Preparation method of anti-poisoning SCR denitration catalyst

Abstract

The application discloses a kind of preparation methods of anti-poisoning SCR denitration catalyst, to solve the technical problems that the performance of anti-alkali and sulfide poisoning of SCR denitration catalyst in the prior art needs to be further improved, the present application comprises the following steps: titanium dioxide, pretreated red mud, composite vanadium-iron particles, acidic zirconium sulfate, calcium fluoride, sodium silicate, acrylamide, N,N'-methylene bisacrylamide and deionized water are mixed and stirred, the temperature of reaction system is increased to 70-80 DEG C, initiator solution is added dropwise to the reaction system, and the reaction is kept for 2-3h, stirring until the system is gelled, and defoaming;The present application is modified by germanium and manganese on vanadium-iron coprecipitated particles, and cooperates with pretreated red mud, titanium dioxide and acidic zirconium sulfate, which not only effectively improves the denitration efficiency and denitration activity of the denitration catalyst, but also improves the anti-alkali and sulfide poisoning performance of the denitration catalyst.

Description

Technical Field

[0001] This invention relates to the field of denitrification catalytic materials technology, specifically to a method for preparing an anti-poisoning SCR denitrification catalyst. Background Technology

[0002] Nitrogen oxides are one of the main air pollutants that cause acid rain, photochemical smog, and ozone layer depletion, posing serious threats to human health and the ecological environment. Currently, the main principle of selective catalytic reduction (SCR) of nitrogen oxides using NH3 as a reducing agent is to selectively reduce NOx to N2 under the action of a denitrification catalyst. Due to its efficient and reliable denitrification performance, it has been widely used in industrial fields such as coal-fired power plants.

[0003] SCR denitrification catalyst is the core component of SCR technology. However, in practical applications, the catalyst is exposed to flue gas containing fly ash, SOx, alkali metals (K, Na, etc.), Hg, As, etc. for a long time. These components can easily cause catalyst poisoning and deactivation. Catalyst poisoning not only reduces denitrification efficiency but also shortens the catalyst's service life and increases operating costs.

[0004] Currently, the widely used denitrification catalysts are honeycomb-shaped commercial V2O5-WO3 / TiO2-based catalysts or V2O5-MoO3 / TiO2-based catalysts. Although these catalysts have high denitrification activity, their denitrification efficiency will rapidly decrease, their activity will deteriorate, and their lifespan will be shortened in flue gas containing toxic components such as sulfides and alkali metals.

[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing an anti-poisoning SCR denitrification catalyst, which solves the technical problem that the performance of existing SCR denitrification catalysts in resisting alkali and sulfide poisoning needs to be further improved.

[0007] The objective of this invention can be achieved through the following technical solution: a method for preparing an anti-poisoning SCR denitrification catalyst, comprising the following steps:

[0008] S1. Mix and stir titanium dioxide, pretreated red mud, composite vanadium-iron particles, acidic zirconium sulfate, calcium fluoride, sodium silicate, acrylamide, N,N′-methylenebisacrylamide and deionized water. Raise the temperature of the reaction system to 70-80℃, add initiator solution dropwise to the reaction system, keep the reaction at the temperature for 2-3 hours, stir until the system gels, degas, and obtain a mixed gel.

[0009] S2. Pour the mixed gel into a mold at 80-90℃, allow it to gel for 60-80 minutes, demold and dry it to obtain the denitrification catalyst preform.

[0010] S3. The denitrification catalyst blank is calcined at high temperature to obtain the denitrification catalyst.

[0011] The synthesis reaction mechanism of denitration catalyst is as follows:

[0012] In the preparation process, acrylamide and N,N′-methylenebisacrylamide act as monomers and crosslinking agents, respectively, undergoing free radical polymerization under the initiator of potassium persulfate. Simultaneously, the silica colloid generated from the hydrolysis of sodium silicate interacts with the polymer formed by acrylamide to form a gel. Titanium dioxide, pretreated red mud, composite vanadium-iron particles, acidic zirconium sulfate, and calcium fluoride are uniformly dispersed as inorganic particles in the gel. As the polymerization reaction proceeds, the polymer chains continuously grow and intertwine, forming a three-dimensional network structure. Furthermore, the crosslinking effect of the silica colloid also promotes gel formation. When the polymer chains and silica colloids intertwine to a certain extent, the system gels, forming a stable mixed gel. After the mixed gel solidifies in the mold, it is dried to remove the moisture. During the calcination process, the organic matter in the catalyst preform undergoes pyrolysis and combustion, generating and escaping gases, leaving a porous structure. Calcium fluoride acts as a sintering aid, promoting the growth of grains and the stability of the crystal phase in the catalyst. At high temperatures, calcium fluoride interacts with other components in the catalyst to form a solid solution, which helps in grain growth and grain boundary clarification, thereby improving the thermal and chemical stability of the catalyst.

[0013] Further, in step S1, the ratio of titanium dioxide, pretreated red mud, composite vanadium-iron particles, acidic zirconium sulfate, calcium fluoride, sodium silicate, acrylamide, N,N′-methylenebisacrylamide, deionized water, and initiator solution is 2g:7g:3g:5g:1g:15g:5g:1g:90mL:10mL, and the initiator solution is composed of potassium persulfate and deionized water at a ratio of 1g:50mL; in step S2, the programmed drying includes: after demolding, placing the material in a drying oven at a temperature of 60-70℃ and drying for 20h; then raising the temperature of the drying oven to 90-95℃ at a rate of 2℃ / min and maintaining the temperature for 24h to obtain the catalyst blank; in step S3, the high-temperature calcination temperature is 700-760℃ and the calcination time is 3-5h.

[0014] Furthermore, the preparation method of titanium dioxide is as follows: hydrofluoric acid is added to tetrabutyl titanate, the reaction system is sealed, the temperature of the reaction system is raised to 160-180℃, the reaction is kept at this temperature for 20-22 hours, and then post-processed and calcined to obtain titanium dioxide.

[0015] The synthesis reaction mechanism of titanium dioxide is as follows:

[0016] During the reaction, tetrabutyl titanate is used as the titanium source and hydrofluoric acid is used as the catalyst to accelerate the hydrolysis of tetrabutyl titanate. The hydroxyl compounds of titanium generated by hydrolysis undergo a condensation reaction to form titanium oxide precursors with oxide chain or network structure. After high-temperature treatment, fluorine is removed and the titanium oxide precursors undergo a phase transition. At the same time, the internal structure of the crystal is optimized, forming a more stable and ordered arrangement, thus preparing titanium dioxide nanoparticles with high specific surface area.

[0017] Furthermore, the ratio of tetrabutyl titanate to hydrofluoric acid is 10g:3mL, the concentration of hydrofluoric acid is 40%, and the post-treatment includes: after the reaction is completed, the reaction system temperature is lowered to room temperature, filtered, the filter cake is washed with deionized water until neutral and then dried, the filter cake is transferred to a drying oven at a temperature of 80-90℃, dried to constant weight, ground, passed through a 100-mesh sieve, calcined at a temperature of 580-620℃ for a calcination time of 90-120min, and the calcination atmosphere is air.

[0018] Furthermore, the preparation method of composite vanadium-iron particles is as follows: vanadium-iron coprecipitated particles and deionized water are mixed and stirred, the temperature of the reaction system is raised to 60-70℃, germanium-manganese mixed solution is added dropwise to the reaction system, then ammonia water is added to the reaction system to adjust the pH of the system to 11-12, the system is kept at the temperature for 2-3 hours, and then post-treated and calcined to obtain composite vanadium-iron particles.

[0019] The synthesis reaction mechanism of composite vanadium-iron particles is as follows:

[0020] In the reaction process, germanium acetate and manganese acetate are used as metal sources, and vanadium-iron coprecipitated particles are used as the basic reaction materials. After mixing them by stirring, the pH of the system is adjusted to alkaline with ammonia water to promote the precipitation of germanium and manganese ions in the form of hydroxides. At the same time, they tightly bind with the vanadium-iron coprecipitated particles to form a composite precipitate. In addition, the addition of ammonia water may also promote the hydroxylation of the particle surface and enhance the interaction between particles. After high temperature treatment, germanium and manganese ions interact with vanadium and iron elements in the vanadium-iron coprecipitated particles to form stable composite vanadium-iron particles.

[0021] Furthermore, the ratio of the vanadium-iron coprecipitated particles, deionized water, and germanium-manganese mixed solution is 10g:100mL:20mL. The germanium-manganese mixed solution is composed of germanium acetate, manganese acetate, and deionized water at a ratio of 1g:5g:20mL. The post-treatment includes: after the reaction is complete, the reaction system temperature is lowered to room temperature, filtered, the filter cake is washed three times with deionized water and then dried, the filter cake is transferred to a drying oven at a temperature of 80-90℃, dried to constant weight, ground, passed through an 80-mesh sieve, and calcined to obtain composite vanadium-iron particles. The calcination temperature is 480-500℃, the calcination time is 4-6 hours, and the calcination atmosphere is air.

[0022] Furthermore, the preparation method of vanadium-iron coprecipitated particles is as follows: ammonium vanadate solution is added dropwise to ferric nitrate solution, stirred at room temperature until the system dissolves, 10-15 wt% ammonia water is added to the reaction system, the temperature of the reaction system is raised to 85-95℃, the reaction is kept at this temperature for 8-9 hours, and then post-processed and calcined to obtain vanadium-iron coprecipitated particles.

[0023] The synthesis reaction mechanism of vanadium-iron coprecipitated particles is as follows:

[0024] During the reaction, the pH of the mixed acid solution composed of ferric nitrate nonahydrate and ammonium metavanadate gradually increases with the addition of ammonia. Iron and vanadium ions begin to combine with hydroxide ions to form precipitates of ferric hydroxide and vanadium hydroxide. High-temperature stirring promotes the complete formation of the precipitate and the growth of crystals, forming vanadium and iron hydroxide precipitates at a certain temperature. Then, through high-temperature calcination, the hydroxide ions in the hydroxide may lose hydrogen atoms to form oxygen ions, which combine with metal ions to form oxides, optimizing the particle structure. Thus, the vanadium and iron hydroxide precipitate is transformed into vanadium and iron oxides, and vanadium-iron coprecipitate particles are prepared.

[0025] Furthermore, the volume ratio of the ammonium vanadate solution, ferric nitrate solution, and ammonia is 0.8-1.2:4-5:1.8-2.2. The ammonium vanadate solution is composed of ammonium metavanadate and 6wt% acetic acid aqueous solution at a ratio of 1g:20mL. The ferric nitrate solution is composed of ferric nitrate nonahydrate and deionized water at a ratio of 1g:15mL. The mass fraction of the ammonia is 10-15%. The post-treatment includes: after the reaction is complete, the reaction system temperature is lowered to room temperature, filtered, the filter cake is washed with deionized water until neutral, dried, transferred to a drying oven at 80-90℃, dried to constant weight, ground, passed through an 80-mesh sieve, and calcined to obtain vanadium-iron coprecipitate particles. The calcination temperature is 460-480℃, the calcination time is 3-5h, and the calcination atmosphere is air.

[0026] Furthermore, the preparation method of pretreated red mud is as follows: red mud and nitric acid are mixed and stirred, the temperature of the reaction system is raised to 70-80℃, and the temperature is kept for 2-3 hours. Dilute ammonia water is added to the reaction system to adjust the pH of the system to 9-10, and the temperature is kept for 80-100 minutes. After post-treatment, the red mud is calcined to obtain pretreated red mud.

[0027] The synthesis reaction mechanism of pretreated red mud is as follows:

[0028] During the reaction, the red mud is kept warm and stirred with nitric acid to promote the dissolution of alkaline harmful substances such as sodium and calcium in the red mud. Then, by adjusting the pH of the system, the effective components such as iron, silicon and titanium are retained. After high-temperature calcination, the hydroxides in the alkali precipitated solids are further converted into oxides, while residual water and organic matter are removed, thus preparing pretreated red mud.

[0029] Furthermore, the ratio of red mud to nitric acid is 1g:4mL, the concentration of nitric acid is 6-8mol / L, the concentration of dilute ammonia is 2-3mol / L, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, filtered, the filter cake is washed with deionized water until neutral and then dried, the filter cake is transferred to a drying oven at a temperature of 85-95℃, dried to constant weight, and calcined to obtain pretreated red mud. The calcination temperature is 550-580℃, the calcination time is 5-6h, and the calcination atmosphere is air.

[0030] The present invention has the following beneficial effects:

[0031] 1. The anti-poisoning SCR denitration catalyst of the present invention comprises vanadium-iron co-precipitated particles composed of vanadium and iron. Vanadium typically exhibits high denitration activity, while iron can inhibit its loss and maintain catalyst activity by forming chemical bonds or physical adsorption with these active components. Iron possesses an unfilled d-electron shell, enabling it to form chemical adsorption with sulfur oxides or alkali metal ions, adsorbing these ions onto the catalyst surface and preventing further diffusion into the catalyst interior or occupation of more active sites. Furthermore, iron is a variable-valence metal element with redox properties, which helps prevent catalyst poisoning. Subsequently, the redox properties can be adjusted to adapt to different reaction conditions, reduce the impact of poisons on catalyst performance, and enhance the stability and anti-poisoning properties of the catalyst. The modification of vanadium-iron co-precipitated particles with catalytically active manganese further enhances the overall catalytic activity of the catalyst, thereby improving the denitrification efficiency. In addition, manganese has a strong adsorption capacity for sulfur oxides or alkali metal ions, and its interaction with iron further improves the catalyst's anti-poisoning properties. Germanium can promote electron transfer in the catalytic reaction. As a "bridge" for electron transfer, it accelerates the electron transfer step in the catalytic reaction, thereby improving the denitrification efficiency.

[0032] 2. The anti-poisoning SCR denitrification catalyst of the present invention, through the treatment of red mud, promotes the dissolution and separation of substances such as sodium and calcium in the red mud, thereby providing more active sites for effective components such as iron, silicon, and titanium, and improving the denitrification activity. By treating the red mud, substances such as sodium and calcium are removed, avoiding their reaction with the active sites of the catalyst in an alkaline environment, thus preventing catalyst poisoning. Titanium dioxide itself has certain antioxidant and chemical stability, and can resist the oxidation reaction of SO2 on the catalyst surface. At the same time, it is not easy to react with alkaline substances, so titanium dioxide can maintain its catalytic activity in an alkaline environment, thereby improving the anti-alkali poisoning performance.

[0033] 3. The anti-poisoning SCR denitration catalyst of the present invention uses acidic zirconium sulfate, a compound with high chemical stability. Stable ionic bonds are formed between zirconium ions and sulfate ions in its molecular structure, resulting in high stability of the entire molecule. Adding acidic zirconium sulfate to the denitration catalyst provides more acidic sites, which is beneficial for the adsorption and activation of nitrogen oxides, thereby increasing the reaction rate of nitrogen oxides with reducing agents (such as NH3), and thus improving denitration efficiency and activity. Acidic zirconium sulfate can occupy the active centers of SO2 oxidation on the catalyst surface, thereby inhibiting the oxidation reaction of SO2 and effectively reducing the SO2 / SO3 conversion rate, thus improving the overall performance of the catalyst. The strongly acidic zirconium sulfate can neutralize some of the alkaline sites on the surface of the denitration catalyst, making the acid-base balance on the catalyst surface more even, thereby reducing the negative impact of alkaline substances on the catalyst and improving the catalyst's resistance to alkali poisoning. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] This embodiment provides a method for preparing an anti-poisoning SCR denitrification catalyst and an alkali-poisoning denitrification catalyst, including the following steps:

[0037] S1. Preparation of vanadium-iron coprecipitated particles

[0038] Ammonium metavanadate and 6 wt% aqueous acetic acid were mixed at a ratio of 1 g: 20 mL and stirred until the system was dissolved to obtain an ammonium metavanadate solution for later use.

[0039] Mix ferric nitrate nonahydrate and deionized water at a ratio of 1g:15mL, and stir until the system is dissolved to obtain a ferric nitrate solution for later use.

[0040] Weigh out 4L of ferric nitrate solution and add it to the reaction vessel. Stir. Add 0.8L of ammonium vanadate solution dropwise to the reaction vessel and stir at room temperature until the system dissolves. Add 1.8L of 10wt% ammonia water to the reaction vessel. Raise the temperature of the reaction vessel to 85℃ and keep it at that temperature for 8 hours. Lower the temperature of the reaction vessel to room temperature and filter. Wash the filter cake with deionized water until neutral and then dry it. Transfer the filter cake to a drying oven at 80℃ and dry it to constant weight. Grind the powder and pass it through an 80-mesh sieve to obtain metal powder. Place the metal powder in a muffle furnace at 460℃ and keep it at that temperature for 3 hours. Cool the muffle furnace to room temperature and discharge the powder to obtain vanadium-iron coprecipitated particles.

[0041] S2, Preparation of composite vanadium-iron particles

[0042] Germanium acetate, manganese acetate and deionized water were mixed at a ratio of 1g:5g:20mL and stirred until the system was dissolved to obtain a germanium-manganese mixed solution for later use.

[0043] Weigh 200g of vanadium-iron coprecipitated particles and 2L of deionized water and add them to the reaction vessel. Stir the mixture and raise the temperature of the reaction vessel to 60℃. Add 400mL of germanium-manganese mixed solution dropwise to the reaction vessel. After the addition is complete, stir for 30min. Add ammonia water to the reaction vessel to adjust the pH of the system to 11. Keep the mixture at this temperature for 2h. Lower the temperature of the reaction vessel to room temperature and filter the mixture. Wash the filter cake three times with deionized water and dry it. Transfer the filter cake to a drying oven at 80℃ and dry it to constant weight. Grind the mixture and pass it through an 80-mesh sieve to obtain a solid. Place the solid in a muffle furnace at 480℃ and calcine it for 4h. Allow the muffle furnace to cool naturally to room temperature to obtain composite vanadium-iron particles.

[0044] S3, Preparation of titanium dioxide

[0045] Weigh 500g of tetrabutyl titanate and add it to a three-necked flask with a polytetrafluoroethylene liner. Stir the mixture and add 150mL of 40wt% hydrofluoric acid to the flask. After sealing the flask, raise the temperature of the flask to 160℃ and maintain the temperature for 20h. Then, lower the temperature of the flask to room temperature and filter the mixture. Wash the filter cake with deionized water until neutral and then dry it. Transfer the filter cake to a drying oven at 80℃ and dry it to constant weight. Grind the cake and pass it through a 100-mesh sieve to obtain nanoparticles. Transfer the nanoparticles to a muffle furnace at 580℃ and calcine them for 90min. Then, lower the temperature of the muffle furnace to room temperature to obtain titanium dioxide.

[0046] S4. Preparation of pretreated red mud

[0047] Weigh out 500g of red mud and 2L of 6mol / L nitric acid and add them to the reactor. Stir the reactor and raise the temperature to 70℃. Keep the temperature and stir for 2 hours. Add 2mol / L ammonia water to the reactor to adjust the pH of the system to 9. Keep the temperature and stir for 80 minutes. Lower the temperature of the reactor to room temperature and filter. Wash the filter cake with deionized water until neutral and then dry it. Transfer the filter cake to a drying oven at 85℃ and dry it to constant weight. Transfer the solid to a muffle furnace at 550℃ and calcine it for 5 hours. Lower the temperature of the muffle furnace to room temperature and discharge the material to obtain pretreated red mud.

[0048] S5. Preparation of composite gel

[0049] Potassium persulfate and deionized water were mixed evenly at a ratio of 1g:50mL to obtain an initiator solution for later use.

[0050] Weigh out 100g of titanium dioxide, 350g of pretreated red mud, 150g of composite vanadium-iron particles, 250g of acidic zirconium sulfate, 50g of calcium fluoride, 750g of sodium silicate, 250g of acrylamide, 20g of N,N′-methylenebisacrylamide, and 4.5L of deionized water and add them to a reaction vessel. Stir the vessel and raise the temperature to 70℃. Add 500mL of initiator solution dropwise to the reaction system. After the addition is complete, keep the reaction at this temperature for 2 hours and stir until the system gels. Lower the temperature of the reaction vessel to room temperature and degas the vessel to -0.1MPa to obtain a mixed gel.

[0051] S6. Preparation of denitrification catalyst

[0052] The mixed gel was poured into a mold at 80°C and allowed to gel for 60 min. After demolding, the material was placed in a drying oven at 60°C and dried for 20 h. The drying oven was then heated to 90°C at a rate of 2°C / min and kept at that temperature for 24 h to obtain the catalyst preform.

[0053] The denitrification catalyst blank was placed in a muffle furnace, and the temperature of the muffle furnace was increased to 700℃ at a heating rate of 3℃ / min. The temperature was held for calcination for 3 hours, and then naturally cooled to room temperature. The catalyst was then discharged to obtain the denitrification catalyst.

[0054] S7. Preparation of alkali poisoning denitrification catalyst

[0055] The denitration catalyst and 0.5wt% sodium carbonate solution were mixed at a ratio of 1g:1mL and ultrasonically dispersed for 2h. The catalyst was then removed from the solution and dried in a drying oven at 100℃ for 3h. Finally, it was transferred to a muffle furnace at 380℃ and calcined for 4h to obtain the alkali-poisoned denitration catalyst.

[0056] Example 2

[0057] This embodiment provides a method for preparing an anti-poisoning SCR denitrification catalyst and an alkali-poisoning denitrification catalyst, including the following steps:

[0058] S1. Preparation of vanadium-iron coprecipitated particles

[0059] Ammonium metavanadate and 6 wt% aqueous acetic acid were mixed at a ratio of 1 g: 20 mL and stirred until the system was dissolved to obtain an ammonium metavanadate solution for later use.

[0060] Mix ferric nitrate nonahydrate and deionized water at a ratio of 1g:15mL, and stir until the system is dissolved to obtain a ferric nitrate solution for later use.

[0061] Weigh out 4.5 L of ferric nitrate solution and add it to the reaction vessel. Stir. Add 1.0 L of ammonium vanadate solution dropwise to the reaction vessel and stir at room temperature until the system dissolves. Add 2.0 L of 13 wt% ammonia water to the reaction vessel. Raise the temperature of the reaction vessel to 90 °C and keep it at that temperature for 8.5 h. Lower the temperature of the reaction vessel to room temperature, filter, wash the filter cake with deionized water until neutral, and then dry it. Transfer the filter cake to a drying oven at 85 °C and dry it to constant weight. Grind the powder and pass it through an 80-mesh sieve to obtain metal powder. Place the metal powder in a muffle furnace at 470 °C and keep it at that temperature for 4 h. Cool the muffle furnace to room temperature and discharge the powder to obtain vanadium-iron coprecipitated particles.

[0062] S2, Preparation of composite vanadium-iron particles

[0063] Germanium acetate, manganese acetate and deionized water were mixed at a ratio of 1g:5g:20mL and stirred until the system was dissolved to obtain a germanium-manganese mixed solution for later use.

[0064] Weigh 200g of vanadium-iron coprecipitated particles and 2L of deionized water and add them to the reaction vessel. Stir the mixture and raise the temperature of the reaction vessel to 65℃. Add 400mL of germanium-manganese mixed solution dropwise to the reaction vessel. After the addition is complete, stir for 40min. Add ammonia water to the reaction vessel to adjust the pH of the system to 11.5. Keep the mixture at this temperature for 2.5h. Then, lower the temperature of the reaction vessel to room temperature and filter the mixture. Wash the filter cake three times with deionized water and dry it. Transfer the filter cake to a drying oven at 85℃ and dry it to constant weight. Grind the mixture and pass it through an 80-mesh sieve to obtain a solid. Place the solid in a muffle furnace at 490℃ and calcine it for 5h. Allow the muffle furnace to cool naturally to room temperature to obtain composite vanadium-iron particles.

[0065] S3, Preparation of titanium dioxide

[0066] Weigh 500g of tetrabutyl titanate and add it to a three-necked flask with a polytetrafluoroethylene liner. Stir the mixture. Add 150mL of 40wt% hydrofluoric acid to the three-necked flask. After sealing the flask, raise the temperature of the three-necked flask to 170℃ and maintain the temperature for 21h. Then, lower the temperature of the three-necked flask to room temperature, filter the mixture, wash the filter cake with deionized water until neutral, and then dry it. Transfer the filter cake to a drying oven at 85℃ and dry it to constant weight. Grind the powder and pass it through a 100-mesh sieve to obtain nanoparticles. Transfer the nanoparticles to a muffle furnace at 600℃ and calcine them for 105min. Then, lower the temperature of the muffle furnace to room temperature to obtain titanium dioxide.

[0067] S4. Preparation of pretreated red mud

[0068] Weigh out 500g of red mud and 2L of 7mol / L nitric acid and add them to the reactor. Stir the reactor and raise the temperature to 75℃. Keep the temperature and stir for 2.5h. Add 2.5mol / L ammonia water to the reactor to adjust the pH of the system to 9.5. Keep the temperature and stir for 90min. Lower the temperature of the reactor to room temperature and filter. Wash the filter cake with deionized water until neutral and then dry it. Transfer the filter cake to a drying oven at 90℃ and dry it to constant weight. Transfer the solid to a muffle furnace at 565℃ and calcine it for 5.5h. Lower the temperature of the muffle furnace to room temperature and discharge the material to obtain pretreated red mud.

[0069] S5. Preparation of composite gel

[0070] Potassium persulfate and deionized water were mixed evenly at a ratio of 1g:50mL to obtain an initiator solution for later use.

[0071] Weigh out 100g of titanium dioxide, 350g of pretreated red mud, 150g of composite vanadium-iron particles, 250g of acidic zirconium sulfate, 50g of calcium fluoride, 750g of sodium silicate, 250g of acrylamide, 20g of N,N′-methylenebisacrylamide, and 4.5L of deionized water and add them to a reaction vessel. Stir the vessel and raise the temperature to 75℃. Add 500mL of initiator solution dropwise to the reaction system. After the addition is complete, keep the reaction at this temperature for 2.5h and stir until the system gels. Lower the temperature of the reaction vessel to room temperature and degas the vessel to -0.1MPa to obtain a mixed gel.

[0072] S6. Preparation of denitrification catalyst

[0073] The mixed gel was poured into a mold at 85°C and allowed to gel for 70 min. After demolding, the material was placed in a drying oven at 65°C and dried for 20 h. The drying oven was then heated to 93°C at a rate of 2°C / min and kept at that temperature for 24 h to obtain the catalyst preform.

[0074] The denitrification catalyst blank was placed in a muffle furnace, and the temperature of the muffle furnace was increased to 730°C at a heating rate of 4°C / min. The temperature was held for 4 hours and then naturally cooled to room temperature. The catalyst was then discharged to obtain the denitrification catalyst.

[0075] S7. Preparation of alkali poisoning denitrification catalyst

[0076] The denitration catalyst and 0.5wt% sodium carbonate solution were mixed at a ratio of 1g:1mL and ultrasonically dispersed for 2h. The catalyst was then removed from the solution and dried in a drying oven at 100℃ for 3h. Finally, it was transferred to a muffle furnace at 380℃ and calcined for 4h to obtain the alkali-poisoned denitration catalyst.

[0077] Example 3

[0078] This embodiment provides a method for preparing an anti-poisoning SCR denitrification catalyst and an alkali-poisoning denitrification catalyst, including the following steps:

[0079] S1. Preparation of vanadium-iron coprecipitated particles

[0080] Ammonium metavanadate and 6 wt% aqueous acetic acid were mixed at a ratio of 1 g: 20 mL and stirred until the system was dissolved to obtain an ammonium metavanadate solution for later use.

[0081] Mix ferric nitrate nonahydrate and deionized water at a ratio of 1g:15mL, and stir until the system is dissolved to obtain a ferric nitrate solution for later use.

[0082] Weigh out 5L of ferric nitrate solution and add it to the reaction vessel. Stir. Add 1.2L of ammonium vanadate solution dropwise to the reaction vessel and stir at room temperature until the system dissolves. Add 2.2L of 15wt% ammonia water to the reaction vessel. Raise the temperature of the reaction vessel to 95℃ and keep it at that temperature for 9 hours. Lower the temperature of the reaction vessel to room temperature and filter. Wash the filter cake with deionized water until neutral and then dry it. Transfer the filter cake to a drying oven at 90℃ and dry it to constant weight. Grind the powder and pass it through an 80-mesh sieve to obtain metal powder. Place the metal powder in a muffle furnace at 480℃ and keep it at that temperature for 5 hours. Cool the muffle furnace to room temperature and discharge the powder to obtain vanadium-iron coprecipitated particles.

[0083] S2, Preparation of composite vanadium-iron particles

[0084] Germanium acetate, manganese acetate and deionized water were mixed at a ratio of 1g:5g:20mL and stirred until the system was dissolved to obtain a germanium-manganese mixed solution for later use.

[0085] Weigh 200g of vanadium-iron coprecipitated particles and 2L of deionized water and add them to the reaction vessel. Stir the mixture and raise the temperature of the reaction vessel to 70℃. Add 400mL of germanium-manganese mixed solution dropwise to the reaction vessel. After the addition is complete, stir for 50min. Add ammonia water to the reaction vessel to adjust the pH of the system to 12. Keep the mixture at this temperature for 3h. Lower the temperature of the reaction vessel to room temperature and filter the mixture. Wash the filter cake three times with deionized water and dry it. Transfer the filter cake to a drying oven at 90℃ and dry it to constant weight. Grind the mixture and pass it through an 80-mesh sieve to obtain a solid. Place the solid in a muffle furnace at 500℃ and calcine it for 6h. Allow the muffle furnace to cool naturally to room temperature to obtain composite vanadium-iron particles.

[0086] S3, Preparation of titanium dioxide

[0087] Weigh 500g of tetrabutyl titanate and add it to a three-necked flask with a polytetrafluoroethylene liner. Stir the mixture and add 150mL of 40wt% hydrofluoric acid to the flask. After sealing the flask, raise the temperature of the flask to 180℃ and maintain the temperature for 22h. Then, lower the temperature of the flask to room temperature and filter the mixture. Wash the filter cake with deionized water until neutral and then dry it. Transfer the filter cake to a drying oven at 90℃ and dry it to constant weight. Grind the cake and pass it through a 100-mesh sieve to obtain nanoparticles. Transfer the nanoparticles to a muffle furnace at 620℃ and calcine them for 120min. Then, lower the temperature of the muffle furnace to room temperature to obtain titanium dioxide.

[0088] S4. Preparation of pretreated red mud

[0089] Weigh out 500g of red mud and 2L of 8mol / L nitric acid and add them to the reactor. Stir the reactor and raise the temperature to 80℃. Keep the temperature and stir for 3 hours. Add 3mol / L ammonia water to the reactor to adjust the pH of the system to 10. Keep the temperature and stir for 100 minutes. Lower the temperature of the reactor to room temperature and filter. Wash the filter cake with deionized water until neutral and then dry it. Transfer the filter cake to a drying oven at 95℃ and dry it to constant weight. Transfer the solid to a muffle furnace at 580℃ and calcine it for 6 hours. Lower the temperature of the muffle furnace to room temperature and discharge the material to obtain pretreated red mud.

[0090] S5. Preparation of composite gel

[0091] Potassium persulfate and deionized water were mixed evenly at a ratio of 1g:50mL to obtain an initiator solution for later use.

[0092] Weigh out 100g of titanium dioxide, 350g of pretreated red mud, 150g of composite vanadium-iron particles, 250g of acidic zirconium sulfate, 50g of calcium fluoride, 750g of sodium silicate, 250g of acrylamide, 20g of N,N′-methylenebisacrylamide, and 4.5L of deionized water and add them to a reaction vessel. Stir the vessel and raise the temperature to 80℃. Add 500mL of initiator solution dropwise to the reaction system. After the addition is complete, keep the reaction at this temperature for 3 hours and stir until the system gels. Lower the temperature of the reaction vessel to room temperature and degas the vessel to -0.1MPa to obtain a mixed gel.

[0093] S6. Preparation of denitrification catalyst

[0094] The mixed gel was poured into a mold at 90℃ and allowed to gel for 80 min. After demolding, the material was placed in a drying oven at 70℃ and dried for 20 h. The drying oven was then heated to 95℃ at a rate of 2℃ / min and kept at that temperature for 24 h to obtain the catalyst preform.

[0095] The denitrification catalyst blank was placed in a muffle furnace, and the temperature of the muffle furnace was increased to 760°C at a heating rate of 5°C / min. The temperature was held for 5 hours and then naturally cooled to room temperature. The catalyst was then discharged to obtain the denitrification catalyst.

[0096] S7. Preparation of alkali poisoning denitrification catalyst

[0097] The denitration catalyst and 0.5wt% sodium carbonate solution were mixed at a ratio of 1g:1mL and ultrasonically dispersed for 2h. The catalyst was then removed from the solution and dried in a drying oven at 100℃ for 3h. Finally, it was transferred to a muffle furnace at 380℃ and calcined for 4h to obtain the alkali-poisoned denitration catalyst.

[0098] Comparative Example 1

[0099] The difference between this comparative example and Example 3 is that step S2 is omitted, and the vanadium-iron coprecipitated particles in step S1 are used instead of the composite vanadium-iron particles in step S5.

[0100] Comparative Example 2

[0101] The difference between this comparative example and Example 3 is that step S4 is omitted, and the red mud in step S4 is used instead of the pretreated red mud in step S5.

[0102] Comparative Example 3

[0103] The difference between this comparative example and Example 3 is that acidic zirconium sulfate was not added in step S5.

[0104] Performance testing:

[0105] Referring to the standard GB / T 31587-2015 "Cellular Flue Gas Denitrification Catalysts", the denitrification efficiency, SO2 / SO3 conversion rate and denitrification activity of the denitrification catalysts and alkali poisoning denitrification catalyst samples prepared in Examples 1-3 and Comparative Examples 1-3 were determined at 380℃. The specific test results are shown in Table 1 below.

[0106] Table 1 - Performance Test Data of Samples

[0107]

[0108]

[0109] Data Analysis:

[0110] Comparative analysis of the data in Table 1 shows that the anti-poisoning SCR denitrification catalyst prepared in this invention achieves a denitrification efficiency of 91.4%, a SO2 / SO3 conversion rate reduced to 0.22%, and a denitrification activity of 42 m / h. After simulated alkali poisoning, the sample's denitrification efficiency reaches 90.7%, the retention rate reaches 99.23%, the SO2 / SO3 conversion rate is 0.25%, the growth rate is 12%, the denitrification activity reaches 40 m / h, and the decay rate is 4.76%. All test results are superior to the comparative example. Therefore, this invention, through the modification of vanadium-iron coprecipitated particles with germanium and manganese and their combination with pretreated red mud, titanium dioxide, and acidic zirconium sulfate, not only effectively improves the denitrification efficiency and denitrification activity of the denitrification catalyst, but also enhances the catalyst's resistance to alkali and sulfide poisoning.

[0111] 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 specific implementations. 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 an anti-poisoning SCR denitration catalyst, characterized in that, Includes the following steps: S1. Mix and stir titanium dioxide, pretreated red mud, composite vanadium-iron particles, acidic zirconium sulfate, calcium fluoride, sodium silicate, acrylamide, N,N′-methylenebisacrylamide and deionized water. Raise the temperature of the reaction system to 70-80℃, add initiator solution dropwise to the reaction system, keep the reaction at the temperature for 2-3 hours, stir until the system gels, degas, and obtain a mixed gel. S2. Pour the mixed gel into a mold at 80-90℃, allow it to gel for 60-80 minutes, demold and dry it to obtain the denitrification catalyst preform. S3. The denitrification catalyst blank is calcined at high temperature to obtain the denitrification catalyst; The preparation method of composite vanadium-iron particles is as follows: vanadium-iron coprecipitated particles and deionized water are mixed and stirred. The temperature of the reaction system is raised to 60-70℃. A germanium-manganese mixed solution is added dropwise to the reaction system. Then, ammonia water is added to the reaction system to adjust the pH of the system to 11-12. The system is kept at this temperature for 2-3 hours, followed by post-treatment and calcination to obtain composite vanadium-iron particles. The ratio of the amount of vanadium-iron coprecipitated particles, deionized water, and germanium-manganese mixed solution is 10g:100mL:20mL. The germanium-manganese mixed solution is composed of germanium acetate, manganese acetate, and deionized water at a ratio of 1g:5g:20mL. The calcination temperature is 480-500℃, the calcination time is 4-6 hours, and the calcination atmosphere is air.

2. The preparation method of the anti-poisoning SCR denitration catalyst according to claim 1, characterized in that, In step S1, the ratio of titanium dioxide, pretreated red mud, composite vanadium-iron particles, acidic zirconium sulfate, calcium fluoride, sodium silicate, acrylamide, N,N′-methylenebisacrylamide, deionized water, and initiator solution is 2g:7g:3g:5g:1g:15g:5g:1g:90mL:10mL, and the initiator solution is composed of potassium persulfate and deionized water at a ratio of 1g:50mL; In step S2, the programmed drying includes: after demolding, placing the material in a drying oven at a temperature of 60-70℃ and drying for 20h; then raising the temperature of the drying oven to 90-95℃ at a rate of 2℃ / min and holding it at that temperature for 24h to obtain a denitrification catalyst preform; In step S3, the high-temperature calcination temperature is 700-760℃ and the calcination time is 3-5h.

3. The preparation method of the anti-poisoning SCR denitration catalyst according to claim 1, characterized in that, The preparation method of titanium dioxide is as follows: hydrofluoric acid is added to tetrabutyl titanate, the reaction system is sealed, the temperature of the reaction system is raised to 160-180℃, the reaction is kept at this temperature for 20-22 hours, and then the reaction is post-treated and calcined to obtain titanium dioxide.

4. The preparation method of the anti-poisoning SCR denitrification catalyst according to claim 3, characterized in that, The ratio of titanate n-butyl ester to hydrofluoric acid is 10g:3mL, the concentration of hydrofluoric acid is 40wt%, the calcination temperature is 580-620℃, the calcination time is 90-120min, and the calcination atmosphere is air.

5. The preparation method of the anti-poisoning SCR denitration catalyst according to claim 1, characterized in that, The preparation method of vanadium-iron coprecipitated particles is as follows: ammonium vanadate solution is added dropwise to ferric nitrate solution, stirred at room temperature until the system dissolves, ammonia water is added to the reaction system, the temperature of the reaction system is raised to 85-95℃, the reaction is kept at this temperature for 8-9 hours, and then post-processed and calcined to obtain vanadium-iron coprecipitated particles.

6. The method for preparing an anti-poisoning SCR denitrification catalyst according to claim 5, characterized in that, The volume ratio of the ammonium vanadate solution, ferric nitrate solution, and ammonia is 0.8-1.2:4-5:1.8-2.

2. The ammonium vanadate solution is composed of ammonium metavanadate and 6wt% acetic acid aqueous solution at a ratio of 1g:20mL. The ferric nitrate solution is composed of ferric nitrate nonahydrate and deionized water at a ratio of 1g:15mL. The mass fraction of the ammonia is 10-15%. The calcination temperature is 460-480℃, the calcination time is 3-5h, and the calcination atmosphere is air.

7. The preparation method of the anti-poisoning SCR denitration catalyst according to claim 1, characterized in that, The preparation method of pretreated red mud is as follows: mix red mud and nitric acid, raise the temperature of the reaction system to 70-80℃, keep it at the temperature for 2-3 hours, add dilute ammonia water to the reaction system, adjust the pH of the system to 9-10, keep it at the temperature for 80-100 minutes, perform post-treatment, and calcine to obtain pretreated red mud.

8. The method for preparing an anti-poisoning SCR denitrification catalyst according to claim 7, characterized in that, The ratio of red mud to nitric acid is 1g:4mL, the concentration of nitric acid is 6-8mol / L, the concentration of dilute ammonia is 2-3mol / L, the calcination temperature is 550-580℃, the calcination time is 5-6h, and the calcination atmosphere is air.

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