A catalytic flue gas desulfurization agent and its preparation method

Abstract

This invention discloses a catalytic flue gas desulfurizing agent and its preparation method, belonging to the field of flue gas desulfurization technology. Specific steps include: mixing a carrier with a glucose aqueous solution, molding the mixture, and then subjecting it to drying and calcination. The carrier is then impregnated with an active metal impregnation solution, followed by drying and calcination to finally obtain the catalytic flue gas desulfurizing agent. The carrier is prepared by forming particles in a granulation container using a specific doping composition and a curing agent, followed by calcination. Compared with existing technologies, the catalyst of this invention maintains a high specific surface area and an open mesoporous structure at high temperatures, enhancing mass transfer efficiency and mechanical strength, significantly improving the dispersibility of active components and the diffusion efficiency of reactants, achieving excellent desulfurization effects, and showing promising industrial application prospects.

Description

Technical Field

[0001] This invention relates to the field of flue gas desulfurization technology, and in particular to a catalytic flue gas desulfurization agent and its preparation method. Background Technology

[0002] Flue gas desulfurization (FGD) technology is a key means of reducing sulfur dioxide (SO2) and sulfur trioxide (SO3) emissions, and is widely used in industries such as petroleum refining and coal-fired power generation. The regeneration flue gas from catalytic cracking (FCC) units contains a large amount of sulfur oxides (SO3). x Of which SO2 accounts for more than 90%, it also contains a certain proportion of SO3 (usually accounting for SO2). x The total amount is 5%-10%, and in extreme cases it can reach over 30%. Wet desulfurization technologies (such as sodium alkali method, ammonia method, etc.) can effectively remove SO2 from flue gas, but the removal efficiency for SO3 is limited (usually only about 70%). The unremoved SO3 combines with water vapor in the flue gas to form submicron-sized sulfuric acid mist, which, after being emitted into the atmosphere, produces Rayleigh scattering of sunlight, forming a visible "blue plume".

[0003] Blue plumes not only cause visual pollution but also bring a series of environmental and equipment problems: sulfuric acid mist settles near chimneys, harming human health and causing burning sensations in the eyes, throat, and other mucous membranes; the acid mist reacts with metal particles in the air to form sulfates, exacerbating smog pollution; at the same time, the presence of SO3 significantly increases the acid dew point temperature of flue gas, increasing the corrosion risk of equipment such as flues and chimneys. Studies have shown that blue plumes may appear when the concentration of sulfuric acid mist aerosol in flue gas reaches 5-10 μg / g, and the probability of occurrence increases significantly when the concentration reaches 10-20 μg / g.

[0004] Currently, most commercially available catalytic flue gas desulfurization agents are based on alumina supports, with different metal elements doped to improve catalyst activity and stability. For example, Chinese patent application CN109420505A discloses a flue gas desulfurization catalyst and its preparation method. This catalyst uses carbon-containing alumina as a support and is doped with active metals such as Co, Ni, Mo, and W, exhibiting large pore volume and specific surface area, making it suitable for flue gas desulfurization. However, this catalyst is prone to lattice rearrangement and α-phase transformation under high-temperature conditions, leading to a decrease in specific surface area and poor dispersion of active components, thus affecting desulfurization performance. Another example is Chinese patent application CN106732631A, which discloses a highly active flue gas desulfurization catalyst and its preparation method. This catalyst uses hydrothermal carbonization to form a gradient distribution of carbon on a silicon-containing alumina support, improving the catalyst's desulfurization activity and mechanical strength. However, this method has a complex preparation process, high cost, and the catalyst's stability still needs improvement during long-term operation.

[0005] While existing technologies using sulfur transfer additives can reduce SO3 emissions to some extent, they still have significant shortcomings: conventional additives have excessively strong oxidizing power, oxidizing too much SO2 to SO3 and increasing the load on downstream treatment processes; the adsorption materials have limited capacity, resulting in insufficient adsorption efficiency for SO3; and unreasonable pore size and volume structures lead to sulfate deposition and pore blockage, affecting the long-term effectiveness of the additives. Therefore, developing a novel flue gas desulfurizing agent capable of efficiently removing SO3 and eliminating blue plumes is of great significance for environmental protection and equipment safety. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention aims to provide a catalytic flue gas desulfurizer with higher specific surface area, better thermal stability, and better dispersion of active components, as well as a method for its preparation.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] A method for preparing a catalytic flue gas desulfurization agent is as follows:

[0009] Take the carrier, add glucose aqueous solution, let it stand at room temperature to air dry, and then stir to form agglomerated particles; add mixed solution, binder and pore-forming agent, knead until good plasticity is achieved, and then prepare microspheres; dry at room temperature overnight, then dry again, place in a high-temperature furnace and heat to a certain temperature and hold, then introduce nitrogen gas to continue heating and maintain the temperature, and cool naturally to obtain a carbon-containing alumina carrier; impregnate the carbon-containing alumina carrier with an active metal impregnation solution, filter off the excess solution, dry, then calcine in nitrogen gas, and cool to room temperature to obtain a catalytic flue gas desulfurization agent. 0-180um, 80um spheres

[0010] The carrier is prepared as follows:

[0011] S1. Add the doping composition to water to prepare a dopant solution, add aluminum isopropoxide to hot water to obtain an aluminum salt solution, add the dopant solution to the aluminum salt solution and mix well, add nitric acid aqueous solution and reflux overnight, then add nitric acid aqueous solution dropwise to obtain a pretreated product;

[0012] S2. The pretreated material is granulated in a granulation container. The granulation container is divided into a hot paraffin oil layer and a curing agent aqueous solution layer from top to bottom. After the pretreated material droplets pass through the hot paraffin oil layer, they are cured in the curing agent aqueous solution layer. The wet particles are collected, washed and dried. The dried particles are calcined in air, heated to the target temperature and kept at that temperature to obtain the carrier.

[0013] Preferably, the preparation method of the catalytic flue gas desulfurization agent is as follows:

[0014] Take 100-150 parts of carrier and add 150-250 parts of 20-45wt% glucose aqueous solution. Let the mixture stand at room temperature and air dry. Stir to form non-sticky granules. Then add 50-70 parts of the mixed solution, 1-3 parts of binder, and 4-8 parts of pore-forming agent. The mixed solution is an aqueous solution containing 0.2-0.4wt% sulfuric acid and 3-5wt% nitric acid. After thorough kneading to form a material with good plasticity, prepare microspheres. Dry overnight at room temperature and then at 90-120℃. Dry for 3-8 hours, then place the dried sample in a high-temperature furnace, heat to 400-500℃ and hold for 1-5 hours. Then, introduce nitrogen and continue heating to 600-700℃, and maintain the temperature for 1-5 hours. Allow it to cool naturally to obtain a carbon-containing alumina carrier. Impregnate the carbon-containing alumina carrier with an active metal impregnation solution for 2-6 hours, filter out excess solution, and then dry at 90-120℃ for 3-8 hours. Finally, calcine it in nitrogen at 600-650℃ for 4-6 hours and cool to room temperature to obtain the catalytic flue gas desulfurization agent.

[0015] The binder is at least one of carboxymethyl cellulose and guar gum powder.

[0016] The pore-forming agent is polyethylene glycol.

[0017] The active metal impregnation solution contains one or more elements selected from Co, Ni, Mo, W, Fe, Cu, Mn, Zn, Pt, and Ce.

[0018] Preferably, the active metal impregnation solution contains Mo and Mn elements.

[0019] Preferably, the carrier is prepared by the following method, in parts by weight:

[0020] S1. Add 4-8 parts of the doping composition to 250-350 parts of water to prepare a doping solution; add 400-500 parts of aluminum isopropoxide to 800-1200 parts of water at 80-90℃ to obtain an aluminum salt solution; add the doping solution to the aluminum salt solution and mix well, then add 120-160 parts of 0.5-2 mol / L nitric acid aqueous solution, reflux at 90-100℃ overnight, and then add an additional 50-90 parts of 0.5-2 mol / L nitric acid aqueous solution to obtain a pretreated product;

[0021] S2. Granulate the pretreated material in a granulation container, which has two layers from top to bottom: an upper layer of paraffin oil at 75-85℃ and a lower layer of 8-12wt% curing agent aqueous solution. The volume ratio of the two layers is 2-6:1. The pretreated material is injected dropwise into the granulation container. The droplets first pass through the upper hot paraffin oil layer to form droplets, and then fall into the lower solution to solidify for 60-120 minutes. Collect the wet particles and wash them sequentially with cold water, hot water at 40-70℃, and anhydrous ethanol. Dry them at 30-50℃ for 12-48 hours. Calcinate the dried particles in air, raising the temperature to the target temperature of 750-850℃ at a heating rate of 1-3℃ / min and holding for 1-5 hours. Then raise the temperature to 1100-1300℃ and hold for 1-5 hours to obtain the carrier.

[0022] The doping composition is at least one of ZrOCl2•8H2O, Ce(NO3)3•6H2O, Mg(NO3)2•6H2O, La(NO3)3•6H2O, Y(NO3)3•6H2O, and ethyl silicate.

[0023] Preferably, the doped composition consists of La(NO3)3•6H2O and ethyl silicate.

[0024] The curing agent is at least one of urea and ammonium carbonate.

[0025] The roles of each substance in the preparation of the catalytic flue gas desulfurization agent are as follows:

[0026] La(NO3)3·6H2O serves as a dopant, stabilizing the alumina lattice, suppressing high-temperature phase transitions, and improving the thermal stability of the carrier.

[0027] Ethyl silicate serves as a silicon source, generating SiO2, which enhances the pore structure and mechanical strength of the support.

[0028] Water is used as a solvent to dissolve the dopant and aluminum isopropoxide, promoting uniform mixing.

[0029] Aluminum isopropoxide, as an alumina precursor, forms an alumina carrier framework through hydrolysis and calcination.

[0030] Aqueous nitric acid (in the carrier preparation process) is used as a solvent to promote the hydrolysis and dissolution of aluminum isopropoxide, forming a stable sol.

[0031] Paraffin oil, as the oil phase layer, forms uniform droplets during the granulation process and prevents agglomeration before solidification.

[0032] Ammonium carbonate aqueous solution is used as a curing agent. It decomposes to generate CO2 bubbles, creating uniform pores in the carrier.

[0033] Cold water is used as a detergent to remove impurities from the surface of the particles and to remove particles that have cooled and solidified.

[0034] Hot water is used as a detergent to further clean the particles and remove organic residues.

[0035] Anhydrous ethanol is used as a detergent to remove moisture and organic impurities, thereby improving particle purity.

[0036] A glucose aqueous solution serves as a carbon source, and upon pyrolysis, it forms a carbon layer on the surface of alumina, enhancing its adsorption and catalytic properties.

[0037] Sulfuric acid, as an additive, creates an acidic environment that promotes gelation and improves moldability.

[0038] The mixed solution (in the main preparation) acts as a solvent to improve the plasticity and formability of the material.

[0039] Guess powder acts as a binder, enhancing the mechanical strength and integrity of the particles.

[0040] Polyethylene glycol-400, as a pore-forming agent, increases the porosity and pore size distribution of the carrier after pyrolysis.

[0041] The active metal impregnation solution (ammonium molybdate and manganese nitrate) provides active metals Mo and Mn as catalytic active centers for the sulfur dioxide reduction reaction.

[0042] Compared with the prior art, the present invention has the following beneficial technical effects:

[0043] 1) This invention utilizes the synergistic effect of La doping and the amorphous SiO2 layer generated by the hydrolysis of ethyl silicate to maintain a high specific surface area and open mesoporous structure on the support at high temperatures, thereby promoting the dispersion of active components and the diffusion of reactants, and improving the activity and stability of the catalyst.

[0044] 2) The CO2 microbubbles generated by the decomposition of the ammonium carbonate curing agent of the present invention form a uniform mesoporous structure in the gel, which improves the pore volume and pore size distribution, enhances the mass transfer efficiency and mechanical strength, and avoids pore blockage or local pore collapse caused by other curing agents.

[0045] 3) The preparation process of this invention is simple and efficient, easy to industrialize, and has low cost, with good prospects for industrial application. At the same time, it shows excellent desulfurization performance in practical applications, which is helpful for environmental protection. Detailed Implementation

[0046] Main source of materials:

[0047] γ-phase alumina, model: YC-ALY20, particle size: 200 mesh, Qinghe County Chaotai Metal Materials Co., Ltd.

[0048] Sesbania powder, product number: 001, Jinan Aitai Biotechnology Co., Ltd.

[0049] Polyethylene glycol-400, Shandong Baihua Chemical Co., Ltd.

[0050] The active metal impregnation solution is prepared by adding 400 mL of water to a beaker, weighing 36.81 g of ammonium molybdate, adding it to the beaker, and stirring until completely dissolved; weighing 37.88 g of 50 wt% manganese nitrate aqueous solution, adding it to the beaker while stirring to ensure that all solids are completely dissolved and the solution becomes clear and homogeneous; finally, adding water to make up to the 500 mL mark, shaking well, and obtaining the active metal impregnation solution.

[0051] All other raw materials used in the embodiments and comparative examples of this invention are commercially available products.

[0052] Example 1

[0053] A method for preparing a catalytic flue gas desulfurization agent is as follows, in parts by weight:

[0054] Take 120 parts of the carrier and add 200 parts of 40wt% glucose aqueous solution. Let the mixture stand and air dry at room temperature, and stir to form non-sticky granules. Then add 60 parts of the mixed solution, 2 parts of guar gum powder and 6 parts of polyethylene glycol-400. The mixed solution is an aqueous solution containing 0.3wt% sulfuric acid and 4.0wt% nitric acid. After kneading thoroughly to form a material with good plasticity, prepare microspheres with an average diameter of 80µm. Dry overnight at room temperature, and then dry at 100℃ for 5 hours. Place the dried sample in a high-temperature furnace, heat to 450℃ and hold for 3 hours. Then introduce nitrogen and continue heating to 680℃, and then keep at that temperature for 3 hours. After natural cooling, obtain carbon-containing alumina carrier. Impregnate the carbon-containing alumina carrier with 150 parts of active metal impregnation solution for 4 hours, filter off the excess solution, dry at 100℃ for 5 hours, and then calcine at 620℃ in nitrogen for 5 hours. After cooling to room temperature, obtain the catalytic flue gas desulfurization agent.

[0055] The carrier is prepared by the following method, in parts by weight:

[0056] S1. Add 3 parts La(NO3)3•6H2O and 3 parts ethyl silicate to 300 parts water to prepare a doping solution; add 400 parts aluminum isopropoxide to 1000 parts water at 85°C to obtain an aluminum salt solution; add the doping solution to the aluminum salt solution and mix well, then add 140 parts of 1mol / L nitric acid aqueous solution, reflux at 95°C overnight, and then add an additional 70 parts of 1mol / L nitric acid aqueous solution to obtain the pretreated product;

[0057] S2. The pretreated material is granulated in a granulation container, which has two layers from top to bottom: an upper layer of paraffin oil at 80°C and a lower layer of 10wt% ammonium carbonate aqueous solution. The volume ratio of the two layers is 4:1. The pretreated material is injected dropwise into the granulation container. The droplets first pass through the upper hot paraffin oil layer to form droplets, and then fall into the lower solution to solidify for 90 minutes. The wet particles are collected and washed sequentially with cold water, 50°C hot water, and anhydrous ethanol. The particles are dried at 40°C for 24 hours. The dried particles are calcined in air, heated to the target temperature of 800°C at a heating rate of 2°C / min and held for 3 hours, and then heated to 1200°C and held for 3 hours to obtain the carrier.

[0058] Example 2

[0059] The preparation method of the catalytic flue gas desulfurizing agent is basically the same as that in Example 1, except that the preparation method of the carrier is different.

[0060] The carrier is prepared by the following method, in parts by weight:

[0061] S1. Add 3 parts ZrOCl2•8H2O and 3 parts Y(NO3)3·6H2O to 300 parts water to prepare a doping solution; add 400 parts aluminum isopropoxide to 1000 parts water at 85℃ to obtain an aluminum salt solution; add the doping solution to the aluminum salt solution and mix well, then add 140 parts of 1mol / L nitric acid aqueous solution, reflux at 95℃ overnight, and then add an additional 70 parts of 1mol / L nitric acid aqueous solution to obtain the pretreated product;

[0062] S2. The pretreated material is granulated in a granulation container, which has two layers from top to bottom: an upper layer of paraffin oil at 80°C and a lower layer of 10wt% ammonium carbonate aqueous solution. The volume ratio of the two layers is 4:1. The pretreated material is injected dropwise into the granulation container. The droplets first pass through the upper hot paraffin oil layer to form droplets, and then fall into the lower solution to solidify for 90 minutes. The wet particles are collected and washed sequentially with cold water, 50°C hot water, and anhydrous ethanol. The particles are dried at 40°C for 24 hours. The dried particles are calcined in air, heated to the target temperature of 800°C at a heating rate of 2°C / min and held for 3 hours, and then heated to 1200°C and held for 3 hours to obtain the carrier.

[0063] Example 3

[0064] The preparation method of the catalytic flue gas desulfurizing agent is basically the same as that in Example 1, except that the preparation method of the carrier is different.

[0065] The carrier is prepared by the following method, in parts by weight:

[0066] S1. Add 3 parts Ce(NO3)3·6H2O and 3 parts Mg(NO3)2·6H2O to 300 parts water to prepare a doping solution; add 400 parts aluminum isopropoxide to 1000 parts water at 85℃ to obtain an aluminum salt solution; add the doping solution to the aluminum salt solution and mix well, then add 140 parts 1mol / L nitric acid aqueous solution, reflux at 95℃ overnight, and then add an additional 70 parts 1mol / L nitric acid aqueous solution to obtain the pretreated product;

[0067] S2. The pretreated material is granulated in a granulation container, which has two layers from top to bottom: an upper layer of paraffin oil at 80°C and a lower layer of 10wt% ammonium carbonate aqueous solution. The volume ratio of the two layers is 4:1. The pretreated material is injected dropwise into the granulation container. The droplets first pass through the upper hot paraffin oil layer to form droplets, and then fall into the lower solution to solidify for 90 minutes. The wet particles are collected and washed sequentially with cold water, 50°C hot water, and anhydrous ethanol. The particles are dried at 40°C for 24 hours. The dried particles are calcined in air, heated to the target temperature of 800°C at a heating rate of 2°C / min and held for 3 hours, and then heated to 1200°C and held for 3 hours to obtain the carrier.

[0068] Example 4

[0069] The preparation method of the catalytic flue gas desulfurizing agent is basically the same as that in Example 1, except that the preparation method of the carrier is different.

[0070] The carrier is prepared by the following method, in parts by weight:

[0071] S1. Add 3 parts La(NO3)3•6H2O and 3 parts ethyl silicate to 300 parts water to prepare a doping solution; add 400 parts aluminum isopropoxide to 1000 parts water at 85°C to obtain an aluminum salt solution; add the doping solution to the aluminum salt solution and mix well, then add 140 parts of 1mol / L nitric acid aqueous solution, reflux at 95°C overnight, and then add an additional 70 parts of 1mol / L nitric acid aqueous solution to obtain the pretreated product;

[0072] S2. Granulate the pretreated material in a granulation container. The granulation container has two layers from top to bottom: an upper layer of paraffin oil at 80°C and a lower layer of 10wt% urea aqueous solution. The volume ratio of the two layers is 4:1. The pretreated material is injected dropwise into the granulation container. The droplets first pass through the upper hot paraffin oil layer to form droplets, and then fall into the lower solution to solidify for 90 minutes. The wet particles are collected and washed sequentially with cold water, 50°C hot water, and anhydrous ethanol. The particles are dried at 40°C for 24 hours. The dried particles are calcined in air, heated to the target temperature of 800°C at a heating rate of 2°C / min and held for 3 hours, and then heated to 1200°C and held for 3 hours to obtain the carrier.

[0073] Example 5

[0074] The preparation method of the catalytic flue gas desulfurizing agent is basically the same as that in Example 1, except that the preparation method of the carrier is different.

[0075] The carrier is prepared by the following method, in parts by weight:

[0076] S1. Add 6 parts of La(NO3)3•6H2O to 300 parts of water to prepare a doping solution; add 400 parts of aluminum isopropoxide to 1000 parts of water at 85°C to obtain an aluminum salt solution; add the doping solution to the aluminum salt solution and mix well, then add 140 parts of 1mol / L nitric acid aqueous solution, reflux at 95°C overnight, and then add an additional 70 parts of 1mol / L nitric acid aqueous solution to obtain the pretreated product;

[0077] S2. The pretreated material is granulated in a granulation container, which has two layers from top to bottom: an upper layer of paraffin oil at 80°C and a lower layer of 10wt% ammonium carbonate aqueous solution. The volume ratio of the two layers is 4:1. The pretreated material is injected dropwise into the granulation container. The droplets first pass through the upper hot paraffin oil layer to form droplets, and then fall into the lower solution to solidify for 90 minutes. The wet particles are collected and washed sequentially with cold water, 50°C hot water, and anhydrous ethanol. The particles are dried at 40°C for 24 hours. The dried particles are calcined in air, heated to the target temperature of 800°C at a heating rate of 2°C / min and held for 3 hours, and then heated to 1200°C and held for 3 hours to obtain the carrier.

[0078] Example 6

[0079] The preparation method of the catalytic flue gas desulfurizing agent is basically the same as that in Example 1, except that the preparation method of the carrier is different.

[0080] The carrier is prepared by the following method, in parts by weight:

[0081] S1. Add 6 parts of ethyl silicate to 300 parts of water to prepare a doping solution; add 400 parts of aluminum isopropoxide to 1000 parts of water at 85°C to obtain an aluminum salt solution; add the doping solution to the aluminum salt solution and mix well, then add 140 parts of 1 mol / L nitric acid aqueous solution, reflux at 95°C overnight, and then add an additional 70 parts of 1 mol / L nitric acid aqueous solution to obtain the pretreated product;

[0082] S2. The pretreated material is granulated in a granulation container, which has two layers from top to bottom: an upper layer of paraffin oil at 80°C and a lower layer of 10wt% ammonium carbonate aqueous solution, with a volume ratio of 4:1. The pretreated material is injected dropwise into the granulation container. The droplets first pass through the upper hot paraffin oil layer to form droplets, and then fall into the lower solution to solidify for 90 minutes. The wet granules are collected and washed sequentially with cold water, 50°C hot water, and anhydrous ethanol. They are then dried at 40°C for 24 hours. The dried granules are calcined in air, heated to the target temperature of 800°C at a heating rate of 2°C / min and held for 3 hours, and then heated to 1200°C and held for 3 hours to obtain the carrier. Spray drying.

[0083] Comparative Example 1

[0084] The preparation method of the catalytic flue gas desulfurizing agent is basically the same as that in Example 1, except that the preparation method of the carrier is different.

[0085] The carrier is prepared by the following method, in parts by weight:

[0086] S1. Add 3 parts ZrOCl2•8H2O and 3 parts La(NO3)3•6H2O to 300 parts water to prepare a doping solution; add 400 parts aluminum isopropoxide to 1000 parts water at 85℃ to obtain an aluminum salt solution; add the doping solution to the aluminum salt solution and mix well, then add 140 parts of 1mol / L nitric acid aqueous solution, reflux at 95℃ overnight, and then add an additional 70 parts of 1mol / L nitric acid aqueous solution to obtain the pretreated product;

[0087] S2. The pretreated material is granulated in a granulation container, which has two layers from top to bottom: an upper layer of paraffin oil at 80°C and a lower layer of 10wt% ammonium carbonate aqueous solution. The volume ratio of the two layers is 4:1. The pretreated material is injected dropwise into the granulation container. The droplets first pass through the upper hot paraffin oil layer to form droplets, and then fall into the lower solution to solidify for 90 minutes. The wet particles are collected and washed sequentially with cold water, 50°C hot water, and anhydrous ethanol. The particles are dried at 40°C for 24 hours. The dried particles are calcined in air, heated to the target temperature of 800°C at a heating rate of 2°C / min and held for 3 hours, and then heated to 1200°C and held for 3 hours to obtain the carrier.

[0088] Comparative Example 2

[0089] The preparation method of the catalytic flue gas desulfurizing agent is basically the same as that in Example 1, except that the preparation method of the carrier is different.

[0090] The carrier is prepared by the following method, in parts by weight:

[0091] S1. Add 3 parts La(NO3)3•6H2O and 3 parts ethyl silicate to 300 parts water to prepare a doping solution; add 400 parts aluminum isopropoxide to 1000 parts water at 85°C to obtain an aluminum salt solution; add the doping solution to the aluminum salt solution and mix well, then add 140 parts of 1mol / L nitric acid aqueous solution, reflux at 95°C overnight, and then add an additional 70 parts of 1mol / L nitric acid aqueous solution to obtain the pretreated product;

[0092] S2. Granulate the pretreated material in a granulation container. The granulation container has two layers from top to bottom: an upper layer of paraffin oil at 80°C and a lower layer of 10wt% ammonia solution. The volume ratio of the two layers is 4:1. The pretreated material is injected dropwise into the granulation container. The droplets first pass through the upper hot paraffin oil layer to form droplets, and then fall into the solution in the lower layer to solidify for 90 minutes. The wet particles are collected and washed sequentially with cold water, 50°C hot water, and anhydrous ethanol. The particles are dried at 40°C for 24 hours. The dried particles are calcined in air, heated to the target temperature of 800°C at a heating rate of 2°C / min and held for 3 hours, and then heated to 1200°C and held for 3 hours to obtain the carrier.

[0093] Comparative Example 3

[0094] The preparation method of the catalytic flue gas desulfurizing agent is basically the same as that in Example 1, except that the carrier is an equal amount of γ-phase alumina.

[0095] Test Example 1

[0096] Determination of specific surface area, pore volume, and average pore size:

[0097] The catalytic flue gas desulfurizing agents prepared in Examples 1-6 and Comparative Examples 1-3 were tested using a BET surface area analyzer 3H-2000BET-M. The pore size distribution was calculated using the BJH model based on the isothermal adsorption curves of the samples.

[0098] The test results are shown in Table 1.

[0099] Table 1

[0100] Experimental protocol <![CDATA[BET specific surface area (m 2 / g)]]> <![CDATA[Pore volume (cm 3 / g)]]> Average pore size (nm) Example 1 385 2.78 21.26 Example 2 278 1.85 19.47 Example 3 302 2.15 20.13 Example 4 342 2.51 20.98 Example 5 366 2.52 20.23 Example 6 351 2.26 19.52 Comparative Example 1 316 2.02 19.95 Comparative Example 2 295 2.02 19.78 Comparative Example 3 185 0.95 17.26

[0101] Test Example 2

[0102] Catalytic performance test

[0103] The performance of the catalytic flue gas desulfurizing agents prepared in Examples 1-6 and Comparative Examples 1-3 was tested. This catalytic performance test aimed to simulate the front-end treatment stage of an industrial fluidized bed reactor. The test was conducted in an atmospheric pressure fluidized bed reactor at a reaction temperature of 700℃. 0.5g of the microspherical catalytic flue gas desulfurizing agent prepared according to this invention was loaded into the reactor, and simulated flue gas (composition: N2 as balance gas, O2 3%, CO2 12%, SO2 1800mg / m³) was introduced. 3 SO3 180mg / m 3 (excluding H2), airspeed maintained at 10,000 h -1 The catalyst carries out the desulfurization reaction under these conditions, and its role is to remove high concentrations of sulfur oxides (SO2 / SO3) to reduce the processing load on downstream processes.

[0104] Table 2

[0105] Experimental protocol <![CDATA[Total sulfur concentration at the outlet (mg / m 3 )]]> Example 1 185.3 Example 2 485.3 Example 3 414.6 Example 4 373.2 Example 5 348.8 Example 6 433.9 Comparative Example 1 457.2 Comparative Example 2 472.6 Comparative Example 3 681.9

[0106] Example 1 exhibits superior catalytic performance compared to other doping combinations, primarily due to the synergistic effect of La-Si co-doping and ammonium carbonate curing agent. La 3+ It can occupy octahedral vacancies in alumina, effectively suppressing lattice rearrangement and delaying the α-phase transformation, thus maintaining good thermal stability at high temperatures, which is superior to the Zr-La combination in Comparative Example 1. Simultaneously, the amorphous SiO2 layer formed by tetraethyl orthosilicate acts as a physical barrier at high temperatures, preventing grain aggregation, while the Zr-Y combination in Example 2 and the Ce-Mg combination in Example 3 lack this barrier effect. Data from Examples 1 and 5 and 6 show that this dual effect allows the support to maintain a high specific surface area (385 m²) at 1200℃. 2 The open mesoporous structure (pore size 21.26 nm) greatly promotes the dispersion of the active components of Mo-Mn and the diffusion of reactants, ultimately achieving a lower total sulfur concentration at the outlet.

[0107] Example 1 exhibits superior catalytic performance compared to Example 4 and Comparative Example 2, primarily due to the use of ammonium carbonate as a curing agent. The decomposition of ammonium carbonate generates CO2 microbubbles, which form a uniform mesoporous structure within the gel, significantly increasing the pore volume (2.78 cm³). 3 The urea used in Example 4 had a surface area of ​​21.26 nm and a pore size of 21.26 nm. In contrast, the urea used in Example 4 left carbon residue after decomposition, which could lead to pore blockage and a decrease in specific surface area to 342 m². 2 The concentration of ammonia in Comparative Example 2 was / g, and the curing speed was slow with uneven pore size distribution. In contrast, the ammonia water used in Comparative Example 2 had no pore-forming effect; its alkaline environment even caused local pore collapse, reducing the pore volume to 2.02 cm³. 3 / g, thus reducing mass transfer efficiency.

Claims

1. A method for preparing a catalytic flue gas desulfurization agent, characterized in that, The method is as follows: Take the carrier, add glucose aqueous solution, let it stand at room temperature and air dry, then stir to form granular particles; add mixed solution, binder and pore-forming agent, knead until good plasticity, and prepare microsphere particles; dry at room temperature overnight, then dry again, put it in a high temperature furnace and heat to a certain temperature and keep it at that temperature, then introduce nitrogen gas to continue heating and keep it at a constant temperature, and cool naturally to obtain carbon-containing alumina carrier; impregnate the carbon-containing alumina carrier with active metal impregnation solution, filter off the excess solution and dry, then calcine in nitrogen gas, and cool to room temperature to obtain catalytic flue gas desulfurization agent; The carrier is prepared as follows: S1. Add the doping composition to water to prepare a dopant solution, add aluminum isopropoxide to hot water to obtain an aluminum salt solution, add the dopant solution to the aluminum salt solution and mix well, add nitric acid aqueous solution and reflux overnight, then add nitric acid aqueous solution dropwise to obtain a pretreated product; S2. Granulate the pretreated material in a granulation container. The granulation container is divided into a hot paraffin oil layer and a curing agent aqueous solution layer from top to bottom. After the pretreated material droplets pass through the hot paraffin oil layer, they are cured in the curing agent aqueous solution layer. Collect the wet particles, wash and dry them. Calcine the dried particles in air, raise the temperature to the target temperature and keep it at the temperature to obtain the carrier. The mixed solution is an aqueous solution containing 0.2-0.4 wt% sulfuric acid and 3-5 wt% nitric acid; The doped composition consists of La(NO3)3•6H2O and ethyl silicate; The active metal impregnation solution contains one or more elements selected from Co, Ni, Mo, W, Fe, Cu, Mn, Zn, Pt, and Ce. The curing agent is ammonium carbonate.

2. The preparation method of the catalytic flue gas desulfurizing agent as described in claim 1, characterized in that, By weight, the method is as follows: Take 100-150 parts of carrier and add 150-250 parts of 20-45wt% glucose aqueous solution. Let the mixture stand at room temperature and air dry. Stir to form non-sticky granules. Then add 50-70 parts of the mixed solution, 1-3 parts of binder, and 4-8 parts of pore-forming agent. The mixed solution is an aqueous solution containing 0.2-0.4wt% sulfuric acid and 3-5wt% nitric acid. After thorough kneading to form a material with good plasticity, prepare microspheres. Dry overnight at room temperature and then at 90-120℃. Dry for 3-8 hours, then place the dried sample in a high-temperature furnace, heat to 400-500℃ and hold for 1-5 hours. Then, introduce nitrogen and continue heating to 600-700℃, and maintain the temperature for 1-5 hours. Allow it to cool naturally to obtain a carbon-containing alumina carrier. Impregnate the carbon-containing alumina carrier with an active metal impregnation solution for 2-6 hours, filter out excess solution, and then dry at 90-120℃ for 3-8 hours. Finally, calcine it in nitrogen at 600-650℃ for 4-6 hours and cool to room temperature to obtain the catalytic flue gas desulfurization agent.

3. The preparation method of the catalytic flue gas desulfurizing agent as described in claim 2, characterized in that, The binder is at least one of carboxymethyl cellulose and guar gum powder.

4. The preparation method of the catalytic flue gas desulfurizing agent as described in claim 2, characterized in that, The pore-forming agent is polyethylene glycol.

5. The method for preparing the catalytic flue gas desulfurizing agent as described in claim 2, characterized in that, The carrier is prepared by the following method, in parts by weight: S1. Add 4-8 parts of the doping composition to 250-350 parts of water to prepare a dopant solution; add 400-500 parts of aluminum isopropoxide to 800-1200 parts of water at 80-90℃ to obtain an aluminum salt solution. Add the dopant solution to the aluminum salt solution and mix thoroughly. Then add 120-160 parts of 0.5-2 mol / L nitric acid aqueous solution and reflux overnight at 90-100℃. Then add an additional 50-90 parts of 0.5-2 mol / L nitric acid aqueous solution to obtain the pretreated product. S2. Granulate the pretreated material in a granulation container, which has two layers from top to bottom: an upper layer of paraffin oil at 75-85℃ and a lower layer of 8-12wt% curing agent aqueous solution. The volume ratio of the two layers is 2-6:

1. The pretreated material is injected dropwise into the granulation container. The droplets first pass through the upper hot paraffin oil layer to form droplets, and then fall into the lower solution to solidify for 60-120 minutes. Collect the wet particles and wash them sequentially with cold water, hot water at 40-70℃, and anhydrous ethanol. Dry them at 30-50℃ for 12-48 hours. Calcinate the dried particles in air, raising the temperature to the target temperature of 750-850℃ at a heating rate of 1-3℃ / min and holding for 1-5 hours. Then raise the temperature to 1100-1300℃ and hold for 1-5 hours to obtain the carrier.

6. A catalytic flue gas desulfurization agent, characterized in that, It is prepared by the preparation method described in any one of claims 1-5.