Recycling method of SCR (Selective Catalytic Reduction) denitration catalyst

Abstract

The invention discloses a recycling method of an SCR (Selective Catalytic Reduction) denitration catalyst. The recycling method comprises the following steps: (1) carrying out soot blowing, washing and drying treatment on an inactivated SCR denitration catalyst to obtain a pickling material; (2) crushing the acid-washed material in the step (1), adsorbing an alkaline solution by the crushed material, and performing sealed warm activation treatment to obtain an alkali-activated material; (3) mixing the alkali activated material obtained in the step (2) with a pore-foaming agent, and carrying out molding, pore-forming, drying and roasting on the mixed material to obtain a molded catalyst; and (4) immersing the formed catalyst in the step (3) into a vanadium-containing solution for dipping, drying the dipped material, roasting in a nitrogen atmosphere, and activating in an ammonia atmosphere to obtain the SCR denitration catalyst. The inactivated SCR denitration catalyst is used as a raw material, and the prepared denitration catalyst is high in micron-sized through pore channel content, high in dust blocking resistance, good in NOx conversion effect and low in catalyst production cost.

Description

Technical Field

[0001] This invention belongs to the fields of environmental protection technology and denitrification catalysis, and specifically relates to a method for reusing SCR denitrification catalyst. Background Technology

[0002] Selective catalytic reduction (SCR) is the most widely used technology for removing nitrogen oxides from flue gas, offering advantages such as high denitrification efficiency and good selectivity. NH3-SCR denitrification technology uses ammonia as a reducing agent, with the aid of a catalyst, to selectively reduce NOx in flue gas into harmless nitrogen and water. The V2O5-WO3(MoO3) / TiO2 catalyst is currently the most commonly used commercial SCR denitrification catalyst.

[0003] With the widespread use of SCR catalysts, the disposal or deactivated SCR catalysts have become a major solid waste treatment problem in this field. Causes of catalyst deactivation include fly ash blockage, poisoning, wear, and sintering. Regenerating spent flue gas denitrification catalysts can improve or restore their activity, enabling them to be recycled.

[0004] CN102962079A discloses a method for regenerating a waste vanadium-titanium-based SCR flue gas denitrification catalyst. The specific steps are as follows: (1) The waste vanadium-titanium-based SCR flue gas denitrification catalyst is purged and ball-milled to obtain its recycled material; (2) Metal oxides, additives, inorganic additives and the waste vanadium-titanium-based SCR flue gas denitrification catalyst recycled material are mixed in a mass ratio, ball-milled and dried to obtain regenerated SCR flue gas denitrification catalyst powder; (3) Appropriate amounts of binder, lubricant and water are added to the regenerated SCR flue gas denitrification catalyst powder, mixed evenly, granulated, kneaded, aged and extruded to obtain a regenerated SCR flue gas denitrification catalyst blank; (4) The blank is dried and calcined to obtain the regenerated SCR flue gas denitrification catalyst.

[0005] CN105709861A discloses a method for regenerating an SCR denitrification catalyst, comprising: (1) blowing, cleaning and drying the waste and deactivated SCR denitrification catalyst; (2) crushing the dried waste SCR denitrification catalyst and adding a strong alkaline solution with a mass concentration of 10wt%-40wt% and reacting at a temperature of 150-200℃ for 3-8 hours; (3) adjusting the pH value of the reaction solution in step (2) to 9-10, filtering and separating to obtain a recovery solution containing sodium tungstate and sodium vanadate, and adjusting the vanadium concentration in the regenerated solution to 2-10g / L; (4) immersing the deactivated SCR denitrification catalyst dried in step (1) in the regenerated solution with the concentration prepared in step (3) at room temperature for regeneration, and then placing it at room temperature for 60min after removal; (5) obtaining the regenerated SCR denitrification catalyst after drying, calcining and cooling the catalyst in step (4).

[0006] When the above method is used to regenerate deactivated SCR denitration catalyst, the improvement of catalyst pore structure is not obvious, the content of macropores in the catalyst is insufficient, which is not conducive to the diffusion of reactants during application. At the same time, the catalyst is easily deactivated again due to blockage by impurities such as dust and particulate matter. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for reusing SCR denitrification catalysts. Using deactivated SCR denitrification catalysts as raw materials, this invention produces a denitrification catalyst with high micron-level through-pore content, strong resistance to dust blockage, good NOx conversion efficiency, and low catalyst production cost.

[0008] The method for reusing the SCR denitrification catalyst of the present invention includes the following: (1) The deactivated SCR denitration catalyst was subjected to soot blowing, washing and drying to obtain pickled material; (2) The pickling material in step (1) is crushed, and after the crushed material adsorbs the alkaline solution, it is sealed and activated at a warm temperature to obtain the alkaline activated material; (3) The alkaline activated material from step (2) is mixed with a pore-forming agent, and the mixture is shaped, pore-forming, dried and calcined to obtain a shaped catalyst; (4) The catalyst formed in step (3) is immersed in a vanadium-containing solution for impregnation. After impregnation, the material is dried, roasted under a nitrogen atmosphere, and activated under an ammonia atmosphere to obtain the SCR denitrification catalyst.

[0009] In the method of this invention, the deactivated SCR denitration catalyst mentioned in step (1) refers to a catalyst whose structure has collapsed and been damaged after long-term use or repeated regeneration and recycling, resulting in significant changes in its physicochemical properties and a 40%-80% loss in denitration activity compared to a fresh catalyst. The deactivated SCR denitration catalyst is a vanadium-tungsten-titanium system catalyst or a vanadium-molybdenum-titanium system catalyst. The deactivated catalyst contains 0.5wt%-10.5wt% V2O5, 0.5wt%-12.5wt% WO3 and / or MoO3, and more than 75wt% TiO2. The catalyst is honeycomb or corrugated plate type.

[0010] In the method of the present invention, step (1) involves using compressed air to purge the surface and pores of the SCR denitrification catalyst to remove dust from the catalyst surface.

[0011] In the method of the present invention, the washing in step (1) is carried out in an acidic solution, wherein the acidic solution is a mixture of strong and weak acids; wherein the strong acid is one or more of sulfuric acid, hydrochloric acid, and nitric acid, and the weak acid is one or more of oxalic acid, citric acid, and acetic acid; the concentration of the strong acid in the acidic solution is 5wt%-10wt%, the concentration of the weak acid is 1wt%-5wt%, the liquid-to-solid volume ratio is 3:1-5:1, and the washing is carried out at room temperature or under heating conditions, the heating temperature is 50-80℃, and the washing time is 4-8 hours. In the method of the present invention, the drying temperature in step (1) is 90-150℃, and the drying time is 1-8 hours.

[0012] In the method of the present invention, the particle size of the pulverized material in step (2) is less than 15 μm.

[0013] In the method of the present invention, the alkaline solution in step (2) is an ammonia solution and / or an ammonium bicarbonate solution, the concentration of ammonium ions in the solution is 1-3M, and the amount of solution used is to saturate the powder material with adsorption.

[0014] In the method of the present invention, the sealing activation treatment in step (2) is carried out in a sealed container, preferably a high-pressure autoclave, with an activation temperature of 150-200℃ and an activation time of 4-8 hours.

[0015] In the method of the present invention, the peak intensity of the diffraction peaks corresponding to 2θ of 15º, 17º, 18º, and 23º in the XRD spectrum of the pore-forming agent described in step (3) is reduced by more than 60% compared with that of the flour raw material, preferably by 75%-90%. The average grain size D corresponding to the peak position of 2θ of 15º is 6.5-8.5 nm, where D=Kλ / (Bcosθ), K is the Scherrer constant, λ is the diffraction wavelength of the target material, B is the half-width of the diffraction peak, and θ is the diffraction angle.

[0016] In the method of this invention, the pore-forming agent in step (3) is obtained by mixing and grinding flour with an alkaline material. The flour is wheat flour, wherein the protein content is 6%-20%, the starch content is 65%-75%, and the remainder consists of moisture, ash, enzymes, fats, and vitamins. The alkaline substance is one or a mixture of several of LiOH, KOH, and NaOH, and the mass ratio of the alkaline substance to the flour is 2:100-10:100, preferably 4:100-8:100. The grinding is preferably carried out in a ball mill, and the grinding time is 40-180 min, preferably 60-120 min.

[0017] In the method of the present invention, the mass ratio of the activated material to the pore-forming agent in step (3) is 100:40-100:25.

[0018] In the method of the present invention, the hole-making process in step (3) is a heat treatment process in a sealed container. The sealed container is preferably a sealed high-pressure autoclave. The volume of wet material accounts for 30% to 70% of the total volume of the sealed container. The heat treatment temperature is 40-90℃ and the heat treatment time is 60-120min.

[0019] In the method of the present invention, the drying temperature in step (3) is 90-150℃ and the drying time is 1-8 hours. The calcination is carried out under an inert atmosphere, which is one or a mixture of gases such as argon, helium, and nitrogen, preferably nitrogen. The calcination temperature is 450-650℃ and the calcination time is 4-8 hours.

[0020] In the method of this invention, the vanadium-containing solution in step (4) is an ammonium vanadate or ammonium metavanadate solution, and the vanadium content in the solution is 0.5-8 g / 100 mL, calculated as oxides. The amount of solution used is sufficient to completely submerge the solid material, and the immersion time is 1-4 hours.

[0021] In the method of the present invention, the drying temperature in step (4) is 90-150℃ and the drying time is 1-8 hours, and the calcination temperature under nitrogen atmosphere is 450-650℃ and the calcination time is 4-8 hours.

[0022] In the method of the present invention, the activation treatment under ammonia atmosphere in step (4) is a roasting treatment under ammonia atmosphere, preferably carried out in a tube furnace, the roasting temperature is 400-650℃, the roasting time is 1-3 hours, and the ammonia pressure in the tube furnace is 0.5-1MPa.

[0023] Compared with the prior art, the present invention has the following advantages: (1) The present invention uses deactivated SCR denitration catalyst powder as raw material to prepare denitration catalyst, thereby reducing the cost of catalyst raw materials and saving the cost of deactivated catalyst post-processing, thus reducing the production cost of catalyst.

[0024] (2) The deactivated SCR denitration catalyst is washed with mixed acid. Due to the dissolution of strong acid and the complexation of weak acid, the alkali metal, alkaline earth metal and other metal impurities in the deactivated catalyst are removed more thoroughly and the active sites are exposed. When the material is activated in a closed environment after adsorbing alkaline solution, the molybdenum and / or tungsten, vanadium and other components in the catalyst are dissolved and dispersed on the catalyst surface under alkaline and closed conditions, which improves the interaction between the active components and the support. At the same time, the active components that have accumulated due to high temperature sintering are redispersed, which increases the dispersion of the active components on the final catalyst surface and enhances the denitration activity of the catalyst.

[0025] (3) The pore-forming agent is obtained by mixing and grinding flour with alkaline substances. During the grinding process, the alkaline substances are adsorbed onto the surface of starch granules through hydrogen bonding. Under the synergistic effect of mechanical force and alkaline substances, the starch molecular bonds are broken, generating shorter molecular chains and branched structures, which improves the swelling, viscosity and toughness of starch. When the molded material is placed in a closed high-pressure container for heating treatment, the starch granules in the material are deeply broken under the action of closed, water vapor, alkaline substances and suitable temperature, and water absorption swelling and foaming reaction occur, so that a large number of micron-sized interconnected pore precursors are formed in the denitration catalyst. Due to the enhanced swelling, viscosity and toughness of starch, the micron-sized pore precursors are easy to form and have a complete structure. During calcination, a large number of micron-sized interconnected pores are formed in the denitration catalyst. This pore structure is conducive to the contact between reactants and catalyst active sites, and at the same time improves the catalyst's resistance to dust and particulate matter blockage and extends the catalyst's service life.

[0026] (4) When the catalyst is calcined and activated under a certain pressure of ammonia atmosphere, ammonia gas undergoes hybridization with the surface of the carbon material in the catalyst, introducing nitrogen-containing functional groups on the surface and pore walls of the porous carbon material, thereby increasing the overall number of nitrogen-containing active sites in the catalyst. During the denitrification reaction, the nitrogen-containing active sites are conducive to the adsorption of reactant molecules such as NOx on the catalyst surface, promoting the denitrification reaction of flue gas. In addition, the introduction of these nitrogen-containing active sites into the catalyst after loading active metal can effectively avoid the shielding and covering of active sites, which is conducive to the activity of active sites. Attached Figure Description

[0027] Figure 1 The XRD patterns of the flour raw material and pore-forming agent in Example 1 are shown.

[0028] Figure 2 This is a scanning electron microscope (SEM) image of the cross-section of the catalyst prepared in Example 1. Detailed Implementation

[0029] The technical solutions and effects of the present invention will be further illustrated below with reference to the embodiments, but the invention is not limited to the following embodiments.

[0030] Method for measuring the proportion of 0.5-30 μm pores in catalysts: The catalyst is cut and adhered to the scanning electron microscope (SEM) stage, with the catalyst cross-section perpendicular to the electron beam. The instrument is adjusted to acquire SEM images. The image area and the area of ​​0.5-30 μm pores in the image are calculated by statistically measuring the image scale. The proportion of 0.5-30 μm pores in the catalyst is obtained by dividing the 0.5-30 μm pore area by the image area. Images are randomly selected during the measurement process, and the average value is calculated for images greater than 50.

[0031] The pore structure of the sample was characterized using a scanning electron microscope (SEM). The specific operation was as follows: The microstructure of the carrier was characterized using a JSM-7500F SEM with an accelerating voltage of 5 kV, an accelerating current of 20 µA, and a working distance of 8 mm.

[0032] Method for determining carbon content in catalyst: The carbon content of the catalyst was determined according to HG / T5594-2019 standard using an EMIA-20E infrared carbon-sulfur analyzer.

[0033] Method for determining nitrogen content in catalyst: The nitrogen content in the catalyst was determined using a UNICUBE elemental analyzer from elementar GmbH, Germany, in accordance with the standard NB / SH / T 0656-2017.

[0034] The deactivated denitrification catalyst used in this invention is a V2O5-WO3 / TiO2 honeycomb SCR denitrification catalyst that has been running for 20,000 hours in a coal-fired power plant. The catalyst contains 2.6 wt% V2O5, 8.6 wt% WO3, and 86.7 wt% TiO2. Example 1

[0035] (1) Use dry and clean compressed air to purge the catalyst to remove the dust accumulated on the catalyst surface and in the pores. After purging, the catalyst is immersed in a mixed acid solution with a sulfuric acid concentration of 6.5 wt% and a citric acid concentration of 3.5 wt% and cleaned at 65°C for 6 hours. After cleaning, the catalyst is rinsed with deionized water and dried at 120°C for 4 hours to obtain the washed material.

[0036] (2) The washed material from step (2) is crushed to a particle size of less than 15 μm. An appropriate amount of ammonia solution with an ammonium ion concentration of 1.8 M is added to the crushed material to saturate the material with adsorption. Then the wet material is transferred to an autoclave, sealed, and heated at 185°C for 5.5 hours. After heating, the material is dried at 120°C for 6 hours to obtain alkali-activated material for later use.

[0037] (3) Weigh an appropriate amount of flour, add sodium hydroxide to the flour (the mass ratio of flour to alkali is 100:5.5), mix evenly, and then grind the mixture in a grinder for 80 minutes to obtain the pore-forming agent (XRD patterns of wheat flour raw material and pore-forming agent are shown in [reference]). Figure 1The peak position of the pore-forming agent is 2θ, which corresponds to an average grain size D of 7.5 nm. Weigh an appropriate amount of the alkali-activated material from step (2) and add the pore-forming agent (the mass ratio of the alkali-activated material to the pore-forming agent is 100:30). Mix them evenly, then add an appropriate amount of deionized water to knead into a plastic body and shape it. Place the shaped wet material in a high-pressure autoclave, seal it, and heat it at 60°C for 100 minutes. After adding the material, dry it at 120°C for 6 hours and calcine it at 450°C under a nitrogen atmosphere for 6 hours.

[0038] (4) The material after calcination in step (3) was immersed in an ammonium metavanadate solution with a V2O5 concentration of 2.5 g / 100 mL for 4 hours. After immersion, the material was dried at 120 °C for 6 hours. The dried material was then placed in a tube furnace and calcined at 450 °C under a nitrogen atmosphere for 6 hours. After the tube furnace cooled, ammonia gas was introduced and the pressure of the ammonia gas in the furnace was controlled at 0.85 MPa. The temperature was raised to 550 °C and calcined for 2 hours to obtain the denitrification catalyst cat-1. The catalyst contained 3.4 wt% V2O5, 6.5 wt% WO3, 74.2 wt% TiO2, 15.0 wt% C, and 0.9 wt% N. The proportion of 0.5-30 μm channels in the catalyst was 31.8%. The scanning electron microscope image of the catalyst is shown in [reference needed]. Figure 2 ,from Figure 2 It is evident that abundant micron-sized through-pores are formed in the catalyst. Example 2

[0039] Same as Example 1, except that in step (1), the concentration of sulfuric acid in the mixed acid is 8 wt% and the concentration of citric acid is 2.5 wt%. In step (2), the ammonia solution is replaced with ammonium bicarbonate solution, the concentration of ammonium ions in the solution is 2.4 M, the pressure vessel heating temperature is 170 °C, and the heating time is 6.5 hours. In step (3), the mass ratio of flour to alkali is 100:6.5, the grinding time is 95 minutes, the mass ratio of alkali-activated material to pore-forming agent is 100:35, the pressure vessel heating temperature is 75 °C, and the heating time is 80 minutes. In step (4), the ammonia pressure is 0.75 MPa, the activation temperature is 500 °C, and the activation time is 2.5 hours to obtain nitrate catalyst cat-2. The catalyst contains 3.6 wt% V2O5, 6.3 wt% WO3, 72.4 wt% TiO2, 16.8 wt% C, and 0.9 wt% N. The proportion of 0.5-30 μm pores in the catalyst is 33.6%. Example 3

[0040] Same as Example 1, except that in step (1), the concentration of sulfuric acid in the mixed acid is 5.5 wt% and the concentration of citric acid is 4.5 wt%. In step (2), the concentration of ammonium ions in the ammonia solution is 1.2 M, the heating temperature of the autoclave is 200 °C, and the heating time is 4.5 hours. In step (3), the mass ratio of flour to alkali is 100:4.5, the grinding time is 110 minutes, the mass ratio of alkali-activated material to pore-forming agent is 100:40, the heating temperature of the autoclave is 45 °C, and the heating time is 120 minutes. In step (4), the ammonia pressure is 0.95 MPa, the activation temperature is 450 °C, and the activation time is 3 hours to obtain the nitrate catalyst cat-3. The catalyst contains 3.5 wt% V2O5, 6.1 wt% WO3, 70.3 wt% TiO2, 19.1 wt% C, and 1.0 wt% N. The proportion of 0.5-30 μm pores in the catalyst is 34.2%. Example 4

[0041] Same as Example 1, except that in step (1), the concentration of sulfuric acid in the mixed acid is 9.5 wt% and the concentration of citric acid is 1.5 wt%. In step (2), the concentration of ammonium ions in the ammonia solution is 3 M, the heating temperature of the autoclave is 155℃, and the heating time is 7.5 hours. In step (3), the mass ratio of flour to alkali is 100:7.5, the grinding time is 65 minutes, the mass ratio of alkali-activated material to pore-forming agent is 100:25, the heating temperature of the autoclave is 90℃, and the heating time is 60 minutes. In step (4), the ammonia pressure is 0.65 MPa, the activation temperature is 600℃, and the activation time is 1.5 hours to prepare the nitrate catalyst cat-4. The catalyst contains 3.8 wt% V2O5, 6.6 wt% WO3, 75.9 wt% TiO2, 12.9 wt% C, and 0.8 wt% N. The proportion of 0.5-30 μm pores in the catalyst is 30.3%.

[0042] Comparative Example 1 Same as Example 1, except that in step (3) when preparing the pore-forming agent, sodium hydroxide was replaced with the same amount of ammonium bicarbonate to prepare the comparative denitrification catalyst cat-5. The catalyst contained 3.3 wt% V2O5, 6.4 wt% WO3, 73.9 wt% TiO2, 15.6 wt% C, and 0.8 wt% N. The catalyst bulk phase did not form abundant micron-sized through-pores.

[0043] Comparative Example 2 Similar to Example 1, except that in step (3), the flour and sodium hydroxide were not ground, but the same amount of materials were directly mixed and molded to obtain the comparative denitrification catalyst cat-6. The catalyst contained 3.2 wt% V2O5, 6.6 wt% WO3, 74.4 wt% TiO2, 14.9 wt% C, and 0.9 wt% N. The catalyst bulk phase did not form abundant micron-sized through-pores.

[0044] Comparative Example 3 Same as Example 1, except without step (2) alkali activation treatment, to obtain the comparative denitrification catalyst cat-7. The catalyst has a V2O5 content of 3.8wt%, a WO3 content of 7.2wt%, a TiO2 content of 74.1wt%, a C content of 14.1wt%, a N content of 0.8wt%, and a 0.5-30μm pore size of 32.3%.

[0045] Comparative Example 4 Same as Example 1, except that the heat treatment container for the wet material after step (3) was changed to a forced-air heating treatment in an oven. The heat treatment temperature and time were the same as in Example 1. Comparative denitrification catalyst cat-8 was obtained. The catalyst contained 3.5wt% V2O5, 6.6wt% WO3, 74.1wt% TiO2, 15.0wt% C, and 0.8wt% N. The catalyst bulk phase did not form abundant micron-level interconnected channels.

[0046] Comparative Example 5 Same as Example 1, except that step (4) reactivation under ammonia atmosphere was missing, and the comparative denitrification catalyst cat-9 was obtained. The catalyst contained 3.6 wt% V2O5, 6.8 wt% WO3, 74.3 wt% TiO2, 15.2 wt% C, and 0.1 wt% N. The proportion of 0.5-30 μm pores in the catalyst was 31.6%.

[0047] Catalyst denitrification activity test: The catalysts from the examples and comparative examples were loaded into a fixed tubular reactor. The simulated flue gas composition was NO, NH3, O2, and carrier gas N2, with a total flow rate of 600 L / h and a space velocity of 5000 h⁻¹. -1 The NH3 / NO ratio is 1.2, and the reaction temperature is controlled at 280℃. The flow rates of each gas are controlled by a mass flow meter and a rotor flow meter. Before entering the reactor, the gas is first mixed in a gas mixer and then preheated in a preheater. The NO concentration at the inlet and outlet is measured by a flue gas analyzer. The catalytic activity of the catalyst is reflected by the NO denitrification activity, which is calculated using the following formula: Denitrification activity = [(C0-C) / C0]×100%.

[0048] In the formula, C0 is the initial NO concentration, and C is the NO concentration in the treated gas.

[0049] The performance test results of the catalyst after 500 hours and 4000 hours of reaction are shown in Table 1.

[0050] Table 1 Catalyst Activity catalyst <![CDATA[NO removal rate at reaction 500 X %,]]> <![CDATA[NO removal rate at reaction 4000 X %,]]> Cat-1 93.6 91.7 Cat-2 95.3 93.3 Cat-3 94.1 92.5 Cat-4 96.6 92.8 Cat-5 76.4 53.6 Cat-6 78.3 52.8 Cat-7 83.6 79.3 Cat-8 79.1 63.2 Cat-9 86.8 84.5 As can be seen from Table 1, the denitrification catalyst prepared by the method of the present invention has high activity and activity stability.

Claims

1. A method for reusing an SCR denitrification catalyst, characterized in that... The process includes the following: (1) Acid-washed material is obtained by blowing, washing and drying the deactivated SCR denitration catalyst; (2) The acid-washed material in step (1) is crushed and then activated by sealing and temperature treatment after the crushed material is adsorbed with alkaline solution; (3) The alkaline activated material in step (2) is mixed with a pore-forming agent and the mixture is shaped, pore-forming, dried and calcined to obtain a shaped catalyst; (4) The shaped catalyst in step (3) is immersed in a vanadium-containing solution for impregnation, and after impregnation, the material is dried, calcined under a nitrogen atmosphere and activated under an ammonia atmosphere to obtain an SCR denitration catalyst.

2. The method according to claim 1, characterized in that: The deactivated SCR denitrification catalyst mentioned in step (1) refers to a catalyst whose structure has collapsed and been damaged after long-term use or repeated regeneration and recycling, and whose physicochemical properties have changed significantly, resulting in a 40%-80% loss in denitrification activity compared to a fresh catalyst; the deactivated SCR denitrification catalyst is a vanadium-tungsten-titanium system catalyst or a vanadium-molybdenum-titanium system catalyst, and the deactivated catalyst contains 0.5wt%-10.5wt% V2O5, 0.5wt%-12.5wt% WO3 and / or MoO3, and more than 75wt% TiO2.

3. The method according to claim 1, characterized in that: The washing in step (1) is carried out in an acidic solution, which is a mixture of strong and weak acids; wherein the strong acid is one or more of sulfuric acid, hydrochloric acid, and nitric acid, and the weak acid is one or more of oxalic acid, citric acid, and acetic acid; the concentration of the strong acid in the acidic solution is 5wt%-10wt%, the concentration of the weak acid is 1wt%-5wt%, the liquid-to-solid volume ratio is 3:1-5:1, the washing is carried out at room temperature or under heating conditions, preferably at a heating temperature of 50-80℃, and the washing time is 4-8 hours.

4. The method according to claim 1, characterized in that: The drying temperature in step (1) is 90-150℃, and the drying time is 1-8 hours.

5. The method according to claim 1, characterized in that: The particle size of the pulverized material described in step (2) is less than 15 μm.

6. The method according to claim 1, characterized in that: The alkaline solution mentioned in step (2) is an ammonia solution and / or an ammonium bicarbonate solution, with an ammonium ion concentration of 1-3M in the solution, and the amount of solution used is to saturate the powder material with adsorption.

7. The method according to claim 1, characterized in that: The sealing activation process described in step (2) is carried out in a sealed container, preferably an autoclave, with an activation temperature of 150-200℃ and an activation time of 4-8 hours.

8. The method according to claim 1, characterized in that: The XRD pattern of the pore-forming agent described in step (3) shows that the peak intensity of the diffraction peaks at 2θ of 15º, 17º, 18º, and 23º is reduced by more than 60% compared with that of the flour raw material, preferably by 75%-90%. The average grain size D corresponding to the peak position at 2θ of 15º is 6.5-8.5 nm, where D=Kλ / (Bcosθ), K is the Scherrer constant, λ is the diffraction wavelength of the target material, B is the half-width of the diffraction peak, and θ is the diffraction angle.

9. The method according to claim 1, characterized in that: The pore-forming agent mentioned in step (3) is obtained by mixing and grinding flour with an alkaline material; the flour is wheat flour, wherein the protein content is 6%-20% and the starch content is 65%-75%; the alkaline substance is one or a mixture of LiOH, KOH and NaOH, and the mass ratio of the alkaline substance to the flour is 2:100-10:100, preferably 4:100-8:100; the grinding is carried out in a ball mill, and the grinding time is 40-180 min, preferably 60-120 min.

10. The method according to claim 1, characterized in that: The mass ratio of the activated material to the pore-forming agent in step (3) is 100:40-100:

25.

11. The method according to claim 1, characterized in that: The pore-forming process described in step (3) is a heat treatment process in a closed container. The closed container is preferably a sealed high-pressure autoclave. The volume of wet material accounts for 30% to 70% of the total volume of the closed container. The heat treatment temperature is 40-90℃ and the heat treatment time is 60-120min.

12. The method according to claim 1, characterized in that: The drying temperature in step (3) is 90-150℃ and the drying time is 1-8 hours; the calcination is carried out under an inert atmosphere, which is one or more of argon, helium and nitrogen, the calcination temperature is 450-650℃ and the calcination time is 4-8 hours.

13. The method according to claim 1, characterized in that: The vanadium-containing solution mentioned in step (4) is ammonium vanadate or ammonium metavanadate solution, and the vanadium content in the solution is 0.5-8g / 100mL based on oxides; the amount of solution used is to completely submerge the solid material, and the immersion time is 1-4 hours.

14. The method according to claim 1, characterized in that: The drying temperature in step (4) is 90-150℃ and the drying time is 1-8 hours; the calcination temperature under nitrogen atmosphere is 450-650℃ and the calcination time is 4-8 hours.

15. The method according to claim 1, characterized in that: The activation treatment under ammonia atmosphere in step (4) is a roasting treatment under ammonia atmosphere, preferably carried out in a tube furnace. The roasting temperature is 400-650℃, the roasting time is 1-3 hours, and the ammonia pressure in the tube furnace is 0.5-1MPa.

Images