive can give full play to the inherent regular microporous structure and surface acidity of ZSM-5 molecular sieve. Through the synergistic effect of acidic sites and variable valence sites provided by lanthanum and manganese oxides, it can carry out efficient ion exchange and chemical adsorption of thallium ions in flue gas, and directionally capture and fix thallium ions in the molecular sieve channels and surface areas. This spatially isolates thallium from the VOx active components on titanium dioxide, inhibits the direct contact between thallium and active sites and the possibility of forming inactive compounds from the source, significantly delays the catalyst poisoning process, and effectively extends the service life of SCR denitrification catalyst to a certain extent. Secondly, the zirconium-phosphorus composite phase in the functional additive forms a heat-resistant and rigid inorganic framework on the surface and within the pores of the support. This framework effectively inhibits the sintering and growth of ZSM-5 microcrystals and the abnormal growth of titanium dioxide grains during high-temperature calcination and long-term operation, maintaining the catalyst's high specific surface area and pore volume. This not only facilitates the diffusion and contact of reactant gases but also prevents the decrease in activity caused by structural collapse or pore blockage. Furthermore, because the functional additive possesses both enhanced surface acidity and ion exchange capacity, even a small amount can significantly improve the catalyst's tolerance to alkali metal and heavy metal ions in complex flue gas environments. This allows the catalyst to maintain high and stable denitrification efficiency even under typical cement kiln conditions (such as around 310℃, dust, SOx, and trace amounts of thallium).

[0027] 2. The functional additives in this invention work synergistically with glass fiber and polymer thickener to improve the plasticity, extrusion molding properties and green body strength of the clay, making the honeycomb wet green body less prone to cracking during drying and calcination. The finished catalyst has good mechanical strength and thermal shock resistance, and can meet the requirements of frequent start-up and shutdown and load changes in cement kiln sites.

[0028] In summary, the SCR denitration catalyst prepared by this invention not only has excellent denitration performance but also good resistance to thallium poisoning, which can effectively extend the service life of the SCR denitration catalyst to a certain extent. It has significant practical value and broad market prospects. Attached Figure Description

[0029] Figure 1 This is a physical image of the thallium-resistant SCR denitrification catalyst for cement kilns prepared in Example 1 of this invention.

[0030] Figure 2 This is a photograph of the functional additive prepared in Example 1 of this invention. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0032] A method for preparing a thallium-resistant SCR denitrification catalyst for cement kilns includes the following steps: Step 1: Add 52.8 parts by weight of titanium dioxide and 5.2 parts by weight of functional additives to a mixer, mix evenly, add deionized water, and stir at 60°C to make a slurry with a moisture content of 38% for later use. Step 2: Add 1 part by weight of ammonium metatungstate, 0.5 parts by weight of stearic acid, and 0.3 parts by weight of lactic acid to the mud and mix well to obtain the first mixture. Step 3: Add 2 parts by mass of ammonia water to the first mixture to adjust the pH of the mud to 8.2, then add 10 parts by mass of the modification liquid. Mix and stir for 50 minutes, then heat up and remove moisture until the moisture content of the mud in the mixer is 33%, to obtain the second mixture. The modification liquid is prepared by mixing ammonium metavanadate, monoethanolamine and water in a mass ratio of 1:0.8:2 at 70°C until homogeneous. Step 4: Add 6 parts by weight of glass fiber to the second mixture, mix for 40 minutes, adjust the moisture content of the mud to 30%, then add 0.3 parts by weight of polyethylene oxide and 0.4 parts by weight of carboxymethyl cellulose, continue stirring and adjust until the moisture content of the mud is 25% and the pH value is 7.6; then age it in a mixer to obtain aged mud; the aging time is 8 hours and the aging temperature is 45℃.

[0033] Step 5: The aged mud is extruded into strips and blocks through a pre-extrusion machine. After removing impurities from the mud, the honeycomb catalyst wet preform is extruded through an extrusion die. The extruded honeycomb catalyst wet preform is dried and calcined to obtain the thallium-resistant SCR denitrification catalyst. The drying temperature is 90℃ and the drying time is 12h. The calcination temperature is 550℃ and the calcination time is 35h.

[0034] The preparation method of the functional additive is as follows: Step 1: Disperse ZSM-5 molecular sieve uniformly in deionized water at a dosage ratio of 10 g / L, add lanthanum nitrate and manganese nitrate, mix and stir evenly, then add 15% (by volume) of ammonium molybdate solution with a concentration of 0.1 g / mL to the resulting mixture at room temperature, and adjust the pH to 9; after stirring at room temperature for 4 hours, transfer to a reaction vessel and react at 190℃ for 12 hours; after the reaction is complete, perform solid-liquid separation, water washing, vacuum drying and sintering treatment on the reaction solution in sequence to obtain the modified porous carrier; The second step involves uniformly dispersing the modified porous carrier in a 50 g / L zirconium oxychloride aqueous solution at a dosage ratio of 50 g / L. While stirring, an equal volume of ammonium dihydrogen phosphate aqueous solution with a concentration of 30 g / L is added. The mixture is stirred and reacted at 140°C for 10 hours. After the reaction is complete, the reaction solution is subjected to solid-liquid separation, washing, vacuum drying, and sintering to obtain the functional additive. In the first step, the concentration of lanthanum nitrate in the mixed solution is 0.3 mol / L, and the concentration of manganese nitrate is 0.5 mol / L. The vacuum drying temperature in both the first and second steps is 100℃, and the vacuum drying time is 6 hours. The sintering temperature in both the first and second steps was 450℃, and the sintering time was 5h. During sintering, a hydrogen-argon mixture with a hydrogen volume percentage of 5% was used as the atmosphere, and the heating rate was 5℃ / min. Example 2

[0035] A method for preparing a thallium-resistant SCR denitrification catalyst for cement kilns includes the following steps: Step 1: Add 54.5 parts by weight of titanium dioxide and 6.5 parts by weight of functional additives to a mixer, mix evenly, then add deionized water and stir at 70°C to form a slurry with a moisture content of 39%, set aside. Step 2: Add 1.5 parts by weight of ammonium metatungstate, 0.7 parts by weight of stearic acid, and 0.4 parts by weight of lactic acid to the mud and mix well to obtain the first mixture. Step 3: Add 3 parts by mass of ammonia water to the first mixture to adjust the pH of the mud to 8.5, then add 15 parts by mass of the modification liquid. Mix and stir for 60 minutes, then heat up and remove moisture until the moisture content of the mud in the mixer is 33-34%, to obtain the second mixture. The modification liquid is prepared by mixing ammonium metavanadate, monoethanolamine and water in a mass ratio of 1:1:3 at 75°C until homogeneous. Step 4: Add 6.5 parts by weight of glass fiber to the second mixture, mix for 50 minutes, adjust the moisture content of the mud to 31%, then add 0.4 parts by weight of polyethylene oxide and 0.5 parts by weight of carboxymethyl cellulose, continue stirring and adjust until the moisture content of the mud is 26% and the pH value is 7.8; then age in a mixer to obtain aged mud; wherein, the aging time in step 4 is 10 hours and the aging temperature is 35℃; Step 5: The aged mud is extruded into strips and blocks through a pre-extrusion machine. After removing impurities from the mud, the honeycomb catalyst wet preform is extruded through an extrusion die. The extruded honeycomb catalyst wet preform is dried and calcined to obtain the thallium-resistant SCR denitrification catalyst. The drying temperature is 110℃ and the drying time is 8h. The calcination temperature is 570℃ and the calcination time is 35h.

[0036] The preparation method of the functional additive is as follows: Step 1: Disperse ZSM-5 molecular sieve uniformly in deionized water at a dosage ratio of 20 g / L, add lanthanum nitrate and manganese nitrate, mix and stir evenly, then add 20% of the volume of ammonium molybdate solution with a concentration of 0.2 g / mL to the resulting mixture at room temperature, and adjust the pH to 9.5; after stirring at room temperature for 5 h, transfer to a reaction vessel and react at 210℃ for 10 h; after the reaction is complete, perform solid-liquid separation, water washing, vacuum drying and sintering treatment in sequence to obtain the modified porous carrier; The second step involves uniformly dispersing the modified porous carrier in a 60 g / L zirconium oxychloride aqueous solution at a dosage ratio of 60 g / L. While stirring, an equal volume of ammonium dihydrogen phosphate aqueous solution with a concentration of 40 g / L is added. The mixture is stirred and reacted at 150°C for 8 hours. After the reaction is complete, the reaction solution is subjected to solid-liquid separation, washing, vacuum drying, and sintering to obtain the functional additive. In the first step, the concentration of lanthanum nitrate in the mixed solution is 0.5 mol / L, and the concentration of manganese nitrate is 0.8 mol / L. The vacuum drying temperature in both the first and second steps is 110℃, and the vacuum drying time is 5 hours. The sintering temperature in both the first and second steps is 500℃ and the sintering time is 4h. During sintering, a hydrogen-argon mixture with a hydrogen volume percentage of 8% is used as the atmosphere, and the heating rate is 10℃ / min. Example 3

[0037] A method for preparing a thallium-resistant SCR denitrification catalyst for cement kilns includes the following steps: Step 1: Add 56.5 parts by weight of titanium dioxide and 7.9 parts by weight of functional additives to a mixer, mix evenly, then add deionized water and stir at 80°C to form a slurry with a moisture content of 38-39%, set aside. Step 2: Add 2 parts by weight of ammonium metatungstate, 1 part by weight of stearic acid, and 0.5 parts by weight of lactic acid to the mud and mix well to obtain the first mixture. Step 3: Add 3 parts by mass of ammonia water to the first mixture to adjust the pH of the mud to 8.5, then add 20 parts by mass of the modification liquid. Mix and stir for 570 minutes, then heat up and remove moisture until the moisture content of the mud in the mixer is 34%, to obtain the second mixture. The modification liquid is prepared by mixing ammonium metavanadate, monoethanolamine and water in a mass ratio of 1:1.2:4 at 70-80℃ until homogeneous. Step 4: Add 6.5 parts by weight of glass fiber to the second mixture, mix for 60 minutes, adjust the moisture content of the mud to 31%, then add 0.5 parts by weight of polyethylene oxide and 0.6 parts by weight of carboxymethyl cellulose, continue stirring and adjust until the moisture content of the mud is 27% and the pH value is 8.0; then age in a mixer to obtain aged mud; the aging time is 12 hours and the aging temperature is 25℃. Step 5: The aged mud is extruded into strips and blocks through a pre-extrusion machine. After removing impurities from the mud, the honeycomb catalyst wet preform is extruded through an extrusion die. The extruded honeycomb catalyst wet preform is dried and calcined to obtain the thallium-resistant SCR denitrification catalyst. The drying temperature is 130℃ and the drying time is 5h. The calcination temperature is 580℃ and the calcination time is 30h.

[0038] The preparation method of the functional additive is as follows: Step 1: Disperse ZSM-5 molecular sieve uniformly in deionized water at a dosage ratio of 30 g / L, add lanthanum nitrate and manganese nitrate, mix and stir evenly, then add 20% of the volume of ammonium molybdate solution with a concentration of 0.2 g / mL to the resulting mixture at room temperature, and adjust the pH to 10; after stirring at room temperature for 6 hours, transfer to a reaction vessel and react at 230℃ for 8 hours; after the reaction is complete, perform solid-liquid separation, water washing, vacuum drying and sintering treatment in sequence to obtain the modified porous carrier; The second step involves uniformly dispersing the modified porous carrier in a 70 g / L zirconium oxychloride aqueous solution at a dosage ratio of 80 g / L. While stirring, an equal volume of 50 g / L ammonium dihydrogen phosphate aqueous solution is added, and the mixture is stirred and reacted at 160°C for 6 hours. After the reaction is complete, the reaction solution is subjected to solid-liquid separation, washing, vacuum drying, and sintering treatment to obtain the functional additive. In the first step, the concentration of lanthanum nitrate in the mixed solution is 0.8 mol / L, and the concentration of manganese nitrate is 1.0 mol / L. The vacuum drying temperature in both the first and second steps is 120℃, and the vacuum drying time is 4 hours. The sintering temperature in both the first and second steps is 450-550℃, and the sintering time is 3-5h. During sintering, a hydrogen-argon mixture with a hydrogen volume percentage of 10% is used as the atmosphere, and the heating rate is 10℃ / min.

[0039] Comparative Example 1: The difference between this comparative example and Example 1 is that an equal amount of ZSM-5 molecular sieve is used to replace the functional additive in the preparation of this comparative example.

[0040] Comparative Example 2: The difference between this comparative example and Example 1 is that an equal amount of modified porous carrier is used to replace the functional additive in the preparation of this comparative example.

[0041] Performance Testing: The SCR denitrification catalysts prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to denitrification experiments. The specific test conditions for the denitrification experiments were as follows: the cut catalyst samples were placed in a micro-activity evaluation device, the reaction temperature was set to 310℃, and the flue gas component NO... x The reaction mixture consisted of 195 ppm of nitrogen, 2.6% of oxygen, and 205 ppm of NH3, with N2 as the carrier gas and a space velocity of 13333 h⁻¹. -1 Wherein, denitrification efficiency = (inlet NO) x Concentration - Export NO x Concentration) / Inlet NO x Concentration × 100%; Specific surface area, pore volume and pore size were tested using a specific surface area and pore size analyzer, and the test data were recorded in Table 1 and Table 2.

[0042] Table 1 shows the denitrification efficiency of each group of SCR denitrification catalyst samples.

[0043] Table 2 shows the relationship between specific surface area and pore volume and pore size of each group of SCR denitrification catalyst samples.

[0044] By comparing and analyzing the relevant data in the table, it can be seen that the SCR denitrification catalyst prepared by this invention not only has excellent denitrification performance but also good resistance to thallium poisoning, which can effectively extend the service life of the SCR denitrification catalyst to a certain extent, demonstrating significant practical value and broad market prospects. This indicates that the preparation method and application of the thallium-resistant SCR denitrification catalyst for cement kilns provided by this invention have broader market prospects and are more suitable for widespread application.

[0045] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0046] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a catalyst for the SCR denitration of cement kilns resistant to thallium, characterized in that, Includes the following steps: Step 1: Add 52.8-56.5 parts by weight of titanium dioxide and 5.2-7.9 parts by weight of functional additives to a mixer, mix evenly, then add deionized water and stir at 60-80℃ to form a slurry with a moisture content of 38-39%, and set aside. Step 2: Add 1-2 parts by weight of ammonium metatungstate, 0.5-1 parts by weight of stearic acid, and 0.3-0.5 parts by weight of lactic acid to the mud and mix evenly to obtain the first mixture. Step 3: Add 2-3 parts by weight of ammonia water to the first mixture, adjust the pH of the mud to 8.2-8.5, then add 10-20 parts by weight of the modification liquid, mix and stir for 50-70 minutes, then heat up and remove moisture until the moisture content of the mud in the mixer is 33-34%, to obtain the second mixture. Step 4: Add 6-6.5 parts by weight of glass fiber to the second mixture, mix for 40-60 minutes, adjust the moisture content of the mud to 30-31%, then add 0.3-0.5 parts by weight of polyethylene oxide and 0.4-0.6 parts by weight of carboxymethyl cellulose, continue stirring and adjusting until the moisture content of the mud is 25-27% and the pH value is 7.6-8.0; then age in the mixer to obtain aged mud. Step 5: The aged mud is extruded into strips and blocks through a pre-extrusion machine. After removing impurities from the mud, the honeycomb catalyst wet preform is extruded through an extrusion die. The extruded honeycomb catalyst wet preform is dried and calcined to obtain the thallium-resistant SCR denitrification catalyst.

2. The method for preparing a catalyst for SCR denitration resistant to thallium for a cement kiln according to claim 1, characterized in that, The preparation method of the functional additive is as follows: Step 1: Disperse ZSM-5 molecular sieve uniformly in deionized water at a dosage ratio of 10-30 g / L, add lanthanum nitrate and manganese nitrate, mix and stir evenly, then add 15-20% by volume of ammonium molybdate solution with a concentration of 0.1-0.2 g / mL to the resulting mixture at room temperature, and adjust the pH to 9-10; after stirring at room temperature for 4-6 hours, transfer to a reaction vessel and react at 190-230℃ for 8-12 hours; after the reaction is complete, perform solid-liquid separation, water washing, vacuum drying and sintering treatment on the reaction solution in sequence to obtain the modified porous carrier; The second step involves uniformly dispersing the modified porous carrier in a 50-70 g / L zirconium oxychloride aqueous solution at a dosage ratio of 50-80 g / L. While stirring, an equal volume of ammonium dihydrogen phosphate aqueous solution with a concentration of 30-50 g / L is added. The reaction is carried out at a temperature of 140-160℃ for 6-10 hours. After the reaction is completed, the reaction solution is subjected to solid-liquid separation, washing, vacuum drying, and sintering treatment to obtain the functional additive.

3. The method for preparing a catalyst for SCR denitration resistant to thallium for a cement kiln according to claim 2, characterized in that: The concentration of lanthanum nitrate in the mixture of the first step is 0.3-0.8 mol / L, and the concentration of manganese nitrate is 0.5-1.0 mol / L.

4. The method for preparing a catalyst for the removal of NOx by SCR according to claim 2, characterized in that: The vacuum drying temperature in both the first and second steps is 100-120℃, and the vacuum drying time is 4-6 hours.

5. The method for preparing a catalyst for the removal of NOx by SCR according to claim 2, characterized in that: The sintering temperature in both the first and second steps is 450-550℃, and the sintering time is 3-5h. During sintering, a hydrogen-argon mixture with a hydrogen volume percentage of 5-10% is used as the atmosphere, and the heating rate is 5-10℃ / min.

6. The method for preparing a catalyst for the removal of NOx by SCR according to claim 1, characterized in that: The modified solution in step three is prepared by mixing metavanadate, monoethanolamine and water at a mass ratio of 1:0.8-1.2:2-4 at 70-80°C until homogeneous.

7. The method for preparing a catalyst for the removal of NOx by SCR according to claim 6, characterized in that: The metavanadate is ammonium metavanadate.

8. The method for preparing a thallium-resistant SCR denitrification catalyst for cement kilns according to claim 1, characterized in that, The aging time in step four is 8-12 hours, and the aging temperature is 25-45℃.

9. The method for preparing a catalyst for the removal of NOx by SCR according to claim 1, characterized in that: The drying temperature in step five is 90-130℃, and the drying time is 5-12h; the calcination temperature is 550-580℃, and the calcination time is 30-35h.

10. The application of the thallium-resistant SCR denitrification catalyst for cement kilns prepared by the preparation method according to any one of claims 1-9 in the denitrification of industrial tail gas in cement kilns.

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