Filter bag integrated supported denitration catalyst and preparation method thereof

Abstract

The invention relates to the technical field of low-temperature NH-SCR denitration catalytic materials and preparation thereof, in particular to a filter bag integrated supported denitration catalyst and a preparation method thereof.The filter bag integrated supported denitration catalyst comprises a modified fiber filter bag and a catalytic material supported on the modified fiber filter bag, and the catalytic material comprises magnesium-aluminum composite oxide and manganese-containing oxide; the content of the magnesium-aluminum composite oxide accounts for 70-90%, the magnesium-aluminum composite oxide is a mixture of a mixed metal oxide and spinel, and the molar ratio of Mg to Al is (2: 1)-(4: 1); the content of the manganese-containing oxide accounts for 10%-30%, and the manganese-containing oxide comprises MnO, MnO and MgMnO; the magnesium-aluminum composite oxide and the manganese-containing oxide are loaded on the surface of the modified fiber filter bag, efficient removal of nitric oxide (NOx) under the low-temperature condition is achieved, meanwhile, the dust removal and catalysis functions are integrated, and the low-temperature catalytic purification device is suitable for low-temperature catalytic purification treatment of nitric oxide in industrial flue gas.

Description

Technical Field

[0001] The present invention relates to the technical field of low-temperature NH3-SCR denitration catalytic materials and preparation thereof, and in particular to a filter bag integrated loaded denitration catalyst and a preparation method thereof. Background Art

[0002] With increasingly stringent global environmental regulations, the efficient removal of nitrogen oxides (NOx) from industrial flue gas has become a core challenge in air pollution control. Among the currently widely used selective catalytic reduction (SCR) technologies, the traditional V2O5-WO3(MoO3) / TiO2 catalyst has stable performance, but its operating temperature range is limited to 300-400°C, and the toxicity of vanadium restricts its further application. The development of low-temperature denitrification catalysts can avoid the high energy consumption of flue gas reheating and has significant energy-saving and carbon-reduction benefits. Although existing manganese-based catalysts have low-temperature activity, they have complex preparation processes. For example, the combustion method requires high-temperature combustion of raw materials, which is highly polluting and dangerous. In addition, their practicality is limited, such as difficulties in large-scale production and poor adaptability to room-temperature applications. In addition, the separation design of traditional denitrification catalysts from filter bags leads to high system pressure loss and high energy consumption, as well as insufficient sulfur and water resistance and poor mechanical stability, making them difficult to adapt to complex industrial conditions.

[0003] In recent years, much research on vanadium-free catalysts has focused on transition metal oxides and rare earth metal oxides, including Ce-, Fe-, Cu-, and Mn-based catalysts. Notably, manganese oxide (MnOx) exhibits excellent redox properties due to its diverse chemical states and abundant lattice defects. It also possesses extremely strong surface acidity, demonstrating good low-temperature activity in the catalytic reduction of NOx, making it a prime candidate for research on novel low-temperature denitrification catalysts. MgAlOx mixed oxides derived from MgAl-LDH have long attracted significant attention for NOx adsorption. MgAlOx composite oxides offer advantages such as large specific surface area, controllable acid-base properties, and enhanced thermal stability after high-temperature calcination, making them a potential support material for NH3-SCR catalysts. However, MgAlOx as an SCR catalyst support has rarely been studied in previous studies.

[0004] An article titled "Preparation and Performance Study of Low-Temperature SCR DeNOx Catalysts" published in Chemical Engineering Management (Volume 33, 2024, Pages 150-153) publicly reported a successful preparation of a modified lotus leaf carbon carrier by sodium cyanide pretreatment and 800°C calcination process, and the synthesis of a 10% Mn / LBC catalyst by ultrasonic-assisted impregnation.

[0005] According to the search, a Chinese invention patent with an application date of 2020-08-31 and application number CN202010901202.9 discloses a method for preparing an NH3-SCR low-temperature denitrification catalyst. The preparation method is to dissolve manganese nitrate, cerium nitrate and fuel in deionized water, add TiO2 to the mixed solution and stir evenly, place the resulting product in a preheated combustion chamber and burn it rapidly, and then continue to calcine for a certain time to obtain a Mn-Ce-O / TiO2 denitrification catalyst.

[0006] The aforementioned patent optimizes a manganese-based denitrification catalyst. The catalyst produced by this method exhibits excellent water and sulfur resistance in low-temperature denitrification reactions, which to some extent solves the problems associated with denitrification catalysts. However, some defects still exist. It fails to fully consider practicality and ignores the limitations of the process flow. For example, the preparation method is complex and dangerous, and the raw materials need to be burned during the preparation process, which causes significant environmental pollution. These limitations restrict the possibility of large-scale production and also pose difficulties in practical application at room temperature. Therefore, in order to promote the development of efficient denitrification catalysts, it is necessary to further optimize the interaction between the catalytically active material and the support, and to increase the concentration of Mn4+ and chemically adsorbed oxygen species. This is a major challenge currently faced.

[0007] Therefore, effectively solving the synergistic problem of active site construction and filter bag loading and developing new denitrification technologies that are efficient, economical and adaptable to complex working conditions have become research hotspots. Summary of the Invention

[0008] In order to solve some of the problems existing in the above-mentioned prior art, the present invention provides a filter bag integrated loaded denitrification catalyst, which realizes the efficient removal of nitrogen oxides (NOx) under low temperature conditions by loading magnesium-aluminum composite oxide and manganese-containing oxide on the surface of modified fiber filter bags. At the same time, it integrates dust removal and catalytic functions, and is suitable for low-temperature catalytic purification treatment of nitrogen oxides in industrial flue gas.

[0009] To achieve the above-mentioned purpose, the present invention provides a filter bag integrated loaded denitrification catalyst, comprising a modified fiber filter bag and a catalytic material loaded on the modified fiber filter bag, wherein the catalytic material comprises a magnesium-aluminum composite oxide and a manganese-containing oxide; the content of the magnesium-aluminum composite oxide is 70 to 90%, and the magnesium-aluminum composite oxide is a mixture of mixed metal oxides and spinel, wherein the molar ratio of Mg to Al is 2:1 to 4:1; the content of the manganese-containing oxide is 10 to 30%, and the manganese-containing oxide includes MnO2, Mn3O4 and MgMn2O4.

[0010] As a further improvement of the present invention, in order to regulate the crystal form of the carrier by the calcination temperature and adapt to the catalytic requirements under different working conditions; the magnesium-aluminum composite oxide is prepared by calcining a layered double hydroxide at 500-850°C for 3-5 hours, and the raw materials for preparing the layered double hydroxide include Mg(NO3)2, Al(NO3)3 and urea; the amount of Mg(NO3)2 is 0.2-0.4 mol, the amount of Al(NO3)3 is 0.1 mol, and the amount of urea is 2.1-3.3 mol.

[0011] As a further improvement of the present invention, in order to make the manganese-containing oxide uniformly dispersed on the surface of the magnesium-aluminum composite oxide and avoid the reduction of active sites caused by agglomeration; the catalytic material also includes a manganese-containing salt, and the manganese-containing salt is manganese acetate, manganese nitrate or manganese sulfate; the manganese-containing salt is prepared into a manganese-containing salt solution according to mass percentage, and the manganese-containing oxide is loaded on the magnesium-aluminum composite oxide by impregnation with the manganese-containing salt solution.

[0012] As a further improvement of the present invention, in order to provide a rapid diffusion channel, reduce mass transfer resistance, and improve reaction efficiency; at the same time, effectively intercept flue gas particulate matter and maintain long-term stable catalytic activity; the catalytic material has a multi-level pore structure, and the multi-level pore structure is formed by the collapse of the layered structure after high-temperature calcination of the layered double hydroxide of magnesium-aluminum composite oxide.

[0013] One beneficial effect of the present invention is that: through the integrated design of structure and function, the catalytic material with MgAlOx as the carrier and MnOx as the active component is uniformly loaded on the modified fiber filter bag to form a catalytic and filtration integrated functional material with a multi-level pore structure, breaking through the limitations of traditional separation design; the carrier is obtained by high-temperature calcination of layered double hydroxide, and has a large specific surface area and strong adsorption capacity. The high dispersion of the active components provides efficient reaction adsorption sites, so that the catalyst can achieve high NO conversion rate and N2 selectivity in the low temperature range of 100-300°C, and has strong sulfur and water resistance, which improves the accessibility of catalytic reaction sites; the composite structure of the catalyst and the filter bag fiber reduces the flue gas flow resistance, and the system pressure loss is significantly reduced compared with the traditional discrete design, with the advantages of high mechanical stability and easy modular replacement; at the same time, the particle interception function of the filter bag can avoid catalyst poisoning and extend the service life.

[0014] The present invention also provides a method for preparing a filter bag integrated supported denitration catalyst, comprising the following steps:

[0015] Step 1: dissolving 0.2-0.4 mol Mg(NO3)2, 0.1 mol Al(NO3)3, and 2.1-3.3 mol urea in deionized water, and subjecting to dynamic crystallization at 95-100°C for 8-10 hours, followed by static aging at the same temperature for 10-12 hours;

[0016] Step 2: Filter the precipitate, wash it with deionized water 3 to 4 times, and dry it at 100 to 110° C. for 10 to 12 hours to obtain a layered double hydroxide precursor;

[0017] Step 3: calcining the layered double hydroxide precursor at 500-850° C. for 3-5 hours to obtain a magnesium-aluminum composite oxide solid, then ball-milling the solid into a powder, and sieving the powder within the range of 200-300 mesh to use as a catalyst support;

[0018] Step 4: Prepare a manganese salt solution according to mass percentage, add magnesium-aluminum composite oxide carrier powder, stir thoroughly, evaporate to dryness, and calcine at 500-850°C for 3-5 hours; then ball-mill and sieve the calcined solid material to obtain catalytic material particles with a particle size of 100-200 mesh;

[0019] Step 5: Prepare a solution containing a dispersant, add catalytic material particles, stir for 8 to 10 hours to uniformly disperse them, and impregnate the filter bag with the solution system to obtain a filter bag integrated supported denitrification catalyst;

[0020] Step 6: Perform denitrification treatment on the filter bag. Prepare a solution containing a dispersant again, add the catalyst prepared above, stir for 8 to 10 hours to evenly disperse it in the solution system, and impregnate the filter bag with the obtained solution system; then pass the high-temperature flue gas through a waste heat recovery or cooling device to adjust it to a suitable catalyst temperature range of 100 to 300°C; then spray ammonia water or pyrolyzed urea solution upstream of the filter bag area to ensure uniform mixing with the flue gas; the flue gas enters the filter bag area, and particulate matter is intercepted by the filter bag; at the same time, NOx and NH3 undergo SCR reaction on the surface of the supported catalyst.

[0021] As a further improvement of the present invention, in order to inhibit particle agglomeration through steric hindrance effect and electrostatic repulsion, the catalytic material forms a stable colloidal dispersion system in the solution, and the interface compatibility and adaptability are improved; the dispersant in step five includes citric acid, triethanolamine, 50% sodium polyacrylate + 50% citric acid, carboxymethyl cellulose, polyvinyl alcohol, and ethylenediaminetetraacetic acid.

[0022] As a further improvement of the present invention, in order to form a stable dispersion system, avoid secondary pollution caused by excessive NH3 or a decrease in denitrification efficiency caused by insufficient NH3, and reduce energy consumption; the amount of the dispersant in step six is ​​0.5-5% of the weight of the catalyst, and the injection amount of the ammonia water or hot urea solution is determined according to the stoichiometric ratio based on the concentration of NOx in the flue gas.

[0023] As a further improvement of the present invention, in order to break through the high temperature limitation of traditional catalysts and adapt to the temperature range after industrial flue gas waste heat recovery; the catalyst is used for low-temperature NH3-SCR denitrification reaction, and the reaction temperature is 100-300°C.

[0024] Another beneficial effect of the present invention is that the preparation method adopts a urea hydrolysis-roasting-impregnation process, which does not require toxic raw materials, is simple in process, low in cost, pollution-free, and easy to implement industrially; the synergistic effect of the multi-level pore structure and the carrier-active component not only improves the catalytic efficiency, but also achieves the synergistic enhancement of dust capture and NOx degradation, providing an efficient and economical solution for industrial flue gas purification.

[0025] When the present invention is working, first, 0.2-0.4 mol Mg(NO3)21, 0.1 mol Al(NO3)32, and 2.1-3.3 mol urea are dissolved in deionized water, and dynamically crystallized at 95 to 100°C for 8 to 10 hours to ensure complete decomposition of the urea; static aging is carried out at the same temperature for 10 to 12 hours, the resulting precipitate is filtered, washed with deionized water 3 to 4 times, and then the washed precipitate is dried at 100 to 110°C for 10 to 12 hours to obtain a layered double hydroxide precursor; then it is calcined at 500 to 850°C for 3 to 5 hours to obtain a magnesium-aluminum composite oxide solid, the solid is ball-milled into powder, and the powder in the range of 200 to 300 mesh is taken as a catalyst carrier for standby use, a manganese salt solution is prepared according to mass percentage, and a certain amount of the above-mentioned magnesium-aluminum composite oxide is added. The carrier powder is fully stirred and evaporated, and then calcined at 500 to 850°C for 3 to 5 hours. The calcined solid is then ball-milled and sieved to obtain particles with a particle size of 100 to 200 mesh, which is the required catalyst. A solution containing a dispersant is prepared, and the prepared catalyst is added and stirred for 8 to 10 hours to uniformly disperse it in the solution system. The obtained solution system is impregnated with a filter bag. The high-temperature flue gas is first passed through a waste heat recovery or cooling device to adjust it to a temperature range suitable for the catalyst. Ammonia water or pyrolyzed urea solution is sprayed upstream of the filter bag area to ensure uniform mixing with the flue gas. The flue gas enters the filter bag area, and the particulate matter is intercepted by the filter bag. At the same time, NOx and NH3 undergo SCR reaction on the surface of the loaded catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings:

[0027] Figure 1 This is the X-ray diffraction (XRD) pattern of the magnesium-aluminum composite oxide precursor in Example 1 of the present invention.

[0028] Figure 2 This is the X-ray diffraction (XRD) pattern of the catalyst support powder calcined at 500° C. in Example 1 of the present invention.

[0029] Figure 3 This is the X-ray diffraction (XRD) pattern of the catalyst support powder calcined at 850° C. in Example 1 of the present invention.

[0030] Figure 4 This is the X-ray diffraction (XRD) pattern of the catalyst powder calcined at 500° C. in Example 1 of the present invention.

[0031] Figure 5 This is the X-ray diffraction (XRD) pattern of the catalyst powder calcined at 850° C. in Example 1 of the present invention.

[0032] Figure 6 This is a comparison diagram of the filter material before and after impregnation with the catalyst in Example 1 of the present invention. DETAILED DESCRIPTION

[0033] In order to make people in this technical field better understand the technical solution in this application, Figure 1-6 The present invention is further described. The following examples are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0034] A filter bag integrated supported denitrification catalyst, comprising a modified fiber filter bag and a catalytic material supported on the modified fiber filter bag, wherein the catalytic material comprises a magnesium-aluminum composite oxide and a manganese-containing oxide; the content of the magnesium-aluminum composite oxide is 70-90%, and the magnesium-aluminum composite oxide is a mixture of mixed metal oxides and spinel, wherein the molar ratio of Mg to Al is 2:1-4:1; the content of the manganese-containing oxide is 10-30%, and the manganese-containing oxide comprises MnO2, Mn3O4 and MgMn2O4; the magnesium-aluminum composite oxide is prepared by calcining a layered double hydroxide at 500-850°C for 3-5 hours, and the layered double hydroxide The preparation raw materials include Mg(NO3)2, Al(NO3)3 and urea; the amount of Mg(NO3)2 is 0.2-0.4 mol, the amount of Al(NO3)3 is 0.1 mol, and the amount of urea is 2.1-3.3 mol; the catalytic material also includes a manganese-containing salt, which is manganese acetate, manganese nitrate or manganese sulfate; the manganese-containing salt is prepared into a manganese-containing salt solution according to mass percentage, and the manganese-containing oxide is loaded on the magnesium-aluminum composite oxide by impregnation with the manganese-containing salt solution; the catalytic material has a multi-level pore structure, and the multi-level pore structure is formed by the collapse of the layered structure of the layered double hydroxide of the magnesium-aluminum composite oxide after high-temperature calcination.

[0035] A method for preparing a filter bag integrated supported denitration catalyst comprises the following steps:

[0036] Step 1: dissolving 0.2-0.4 mol Mg(NO3)2, 0.1 mol Al(NO3)3, and 2.1-3.3 mol urea in deionized water, and subjecting to dynamic crystallization at 95-100°C for 8-10 hours, followed by static aging at the same temperature for 10-12 hours;

[0037] Step 2: Filter the precipitate, wash it with deionized water 3 to 4 times, and dry it at 100 to 110° C. for 10 to 12 hours to obtain a layered double hydroxide precursor;

[0038] Step 3: calcining the layered double hydroxide precursor at 500-850° C. for 3-5 hours to obtain a magnesium-aluminum composite oxide solid, then ball-milling the solid into a powder, and sieving the powder within the range of 200-300 mesh to use as a catalyst support;

[0039] Step 4: Prepare a manganese salt solution according to mass percentage, add magnesium-aluminum composite oxide carrier powder, stir thoroughly, evaporate to dryness, and calcine at 500-850°C for 3-5 hours; then ball-mill and sieve the calcined solid material to obtain catalytic material particles with a particle size of 100-200 mesh;

[0040] Step 5: Prepare a solution containing a dispersant, add catalytic material particles, stir for 8 to 10 hours to uniformly disperse them, and impregnate the filter bag with the solution system to obtain a filter bag integrated supported denitrification catalyst;

[0041] Step 6: Carry out denitrification treatment in the filter bag. Prepare a solution containing a dispersant again, add the catalyst prepared above, stir for 8 to 10 hours to evenly disperse it in the solution system, and impregnate the filter bag with the obtained solution system; then pass the high-temperature flue gas through a waste heat recovery or cooling device to adjust it to a suitable temperature range of 100 to 300°C for the catalyst; then spray ammonia water or pyrolyzed urea solution upstream of the filter bag area to ensure uniform mixing with the flue gas; the flue gas enters the filter bag area, and the particulate matter is intercepted by the filter bag; at the same time, NOx and NH3 undergoes an SCR reaction on the surface of the supported catalyst; the dispersant in step five includes citric acid, triethanolamine, 50% sodium polyacrylate + 50% citric acid, carboxymethyl cellulose, polyvinyl alcohol, and ethylenediaminetetraacetic acid; the amount of the dispersant in step six is ​​0.5-5% of the weight of the catalyst, and the injection amount of the ammonia water or hot urea solution is determined according to the stoichiometric ratio based on the concentration of NOx in the flue gas; the catalyst is used for a low-temperature NH3-SCR denitrification reaction at a reaction temperature of 100-300°C.

[0042] When the present invention is working, first, 0.2-0.4 mol Mg(NO3)21, 0.1 mol Al(NO3)32, and 2.1-3.3 mol urea are dissolved in deionized water, and dynamically crystallized at 95 to 100°C for 8 to 10 hours to ensure complete decomposition of the urea; static aging is carried out at the same temperature for 10 to 12 hours, the resulting precipitate is filtered, washed with deionized water 3 to 4 times, and then the washed precipitate is dried at 100 to 110°C for 10 to 12 hours to obtain a layered double hydroxide precursor; then it is calcined at 500 to 850°C for 3 to 5 hours to obtain a magnesium-aluminum composite oxide solid, the solid is ball-milled into powder, and the powder in the range of 200 to 300 mesh is taken as a catalyst carrier for standby use, a manganese salt solution is prepared according to mass percentage, and a certain amount of the above-mentioned magnesium-aluminum composite oxide is added. The carrier powder is fully stirred and evaporated, and then calcined at 500 to 850°C for 3 to 5 hours. The calcined solid is then ball-milled and sieved to obtain particles with a particle size of 100 to 200 mesh, which is the required catalyst. A solution containing a dispersant is prepared, and the prepared catalyst is added and stirred for 8 to 10 hours to uniformly disperse it in the solution system. The obtained solution system is impregnated with a filter bag. The high-temperature flue gas is first passed through a waste heat recovery or cooling device to adjust it to a temperature range suitable for the catalyst. Ammonia water or pyrolyzed urea solution is sprayed upstream of the filter bag area to ensure uniform mixing with the flue gas. The flue gas enters the filter bag area, and the particulate matter is intercepted by the filter bag. At the same time, NOx and NH3 undergo SCR reaction on the surface of the loaded catalyst.

[0043] Example 1:

[0044] 0.2 mol Mg(NO3)2, 0.1 mol Al(NO3)3 and 2.1 mol urea are dissolved in deionized water and dynamically crystallized at 95-100°C for 8-10 hours to ensure complete decomposition of urea, and statically aged at the same temperature for 10-12 hours; then the precipitate is filtered and washed with deionized water for 3-4 times, and the washed precipitate is dried at 100-110°C for 10-12 hours to obtain a magnesium-aluminum composite oxide precursor, and the magnesium-aluminum composite oxide precursor is calcined at 500°C for 3 hours to obtain a magnesium-aluminum composite oxide solid, and the solid is ground into powder and the powder in the range of 200-300 mesh is taken as a catalyst carrier and set aside.

[0045] A manganese nitrate solution was prepared at a ratio of 20% of the total weight of the catalyst, and then a certain amount of the above-mentioned magnesium-aluminum composite oxide carrier powder was added. The solution was thoroughly stirred and evaporated to dryness. The solution was then calcined at 500°C for 5 hours. The calcined solid was then crushed and sieved to obtain particles with a particle size of 100-200 mesh, which was the desired catalyst.

[0046] Then, a solution containing a dispersant is prepared, and the prepared catalyst is added and stirred for 8 to 10 hours to uniformly disperse it in the solution system. The obtained solution system is impregnated into a filter bag and dried to obtain a filter material integrated supported catalyst.

[0047] Example 2:

[0048] First, a powder carrier was prepared in exactly the same manner as in Example 1 above. Then, a manganese nitrate solution was prepared at a ratio of 20% of the total weight of the catalyst. A certain amount of the magnesium-aluminum composite oxide carrier powder was added, stirred thoroughly, and evaporated to dryness. The mixture was then calcined at 850°C for 5 hours. The calcined solid was crushed and sieved to obtain particles with a particle size of 100 to 200 mesh, which was the desired catalyst. A solution containing a dispersant was then prepared, the prepared catalyst was added, and stirred for 8 to 10 hours to uniformly disperse it in the solution system. The obtained solution system was then impregnated into a filter bag and dried to obtain a filter-integrated supported catalyst.

[0049] Example 3:

[0050] 0.3 mol Mg(NO3)2, 0.1 mol Al(NO3)3 and 2.7 mol urea are dissolved in deionized water, and dynamically crystallized at 95-100°C for 8-10 hours to ensure complete decomposition of urea, and statically aged at the same temperature for 10-12 hours; the precipitate is filtered, washed with deionized water 3-4 times, and then the washed precipitate is dried at 100-110°C for 10-12 hours to obtain a magnesium-aluminum composite oxide precursor, and the magnesium-aluminum composite oxide precursor is calcined at 500°C for 3 hours to obtain a magnesium-aluminum composite oxide solid, and the solid is ground into powder and the powder in the range of 200-300 mesh is taken as a catalyst carrier and set aside.

[0051] A manganese nitrate solution was prepared at a ratio of 20% of the total weight of the catalyst, and then a certain amount of the above-mentioned magnesium-aluminum composite oxide carrier powder was added. The solution was thoroughly stirred and evaporated to dryness. The solution was then calcined at 500°C for 5 hours. The calcined solid was then crushed and sieved to obtain particles with a particle size of 100-200 mesh, which was the desired catalyst.

[0052] Then, a solution containing a dispersant is prepared, and the prepared catalyst is added and stirred for 8 to 10 hours to uniformly disperse it in the solution system. The obtained solution system is impregnated into a filter bag and dried to obtain a filter material integrated supported catalyst.

[0053] Example 4:

[0054] First, a powder carrier was prepared in exactly the same manner as in Example 3 above. Then, a manganese nitrate solution was prepared at a ratio of 20% of the total weight of the catalyst. A certain amount of the magnesium-aluminum composite oxide carrier powder was added, stirred thoroughly, and evaporated to dryness. The mixture was then calcined at 850°C for 5 hours. The calcined solid was crushed and sieved to obtain particles with a particle size of 100 to 200 mesh, which was the desired catalyst. A solution containing a dispersant was then prepared, the prepared catalyst was added, and stirred for 8 to 10 hours to uniformly disperse it in the solution system. The obtained solution system was then impregnated into a filter bag and dried to obtain a filter-integrated supported catalyst.

[0055] Embodiment 5:

[0056] 0.4 mol Mg(NO3)2, 0.1 mol Al(NO3)3 and 3.3 mol urea are dissolved in deionized water, and dynamically crystallized at 95-100°C for 8-10 hours to ensure complete decomposition of urea, and statically aged at the same temperature for 10-12 hours; the precipitate is filtered, washed with deionized water 3-4 times, and then the washed precipitate is dried at 100-110°C for 10-12 hours to obtain a magnesium-aluminum composite oxide precursor, and the magnesium-aluminum composite oxide precursor is calcined at 500°C for 3 hours to obtain a magnesium-aluminum composite oxide solid, and the solid is ground into powder and the powder in the range of 200-300 mesh is taken as a catalyst carrier and set aside.

[0057] A manganese nitrate solution was prepared at a ratio of 20% of the total weight of the catalyst, and then a certain amount of the above-mentioned magnesium-aluminum composite oxide carrier powder was added. The solution was thoroughly stirred and evaporated to dryness. The solution was then calcined at 500°C for 5 hours. The calcined solid was then crushed and sieved to obtain particles with a particle size of 100-200 mesh, which was the desired catalyst.

[0058] Then, a solution containing a dispersant is prepared, and the prepared catalyst is added and stirred for 8 to 10 hours to uniformly disperse it in the solution system. The obtained solution system is impregnated into a filter bag and dried to obtain a filter material integrated supported catalyst.

[0059] Example 6:

[0060] First, a powder carrier was prepared in exactly the same manner as in Example 5 above. Then, a manganese nitrate solution was prepared at 20% of the total weight of the catalyst. A certain amount of the magnesium-aluminum composite oxide carrier powder was added, stirred thoroughly, and evaporated to dryness. The mixture was then calcined at 850°C for 5 hours. The calcined solid was crushed and sieved to obtain particles with a particle size of 100 to 200 mesh, which was the desired catalyst. A solution containing a dispersant was then prepared, the prepared catalyst was added, and stirred for 8 to 10 hours to uniformly disperse it in the solution system. The obtained solution system was then impregnated into a filter bag and dried to obtain a filter-integrated supported catalyst.

[0061] The catalyst of Example 1 of the present invention was evaluated in a microreactor at a reaction temperature of 100-250°C in an atmosphere of 500 ppm NO, 500 ppm NH3, 5% O2, and 5% H2O, with 50 ppm SO2 and N2 as the balance gas, and a total flow rate of 200 mL min -1 The NOx concentration in the outflowing gas was analyzed by gas chromatography.

[0062]

[0063]

[0064]

[0065] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and modifications to some of the technical features therein according to the disclosed technical content without creative labor, and these substitutions and modifications are all within the protection scope of the present invention.

Claims

1. A filter bag integrated supported denitrification catalyst, characterized by: It includes a modified fiber filter bag and a catalytic material loaded on the modified fiber filter bag, wherein the catalytic material includes a magnesium-aluminum composite oxide and a manganese-containing oxide; the content of the magnesium-aluminum composite oxide is 70-90%, and the magnesium-aluminum composite oxide is a mixture of mixed metal oxides and spinel, wherein the molar ratio of Mg to Al is 2:1-4:1; the content of the manganese-containing oxide is 10-30%, and the manganese-containing oxide includes MnO2, Mn3O4 and MgMn2O4.

2. The filter bag integrated supported denitration catalyst according to claim 1, characterized in that: The magnesium-aluminum composite oxide is prepared by calcining a layered double hydroxide at 500-850°C for 3-5 hours. The raw materials for preparing the layered double hydroxide include Mg(NO3)2, Al(NO3)3 and urea; the amount of Mg(NO3)2 is 0.2-0.4 mol, the amount of Al(NO3)3 is 0.1 mol, and the amount of urea is 2.1-3.3 mol.

3. The filter bag integrated supported denitration catalyst according to claim 1, characterized in that: The catalytic material also includes a manganese salt, which is manganese acetate, manganese nitrate or manganese sulfate; the manganese salt is prepared into a manganese salt solution according to mass percentage, and the manganese oxide is loaded on the magnesium-aluminum composite oxide by impregnation with the manganese salt solution.

4. The filter bag integrated supported denitration catalyst according to claim 1, characterized in that: The catalytic material has a multi-level pore structure, and the multi-level pore structure is formed by the collapse of the layered structure after the layered double hydroxide of the magnesium-aluminum composite oxide is calcined at high temperature.

5. A method for preparing a filter bag integrated supported denitration catalyst, characterized in that: The following steps are involved: Step 1: dissolving 0.2-0.4 mol Mg(NO3)2, 0.1 mol Al(NO3)3, and 2.1-3.3 mol urea in deionized water, and subjecting to dynamic crystallization at 95-100°C for 8-10 hours, followed by static aging at the same temperature for 10-12 hours; Step 2: Filter the precipitate, wash it with deionized water 3 to 4 times, and dry it at 100 to 110° C. for 10 to 12 hours to obtain a layered double hydroxide precursor; Step 3: calcining the layered double hydroxide precursor at 500-850° C. for 3-5 hours to obtain a magnesium-aluminum composite oxide solid, then ball-milling the solid into a powder, and sieving the powder within the range of 200-300 mesh to use as a catalyst support; Step 4: Prepare a manganese salt solution according to mass percentage, add magnesium-aluminum composite oxide carrier powder, stir thoroughly, evaporate to dryness, and calcine at 500-850°C for 3-5 hours; then ball-mill and sieve the calcined solid material to obtain catalytic material particles with a particle size of 100-200 mesh; Step 5: Prepare a solution containing a dispersant, add catalytic material particles, stir for 8 to 10 hours to uniformly disperse them, and impregnate the filter bag with the solution system to obtain a filter bag integrated supported denitrification catalyst; Step 6: Perform denitrification treatment on the filter bag. Prepare a solution containing a dispersant again, add the catalyst prepared above, and stir for 8 to 10 hours to evenly disperse it in the solution system. Then, impregnate the filter bag with the obtained solution system. Then, pass the high-temperature flue gas through a waste heat recovery or cooling device to adjust it to the catalyst's suitable temperature range of 100 to 300°C. Then, spray ammonia water or pyrolyzed urea solution upstream of the filter bag area to ensure uniform mixing with the flue gas. The flue gas enters the filter bag area and the particulate matter is intercepted by the filter bag; at the same time, NOx and NH3 undergo SCR reaction on the surface of the supported catalyst.

6. The method for preparing the filter bag integrated supported denitration catalyst according to claim 5, characterized in that: The dispersant in step 5 includes citric acid, triethanolamine, 50% sodium polyacrylate + 50% citric acid, carboxymethyl cellulose, polyvinyl alcohol, and ethylenediaminetetraacetic acid.

7. The method for preparing the filter bag integrated supported denitration catalyst according to claim 5, characterized in that: The amount of the dispersant in step six is ​​0.5-5% of the weight of the catalyst, and the amount of the ammonia water or hot urea solution sprayed is determined according to the stoichiometric ratio based on the concentration of NOx in the flue gas.

8. The filter bag integrated supported denitration catalyst according to claim 5, characterized in that: The catalyst is used for low-temperature NH3-SCR denitration reaction, and the reaction temperature is 100-300°C.

Images