A denitration catalyst, its preparation method and application

Abstract

The present invention relates to the technical field of resource utilization of catalysts, and discloses a denitration catalyst, a preparation method thereof and an application. The method includes: sequentially performing purging, rinsing, bubbling cleaning, ultrasonic cleaning and pickling on the deactivated denitration catalyst to obtain an intermediate material; mixing manganese acetate tetrahydrate, polyvinylpyrrolidone, urea and water to obtain a mixed solution A; mixing 1,3,5-benzenetricarboxylic acid, N,N-dimethylformamide, pseudoboehmite, cobalt chromate and water to obtain a mixed solution B; mixing the mixed solution A and the mixed solution B to obtain an impregnation solution; impregnating the intermediate material in the impregnation solution, and then performing solid-liquid separation, drying and calcination. The method of the present invention can regenerate the denitration catalyst used in the conventional thermal power industry across industries to obtain a catalyst that can meet the complex flue gas conditions in the coking industry.

Description

Technical Field

[0001] The present invention relates to the technical field of resource utilization of catalysts, and particularly relates to a denitration catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Among numerous air pollutants, nitrogen oxides (NOx) can trigger ·OH free radical chemical reactions and generate PM 2.5 under light conditions, and their deep emission reduction has received extensive attention from society. With the large-scale realization of ultra-low emissions in the power industry, the current focus of air pollution prevention and control in China has shifted from the power industry to the non-electric industry, and coke oven flue gas is one of the focuses of attention.

[0003] Compared with the conventional thermal power industry, the flue gas temperature in the coke oven industry is relatively low. The exhaust gas temperature of most coking enterprises is between 170 and 210 °C, and the flue gas contains relatively high moisture and sulfur dioxide. Objectively, this requires the denitration catalyst to have relatively high medium and low temperature activity. At present, the conventional low-temperature catalysts on the market can only meet certain activity in low-temperature flue gas. However, if the flue gas has both relatively high moisture and sulfur content, it will greatly reduce the service life of the catalyst and the stability of denitration. At the same time, in this temperature range, SO2 in the flue gas is easily oxidized by the denitration catalyst to SO3, and then reacts with NH3 and H2O to generate ammonium bisulfate, which deposits on the catalyst surface and blocks the catalyst active sites, resulting in a decrease in catalyst activity. In addition, the water vapor in the flue gas also has a strong inhibitory effect on the activity of the denitration catalyst, mainly because water vapor and NH3 have competitive adsorption on the reaction active sites, and the lower the flue gas temperature, the stronger the inhibitory effect of water vapor on the catalyst activity. For independent coking enterprises, the water content of the flue gas is as high as 20%, and the inhibitory effect of water vapor is particularly obvious. In addition, in the previous desulfurization process, the use of sodium-based desulfurizer will inevitably introduce alkali metals into the coke oven flue gas. Alkali metals are the main substances causing the deactivation of denitration catalysts. They will not only deposit on the catalyst surface and block the small holes, reducing the specific surface area and pore volume of the catalyst, causing physical poisoning of the catalyst; but also combine with acidic sites such as V and W on the catalyst surface, weakening the surface acidity of the catalyst, resulting in chemical deactivation of the catalyst.

[0004] Based on the characteristics of coke oven flue gas and the process route, the catalyst suitable for this environment must have the characteristics of sulfur resistance, water resistance, alkali poisoning resistance and low temperature and high denitrification efficiency. At present, the mainstream regeneration technology for low-temperature catalysts on the market is to use the deactivated low-temperature catalyst for simple soot blowing, water washing, and acid washing, and then soak and dry it with one or more active liquids of vanadium, manganese, cerium, and molybdenum to complete the regeneration. However, the low-temperature activity of the catalyst regenerated by this method is difficult to fully restore, the mechanical strength decreases, the life is short in a low-temperature, high-sulfur, high-humidity, and high-alkali metal environment, and it is difficult to achieve standard denitrification. The regenerated low-temperature catalyst can only be used in flue gas conditions with a relatively single environment. If complex flue gas conditions are encountered, the life of this type of catalyst will be sharply shortened, and the denitrification efficiency will be greatly reduced. If the deactivated low-temperature catalyst is severely damaged, it cannot be regenerated, the application area is greatly reduced, and the resource utilization rate is extremely low. Summary of the invention

[0005] The purpose of the present invention is to overcome the problem of the difficulty in regenerating the denitration catalyst of coke oven flue gas in the prior art, and to provide a denitration catalyst and its preparation method and application. The method not only realizes the resource utilization of waste denitration catalysts in the conventional thermal power industry, but also can produce a denitration catalyst suitable for coke oven flue gas that can be used in a low temperature range and a complex environment of high sulfur, high humidity and high alkali metal.

[0006] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a denitration catalyst, the method comprising the following steps:

[0007] (1) The deactivated denitration catalyst is sequentially purged, rinsed, bubbled, ultrasonically cleaned and acid washed to obtain an intermediate material;

[0008] (2) manganese acetate tetrahydrate, polyvinyl pyrrolidone, urea and water are added to obtain a mixed solution A;

[0009] (3) mixing 1,3,5-trimethylbenzene carboxylic acid, N,N-dimethylformamide, pseudo-boehmite, cobalt chromate and water to obtain a mixed solution B;

[0010] (4) Mixing the mixed solution A and the mixed solution B to obtain an impregnation solution;

[0011] (5) impregnating the intermediate material obtained in step (1) in the impregnation solution obtained in step (4), and then performing solid-liquid separation, drying and calcining;

[0012] Among them, the cleaning solution used in bubbling cleaning is a nicotinamide aqueous solution; the pickling solution used in pickling contains citric acid and sulfuric acid.

[0013] Preferably, in step (1), compressed air of 0.3-0.7 Mpa is used for purging.

[0014] Preferably, the concentration of the nicotinamide aqueous solution is 0.5-3 wt%.

[0015] Preferably, the conditions for bubbling cleaning include: temperature of 35-40 °C and time of 15-30 min.

[0016] Preferably, the concentration of citric acid in the pickling solution is 0.5-5 wt%, and the concentration of citric acid is the same as that of sulfuric acid.

[0017] Preferably, in step (2), based on the total weight of manganese acetate tetrahydrate, polyvinylpyrrolidone, water and urea, the dosage of manganese acetate tetrahydrate is 4-10 wt%, the dosage of polyvinylpyrrolidone is 0.5-8 wt%, and the dosage of urea is 2-5 wt%.

[0018] Preferably, the specific process of step (2) includes: mixing manganese acetate tetrahydrate, polyvinylpyrrolidone and water, then adding urea, and then mixing at 40-50 °C for 30-60 min to obtain a mixed solution A.

[0019] Preferably, in step (3), based on the total weight of 1,3,5-benzenetricarboxylic acid, N,N-dimethylformamide, water, pseudoboehmite and cobalt chromate, the dosage of 1,3,5-benzenetricarboxylic acid is 15-35 wt%, the dosage of N,N-dimethylformamide is 25-40 wt%, the dosage of pseudoboehmite is 10-15 wt%, and the dosage of cobalt chromate is 3-8 wt%;

[0020] Preferably, the specific process of step (3) includes: mixing 1,3,5-benzenetricarboxylic acid (H3BTC), N,N-dimethylformamide (DMF) and water, then adding pseudoboehmite and cobalt chromate, and then mixing at 70-80 °C for 45-70 min to obtain a mixed solution B.

[0021] Preferably, in step (4), the volume ratio of the mixed solution A to the mixed solution B is 1:0.2-5;

[0022] Preferably, in step (4), the mixing temperature is 40-50 °C.

[0023] Preferably, in step (5), the conditions for impregnation include: temperature of 40-60 °C and time of 60-150 min.

[0024] The second aspect of the present invention provides a denitration catalyst obtained by the method described above.

[0025] The third aspect of the present invention provides the application of the denitration catalyst described above in the denitration of flue gas in the coking industry.

[0026] Although the existing technologies can realize the regeneration of waste denitration catalysts in the conventional thermal power industry, it is difficult to restore the original activity and mechanical strength of the catalysts, and it is even more difficult to make the regenerated catalysts be used across industries in complex environments with low temperature, high sulfur, high humidity, and high alkali metals. By using the method described in the present invention, the denitration catalysts used in the conventional thermal power industry can be regenerated across industries to obtain catalysts that can meet the complex flue gas conditions in the coking industry. The regenerated catalyst prepared by the method described in the present invention has high activity in the low temperature range and has certain resistance in environments with high humidity, high sulfur, and high alkali metals; it can have a denitration efficiency of more than 85% between 100°C and 160°C and a denitration efficiency of more than 95% between 160°C and 220°C; and it has excellent N2 selectivity and mechanical strength. Detailed Embodiments

[0027] The following provides a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0028] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values and individual point values of each range, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0029] The first aspect of the present invention provides a method for preparing a denitration catalyst, and the method includes the following steps:

[0030] (1) Sequentially subject the deactivated denitration catalyst to purging, rinsing, bubbling cleaning, ultrasonic cleaning, and pickling to obtain an intermediate material;

[0031] (2) Mix manganese acetate tetrahydrate, polyvinylpyrrolidone, urea, and water to obtain a mixed solution A;

[0032] (3) Mix 1,3,5-benzenetricarboxylic acid, N,N-dimethylformamide, pseudo-boehmite, cobalt chromate, and water to obtain a mixed solution B;

[0033] (4) Mix the mixed solution A and the mixed solution B to obtain an impregnation solution;

[0034] (5) Immerse the intermediate material obtained in step (1) in the impregnation solution obtained in step (4), and then perform solid-liquid separation, drying, and calcination;

[0035] Among them, the cleaning solution used for bubbling cleaning is a nicotinamide aqueous solution; the pickling solution used for pickling contains citric acid and sulfuric acid.

[0036] The method described in the present invention can realize the resource utilization and cross-industry regeneration of denitration catalysts (vanadium-tungsten-titanium SCR denitration catalysts) used in the conventional thermal power industry, and the prepared catalyst has high activity in the low temperature range, has a certain resistance to high humidity, high sulfur, and high alkali metal environments, and can meet the complex flue gas conditions of the coking industry.

[0037] In the present invention, the deactivated denitration catalyst is a vanadium-tungsten-titanium SCR denitration catalyst used in the thermal power industry, which contains not only the original components such as vanadium, tungsten, and titanium, but also toxic substances that cause catalyst deactivation, including alkali metal elements, alkaline earth metal elements, ammonium sulfate substances, iron elements, etc. The ammonium sulfate substances include ammonium sulfate, ammonium hydrogen sulfate, and calcium sulfate, etc.

[0038] In the method of the present invention, compressed air is used to purge the surface dust and smoke in the pores of the deactivated denitration catalyst to ensure that the pores inside the catalyst are not blocked. In a preferred embodiment, in step (1), compressed air of 0.3-0.7 Mpa is used for purging.

[0039] In a preferred embodiment, in step (1), the solution used for flushing can be water. Further preferably, high-pressure water flushing can be used. Generally, it is best to keep the muzzle of the high-pressure water gun about 20 to 25 cm away from the air inlet end of the catalyst. At this time, the water column sprayed from the muzzle does not diverge over a large area and still maintains a certain pressure; at the same time, the purge area is also expanded, which is conducive to improving the flushing efficiency. When the gauge pressure of the high-pressure water pump is 8 to 16 MPa, it can not only not destroy the structure of the denitration catalyst itself, but also use the maximum pressure to clear the blockage of the catalyst pores. The flushing time can be 10-20 minutes.

[0040] In a preferred case, the cleaning solution used for bubbling cleaning is a nicotinamide aqueous solution with a concentration of 0.5-3wt%; the conditions for bubbling cleaning include: a temperature of 35-40°C and a time of 15-30 minutes. The present invention adds nicotinamide as a co-solvent to ensure that the solution completely submerges the catalyst, and performs bubbling cleaning, which can clean the smoke and floating ash that cannot be blown away by compressed air to the greatest extent.

[0041] According to a specific embodiment of the present invention, the cleaning solution used for the bubbling cleaning can be prepared according to the following steps: mixing deionized water with nicotinamide.

[0042] In a preferred embodiment, ultrasonic cleaning can be performed with deionized water at 30-40° C., the ultrasonic frequency can be 20-60 kHz, and the ultrasonic cleaning time can be 25-35 min.

[0043] In the present invention, the pickling uses a mixed acid solution of organic acid + inorganic acid, which is beneficial to the "total spectrum" removal of "toxic" alkali metal elements. The organic pickling mainly removes some toxic elements such as Fe, P, Mg, Zn, and Ca in the catalyst, while sulfuric acid can mainly remove some toxic elements such as Fe, Na, and K in the catalyst. Ensure that the content of iron oxides therein is less than 100 ppm, and more than 92% of K, Na, and Ca ions in the catalyst are removed. Basically, the elements that can cause catalyst poisoning and deactivation in the flue gas of the conventional thermal power industry can be cleaned or controlled within the national standard range. In the preferred case, in the pickling solution, the concentration of citric acid is 0.5 - 5 wt%, and the concentration of citric acid is the same as that of sulfuric acid.

[0044] According to a specific embodiment of the present invention, the pickling solution can be obtained by mixing citric acid, sulfuric acid and water.

[0045] According to some preferred embodiments of the present invention, the method further includes: rinsing the material obtained after pickling with water.

[0046] In the present invention, the dust content in the general waste catalyst is 0 - 40 wt%. Through the combined cleaning of compressed air, high-pressure water gun, bubbling cleaning and ultrasonic, not only can the catalyst pore blockage and surface floating ash be cleaned, but also with the help of nicotinamide, the diffusion of "toxic" ions on the catalyst surface into the solution can be accelerated, and at the same time, the exchange of the solution inside and outside the catalyst capillary pores can be promoted, which is beneficial to the deep cleaning of the attached "toxic" ions; on the other hand, it also accelerates the dissolution of the "used active ingredients" inside the catalyst, facilitating the implantation of new active ingredients later. Compared with the conventional direct deionized water cleaning, the removal of toxic elements by this method can be increased by 20 - 35%.

[0047] In the preferred embodiment, in step (2), based on the total weight of manganese acetate tetrahydrate, polyvinylpyrrolidone (PVP), water and urea, the dosage of manganese acetate tetrahydrate is 4 - 10 wt%, the dosage of polyvinylpyrrolidone is 0.5 - 8 wt%, the dosage of urea is 2 - 5 wt%, and the balance is water. Further preferably, the molecular weight of the polyvinylpyrrolidone is 5,000 - 200,000.

[0048] According to some preferred embodiments of the present invention, the specific process of step (2) includes: mixing manganese acetate tetrahydrate, polyvinylpyrrolidone (PVP) and water, then adding urea, and then mixing at 40 - 50 °C for 30 - 60 min to obtain a mixed solution A.

[0049] In the present invention, through step (2), by adding the MOF structure directing agents (PVP and urea), the Mn element can be impregnated and loaded in the form of MOF-Mn, promoting the MnO with a higher valence state of Mn xformation, thereby improving the low-temperature NH3-SCR activity; it can be used to derive MnO x The catalyst has a more abundant pore structure. Compared with the catalyst without the addition of the guiding agent, the specific surface area can be increased by 8%-17%, which is conducive to the exposure of active sites and the adsorption of reactants, thereby enhancing the activity of the catalyst. The impregnating solution introduces MOF-Mn metal oxide, which can provide more Brønsted (B) acid sites for the catalyst. Moreover, due to its high porosity and large specific surface area, it can promote the highly dispersed B acid sites and improve the sulfur resistance of the catalyst; this substance can also introduce hydroxyl groups onto the catalyst. The hydroxyl groups can preferentially adsorb SO2 to form HSO 4- , reducing the chance of the redox sites being attacked by SO2. In addition, HSO 4- can capture NH3 to generate NH4HSO4 and participate in the NH3-SCR reaction, further enhancing the sulfur resistance of the catalyst.

[0050] In a preferred embodiment, in step (3), based on the total weight of 1,3,5-benzenetricarboxylic acid (H3BTC), N,N-dimethylformamide (DMF), water, pseudoboehmite and cobalt chromate, the dosage of 1,3,5-benzenetricarboxylic acid is 15-35 wt%, the dosage of N,N-dimethylformamide is 25-40 wt%, the dosage of pseudoboehmite is 10-15 wt%, the dosage of cobalt chromate is 3-8 wt%, and the balance is water.

[0051] According to some preferred embodiments of the present invention, the specific process of step (3) includes: mixing 1,3,5-benzenetricarboxylic acid (H3BTC), N,N-dimethylformamide (DMF) and water, then adding pseudoboehmite and cobalt chromate, and then mixing at 70-80 °C for 45-70 min to obtain a mixed solution B.

[0052] In the method of the present invention, the introduction of Cr element can react with the introduced Mn element to form CrMn2O4. The formation of CrMn2O4 is related to the reaction between Cr element and SO4 2- attached to the catalyst surface. The generated CrSO4 can inhibit the sulfation of Mn. In the flue gas of the coking industry, there are relatively high SO2 and SO3, which are extremely easy to form sulfuric acid substances with the moisture in the flue duct. Through the cyclic reaction between Cr and Mn (Cr 5+ +2Mn 3+ ↔Cr 3+ +2Mn 4+ ), a specific crystal phase of CrMn2O4 spinel can be formed, which can ensure that the catalyst has a certain water resistance and anti-poisoning ability.

[0053] In the method of the present invention, Co element is introduced, which can also form spinel crystal form of MnCoO4 with Mn. And there is also an interaction mechanism similar to that between Cr and Mn described above in this crystal form (Mn2+ + Co3+ ↔ Mn3+ + Co2+), and its relatively unique surface properties and structural characteristics also endow it with relatively excellent water and sulfur resistance performance. The Co7Mn3O spinel formed on the catalyst surface helps to increase the active center sites and thermal stability, enabling the catalyst to have better redox performance and more surface acid centers. At the same time, this structure also effectively promotes the SO2 / H2O resistance performance. And, part of the Co element will form cobalt oxide (CoO) - like mixtures after calcination. This kind of substance can promote the polymerization of cations in the catalyst, carry out catalytic reactions at high temperatures, and convert the salts attached to it into oxides as soon as possible, playing the role of a dryer; this kind of substance can also shorten the drying and calcination time, improve production efficiency and save energy. Cobalt oxide can also accelerate the curing of the surface active substances after impregnation, improve the surface hardness and corrosion resistance of the catalyst, making it more wear - resistant and anti - toxic under the complex flue gas conditions in the coking plant. x Co 3-x O4, and there is also an interaction mechanism similar to that between Cr and Mn described above in this crystal form (Mn2+ + Co3+ ↔ Mn3+ + Co2+), and its relatively unique surface properties and structural characteristics also endow it with relatively excellent water and sulfur resistance performance. The Co7Mn3O spinel formed on the catalyst surface helps to increase the active center sites and thermal stability, enabling the catalyst to have better redox performance and more surface acid centers. At the same time, this structure also effectively promotes the SO2 / H2O resistance performance. And, part of the Co element will form cobalt oxide (CoO) - like mixtures after calcination. This kind of substance can promote the polymerization of cations in the catalyst, carry out catalytic reactions at high temperatures, and convert the salts attached to it into oxides as soon as possible, playing the role of a dryer; this kind of substance can also shorten the drying and calcination time, improve production efficiency and save energy. Cobalt oxide can also accelerate the curing of the surface active substances after impregnation, improve the surface hardness and corrosion resistance of the catalyst, making it more wear - resistant and anti - toxic under the complex flue gas conditions in the coking plant. 3+ +Co3+ 3+ ↔Mn3+ 4+ +Co2+ 2+ ), and its relatively unique surface properties and structural characteristics also endow it with relatively excellent water and sulfur resistance performance. The Co7Mn3O spinel formed on the catalyst surface helps to increase the active center sites and thermal stability, enabling the catalyst to have better redox performance and more surface acid centers. At the same time, this structure also effectively promotes the SO2 / H2O resistance performance. And, part of the Co element will form cobalt oxide (CoO) - like mixtures after calcination. This kind of substance can promote the polymerization of cations in the catalyst, carry out catalytic reactions at high temperatures, and convert the salts attached to it into oxides as soon as possible, playing the role of a dryer; this kind of substance can also shorten the drying and calcination time, improve production efficiency and save energy. Cobalt oxide can also accelerate the curing of the surface active substances after impregnation, improve the surface hardness and corrosion resistance of the catalyst, making it more wear - resistant and anti - toxic under the complex flue gas conditions in the coking plant. x spinel helps to increase the active center sites and thermal stability, enabling the catalyst to have better redox performance and more surface acid centers. At the same time, this structure also effectively promotes the SO2 / H2O resistance performance. And, part of the Co element will form cobalt oxide (CoO) - like mixtures after calcination. This kind of substance can promote the polymerization of cations in the catalyst, carry out catalytic reactions at high temperatures, and convert the salts attached to it into oxides as soon as possible, playing the role of a dryer; this kind of substance can also shorten the drying and calcination time, improve production efficiency and save energy. Cobalt oxide can also accelerate the curing of the surface active substances after impregnation, improve the surface hardness and corrosion resistance of the catalyst, making it more wear - resistant and anti - toxic under the complex flue gas conditions in the coking plant. x ), and this kind of substance can promote the polymerization of cations in the catalyst, carry out catalytic reactions at high temperatures, and convert the salts attached to it into oxides as soon as possible, playing the role of a dryer; this kind of substance can also shorten the drying and calcination time, improve production efficiency and save energy. Cobalt oxide can also accelerate the curing of the surface active substances after impregnation, improve the surface hardness and corrosion resistance of the catalyst, making it more wear - resistant and anti - toxic under the complex flue gas conditions in the coking plant.

[0054] In a preferred embodiment, in step (4), the volume ratio of the mixed solution A to the mixed solution B is 1:0.2 - 5, specifically it can be 1:0.2, 1:0.5, 1:1, 1:2, 1:3, 1:4 or 1:5; the temperature for mixing the mixed solution A and the mixed solution B is 40 - 50 °C. Reasonably controlling the ratio of the mixed solution A and the mixed solution B is beneficial to further improving the performance of the denitration catalyst.

[0055] In a preferred embodiment, in step (5), the impregnation conditions include: the temperature is 40 - 60 °C, and the time is 60 - 150 min; specifically, the impregnation temperature can be 40 °C, 45 °C, 50 °C, 55 °C or 60 °C; the impregnation time can be 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min or 150 min. In a specific embodiment, the intermediate material can be put into the impregnation solution for rotary impregnation.

[0056] According to some preferred embodiments of the present invention, in step (5), the drying can be carried out by using conventional drying methods in the art. For example, the solid material obtained after the impregnation can be put into a drying oven and dried by blowing air at 70 - 80 °C, and the drying time can be 200 - 300 min.

[0057] In a preferred embodiment, in step (5), the calcination procedure is as follows: heating from room temperature to 150 °C over 50 - 70 min, then heating from 150 °C to 230 °C over 170 - 190 min, then heating from 230 °C to 350 °C over 110 - 130 min, then heating from 350 °C to 400 °C over 20 - 40 min, then heating from 400 °C to 450 °C over 180 - 220 min, and then cooling. In the present invention, after calcination, MOF-Mn can grow along a specific direction, prompting its precursor to exhibit a neatly arranged long strip-like structure, and its micro-level is a porous nanowire structure. This structure can make the agglomeration degree of Mn elements on the catalyst surface lower and the morphology more regular, enabling each active site to fully contact the reaction during the reaction and extending the chemical life of the catalyst.

[0058] According to a specific embodiment of the present invention, in step (5), the specific calcination procedure is as follows: heating from room temperature (about 25 °C) to 150 °C over 60 min, then heating from 150 °C to 230 °C over 180 min, then heating from 230 °C to 350 °C over 120 min, then heating from 350 °C to 400 °C over 30 min, then heating from 400 °C to 450 °C over 200 min, and then naturally cooling.

[0059] If the waste denitration catalyst in the conventional thermal power industry is to be regenerated into a denitration catalyst applicable to the coking industry with low-temperature sulfur resistance, water resistance, and poison resistance, a series of problems need to be overcome, such as a significant decrease in the reaction temperature range of the denitration catalyst, a change in the main active substance, an increase in N2 selectivity, a reduction in SO2 adsorption / oxidation, an increase in the water resistance of the catalyst, an increase in the alkali metal poisoning resistance of the catalyst, and an increase in the mechanical strength of the catalyst. The method described in the present invention overcomes the above difficulties by performing a series of cleaning treatments on the deactivated denitration catalyst, then impregnating it with the impregnating solution described in the present invention, and then performing calcination, obtaining a denitration catalyst that can be applied to the coking industry with low-temperature sulfur resistance, water resistance, and poison resistance.

[0060] The second aspect of the present invention provides a denitration catalyst obtained by the method described above.

[0061] The third aspect of the present invention provides the application of the denitration catalyst described above in flue gas denitration in the coking industry.

[0062] The present invention will be described in detail below through examples, but the protection scope of the present invention is not limited thereto.

[0063] The deactivated denitration catalysts used in the following examples and comparative examples are vanadium-tungsten-titanium-based SCR denitration catalysts used in the thermal power industry and have the same source.

[0064] Example 1

[0065] (1) The deactivated denitration catalyst will be purged of surface floating ash and soot in the pores using compressed air at 0.7 Mpa; then, the deactivated denitration catalyst will be rinsed with high-pressure water for 15 min, and the gauge pressure of the high-pressure water pump is 10 Mpa; then, the deactivated denitration catalyst will be vertically placed into a bubbling cleaning tank and bubbling cleaned with a 0.5 wt% nicotinamide aqueous solution for 20 min, and the bubbling cleaning temperature is 35 °C; then, it will be ultrasonically cleaned with demineralized water at 35 °C, the ultrasonic frequency is 45 KHZ, and the ultrasonic cleaning time is 30 min; then, it will be pickled with a pickling solution, which is obtained by mixing citric acid, sulfuric acid and water, and the concentrations of citric acid and sulfuric acid in the pickling solution are both 0.5 wt%, and the pickling time is 45 min; after pickling, it will be spray rinsed with demineralized water to obtain an intermediate material;

[0066] (2) Manganese acetate tetrahydrate, polyvinylpyrrolidone and demineralized water are mixed, then urea is added, and then they are mixed at 50 °C for 45 min to obtain a mixed solution A; among them, based on the total weight of manganese acetate tetrahydrate, polyvinylpyrrolidone (PVP), water and urea, the dosage of manganese acetate tetrahydrate is 6 wt%, the dosage of polyvinylpyrrolidone is 1 wt%, the dosage of urea is 2 wt%, and the balance is water; the molecular weight of the polyvinylpyrrolidone is 20,000;

[0067] (3) 1,3,5-benzenetricarboxylic acid (H3BTC) and N,N-dimethylformamide are dissolved in demineralized water, stirred for 5 min, pseudo-boehmite and cobalt chromate are added at room temperature, and the temperature is raised to 75 °C and stirred for 60 min to obtain a mixed solution B; among them, based on the total weight of 1,3,5-benzenetricarboxylic acid (H3BTC), N,N-dimethylformamide, water, pseudo-boehmite and cobalt chromate, the dosage of 1,3,5-benzenetricarboxylic acid is 15 wt%, the dosage of N,N-dimethylformamide is 30 wt%, the dosage of pseudo-boehmite is 12 wt%, the dosage of cobalt chromate is 3 wt%, and the balance is water;

[0068] (4) The mixed solution A and the mixed solution B are mixed at 45 °C according to a volume ratio of 1:1 to obtain an impregnating solution;

[0069] (5) The intermediate material obtained in step (1) is impregnated in the impregnating solution obtained in step (4), rotated and impregnated at 50 °C for 120 min, then solid-liquid separation is carried out, and then the obtained solid phase is dried at 75 °C for 250 min; then calcination is carried out, and the specific procedure of calcination is: from room temperature (about 25 °C) it is heated to 150 °C in 60 min, then from 150 °C it is heated to 230 °C in 180 min, then from 230 °C it is heated to 350 °C in 120 min, then from 350 °C it is heated to 400 °C in 30 min, then from 400 °C it is heated to 450 °C in 200 min, and then it is naturally cooled.

[0070] Example 2

[0071] (1) Use compressed air at 0.7 Mpa to blow the surface dust and the soot in the pores of the deactivated denitration catalyst; then use clean water to perform high-pressure water flushing on the deactivated denitration catalyst for 15 min, and the gauge pressure of the high-pressure water pump is 10 Mpa; then vertically place the deactivated denitration catalyst into the bubbling cleaning tank, and use an aqueous solution of nicotinamide with a concentration of 1 wt% for bubbling cleaning for 20 min, and the bubbling cleaning temperature is 35 °C; then perform ultrasonic cleaning with demineralized water at 35 °C, the ultrasonic frequency is 45 KHZ, and the ultrasonic cleaning time is 30 min; then perform pickling with the pickling solution, the pickling solution is obtained by mixing citric acid, sulfuric acid and water, and the concentrations of citric acid and sulfuric acid in the pickling solution are both 2 wt%, and the pickling time is 45 min; after pickling, perform spray flushing with demineralized water to obtain the intermediate material;

[0072] (2) Mix manganese acetate tetrahydrate, polyvinylpyrrolidone and demineralized water, then add urea, and then mix at 50 °C for 45 min to obtain the mixed solution A; wherein, based on the total weight of manganese acetate tetrahydrate, polyvinylpyrrolidone (PVP), water and urea, the dosage of manganese acetate tetrahydrate is 6 wt%, the dosage of polyvinylpyrrolidone is 4 wt%, the dosage of urea is 4 wt%, and the balance is water; the molecular weight of the polyvinylpyrrolidone is 20,000;

[0073] (3) Dissolve 1,3,5-benzenetricarboxylic acid (H3BTC) and N,N-dimethylformamide in demineralized water, stir for 5 min, add pseudoboehmite and cobalt chromate at room temperature, heat up to 75 °C, and stir for 60 min to obtain the mixed solution B; wherein, based on the total weight of 1,3,5-benzenetricarboxylic acid (H3BTC), N,N-dimethylformamide, water, pseudoboehmite and cobalt chromate, the dosage of 1,3,5-benzenetricarboxylic acid is 20 wt%, the dosage of N,N-dimethylformamide is 30 wt%, the dosage of pseudoboehmite is 12 wt%, the dosage of cobalt chromate is 5 wt%, and the balance is water;

[0074] (4) Mix the mixed solution A and the mixed solution B at a volume ratio of 1:1 at 45 °C to obtain the impregnation solution;

[0075] (5) Immerse the intermediate material obtained in step (1) in the impregnating solution obtained in step (4), rotate and impregnate at 50 °C for 120 min, then perform solid-liquid separation, and then dry the obtained solid phase at 75 °C for 250 min; then perform calcination, and the specific calcination procedure is: heat from room temperature (about 25 °C) to 150 °C in 60 min, then heat from 150 °C to 230 °C in 180 min, then heat from 230 °C to 350 °C in 120 min, then heat from 350 °C to 400 °C in 30 min, then heat from 400 °C to 450 °C in 200 min, and then cool naturally.

[0076] Example 3

[0077] (1) Use compressed air at 0.7 Mpa to blow the surface dust and the soot in the pores of the deactivated denitration catalyst; then use clean water to perform high-pressure water flushing on the deactivated denitration catalyst for 15 min, and the gauge pressure of the high-pressure water pump is 10 Mpa; then place the deactivated denitration catalyst vertically into the bubbling cleaning tank, and use a 2 wt% nicotinamide aqueous solution to perform bubbling cleaning for 20 min, and the bubbling cleaning temperature is 35 °C; then use demineralized water at 35 °C to perform ultrasonic cleaning, the ultrasonic frequency is 45 KHZ, and the ultrasonic cleaning time is 30 min; then use an acid cleaning solution for acid cleaning, the acid cleaning solution is obtained by mixing citric acid, sulfuric acid and water, and the concentrations of citric acid and sulfuric acid in the acid cleaning solution are both 3 wt%, and the acid cleaning time is 45 min; after acid cleaning, use demineralized water for spray flushing to obtain an intermediate material;

[0078] (2) Mix manganese acetate tetrahydrate, polyvinylpyrrolidone and demineralized water, then add urea, and then mix at 50 °C for 45 min to obtain a mixed solution A; wherein, based on the total weight of manganese acetate tetrahydrate, polyvinylpyrrolidone (PVP), water and urea, the dosage of manganese acetate tetrahydrate is 8 wt%, the dosage of polyvinylpyrrolidone is 6 wt%, the dosage of urea is 5 wt%, and the balance is water; the molecular weight of the polyvinylpyrrolidone is 20,000;

[0079] (3) Dissolve 1,3,5-benzenetricarboxylic acid (H3BTC) and N,N-dimethylformamide in demineralized water, stir for 5 min, add pseudoboehmite and cobalt chromate at room temperature, heat to 75 °C, and stir for 60 min to obtain a mixed solution B; wherein, based on the total weight of 1,3,5-benzenetricarboxylic acid (H3BTC), N,N-dimethylformamide, water, pseudoboehmite and cobalt chromate, the dosage of 1,3,5-benzenetricarboxylic acid is 25 wt%, the dosage of N,N-dimethylformamide is 40 wt%, the dosage of pseudoboehmite is 13 wt%, the dosage of cobalt chromate is 6 wt%, and the balance is water;

[0080] (4) Mix mixture A and mixture B at a volume ratio of 1:1 at 45 °C to obtain an impregnating solution;

[0081] (5) Immerse the intermediate material obtained in step (1) in the impregnating solution obtained in step (4), rotate and impregnate at 50 °C for 120 min, then perform solid-liquid separation, and then dry the obtained solid phase at 75 °C for 250 min; then perform calcination, and the specific calcination procedure is: heat from room temperature (about 25 °C) to 150 °C in 60 min, then heat from 150 °C to 230 °C in 180 min, then heat from 230 °C to 350 °C in 120 min, then heat from 350 °C to 400 °C in 30 min, then heat from 400 °C to 450 °C in 200 min, and then cool naturally.

[0082] Example 4

[0083] (1) Use compressed air at 0.7 Mpa to blow the surface dust and the dust in the pores of the deactivated denitration catalyst; then use clean water to perform high-pressure water flushing on the deactivated denitration catalyst for 15 min, and the gauge pressure of the high-pressure water pump is 10 Mpa; then vertically place the deactivated denitration catalyst into a bubbling cleaning tank, and use an aqueous solution of nicotinamide with a concentration of 3 wt% for bubbling cleaning for 20 min, and the bubbling cleaning temperature is 35 °C; then perform ultrasonic cleaning with demineralized water at 35 °C, the ultrasonic frequency is 45 KHZ, and the ultrasonic cleaning time is 30 min; then perform pickling with a pickling solution, the pickling solution is obtained by mixing citric acid, sulfuric acid and water, and the concentrations of citric acid and sulfuric acid in the pickling solution are both 5 wt%, and the pickling time is 45 min; after pickling, perform spray flushing with demineralized water to obtain an intermediate material;

[0084] (2) Mix manganese acetate tetrahydrate, polyvinylpyrrolidone and demineralized water, then add urea, and then mix at 50 °C for 45 min to obtain mixture A; wherein, based on the total weight of manganese acetate tetrahydrate, polyvinylpyrrolidone (PVP), water and urea, the dosage of manganese acetate tetrahydrate is 8 wt%, the dosage of polyvinylpyrrolidone is 8 wt%, the dosage of urea is 5 wt%, and the balance is water; the molecular weight of the polyvinylpyrrolidone is 20,000;

[0085] (3) Dissolve 1,3,5-benzenetricarboxylic acid (H3BTC) and N,N-dimethylformamide in deionized water, stir for 5 min, add pseudoboehmite and cobalt chromate at room temperature, heat up to 75 °C, and stir for 60 min to obtain mixture B; wherein, based on the total weight of 1,3,5-benzenetricarboxylic acid (H3BTC), N,N-dimethylformamide, water, pseudoboehmite and cobalt chromate, the dosage of 1,3,5-benzenetricarboxylic acid is 30 wt%, the dosage of N,N-dimethylformamide is 40 wt%, the dosage of pseudoboehmite is 13 wt%, the dosage of cobalt chromate is 8 wt%, and the balance is water;

[0086] (4) Mix mixture A and mixture B at a volume ratio of 1:1 at 45 °C to obtain an impregnating solution;

[0087] (5) Immerse the intermediate obtained in step (1) in the impregnating solution obtained in step (4), rotate and impregnate at 50 °C for 120 min, then perform solid-liquid separation, and then dry the obtained solid phase at 75 °C for 250 min; then perform calcination, and the specific calcination procedure is: heat from room temperature (about 25 °C) to 150 °C in 60 min, then heat from 150 °C to 230 °C in 180 min, then heat from 230 °C to 350 °C in 120 min, then heat from 350 °C to 400 °C in 30 min, then heat from 400 °C to 450 °C in 200 min, and then cool naturally.

[0088] Comparative Example 1

[0089] Carry out according to the method described in Example 4, the difference is that in step (1), the solution used for bubbling cleaning is deionized water.

[0090] Comparative Example 2

[0091] Carry out according to the method described in Example 4, the difference is that in step (1), the pickling solution used is a 5 wt% aqueous citric acid solution.

[0092] Comparative Example 3

[0093] Carry out according to the method described in Example 4, the difference is that in step (1), the pickling solution used is a 5 wt% aqueous sulfuric acid solution.

[0094] Comparative Example 4

[0095] Carry out according to the method described in Example 4, the difference is that in step (2), without PVP and urea, use the same weight of deionized water to replace PVP and urea.

[0096] Comparative Example 5

[0097] The method described in Example 4 was implemented, except that in step (3), instead of using H3BTC and DMF, the same weight of water was used to replace H3BTC and DMF.

[0098] Comparative Example 6

[0099] The method described in Example 4 was implemented, except that in step (3), instead of using pseudo-boehmite, the same weight of water was used to replace pseudo-boehmite.

[0100] Comparative Example 7

[0101] The method described in Example 4 was implemented, except that in step (3), instead of using cobalt chromate, the same weight of water was used to replace cobalt chromate.

[0102] Test Example

[0103] 1. In Examples 1 - 4, the removal rates of toxic substances after bubbling cleaning were detected, and the results are shown in Table 1.

[0104] Among them, the removal rate of each toxic substance after bubbling cleaning was determined by the ratio of the mass of the toxic substance contained in the deactivated denitration catalyst after bubbling cleaning to the mass of the toxic substance contained in the original deactivated denitration catalyst (i.e., the deactivated denitration catalyst before purging).

[0105] Table 1

[0106]

[0107] 2. In Examples 1 - 4 and Comparative Examples 1 - 7, the removal rates of toxic substances after pickling were detected, and the results are shown in Table 2.

[0108] Among them, the removal rate of each toxic substance after bubbling cleaning was determined by the ratio of the mass of the toxic substance contained in the deactivated denitration catalyst after pickling to the mass of the toxic substance contained in the original deactivated denitration catalyst (i.e., the deactivated denitration catalyst before purging).

[0109] Table 2

[0110]

[0111] 3. The axial and radial compressive strengths of the catalysts obtained in the examples and comparative examples were detected, and the results are shown in Table 3.

[0112] Table 3

[0113]

[0114] 4. The denitration performance of the catalysts obtained in the examples and comparative examples was detected.

[0115] The detection is carried out according to the operation process in GB / T 31587. Among them, the detection conditions are adjusted as follows: the flue gas volume space velocity is 3000 h-1 , the water content of the flue gas is 20%, and the sulfur content is 3500 ppm (calculated as SO2); the denitration efficiency detection is carried out at temperatures of 380 °C, 260 °C, and 140 °C respectively.

[0116] The calculation method of the denitration efficiency is: (the concentration of NO at the reactor inlet - the concentration of NO at the reactor outlet) / the concentration of NO at the reactor inlet × 100%. x The concentration of NO at the reactor inlet - the concentration of NO at the reactor outlet) / the concentration of NO at the reactor inlet × 100%. x The concentration of NO at the reactor inlet - the concentration of NO at the reactor outlet) / the concentration of NO at the reactor inlet × 100%. x The concentration of NO at the reactor inlet × 100%.

[0117] The detection results are shown in Table 4.

[0118] Table 4

[0119]

[0120] It can be seen from the content of Tables 1-4 that by using the method described in the present invention, the resource utilization and cross-industry regeneration of waste denitration catalysts can be realized. The prepared catalyst still has excellent denitration performance under the conditions of high water, high sulfur and low temperature, and has excellent N2 selectivity and mechanical strength.

[0121] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A preparation method of a denitration catalyst, characterized in that, The method comprises the following steps: (1) Sequentially subject the deactivated denitrification catalyst to purging, rinsing, bubbling cleaning, ultrasonic cleaning and pickling to obtain an intermediate material; (2) Mix manganese acetate tetrahydrate, polyvinylpyrrolidone, urea and water to obtain a mixed solution A; (3) Mix 1,3,5-benzenetricarboxylic acid, N,N-dimethylformamide, pseudoboehmite, cobalt chromate and water to obtain a mixed solution B; (4) Mix the mixed solution A and the mixed solution B to obtain an impregnating solution; (5) Immerse the intermediate material obtained in step (1) in the impregnating solution obtained in step (4), and then perform solid-liquid separation, drying and calcination; Among them, the cleaning solution used for bubbling cleaning is a nicotinamide aqueous solution; the pickling solution used for pickling contains citric acid and sulfuric acid; The specific process of step (2) includes: mixing manganese acetate tetrahydrate, polyvinylpyrrolidone and water, then adding urea, and then mixing at 40-50 °C for 30-60 min; The specific process of step (3) includes: mixing 1,3,5-benzenetricarboxylic acid, N,N-dimethylformamide and water, then adding pseudoboehmite and cobalt chromate, and then mixing at 70-80 °C for 45-70 min; In step (4), the mixing temperature is 40-50 °C; In step (5), the calcination procedure is: heat up from room temperature to 150 °C in 50-70 min, then heat up from 150 °C to 230 °C in 170-190 min, then heat up from 230 °C to 350 °C in 110-130 min, then heat up from 350 °C to 400 °C in 20-40 min, then heat up from 400 °C to 450 °C in 180-220 min, and then cool down.

2. The method according to claim 1, characterized in that, In step (1), purge with compressed air at 0.3-0.7 Mpa.

3. The method according to claim 1, wherein The concentration of the nicotinamide aqueous solution is 0.5-3 wt%.

4. The method according to claim 1, characterized in that, The conditions for bubbling cleaning include: temperature of 35-40 °C and time of 15-30 min.

5. The method according to any one of claims 1-4, characterized in that, The concentration of citric acid in the pickling solution is 0.5-5 wt%, and the concentration of citric acid is the same as that of sulfuric acid.

6. The method according to claim 1, wherein In step (2), based on the total weight of manganese acetate tetrahydrate, polyvinylpyrrolidone, water and urea, the dosage of manganese acetate tetrahydrate is 4-10 wt%, the dosage of polyvinylpyrrolidone is 0.5-8 wt%, and the dosage of urea is 2-5 wt%.

7. The method according to claim 1, wherein In step (3), based on the total weight of 1,3,5-benzenetricarboxylic acid, N,N-dimethylformamide, water, pseudoboehmite and cobalt chromate, the dosage of 1,3,5-benzenetricarboxylic acid is 15-35 wt%, the dosage of N,N-dimethylformamide is 25-40 wt%, the dosage of pseudoboehmite is 10-15 wt%, and the dosage of cobalt chromate is 3-8 wt%.

8. The method according to claim 1, characterized in that, In step (4), the volume ratio of the mixed solution A to the mixed solution B is 1:0.2-5.

9. The method according to claim 1, 2, 3, 4, 6, 7 or 8, characterized in that In step (5), the impregnation conditions include: temperature of 40-60 °C and time of 60-150 min.

10. The denitrification catalyst obtained by the method according to any one of claims 1-9.

11. Use of the denitration catalyst according to claim 10 in denitrating flue gas in the coking industry.

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