Preparation method of catalyst for catalytic oxidation of carbon monoxide in flue gas

Abstract

The invention discloses a preparation method of a catalyst for catalytic oxidation of carbon monoxide in flue gas. According to the method, gamma-Al2O3 is taken as a carrier, salts of cerium (Ce) and cobalt (Co) are gradually added as active components, high-dispersion loading of the active components is realized by optimizing an impregnation process and heat treatment conditions, and meanwhile, other active auxiliary components are introduced to enhance the catalytic activity, sulfur resistance, chlorine resistance and ammonia poisoning resistance. The conversion rate of the obtained catalyst to CO in complex steel sintering flue gas within the medium-low temperature range of 150-350 DEG C is larger than or equal to 90%, the flue gas CO emission concentration is stably controlled to be smaller than 2800ppm, and the catalyst has excellent poison resistance. The problems that an existing noble metal catalyst is high in cost, and a non-noble metal catalyst is prone to poisoning and insufficient in low-temperature activity are solved, and the catalyst is suitable for efficient purification of steel sintering flue gas.

Description

Technical Field

[0001] This invention belongs to the field of environmental catalysis and iron and steel sintering flue gas treatment technology. Specifically, it relates to a method for preparing a catalyst for low-temperature catalytic oxidation of carbon monoxide (CO) in iron and steel sintering flue gas. It is particularly aimed at the preparation method of a high-efficiency, sulfur-resistant, chlorine-resistant, and ammonia-resistant catalyst with γ-Al2O3 as support and cerium and cobalt as the main active components, and its application under complex flue gas conditions. Background Technology

[0002] Iron and steel sintering flue gas is one of the main waste gases generated during iron and steel production. Its composition is complex, containing not only CO but also impurities such as SO2, NOx, H2O, HCl, NH3, and dust. Furthermore, the flue gas temperature is relatively low (typically between 120–280℃). Currently, purification technologies for CO in iron and steel sintering flue gas mainly include catalytic oxidation, adsorption, and thermal combustion. Among these, catalytic oxidation is widely studied and applied due to its low operating temperature and high efficiency.

[0003] However, existing catalytic oxidation technologies still face many challenges. While noble metal catalysts (such as Pt / Al₂O₃ and Pd / Al₂O₃) exhibit high low-temperature activity, they are expensive and prone to irreversible poisoning in high-sulfur and high-moisture environments, leading to a sharp drop in activity and a shortened lifespan. Non-noble metal catalysts (such as transition metal oxides CuO, Co₃O₄, and MnO)... x While these methods have lower costs, they generally suffer from insufficient low-temperature activity (ignition temperatures are mostly above 200℃), poor resistance to poisoning (especially to SO2 and HCl), and easy sintering and deactivation under high-temperature conditions. In addition, traditional impregnation-calcination preparation processes often lead to uneven dispersion of active components, easily forming low-activity phases (such as CoAl2O4 spinel phase), further reducing catalytic efficiency.

[0004] Studies have shown that the rare earth element cerium (Ce) has a unique ability to store and release oxygen (Ce³). + / Ce 4+ Cobalt (Co)-based catalysts, with their redox pair properties and ability to promote CO oxidation, are widely used in catalyst modification. Cobalt (Co)-based catalysts also show good potential in CO oxidation. However, single-component catalysts still struggle to simultaneously achieve high activity, high stability, and strong resistance to poisoning. Therefore, developing a non-precious metal catalyst with multiple active components, excellent low-temperature activity, and strong resistance to poisoning has become a key research focus in the field of iron and steel sintering flue gas purification. Summary of the Invention

[0005] Based on the shortcomings of existing technologies, this invention proposes a method for preparing a catalyst for the catalytic oxidation of CO in sintering flue gas of iron and steel, specifically targeting the design, preparation, and application of a highly efficient, sulfur-resistant, chlorine-resistant, and ammonia-resistant catalyst with γ-Al2O3 as the support and cerium and cobalt as the main active components under complex flue gas conditions.

[0006] A method for preparing a catalyst for the catalytic oxidation of carbon monoxide in flue gas, according to the present invention, includes the following steps: Step 1: Pre-treat the substrate material γ-Al2O3: Use a tablet press to compress the substrate material γ-Al2O3 to a preset mesh size or crush the substrate material γ-Al2O3 to a preset mesh size; sieve to form γ-Al2O3 particles; then soak the γ-Al2O3 particles in a first solvent (water, ethanol) to wash off surface impurities, then dry and calcine, and nitrogen-seale the calcined γ-Al2O3 particles for later use; Step 2: Add the first preset mass of γ-Al2O3 particles obtained in Step 1 into the first container, and at the same time slowly add the second solvent into the first container until solvent precipitates out on the inner wall of the first container. Measure the volume V of the solution in the first container. Step 3: Place the second solvent with a volume of V into the second container, dissolve the second preset mass of active component in the second solvent, and perform ultrasonic treatment for about 30 minutes. Step 4: Add a first predetermined mass of γ-Al2O3 particles to the solution after ultrasonic treatment in step 3, seal and place in a cool place to stand for more than 24 hours, then dry and calcine to obtain the catalyst; or, Add a first preset mass of γ-Al2O3 particles to the solution after ultrasonic treatment in step 3, seal and place in a cool place to stand for more than 24 hours, and add an auxiliary agent to enhance the medium and low temperature activity and resistance of the catalyst. Then, dry and calcine to obtain the catalyst. Step 5: The obtained catalyst is sieved to remove catalyst particles smaller than the preset size. The sieved catalyst is then used for performance testing of catalytic oxidation of flue gas. The catalyst after testing is then subjected to thermogravimetric and infrared characterization analysis to determine the surface deposition components. Based on the surface component deposition, a catalyst regeneration strategy is determined.

[0007] Optionally, the substrate material γ-Al2O3 in step 1 has a specific surface area of ​​100-150 m² / g and a pore size distribution of 5–100 nm, and is pretreated at 350–550℃ for 6 hours to remove surface impurities and stabilize the crystal form; the tablet press compresses the powder or crushes the spherical γ-Al2O3 to a specified mesh size of 21-99 mesh.

[0008] Optionally, the second solvent in step 2 is an organic solvent or an inorganic solvent, wherein the organic solvent includes methanol or ethanol, and the inorganic solvent includes ultrapure water; the solvent adsorption amount V corresponding to each 2g of γ-Al2O3 is 2-2.5ml, and the organic solvent ratio is methanol:ethanol = 5:1-1:5; the ratio of organic solvent to inorganic solvent is organic solvent:inorganic solvent = 5:1-1:5.

[0009] Optionally, the active component in step 3 includes inorganic salts containing Ce and Co, wherein Ce and Co are selected from one or more of cerium sulfate, cerium chloride, cerium acetate, cerium nitrate, and cobalt sulfate, cobalt chloride, cobalt acetate, and cobalt nitrate, respectively, and are loaded using an equal-volume impregnation method; the ratio of Ce to Ce is 5:1 to 1:5; and the ratios of the four Ce salts are cerium sulfate:cerium chloride:cerium acetate:cerium nitrate = 1:0:0:0, 0:1:0:0, 0:0:1:0, and 0:0:1:0. 0:0:0:1, 1:1:0:0, 1:0:1:0, 1:0:0:1, 0:1:1:0, 0:1:0:1, 0:0:1:1, 1:1:1:0, 1:1:0:1, 1:0:1:1, 0:1:1:1, 1:1:1:1, 2:1:1:1, 1:2:1:1, 1:1:1:2, 1:1:2:1, 2:2:1:1, 2:1:2:1, 2:1:1:2, 1:2:2:1, 1:2:2:1 1:2, 1:1:2:2, 2:2:2:1, 2:2:1:2, 2:1:2:2, 1:2:2:2; the ratios of the four salts of Co are cobalt sulfate: cobalt chloride: cobalt acetate: cobalt nitrate = 1:0:0:0, 0:1:0:0, 0:0:1:0, 0:0:0:1, 1:1:0:0, 1:0:1:0, 1:0:0:1, 0:1:1:0, 0:1:0:1, 0:0:1:1, 1:1:1:0, 1: 1:0:1, 1:0:1:1, 0:1:1:1, 1:1:1:1, 2:1:1:1, 1:2:1:1, 1:1:1:2, 1:1:2:1, 2:2:1:1, 2:1:2:1, 2:1:1:2, 1:2:2:1, 1:2:1:2, 1:1:2:2, 2:2:2:1, 2:2:1:2, 2:1:2:2, 1:2:2:2; the total loading of the active components Ce and Co is 1-20 wt%.

[0010] Optionally, in step 4, during the drying and calcination stages, the drying process involves drying at 80-120℃ for 6-12 hours or freeze-drying at -40-60℃ for more than 12 hours. Microwave-assisted drying or vacuum drying is used during the drying stage to improve the dispersibility of the components. During the calcination process, the temperature is increased from 20℃ to 350-550℃ in an air atmosphere at a rate of 1-5℃ / min, with the temperature held at 200, 250, and 300℃ for 1 hour to control grain growth and avoid the formation of the CoAl2O4 inert phase, and then held at 350-550℃ for 5 hours.

[0011] Optionally, the additive in step 4 is one or both of platinum or palladium, and its total loading is 0.01–1 wt% of the total catalyst mass; wherein the ratio of platinum to palladium is platinum:palladium = 5:1–1:5; the additive is added in the form of chloroplatinic acid, palladium nitrate or rhodium chloride in the post-impregnation stage by the initial wet impregnation method.

[0012] Optionally, the additive in step 4 further includes an anti-poisoning additive, which is one or more of molybdenum, vanadium, tungsten or rhenium, and its loading is 0.5–5 wt% of the total active component mass, used to improve the catalyst's resistance to SO2, Cl and NH3 poisoning; the anti-poisoning additive is added in the form of ammonium molybdate, ammonium metavanadate, ammonium metatungstate or ammonium perrhenate during the impregnation stage.

[0013] Optionally, the catalyst regeneration strategy in step 5 includes catalyst regeneration by washing with dilute acid, heating at 350-500℃, or using dielectric barrier discharge low-temperature plasma discharge reduction, with an activity recovery rate of ≥98% after regeneration.

[0014] Optionally, during performance testing in step 5, the operating temperature is set to 150–350℃ and the flue gas space velocity to 2000–60000 h⁻¹. - ¹; The flue gas composition includes 0.5–2% CO, 5–40% H2O, 0–35 ppm SO2, 0–50 ppm HCl, and 10–500 ppm NH3.

[0015] Optionally, in the performance test in step 5, the catalyst can be integrated with the dust removal unit or the desulfurization unit, or the catalyst can be arranged as a separate carbon monoxide purification unit at the back end of the desulfurization and denitrification system. The catalyst is formed by extrusion molding or coating onto a honeycomb ceramic carrier, and is suitable for fixed-bed or moving-bed reactors.

[0016] The beneficial effects of this invention are: This invention significantly improves the low-temperature activity, anti-poisoning properties, and stability of the catalyst by optimizing the cerium-cobalt ratio, introducing anti-poisoning additives, and improving the preparation process, thereby meeting the purification requirements of sintering flue gas in steelmaking.

[0017] The catalyst obtained by the method described in this invention achieves a CO conversion rate of ≥90% in complex steel sintering flue gas within a low-temperature range of 150–350℃, stably controls the CO emission concentration of the flue gas to less than 2800ppm, and exhibits excellent resistance to poisoning. This invention solves the problems of high cost of existing precious metal catalysts, easy poisoning of non-precious metal catalysts, and insufficient low-temperature activity, and is suitable for the efficient purification of steel sintering flue gas. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart of a catalyst preparation method for catalytic oxidation of carbon monoxide in flue gas in some embodiments of the present invention. Figure 2 This is a flowchart of a method for preparing a cerium-cobalt-aluminum type catalyst for low-temperature catalytic oxidation of carbon monoxide (CO) in steel sintering flue gas, provided in some embodiments of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] See Figure 1 and Figure 2 As shown, this embodiment of the invention provides a method for preparing a catalyst for the catalytic oxidation of CO in steel sintering flue gas, comprising the following steps: The CO catalytic oxidation catalyst substrate γ-Al2O3 prepared in step (1) first needs to be pretreated. The pretreatment process includes using a tablet press to compress the substrate powder to a specified mesh size or crushing the spherical γ-Al2O3 to a specified mesh size and sieving it to form γ-Al2O3 particles. Then, the sieved γ-Al2O3 is soaked in ultrapure water, ethanol or other type I solvents to wash off surface impurities. After that, it is dried and calcined. The pretreated γ-Al2O3 particles are then nitrogen-sealed for later use.

[0023] The catalyst prepared in step (2) first needs to be quantitatively tested for the solvent adsorption capacity of the pretreated γ-Al2O3 particles. 2g of pretreated γ-Al2O3 particles are added to beaker A, and a second solvent is slowly added to beaker A until solvent is precipitated on the inner wall of the beaker, i.e., when wet particles can be seen, the volume V of the second solvent added at this time is recorded, which is the amount of solvent used for 2g of γ-Al2O3 particles.

[0024] Step (3) Put a volume of V of solvent into beaker B, dissolve a certain amount of active component in the solvent and sonicate for 30 minutes. After the sonication is completed, the solution obtained is mixed evenly. You can continue to add γ-Al2O3 particles to beaker B, or you can pour it into an empty beaker A and then add γ-Al2O3 particles.

[0025] Step (4) Seal the mixture of γ-Al2O3 particles and solution and place it in a cool place to stand for more than 24 hours. Then, dry and calcine the catalyst. Alternatively, the catalyst with added additives can be used to enhance its activity and resistance at medium and low temperatures. The additives are added to the beaker and then dried and calcined.

[0026] Step (5) Finally, the catalyst after the performance test is completed is subjected to thermogravimetric and infrared characterization analysis. The surface deposition components are determined by the characterization results, and the corresponding catalyst optimization regeneration strategy is determined by the deposition of different surface components.

[0027] In some embodiments, the γ-Al2O3 carrier in step (1) has a specific surface area of ​​100-150 m² / g and a pore size distribution of 5–100 nm, and is pretreated at 350–550 °C for 6 hours to remove surface impurities and stabilize the crystal form; the tablet press compresses the powder or crushes the spherical γ-Al2O3 to a specified mesh size of 21-29 mesh, 31-39 mesh, 41-49 mesh, 51-59 mesh, 61-69 mesh, 71-79 mesh, 81-89 mesh, or 91-99 mesh.

[0028] In some embodiments, the second solvent in step (2) is an organic solvent or an inorganic solvent. The organic solvent includes methanol or ethanol, and the inorganic solvent includes ultrapure water. The solvent adsorption capacity V is 2-2.5 ml, and the organic solvent ratio is methanol:ethanol = 5:1, 4:1, 3:1, 2:1, 1:0, 1:1, 0:1, 1:2, 1:3, 1:4, 1:5; the ratio of all organic solvents to inorganic solvents is organic solvent:inorganic solvent = 5:1, 4:1, 3:1, 2:1, 1:0, 1:1, 0:1, 1:2, 1:3, 1:4, 1:5.

[0029] In some embodiments, the active component in step (3) is mainly composed of cerium (Ce) and cobalt (Co) inorganic salts, wherein Ce and Co are selected from one or more of the following: cerium sulfate (Ce(SO4)2·4H2O), cerium chloride (CeCl3·6H2O), cerium acetate (Ce(CH3CO2)3·xH2O), cerium nitrate (Ce(NO3)3·6H2O), cobalt sulfate (CoSO4·7H2O), cobalt chloride (CoCl2·6H2O), cobalt acetate (C4H6CoO4·4H2O), and cobalt nitrate (Co(NO3)2·6H2O). The mixture is loaded using an equal-volume impregnation method; the ratio of Ce to Ce is 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, and 1:5; the ratios of the four Ce salts are cerium sulfate:cerium chloride:cerium acetate:cerium nitrate = 1:0:0:0, 0:1:0:0, 0:0:1:0, 0:0:0:1, 1:1:0:0, 1:0:1:0, 1:0:0:1, 0:1:1:0, 0:1:0:1, 0:0:1:1, 1:1:1:0, 1:1:0:1, 1:0:1:1, and 0:1:1. :1, 1:1:1:1, 2:1:1:1, 1:2:1:1, 1:1:1:2, 1:1:2:1, 2:2:1:1, 2:1:2:1, 2:1:1:2, 1:2:2:1, 1:2:1:2, 1:1:2:2, 2:2:2:1, 2:2:1:2, 2:1:2:2, 1:2:2:2; The ratios of the four salts of Co are cobalt sulfate: cobalt chloride: cobalt acetate: cobalt nitrate = 1:0:0:0, 0:1:0:0, 0:0:1:0, 0:0:0:1, 1:1:0:0, 1:0:1:0, 1: 0:0:1, 0:1:1:0, 0:1:0:1, 0:0:1:1, 1:1:1:0, 1:1:0:1, 1:0:1:1, 0:1:1:1, 1:1:1:1, 2:1:1:1, 1:2:1:1, 1:1:1:2, 1:1:2:1, 2:2:1:1, 2:1:2:1, 2:1:1:2, 1:2:2:1, 1:2:1:2, 1:1:2:2, 2:2:2:1, 2:2:1:2, 2:1:2:2, 1:2:2:2; the total loading of the active components Ce and Co is 1-20 wt%.

[0030] In some embodiments, during the drying and calcination stages of step (4), the drying process is carried out at 80-120°C for 6-12 hours or freeze-drying at -40-60°C for more than 12 hours. Microwave-assisted drying or vacuum drying is used in the drying stage to improve the dispersibility of the components. The calcination process is carried out in an air atmosphere with a temperature increase of 1-5°C / min from 20°C to 350-550°C, wherein the temperature is held at 200, 250, and 300°C for 1 hour to control grain growth and avoid the formation of the CoAl2O4 inert phase, and the temperature is held at 350-550°C for 5 hours.

[0031] In some embodiments, the additive used to enhance the low-temperature activity of the catalyst in step (4) can be further enhanced by adding a noble metal additive, wherein the noble metal is one or both of platinum (Pt) or palladium (Pd), and its total loading is 0.01–1 wt% of the total catalyst mass; wherein the ratio of platinum to palladium is platinum:palladium = 5:1, 4:1, 3:1, 2:1, 1:0, 1:1, 0:1, 1:2, 1:3, 1:4, 1:5; the noble metal additive is added in the form of chloroplatinic acid, palladium nitrate or rhodium chloride in the post-impregnation stage by the initial wet impregnation method.

[0032] In some embodiments, step (4) further includes an anti-poisoning agent, which is one or more of molybdenum (Mo), vanadium (V), tungsten (W) or rhenium (Re), and its loading is 0.5–5 wt% of the total active component mass, used to improve the catalyst's resistance to SO2, Cl and NH3 poisoning; the anti-poisoning agent is added in the form of ammonium molybdate, ammonium metavanadate, ammonium metatungstate or ammonium perrhenate during the impregnation stage.

[0033] In some embodiments, the regeneration process in step (5) can be achieved by washing with dilute acid (such as 0.01–0.1M nitric acid), heating at 350–500°C, or using dielectric barrier discharge low-temperature plasma discharge reduction to regenerate the catalyst, and the activity recovery rate after regeneration is ≥98%.

[0034] In some embodiments, the operating temperature is 150–280°C and the space velocity is 2,000–60,000 h⁻¹. - ¹, The flue gas composition includes 0.5–2% CO, 5–40% H2O, 0–35 ppm SO2, 0–50 ppm HCl, and 10–500 ppm NH3.

[0035] In some embodiments, the catalyst can be integrated with dust removal and desulfurization units, or arranged as a separate CO purification unit at the back end of the desulfurization and denitrification system; the catalyst is formed by extrusion molding or coating on a honeycomb ceramic carrier, and is suitable for fixed bed or moving bed reactors.

[0036] Example CO flue gas was supplied from a laboratory gas distribution system with a total flow rate of 1 L / min, a CO concentration of 6000 ppm, an O2 concentration of 16%, and the remainder being nitrogen. The catalyst loading was 0.1 g. The CO inlet and outlet concentrations were obtained using a flue gas analyzer (TESTO 350). The CO conversion efficiency was calculated using the following formula: Example 1 (1) The γ-Al2O3 powder carrier (specific surface area 100-150 m² / g, pore size distribution 5-100 nm) is pretreated at 550℃ for 6 hours, and then the powder is extruded to a specified mesh size of 21-29 using a tablet press.

[0037] (2) Add 2g of pretreated γ-Al2O3 particles to beaker A, and at the same time slowly add ultrapure water to beaker A until solvent precipitates out on the inner wall of the beaker. Record the volume of the solvent as 2.36ml.

[0038] (3) Put 2.36 ml of water into beaker B, and dissolve 9% of cerium nitrate and cobalt nitrate in 2.36 ml of ultrapure water in beaker B (the ratio of cerium nitrate to cobalt nitrate is cerium nitrate: cobalt nitrate = 1:1). Perform sonication for 30 minutes, and then add the mixed solution after sonication to beaker A evenly.

[0039] (4) Seal the mixture of catalyst and solution and place it in a cool place to stand for 24 hours. Then dry the catalyst at 80-120℃ for 12 hours. Calcinate it in air at a rate of 1℃ / min from 20℃ to 400℃, keep it at 200, 250 and 300℃ for 1 hour, and keep it at 400℃ for 5 hours.

[0040] (5) No resistance studies were conducted in this embodiment.

[0041] (6) No regeneration study was conducted in this embodiment.

[0042] Comparative Example 11 Similar to Example 1, except that a tablet press is used to compress the powder or crush the spherical γ-Al2O3 to a specified mesh size of 31-39.

[0043] Comparative Example 12 Similar to Example 1, except that a tablet press is used to compress the powder or crush the spherical γ-Al2O3 to a specified mesh size of 41-49.

[0044] Comparative Example 13 Similar to Example 1, except that a tablet press is used to compress the powder or crush the spherical γ-Al2O3 to a specified mesh size of 51-59.

[0045] Comparative Example 14 Same as Example 1, except that a tablet press is used to compress the powder or crush the spherical γ-Al2O3 to a specified mesh size of 61-69 mesh.

[0046] Comparative Example 15 Similar to Example 1, except that a tablet press is used to compress the powder or crush the spherical γ-Al2O3 to a specified mesh size of 71-79 mesh.

[0047] Comparative Example 16 Similar to Example 1, except that a tablet press is used to compress the powder or crush the spherical γ-Al2O3 to a specified mesh size of 81-89.

[0048] Comparative Example 17 Similar to Example 1, except that a tablet press is used to compress the powder or crush the spherical γ-Al2O3 to a specified mesh size of 91-99 mesh.

[0049] Example 2 (1) The γ-Al2O3 powder carrier (specific surface area 100-150 m² / g, pore size distribution 5-100 nm) is pretreated at 550℃ for 6 hours, and then the powder is extruded to a specified mesh size of 51-59 using a tablet press.

[0050] (2) Add 2g of pretreated γ-Al2O3 particles to beaker A, and at the same time slowly add ultrapure water to beaker A until solvent precipitates out on the inner wall of the beaker. Record the volume of the solvent as 2.41ml.

[0051] (3) Put 2.41 ml of water into beaker B, and dissolve 9% of cerium nitrate and cobalt nitrate in 2.41 ml of ultrapure water in beaker B (the ratio of cerium nitrate to cobalt nitrate is cerium nitrate: cobalt nitrate = 1:1). Perform sonication for 30 minutes, and then add the mixed solution after sonication to beaker A evenly.

[0052] (4) Seal the mixture of catalyst and solution and place it in a cool place to stand for 24 hours. Then dry the catalyst at 80°C for 12 hours. Calcinate it in air at a temperature of 2°C / min from 20°C to 400°C. Keep it at 200, 250 and 300°C for 1 hour and at 400°C for 5 hours.

[0053] (5) No resistance studies were conducted in this embodiment.

[0054] (6) No regeneration study was conducted in this embodiment.

[0055] Comparative Example 21 Same as Example 2, except that the ratio of cerium nitrate to cobalt nitrate is cerium nitrate:cobalt nitrate = 3:1.

[0056] Comparative Example 22 Same as Example 2, except that the ratio of cerium nitrate to cobalt nitrate is cerium nitrate:cobalt nitrate = 2:1.

[0057] Comparative Example 23 Same as Example 2, except that the ratio of cerium nitrate to cobalt nitrate is cerium nitrate:cobalt nitrate = 1:2.

[0058] Comparative Example 24 Same as Example 2, except that the ratio of cerium nitrate to cobalt nitrate is cerium nitrate:cobalt nitrate = 1:3.

[0059] Example 3 (1) The γ-Al2O3 powder carrier (specific surface area 100-150 m² / g, pore size distribution 5-100 nm) is pretreated at 550℃ for 6 hours, and then the powder is extruded to a specified mesh size of 51-59 using a tablet press.

[0060] (2) Add 2g of pretreated γ-Al2O3 particles to beaker A, and at the same time slowly add ultrapure water to beaker A until solvent precipitates out on the inner wall of the beaker. Record the volume of the solvent as 2.39ml.

[0061] (3) Put 2.39 ml of water into beaker B, and dissolve 9% of cerium nitrate and cobalt nitrate in 2.39 ml of ultrapure water in beaker B (the ratio of cerium nitrate to cobalt nitrate is cerium nitrate: cobalt nitrate = 1:3). Perform sonication for 30 minutes, and then add the mixed solution after sonication to beaker A evenly.

[0062] (4) Seal the mixture of catalyst and solution and place it in a cool place to stand for 24 hours. Then dry the catalyst at 80°C for 12 hours. Calcinate it in air at a temperature of 2°C / min from 20°C to 400°C. Keep it at 200, 250 and 300°C for 1 hour and at 400°C for 5 hours.

[0063] (5) No resistance studies were conducted in this embodiment.

[0064] (6) No regeneration study was conducted in this embodiment.

[0065] Comparative Example 31 Same as Example 3, except that the temperature was increased from 20°C to 350°C in air atmosphere at a rate of 2°C / min, and the temperature was maintained at 200, 250, and 300°C for 1 hour, and at 350°C for 5 hours.

[0066] Comparative Example 32 Same as Example 3, except that the temperature was increased from 20°C to 450°C in air atmosphere at a rate of 2°C / min, and the temperature was maintained at 200, 250, and 300°C for 1 hour, and at 450°C for 5 hours.

[0067] Comparative Example 33 Same as Example 3, except that the temperature was increased from 20°C to 500°C in air atmosphere at a rate of 2°C / min, and the temperature was maintained at 200, 250, and 300°C for 1 hour, and at 500°C for 5 hours.

[0068] Example 4 (1) The γ-Al2O3 powder carrier (specific surface area 100-150 m² / g, pore size distribution 5-100 nm) is pretreated at 550℃ for 6 hours, and then the powder is extruded to a specified mesh size of 51-59 using a tablet press.

[0069] (2) Add 2g of pretreated γ-Al2O3 particles to beaker A, and at the same time slowly add ultrapure water to beaker A until solvent precipitates out on the inner wall of the beaker. Record the volume of the solvent as 2.43ml.

[0070] (3) Put 2.43 ml of water into beaker B, and dissolve 9% of cerium nitrate and cobalt nitrate in 2.43 ml of ultrapure water in beaker B (the ratio of cerium nitrate to cobalt nitrate is cerium nitrate: cobalt nitrate = 1:3). Perform sonication for 30 minutes, and then add the mixed solution after sonication evenly into beaker A.

[0071] (4) Seal the mixture of catalyst and solution and place it in a cool place to stand for 24 hours. Then dry the catalyst at 80°C for 12 hours. Calcinate it in air at a temperature of 2°C / min from 20°C to 350°C. Keep it at 200, 250, and 300°C for 1 hour and at 350°C for 5 hours.

[0072] (5) No resistance studies were conducted in this embodiment.

[0073] (6) No regeneration study was conducted in this embodiment.

[0074] Comparative Example 41 Same as Example 4, except that cerium nitrate and cobalt nitrate with a total loading of 5% are dissolved in beaker B.

[0075] Comparative Example 42 Same as Example 4, except that cerium nitrate and cobalt nitrate with a total loading of 7% are dissolved in beaker B.

[0076] Comparative Example 43 Same as Example 4, except that cerium nitrate and cobalt nitrate with a total loading of 11% are dissolved in beaker B.

[0077] Comparative Example 44 Same as Example 4, except that cerium nitrate and cobalt nitrate with a total loading of 13% are dissolved in beaker B.

[0078] Table 1. Experimental results of the examples and comparative examples The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a catalyst for catalytic oxidation of carbon monoxide in flue gas, characterized by, The method comprises the following steps: Step 1: Pretreatment of the base material γ-Al2O3, using a tablet press to extrude the base material γ-Al2O3 to a predetermined mesh size or to crush the base material γ-Al2O3 to a predetermined mesh size; sieving to form γ-Al2O3 particles; then placing the γ-Al2O3 particles in a first solvent for soaking, washing the surface impurities, and then drying and calcining, and sealing the calcined γ-Al2O3 particles under nitrogen for later use; Step 2: Adding the first predetermined mass of γ-Al2O3 particles obtained in step 1 to a first container, and slowly adding a second solvent to the first container until the solvent is precipitated on the inner wall of the first container, and measuring the volume V of the solution in the first container; Step 3: Placing the second solvent with a volume of V into a second container, dissolving the second predetermined mass of active components in the second solvent, and performing ultrasonic treatment for about 30 minutes; Step 4: After ultrasonic treatment in step 3, adding the first predetermined mass of γ-Al2O3 particles to the solution in the second container, sealing and placing in a cool place for 24 hours or more, and then drying and calcining to obtain a catalyst; or, After ultrasonic treatment in step 3, adding the first predetermined mass of γ-Al2O3 particles to the solution, and adding an additive to enhance low-temperature activity and resistance, sealing and placing in a cool place for 24 hours or more, and then drying and calcining to obtain a catalyst; Step 5: Screening the obtained catalyst to remove catalyst particles smaller than the predetermined size, using the screened catalyst in performance testing of catalytic oxidation of flue gas, and then performing thermogravimetric and infrared characterization analysis on the tested catalyst to determine the surface deposited components, and determining the catalyst regeneration strategy according to the surface component deposition.

2. The method of claim 1, wherein, The base material γ-Al2O3 in step 1 has a specific surface area of 100-150 m² / g, a pore size distribution of 5-100 nm, and is pretreated at 350-550°C for 6 hours to remove surface impurities and stabilize the crystal form; The tablet press extrudes the powder or crushes the spherical γ-Al2O3 to a specified mesh size of 21-99 mesh.

3. The method of claim 1, wherein, The second solvent in step 2 is an organic solvent and / or an inorganic solvent, wherein the organic solvent includes methanol or ethanol, and the inorganic solvent includes ultrapure water; the solvent adsorption amount V corresponding to 2g of γ-Al2O3 is 2-2.5ml, the mixed organic solvent ratio is methanol:ethanol=5:1-1:5, and the mixed organic solvent and inorganic solvent ratio is organic solvent:inorganic solvent=5:1-1:

5.

4. The method of claim 1, wherein, The active components in Step 3 include Ce-containing and Co-containing inorganic salts, Ce and Co are respectively selected from one or more of cerium sulfate, cerium chloride, cerium acetate, cerium nitrate, and cobalt sulfate, cobalt chloride, cobalt acetate, cobalt nitrate, and loaded by equal volume impregnation; the ratio of Ce and Co is respectively 5:1-1:5; the ratio of the four salts of Ce is cerium sulfate:cerium chloride:cerium acetate:cerium nitrate = 1:0:0:0, 0:1:0:0, 0:0:1:0, 0:0:0:1, 1:1:0:0, 1:0:1:0, 1:0:0:1, 0:1:1:0, 0:1:0:1, 0:0:1:1, 1:1:1:0, 1:1:0:1, 1:0:1:1, 0:1:1:1, 1:1:1:1, 2:1:1:1, 1:2:1:1, 1:1:1:2, 1:1:2:1, 2:2:1:1, 2:1:2:1, 2:1:1:2, 1:2:2:1, 1:2:1:2, 1:1:2:2, 2:2:2:1, 2:2:1:2, 2:1:2:2, 1:2:2:2; the ratio of the four salts of Co is cobalt sulfate: cobalt chloride: cobalt acetate: cobalt nitrate = 1:0:0:0, 0:1:0:0, 0:0:1:0, 0:0:0:1, 1:1:0:0, 1:0:1:0, 1:0:0:1, 0:1:1:0, 0:1:0:1, 0:0:1:1, 1:1:1:0, 1:1:0:1, 1:0:1:1, 0:1:1:1, 1:1:1:1, 2:1:1:1, 1:2:1:1, 1:1:1:2, 1:1:2:1, 2:2:1:1, 2:1:2:1, 2:1:1:2, 1:2:2:1, 1:2:1:2, 1:1:2:2, 2:2:2:1, 2:2:1:2, 2:1:2:2, 1:2:2:2; the total loading of the active components Ce and Co is 1-20 wt%.

5. The method according to any one of claims 1-4, characterized in that, In Step 4, the drying and calcination stage, the drying process is drying at 80-120℃ for 6-12 hours, or freeze-drying at -40-60℃ for more than 12 hours, and microwave-assisted drying or vacuum drying is used to improve the dispersion of the components; the calcination process is heating at 1-5℃ / min from 20℃ to 350-550℃ in air atmosphere, and holding at 200, 250, 300℃ for 1 hour to control grain growth and avoid the formation of CoAl2O4 inert phase, and holding at 350-550℃ for 5 hours.

6. The method according to any one of claims 1-4, characterized in that, The promoter in Step 4 is one or both of platinum and palladium, with a total loading of 0.01-1 wt% of the total catalyst mass; the ratio of mixed platinum and palladium is platinum:palladium = 5:1-1:5; the promoter is added by initial wet impregnation method with chloroplatinic acid or palladium nitrate in the post-impregnation stage.

7. The method of claim 6, wherein, The auxiliary agent in step 4 also includes an anti-poisoning auxiliary agent, which is one or more of molybdenum, vanadium, tungsten or rhenium, and the loading amount is 0.5-5wt% of the total active component mass, for improving the SO2, Cl and NH3 poisoning resistance of the catalyst; the anti-poisoning auxiliary agent is added in the form of ammonium molybdate, ammonium metavanadate, ammonium metatungstate or ammonium perrhenate in the impregnation stage.

8. The method according to any one of claims 1-4, characterized in that, The catalyst regeneration strategy in step 5 includes catalyst regeneration by dilute acid washing, heating at 350-500℃ or using medium barrier discharge low temperature plasma discharge reduction, and the activity recovery rate after regeneration is ≥98%.

9. The method of claim 8, wherein, When performing performance tests in step 5, the operating temperature is set to 150 - 350 °C and the space velocity of the flue gas is set to 2000 - 60000 h - 1; The flue gas composition includes 0.5-2% CO, 5-40% H2O, 0-35 ppm SO2, 0-50 ppm HCl, and 10-500 ppm NH3.

10. The method of any one of claims 1-4, wherein, In the performance test in step 5, the catalyst is integrated with a dust removal unit or a desulfurization unit, or the catalyst is arranged as a separate carbon monoxide purification unit at the rear end of the desulfurization and denitrification system. The catalyst forming method is extrusion molding or coating on a honeycomb ceramic carrier, and is suitable for fixed bed or moving bed reactors.

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