Carbon monoxide oxidation catalyst as well as preparation method and application thereof

Abstract

The invention relates to a carbon monoxide oxidation catalyst and a preparation method and application thereof.In the aspect of active component design of the catalyst, a palladium-platinum double-metal synergistic effect is adopted, metal palladium dominates carbon monoxide adsorption activation, and metal platinum promotes oxygen dissociation; in the aspect of a carrier structure, vanadium pentoxide is doped with titanium dioxide to form a solid solution compound, and more oxygen vacancies are generated; the preparation method comprises the following steps: dissolving a vanadium source and a titanium source in a mixed solution of an alcohol solvent and a citric acid solution, sequentially carrying out aging treatment, drying treatment and stepped roasting treatment, and carrying out multi-time dipping treatment to obtain a catalyst carrier loaded with noble metal; and finally, carrying out reduction roasting treatment on the catalyst carrier loaded with the noble metal. And a synergistic effect mechanism of double active sites-gradient carrier-dynamic sulfur resistance is constructed.

Description

Technical Field

[0001] This application relates to the field of catalyst technology for air pollution control, and more particularly to a carbon monoxide oxidation catalyst, its preparation method, and its application. Background Technology

[0002] In steel production, the carbon monoxide concentration in the exhaust gas from processes such as sintering and pelletizing typically reaches 8000 mg / m³. 3 ~10000mg / m 3 As a major air pollutant, carbon monoxide poses significant hazards: on the one hand, it participates in the formation of photochemical smog, exacerbating global environmental problems; on the other hand, its affinity for binding to hemoglobin is 200 to 300 times that of oxygen, easily causing serious impacts on the human nervous and cardiovascular systems, thus necessitating its control and elimination.

[0003] Currently, existing methods for treating carbon monoxide are mainly divided into two categories: physical removal and chemical removal. Physical removal (also known as adsorption) refers to reducing carbon monoxide content by adsorbing it using porous, highly absorbent materials. However, this method has drawbacks: physical adsorption is prone to saturation, and materials with high adsorption efficiency are scarce, leading to the need for larger adsorption equipment, which restricts its practical application due to space and financial constraints. In chemical removal, catalytic oxidation is the primary method for removing carbon monoxide. Its principle is to react toxic carbon monoxide with oxygen at a certain temperature, converting it into non-toxic carbon dioxide.

[0004] Currently, widely used catalysts primarily use alumina or molecular sieves as supports, loaded with precious metals such as palladium and platinum. However, these catalysts face several challenges in practical applications: First, traditional impregnation methods result in uneven dispersion of precious metals, requiring 0.8%–1.2% precious metal loading to achieve a 90% conversion rate, leading to high costs. Second, if the flue gas contains 50–300 ppm of sulfur dioxide, the active sites of precious metals are prone to sulfation; for example, literature reports that the activity of a commercial catalyst decreased by 40% after 200 hours of operation in a sulfur-containing environment. Third, conventional supports are prone to phase transformation sintering above 500℃ (e.g., when titanium dioxide transforms from the anatase phase to the rutile phase, the specific surface area decreases by 60%), severely affecting the high-temperature stability of the catalyst. Although existing technologies attempt to improve the catalyst through support modification or the addition of additives, the synergistic optimization problem of precious metal dispersion, oxygen vacancy regulation, and sulfur resistance has not yet been systematically solved.

[0005] In view of this, it is necessary to design a carbon monoxide oxidation catalyst, its preparation method, and its application to solve the above problems. Summary of the Invention

[0006] This application provides a carbon monoxide oxidation catalyst and its preparation method to solve the problems of low noble metal dispersion and poor synergy between oxygen vacancy regulation and sulfur resistance in current catalysts.

[0007] In a first aspect, this application provides a carbon monoxide oxidation catalyst, the catalyst comprising an active component and a support; The active components include palladium and platinum; The carrier comprises vanadium pentoxide-titanium dioxide composite oxide.

[0008] In some embodiments, the molar ratio of vanadium to titanium in the vanadium pentoxide-titanium dioxide composite oxide is (1:5) to (1:3); and / or, In the catalyst, the palladium has a mass percentage of 0.2% to 0.6%; and / or, In the catalyst, the platinum mass percentage is 0.1% to 0.4%; and / or, The molar ratio of palladium to platinum in the active component is (1.5:1) to (3:1).

[0009] Secondly, this application provides a method for preparing the above-mentioned carbon monoxide oxidation catalyst, comprising the following steps: We provide vanadium sources, titanium sources, alcohol solvents, citric acid solutions, and precursor mixed solutions. The alcohol solvent and the citric acid solution are mixed to obtain a first mixture; the vanadium source and the titanium source are dissolved in the first mixture to obtain a vanadium-titanium mixture. The vanadium-titanium mixture was aged to obtain a gel carrier; The gel support was subjected to a first drying treatment and a step-by-step calcination treatment in sequence to obtain a catalyst support; The catalyst support is placed in the precursor mixture solution for impregnation treatment to obtain a catalyst support loaded with noble metals. The catalyst support loaded with noble metals is subjected to reduction roasting treatment to obtain the carbon monoxide oxidation catalyst.

[0010] In some embodiments, the impregnation process includes: The catalyst support is placed in a precursor mixture solution for a first impregnation treatment to obtain a catalyst support impregnated with noble metals; the catalyst support impregnated with noble metals is then subjected to a second drying treatment to obtain a catalyst support loaded with noble metals; the second drying treatment includes: placing the catalyst support impregnated with noble metals under vacuum conditions of 90℃~110℃ for 1.5h~3h; the vacuum degree of the vacuum conditions during the second drying treatment is -0.07MPa~-0.09 MPa; The catalyst support one loaded with noble metal is placed in the precursor mixture solution two for a second impregnation treatment to obtain the catalyst support two impregnated with noble metal; the catalyst support two impregnated with noble metal is then subjected to a third drying treatment to obtain the catalyst support two loaded with noble metal; the third drying treatment includes: placing the catalyst support two impregnated with noble metal in an inert atmosphere at 140℃~160℃ for 1.5h~3h; the gas flow rate of the inert gas in the inert atmosphere is 40mL / min~60mL / min; The catalyst support second loaded with noble metals is placed in the precursor mixed solution third for a third impregnation treatment to obtain the catalyst support loaded with noble metals. The first, second, and third impregnation treatments all meet the following conditions: the impregnation time is 8 min to 15 min; the impregnation temperature is 25℃ to 40℃; ultrasonic-assisted impregnation is used; the frequency of the ultrasonic waves is 30 kHz to 50 kHz, and the power of the ultrasonic waves is 150 W to 250 W; in the first impregnation treatment, the mass of the first precursor mixed solution is 30% to 40% of the saturated adsorption mass of the catalyst support; in the second impregnation treatment, the mass of the second precursor mixed solution is 30% to 40% of the saturated adsorption mass of the first catalyst support loaded with noble metals; in the third impregnation treatment, the mass of the third precursor mixed solution is 30% to 40% of the saturated adsorption mass of the second catalyst support loaded with noble metals.

[0011] In some embodiments, the reduction roasting process includes: heating the catalyst support loaded with noble metal to 300°C~400°C and holding it at that temperature for 2h~4h; the roasting atmosphere during the reduction roasting process consists of hydrogen gas accounting for 3%~7% by volume and inert gas accounting for 93%~97% by volume.

[0012] In some embodiments, the vanadium source includes ammonium metavanadate; and / or, The titanium source includes tetrabutyl titanate; and / or, The alcohol solvent includes any one or more of ethanol, methanol, and isopropanol; and / or, The citric acid solution has a mass concentration of 15% to 25%; and / or, In the vanadium-titanium mixture, the volume ratio of the alcohol solvent to the citric acid solution is (3:1) to (5:1); and / or, In the vanadium-titanium mixture, the molar ratio of vanadium in the vanadium source to titanium in the titanium source is (1:5) to (1:3); and / or, In the vanadium-titanium mixture, the ratio of the molar mass of citric acid in the citric acid solution to the total molar mass of vanadium in the vanadium source and titanium in the titanium source is (1:1) to (1.5:1).

[0013] In some embodiments, the aging treatment includes: aging the vanadium-titanium mixture in a water bath for 18 to 30 hours; the water bath temperature for the water bath treatment is 70°C to 90°C.

[0014] In some embodiments, the first drying process includes drying the gel carrier at 100°C to 150°C for 10 to 15 hours, and then cooling it to 10°C to 30°C; and / or, The stepped calcination process includes sequentially performing a first calcination and a second calcination on the gel carrier after the first drying treatment. The first calcination includes: heating the gel carrier after the first drying treatment to 300℃~400℃ and holding it at that temperature for 1h~3h; the heating rate during the first calcination is 1℃ / min~3℃ / min; The second calcination includes: heating the gel carrier after the first calcination treatment to 550℃~650℃ and holding it at that temperature for 3h~5h; the heating rate during the second calcination is 3℃ / min~8℃ / min.

[0015] In some embodiments, the precursor mixed solution comprises a mixed solution of palladium precursor solution and platinum precursor solution; the palladium precursor solution is selected from palladium chloride solution, palladium nitrate solution, and palladium acetate solution; the platinum precursor solution is selected from chloroplatinic acid solution, ammonium chloroplatinate solution, and platinum nitrate solution; the molar concentration of the palladium precursor solution is 0.08 mol / L to 0.12 mol / L; and the molar concentration of the platinum precursor solution is 0.04 mol / L to 0.06 mol / L.

[0016] Thirdly, this application provides an application of the above-mentioned carbon monoxide oxidation catalyst, which is used for the purification of carbon monoxide in iron and steel smelting flue gas, carbon monoxide in coke oven gas, and carbon monoxide in automobile exhaust.

[0017] The technical solutions provided in this application have the following advantages compared with the prior art: 1. The carbon monoxide oxidation catalyst provided in this application includes: an active component and a support; the active component includes elemental palladium and elemental platinum; the support includes vanadium pentoxide-titanium dioxide composite oxide; in terms of the design of the active component, a palladium-platinum bimetallic synergistic effect is adopted, wherein metallic palladium dominates the adsorption and activation of carbon monoxide, and metallic platinum promotes oxygen dissociation; in terms of the support structure, vanadium pentoxide is doped with titanium dioxide to form a solid solution complex, which is beneficial to increase oxygen vacancies and thus improve the catalyst activity.

[0018] 2. The method for preparing the carbon monoxide oxidation catalyst provided in this application embodiment involves dissolving vanadium and titanium sources in a solution of alcohol solvent and citric acid solution, followed by aging, drying, and step-calcination treatments, and then performing multiple impregnation treatments to obtain a catalyst support loaded with precious metals. Finally, the catalyst support loaded with precious metals is subjected to reduction calcination treatment. This constructs a synergistic mechanism of "dual active sites - gradient support - dynamic sulfur resistance". When applied to iron and steel smelting flue gas, in an iron and steel flue gas environment (1% carbon monoxide, 15% oxygen, 200ppm sulfur dioxide, 300℃), the ignition temperature can be reduced to 130℃ to achieve a carbon monoxide conversion rate of 90%, significantly reducing heating energy consumption. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A scanning electron microscope image of the carbon monoxide oxidation catalyst provided in Example 1 is shown; Figure 2 The following are scanning electron microscope (SEM) images comparing the carbon monoxide oxidation catalyst provided in Example 1 before and after sulfur resistance. Figure 3 The following is a comparison of scanning electron microscopy images of the carbon monoxide oxidation catalyst provided in Comparative Example 3 before and after sulfur resistance. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Various embodiments of this application may exist in the form of a range. It should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of this application. Therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated in this application, it means including any referenced number (fraction or integer) within the indicated range. Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this application can be purchased commercially or prepared by existing methods. In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. In addition, in this application, the terms "comprising," "including," etc., mean "including but not limited to." In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any actual relationship or order between these entities or operations. In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this application, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or multiple.

[0024] This application provides a carbon monoxide oxidation catalyst, the catalyst comprising an active component and a support; The active components include elemental palladium and elemental platinum; The carrier comprises vanadium pentoxide-titanium dioxide composite oxide.

[0025] Thus, in terms of active component design, palladium-platinum bimetallic synergy is adopted, in which palladium metal dominates carbon monoxide adsorption and activation (density functional theory calculations show that the adsorption energy of carbon monoxide on the palladium (111) surface is -1.45 eV), and platinum metal promotes oxygen dissociation (hydrogen temperature-programmed reduction experiments confirm that the bimetallic reduction peak shifts to a lower temperature of 50℃). In terms of carrier structure, vanadium pentoxide doped with titanium dioxide forms a solid solution complex, producing a yield as high as 5.3 × 10⁻⁶ ppm. 18 One oxygen vacancy (signal intensity increased 3 times in electron paramagnetic resonance test with g=2.003).

[0026] As an optional implementation, in the embodiments of this application, the molar ratio of vanadium to titanium in the vanadium pentoxide-titanium dioxide composite oxide is (1:5) to (1:3); preferably, the molar ratio of vanadium to titanium in the vanadium pentoxide-titanium dioxide composite oxide is 1:4.

[0027] At the same time, the molar ratio of vanadium to titanium is controlled to prevent carbon deposition at acidic sites due to excessive vanadium content (>20%) (the carbon deposition is less than 1.2% when the vanadium-titanium ratio is 1:3 as measured by thermogravimetric-differential scanning calorimetry).

[0028] As an optional implementation, in this embodiment of the application, the mass percentage of palladium in the catalyst is 0.2% to 0.6%; In the catalyst, the platinum content is 0.1% to 0.4% by mass. The molar ratio of palladium to platinum in the active component is (1.5:1) to (3:1); preferably, the molar ratio of palladium to platinum in the active component is 2:1.

[0029] By strictly controlling the palladium / platinum molar ratio, sufficient carbon monoxide adsorption site density is ensured while avoiding competitive adsorption caused by excessive platinum content (X-ray photoelectron spectroscopy shows a strong platinum-carbon monoxide adsorption band when the platinum content exceeds 0.3%).

[0030] Based on a general inventive concept, this application provides a method for preparing the above-mentioned carbon monoxide oxidation catalyst, comprising the following steps: Step S1: Provide a vanadium source, a titanium source, an alcohol solvent, a citric acid solution, and a precursor mixed solution; (the solute in the citric acid solution is water, and the solvent is citric acid). Step S2: Mix the alcohol solvent and the citric acid solution to obtain a first mixture; dissolve the vanadium source and the titanium source in the first mixture to obtain a vanadium-titanium mixture; Step S3: The vanadium-titanium mixture is aged to obtain a gel carrier; Step S4: The gel support is subjected to a first drying treatment and a step-by-step calcination treatment in sequence to obtain a catalyst support; Step S5: The catalyst support is placed in the precursor mixture solution for impregnation treatment to obtain a catalyst support loaded with noble metals. Step S6: The catalyst support loaded with noble metals is subjected to reduction roasting treatment to obtain the carbon monoxide oxidation catalyst.

[0031] As an optional implementation, in this embodiment of the application, the method for preparing the carbon monoxide oxidation catalyst further includes: in step S2, a cerium precursor may be added to the first mixture to obtain a vanadium-titanium-cerium mixture.

[0032] The cerium precursor is selected from one of cerium nitrate solution, cerium chloride solution, and cerium acetate solution; preferably, the cerium precursor is cerium nitrate solution.

[0033] The catalyst may further include an auxiliary agent, which includes cerium oxide. The cerium oxide content in the catalyst is 2% to 5% by mass percentage; preferably, the cerium oxide content in the catalyst is 3% by mass percentage.

[0034] Thus, by introducing a certain amount of cerium oxide as an additive, the excellent oxygen storage capacity of cerium can be utilized to dynamically capture sulfur dioxide and form cerium sulfate (in-situ diffuse reflectance infrared Fourier transform spectroscopy confirmed that the characteristic peak intensity of sulfur dioxide decreased by 63%), while releasing lattice oxygen to maintain the catalytic cycle.

[0035] The method for preparing the carbon monoxide oxidation catalyst provided in this application establishes a synergistic mechanism of "dual active sites - gradient support - dynamic sulfur resistance".

[0036] As an optional implementation, in this embodiment of the application, the impregnation process includes: The catalyst support is placed in a precursor mixture solution for a first impregnation treatment to obtain a catalyst support impregnated with a noble metal. The catalyst support impregnated with the noble metal is then subjected to a second drying treatment to obtain a catalyst support loaded with a noble metal. The second drying treatment includes: drying the catalyst support impregnated with the noble metal under a vacuum condition of 90℃~110℃ for 1.5h~3h; the vacuum degree during the second drying treatment is -0.07MPa~-0.09 MPa. Preferably, the second drying treatment includes: drying the catalyst support impregnated with the noble metal under a vacuum condition of 100℃ for 2h; the vacuum degree during the second drying treatment is -0.08MPa. The catalyst support one loaded with noble metal is placed in the precursor mixture solution two for a second impregnation treatment to obtain the catalyst support two impregnated with noble metal; the catalyst support two impregnated with noble metal is then subjected to a third drying treatment to obtain the catalyst support two loaded with noble metal; the third drying treatment includes: placing the catalyst support two impregnated with noble metal in an inert atmosphere at 140℃~160℃ for 1.5h~3h; the gas flow rate of the inert gas in the inert atmosphere is 40mL / min~60 mL / min; preferably, the third drying treatment includes: placing the catalyst support two impregnated with noble metal in an inert atmosphere at 150℃ for 2h; the gas flow rate of the inert gas in the inert atmosphere is 50mL / min. The catalyst support second loaded with noble metals is placed in the precursor mixed solution third for a third impregnation treatment to obtain the catalyst support loaded with noble metals. The first, second, and third impregnation treatments all meet the following conditions: the impregnation time is 8 min to 15 min; the impregnation temperature is 25℃ to 40℃; ultrasonic-assisted impregnation is used; the frequency of the ultrasonic waves is 30 kHz to 50 kHz, and the power of the ultrasonic waves is 150 W to 250 W; in the first impregnation treatment, the mass of the first precursor mixed solution is 30% to 40% of the saturated adsorption mass of the catalyst support; in the second impregnation treatment, the mass of the second precursor mixed solution is 30% to 40% of the saturated adsorption mass of the first catalyst support loaded with noble metals; in the third impregnation treatment, the mass of the third precursor mixed solution is 30% to 40% of the saturated adsorption mass of the second catalyst support loaded with noble metals.

[0037] Preferably, the first impregnation treatment, the second impregnation treatment, and the third impregnation treatment all meet the following conditions: the impregnation time is 9 min to 11 min; the impregnation temperature is 30°C; ultrasonic-assisted impregnation is used; the frequency of the ultrasonic wave is 40 kHz, and the power of the ultrasonic wave is 200 W; in the first impregnation treatment, the mass of the first precursor mixed solution is 35% of the saturated adsorption mass of the catalyst support; in the second impregnation treatment, the mass of the second precursor mixed solution is 35% of the saturated adsorption mass of the first catalyst support loaded with noble metal; and in the third impregnation treatment, the mass of the third precursor mixed solution is 35% of the saturated adsorption mass of the second catalyst support loaded with noble metal.

[0038] In some embodiments of this application, the reduction roasting process includes: heating the catalyst support loaded with noble metal to 300°C~400°C and holding it at that temperature for 2h~4h; the roasting atmosphere during the reduction roasting process consists of hydrogen gas accounting for 3%~7% by volume and inert gas accounting for 93%~97% by volume. Preferably, the reduction roasting process includes: heating the catalyst support loaded with noble metal to 350°C and holding it at that temperature for 3h; the roasting atmosphere during the reduction roasting process consists of hydrogen gas accounting for 5% by volume and inert gas accounting for 95% by volume.

[0039] As an optional implementation, in this embodiment of the application, the vanadium source includes ammonium metavanadate; The titanium source includes tetrabutyl titanate; The alcohol solvent includes any one or more of ethanol, methanol, and isopropanol; The citric acid solution has a mass concentration of 15% to 25%. In the vanadium-titanium mixture, the volume ratio of the alcohol solvent to the citric acid solution is (3:1) to (5:1); In the vanadium-titanium mixture, the molar ratio of vanadium in the vanadium source to titanium in the titanium source is (1:5) to (1:3); In the vanadium-titanium mixture, the ratio of the molar mass of citric acid in the citric acid solution to the total molar mass of vanadium in the vanadium source and titanium in the titanium source is (1:1) to (1.5:1); preferably, in the vanadium-titanium mixture, the ratio of the molar mass of citric acid in the citric acid solution to the total molar mass of vanadium in the vanadium source and titanium in the titanium source is 1.2:1.

[0040] As an optional implementation, in this embodiment of the application, the aging treatment includes: aging the vanadium-titanium mixture in a water bath for 18h~30h; the water bath temperature for the water bath treatment is 70℃~90℃; preferably, the aging treatment is: aging the vanadium-titanium mixture in a water bath for 24h; the water bath temperature for the water bath treatment is 78℃~82℃.

[0041] As an optional implementation, in this embodiment of the application, the first drying process includes drying the gel carrier at 100℃~150℃ for 10h~15h and then cooling it to 10℃~30℃; preferably, the first drying process includes drying the gel carrier at 120℃ for 12h and then cooling it to 10℃~30℃. The stepped calcination process includes sequentially performing a first calcination and a second calcination on the gel carrier after the first drying treatment. The first calcination includes: heating the gel carrier after the first drying treatment to 300℃~400℃ and holding it at that temperature for 1h~3h; the heating rate during the first calcination is 1℃ / min~3℃ / min; preferably, the first calcination includes: heating the gel carrier after the first drying treatment to 350℃ and holding it at that temperature for 2h; the heating rate during the first calcination is 2℃ / min; The second calcination includes: heating the gel carrier after the first calcination treatment to 550℃~650℃ and holding it at that temperature for 3h~5h; the heating rate during the second calcination is 3℃ / min~8℃ / min; preferably, the second calcination includes: heating the gel carrier after the first calcination treatment to 600℃ and holding it at that temperature for 4h; the heating rate during the second calcination is 5℃ / min.

[0042] As an optional implementation, in this embodiment, the precursor mixed solution includes a mixed solution of palladium precursor solution and platinum precursor solution; the palladium precursor solution is selected from palladium chloride solution, palladium nitrate solution, and palladium acetate solution; preferably, the palladium precursor solution is palladium chloride solution; the platinum precursor solution is selected from chloroplatinic acid solution, ammonium chloroplatinate solution, and platinum nitrate solution; preferably, the platinum precursor solution is chloroplatinic acid solution; the molar concentration of the palladium precursor solution is 0.08 mol / L to 0.12 mol / L; preferably, the molar concentration of the palladium precursor solution is 0.1 mol / L; the molar concentration of the platinum precursor solution is 0.04 mol / L to 0.06 mol / L; preferably, the molar concentration of the platinum precursor solution is 0.05 mol / L.

[0043] The carbon monoxide oxidation catalyst prepared by the above method was applied to the flue gas of iron and steel smelting. In the iron and steel flue gas environment (1% carbon monoxide, 15% oxygen, 200 ppm sulfur dioxide, 300℃), the ignition temperature with a carbon monoxide conversion rate of 90% was as low as 135℃~150℃. After operating under sulfur-containing conditions for 100 hours, the activity decay rate of the catalyst was no higher than 10%. After aging at 600℃ for 12 hours, its activity retention rate was no less than 95%.

[0044] Based on a general inventive concept, this application provides an application of the above-mentioned carbon monoxide oxidation catalyst, which is used in the purification treatment of carbon monoxide in iron and steel smelting flue gas, carbon monoxide in coke oven gas, carbon monoxide in transmission gas, and carbon monoxide in automobile exhaust.

[0045] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If no corresponding national standard exists, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0046] Example 1 Example 1 provides a method for preparing a carbon monoxide oxidation catalyst, comprising the following steps: Step S1: Provide ammonium metavanadate, tetrabutyl titanate, anhydrous ethanol, citric acid solution, and precursor mixed solution; Step S2: Mix anhydrous ethanol, the citric acid solution (36g), and the cerium precursor (5g) to obtain a first mixture; dissolve the ammonium metavanadate (12.3g) and tetrabutyl titanate (87.4g) in the first mixture to obtain a vanadium-titanium mixture; the cerium precursor is a cerium nitrate solution; the concentration of the cerium nitrate solution is 0.2 mol / L; The mass of anhydrous ethanol is four times the mass of the citric acid solution; the mass concentration of the citric acid solution is 20%. In the vanadium-titanium mixture, the volume ratio of the alcohol solvent to the citric acid solution is 4:1; In the vanadium-titanium mixture, the molar ratio of vanadium in the vanadium source to titanium in the titanium source is 1:4; Step S3: The vanadium-titanium mixture is aged to obtain a gel carrier; The aging process includes aging the vanadium-titanium mixture in a water bath for 24 hours; the water bath temperature is 80°C.

[0047] Step S4: The gel support is dried at 120℃ for 12 hours, cooled to room temperature, and then subjected to a stepwise calcination treatment to obtain a vanadium-titanium-cerium composite catalyst support. The catalyst support prepared in Example 1 of this case was characterized by nitrogen adsorption-desorption isotherm (BET) analysis, which revealed a specific surface area of ​​approximately 92 m². 2 / g; The stepped calcination process includes sequentially subjecting the gel carrier after the first drying process to a first calcination and a second calcination. The first calcination includes: heating the dried gel carrier to 350°C and holding it at that temperature for 2 hours; the heating rate during the first calcination is 2°C / min. The second calcination includes: heating the gel carrier after the first calcination treatment to 600°C and holding it at that temperature for 4 hours; the heating rate during the second calcination is 5°C / min; Step S5: The catalyst support is placed in the precursor mixture solution for impregnation treatment to obtain a catalyst support loaded with noble metals. The precursor mixture solution comprises a mixture of palladium chloride solution and chloroplatinic acid solution; the volume ratio of the palladium chloride solution to the chloroplatinic acid solution is 3:1; the molar concentration of the palladium chloride solution is 0.1 mol / L; and the molar concentration of the chloroplatinic acid solution is 0.05 mol / L.

[0048] The impregnation process includes: The catalyst support is placed in a precursor mixture solution for a first impregnation treatment to obtain a catalyst support impregnated with a noble metal; the catalyst support impregnated with a noble metal is then subjected to a second drying treatment to obtain a catalyst support loaded with a noble metal; the second drying treatment includes: placing the catalyst support impregnated with a noble metal under vacuum conditions at 100°C for 2 hours; the vacuum degree during the second drying treatment is -0.08 MPa; The catalyst support one loaded with noble metals is placed in the precursor mixture solution two for a second impregnation treatment to obtain the catalyst support two impregnated with noble metals; the catalyst support two impregnated with noble metals is then subjected to a third drying treatment to obtain the catalyst support two loaded with noble metals; the third drying treatment includes: placing the catalyst support two impregnated with noble metals in a nitrogen atmosphere at 150°C for 2 hours; the nitrogen gas flow rate in the nitrogen atmosphere is 50 mL / min; The catalyst support second loaded with noble metals is placed in the precursor mixed solution third for a third impregnation treatment to obtain the catalyst support loaded with noble metals. The first, second, and third impregnation treatments all meet the following conditions: the impregnation time is 10 minutes; the impregnation temperature is 30°C; ultrasonic-assisted impregnation is used; the frequency of the ultrasonic waves is 40 kHz, and the power of the ultrasonic waves is 200 W; in the first impregnation treatment, the mass of the first precursor mixed solution is 35% of the saturated adsorption mass of the catalyst support; in the second impregnation treatment, the mass of the second precursor mixed solution is 35% of the saturated adsorption mass of the first catalyst support loaded with noble metals; in the third impregnation treatment, the mass of the third precursor mixed solution is 35% of the saturated adsorption mass of the second catalyst support loaded with noble metals.

[0049] Step S6: The catalyst support loaded with noble metals is subjected to reduction roasting treatment to obtain the carbon monoxide oxidation catalyst.

[0050] The reduction roasting process includes: heating the catalyst support loaded with noble metals to 350°C at a heating rate of 2°C / min and holding it at that temperature for 3 hours; the roasting atmosphere during the reduction roasting process consists of hydrogen gas accounting for 5% by volume and nitrogen gas accounting for 95% by volume.

[0051] The carbon monoxide oxidation catalyst prepared by the above method was used in the flue gas of iron and steel smelting. The flue gas composition, by volume percentage, was: carbon monoxide: 1%, oxygen: 15%, sulfur dioxide: 200 ppm; the flue gas temperature was 300°C. Results showed that, using only 0.6% of the precious metals (palladium and platinum) in this embodiment, the ignition temperature achieving a 50% carbon monoxide conversion rate could be as low as 120°C (T0). 50 =120℃); the ignition temperature for carbon monoxide conversion of 90% can be as low as 135℃ (T 90 =135℃); after 500 hours of operation under sulfur-containing conditions, the catalyst's activity decay rate was 4.7%. Under conditions containing 200 ppm sulfur dioxide, after 300 hours of operation, the catalyst's activity retention rate was 95.3%.

[0052] After 300 hours of operation, the carbon deposition on the catalyst reached 2.1%.

[0053] Example 2 Example 2 provides a method for preparing a carbon monoxide oxidation catalyst. Compared with Example 1, the difference is that in step S3, the molar ratio of vanadium in the vanadium source to titanium in the titanium source is different in the vanadium-titanium mixture.

[0054] In this embodiment, in the vanadium-titanium mixture, the molar ratio of vanadium in the vanadium source to titanium in the titanium source is 1:3. (That is, 12.3g of ammonium metavanadate and 87.4g of tetrabutyl titanate were used in the experiment;) The remaining steps are the same as in Example 1, and will not be repeated here.

[0055] The carbon monoxide oxidation catalyst prepared by the above method was used in iron and steel smelting flue gas (consistent with Example 1). The results showed that, using only 0.6% of the precious metals (palladium and platinum) as in this example, the ignition temperature achieving a 50% carbon monoxide conversion was 95°C (T0). 50 =95℃); the ignition temperature for carbon monoxide conversion to 90% can be as low as 130℃ (T 90 =130℃); after 500 hours of operation under sulfur-containing conditions, the catalyst's activity decay rate was 9.5%. Under conditions containing 200 ppm sulfur dioxide, the catalyst's activity retention rate was 88% after 100 hours of operation. After 300 hours of operation, the catalyst's carbon deposition reached 1.8%.

[0056] Example 3 Example 3 provides a method for preparing a carbon monoxide oxidation catalyst. The difference from Example 1 is that the type of palladium precursor solution selected in step S3 is different.

[0057] In this embodiment, the palladium precursor solution is palladium acetate.

[0058] The remaining steps are the same as in Example 1, and will not be repeated here.

[0059] The carbon monoxide oxidation catalyst prepared by the above method was used in iron and steel smelting flue gas (consistent with Example 1). The results showed that, using only 0.6% of the precious metals (palladium and platinum) as in this example, the ignition temperature achieving a 50% carbon monoxide conversion was 105°C (T0). 50 =105℃); the ignition temperature for carbon monoxide conversion of 90% can be as low as 148℃ (T 90 =148℃); after 500 hours of operation under sulfur-containing conditions, the catalyst's activity decay rate was 10.5%. Under conditions containing 200 ppm sulfur dioxide, the catalyst's activity retention rate was 85% after 100 hours of operation. After 300 hours of operation, the catalyst's carbon deposition reached 1.9%.

[0060] Example 4 Example 4 provides a method for preparing a carbon monoxide oxidation catalyst. The difference from Example 1 is that no cerium precursor is added in step S2.

[0061] The remaining steps are the same as in Example 1, and will not be repeated here.

[0062] The carbon monoxide oxidation catalyst prepared by the above method was used in iron and steel smelting flue gas (consistent with Example 1). The results showed that, using only 0.6% of the precious metals (palladium and platinum) as in this example, the ignition temperature achieving a 50% carbon monoxide conversion was 105°C (T0). 50 =105℃); the ignition temperature for carbon monoxide conversion of 90% can be as low as 148℃ (T 90 =148℃); after 500 hours of operation under sulfur-containing conditions, the catalyst's activity decay rate was 10.5%. Under conditions containing 200 ppm sulfur dioxide, the catalyst's activity retention rate was 85% after 100 hours of operation. After 300 hours of operation, the catalyst's carbon deposition reached 1.9%.

[0063] Comparative Examples 1-2 Comparative Examples 1 and 2 each provide a method for preparing a carbon monoxide oxidation catalyst. The difference from Example 1 is that in step S3, the molar ratio of vanadium in the vanadium source to titanium in the titanium source is different in the vanadium-titanium mixture.

[0064] In Comparative Example 1, the molar ratio of vanadium in the vanadium source to titanium in the titanium source in the vanadium-titanium mixture is 1:6. In Comparative Example 2, the molar ratio of vanadium in the vanadium source to titanium in the titanium source in the vanadium-titanium mixture is 1:2. The remaining steps are the same as in Example 1, and will not be repeated here.

[0065] The carbon monoxide oxidation catalysts prepared by the methods provided in Comparative Examples 1 and 2 were used in iron and steel smelting flue gas (consistent with Example 1). The results showed that: When using only 0.6% of the precious metals (palladium and platinum) as in Comparative Example 1, the ignition temperature for achieving a 50% carbon monoxide conversion was 155°C (T0). 50 =155℃); the ignition temperature for a carbon monoxide conversion rate of 90% is 155℃ (T 90 =155℃); after 500 hours of operation under sulfur-containing conditions, the catalyst's activity decay rate was 48%. Under conditions containing 200 ppm sulfur dioxide, the catalyst's activity retention rate was 52% after 100 hours of operation. After 300 hours of operation, the catalyst's carbon deposition reached 7.5%.

[0066] When using only 0.6% of the precious metals (palladium and platinum) as in Comparative Example 2, the ignition temperature for achieving a 50% carbon monoxide conversion was 140℃ (T0). 50 =140℃); the ignition temperature for achieving a 90% carbon monoxide conversion rate is 195℃ (T 90=195℃); after 500 hours of operation under sulfur-containing conditions, the catalyst's activity decay rate was 65%. Under conditions containing 200 ppm sulfur dioxide, the catalyst's activity retention rate was 45% after 100 hours of operation. After 300 hours of operation, the catalyst's carbon deposition reached 9.2%.

[0067] Comparative Examples 3-4 Comparative Examples 3 and 4 each provide a method for preparing a carbon monoxide oxidation catalyst. Compared with Example 1, the difference lies in the molar concentration of the palladium precursor solution in step S5. The molar concentration of the palladium precursor solution in Comparative Example 3 is 0.05 mol / L; the molar concentration of the palladium precursor solution in Comparative Example 4 is 0.2 mol / L.

[0068] The remaining steps are the same as in Example 1, and will not be repeated here.

[0069] The carbon monoxide oxidation catalysts prepared by the methods provided in Comparative Examples 3 and 4 were used in iron and steel smelting flue gas (consistent with Example 1). The results showed that: Using the catalyst in Comparative Example 3, the ignition temperature for achieving a 50% carbon monoxide conversion was 132°C (T0). 50 =132℃); the ignition temperature for achieving a 90% carbon monoxide conversion rate is 175℃ (T 90 =175℃); after 500 hours of operation under sulfur-containing conditions, the catalyst's activity decay rate was 38%. Under conditions containing 200 ppm sulfur dioxide, the catalyst's activity retention rate was 65% after 100 hours of operation. After 300 hours of operation, the catalyst's carbon deposition reached 4.5%.

[0070] Using the catalyst in Comparative Example 4, the ignition temperature for achieving a 50% carbon monoxide conversion was 128°C (T0). 50 =128℃); the ignition temperature for achieving a 90% carbon monoxide conversion rate is 168℃ (T 90 =168℃); after 500 hours of operation under sulfur-containing conditions, the catalyst's activity decay rate was 72%. Under conditions containing 200 ppm sulfur dioxide, the catalyst's activity retention rate was 38% after 100 hours of operation. After 300 hours of operation, the catalyst's carbon deposition reached 3.8%.

[0071] Comparative Examples 5-6 Comparative Examples 5 and 6 each provide a method for preparing a carbon monoxide oxidation catalyst. Compared with Example 1, the difference lies in the molar concentration of the platinum precursor solution in step S5. The molar concentration of the platinum precursor solution in Comparative Example 5 is 0.02 mol / L; the molar concentration of the platinum precursor solution in Comparative Example 6 is 0.09 mol / L.

[0072] The carbon monoxide oxidation catalysts prepared by the methods provided in Comparative Examples 5 and 6 were used in iron and steel smelting flue gas (consistent with Example 1). The results showed that: Using the catalyst in Comparative Example 5, the ignition temperature for achieving a 50% carbon monoxide conversion was 118°C (T0). 50 =118℃); the ignition temperature for achieving a 90% carbon monoxide conversion rate is 165℃ (T 90 =165℃); after 500 hours of operation under sulfur-containing conditions, the catalyst's activity decay rate was 22%. Under conditions containing 200 ppm sulfur dioxide, the catalyst's activity retention rate was 78% after 100 hours of operation. After 300 hours of operation, the catalyst's carbon deposition reached 2.8%.

[0073] Using the catalyst in Comparative Example 6, the ignition temperature for achieving a 50% carbon monoxide conversion was 125°C (T0). 50 =125℃); the ignition temperature for achieving a 90% carbon monoxide conversion rate is 180℃ (T 90 =180℃); after 500 hours of operation under sulfur-containing conditions, the catalyst's activity decay rate was 28%. Under conditions containing 200 ppm sulfur dioxide, the catalyst's activity retention rate was 70% after 100 hours of operation. After 300 hours of operation, the catalyst's carbon deposition reached 3.5%.

[0074] Comparative Example 7 Comparative Example 7 provides a method for preparing a carbon monoxide oxidation catalyst, comprising the following steps: (1) Weigh out commercial γ-alumina microspheres (with a specific surface area of ​​250 m²). 2 The γ-alumina support was placed in a forced-air drying oven and dried at 120°C for 2 hours to remove the adsorbed moisture. It was then cooled to room temperature for later use.

[0075] (2) Weigh palladium nitrate (Pd(NO3)2), dissolve it in deionized water, and prepare a palladium precursor solution with a concentration of 0.05 mol / L.

[0076] (3) At room temperature, the palladium precursor solution is slowly and uniformly added to the γ-alumina support by dropwise addition, and the mixture is stirred continuously to ensure uniform wetting, so as to obtain a uniformly mixed mixture; then the mixture is placed at room temperature and aged for 12 hours to obtain an aged product; wherein, the volume of the palladium precursor solution is equal to the total pore volume of the γ-alumina support; (4) Place the aged material in a forced-air drying oven and dry it at 120°C for 12 hours; (5) The dried aged material is placed in a tube furnace and heated from room temperature to 350°C at a heating rate of 2°C / min in a mixed atmosphere of H2 / N2 (H2 volume fraction of 5% and N2 volume fraction of 95%), and is kept at this temperature for 3 hours for reduction. After reduction, it is cooled to room temperature under an inert atmosphere to obtain the catalyst. In the catalyst, the palladium loading (mass percentage) is 0.6%.

[0077] This method uses a γ-alumina support, which is directly reduced at 350℃ after a single impregnation with palladium. Results: T 90 =185℃, under sulfur-containing conditions, the activity decreases by 41.5% after 100h, and the specific surface area decreases by 52% after aging at 600℃.

[0078] Comparing Examples 1, 2, and 1-2, it can be seen that in the vanadium-titanium mixture, the higher the titanium content, the lower the catalyst activity decay rate and the lower the oxygen vacancy density of the catalyst support. However, the ignition temperature of the carbon monoxide conversion of the catalyst used will be higher. Therefore, the titanium content needs to be controlled to a certain extent. This is because excessive TiO2 reduces the V2O5 content on the catalyst surface, thereby reducing the active sites on the catalyst surface. At the same time, it reduces the metal interaction between V and Ti, hindering the conversion of gaseous oxygen to active oxygen. It can also be seen that if the titanium content is too high, not only will the ignition temperature of the carbon monoxide conversion of the catalyst increase, but the activity decay rate of the catalyst itself will also increase significantly, which will lead to serious damage to the efficiency.

[0079] Electron microscopy analysis was performed on the catalysts in Example 1 and Comparative Example 1, and the results are as follows: Figure 1 , Figure 3 As shown, the palladium metal particles in the catalyst prepared in Example 1 are clearly larger. These large-particle palladium metals form metal clusters, making it easier for adsorbed CO and O2 to adsorb onto nearby active sites, thus lowering the ignition temperature for carbon monoxide conversion. However, if the metal clusters become too large and aggregate, resulting in excessively large precious metal particles, the catalyst's activity decay rate will increase.

[0080] Comparing Examples 1 and 4, it is evident that the addition of the cerium precursor increases the ignition temperature at which the catalyst achieves a 50% carbon monoxide conversion, while slightly decreasing the ignition temperature at which it achieves a 90% carbon monoxide conversion; the catalyst's activity decay rate is significantly reduced. This is because the addition of the cerium precursor enhances the catalyst's ability to store and release oxygen, increasing the mobility of active oxygen and thus improving catalyst activity.

[0081] Comparing Example 1 and Comparative Examples 3-4, it can be seen that excessively high molar concentrations of the palladium precursor solution (above 0.12 mol / L) significantly increase the catalyst's activity decay rate, and also raise the ignition temperature at which the catalyst achieves a 90% carbon monoxide conversion rate. Conversely, excessively low molar concentrations of the palladium precursor solution (below 0.08 mol / L) also increase the catalyst's activity decay rate, and further raise the ignition temperature at which the catalyst achieves a 90% carbon monoxide conversion rate. This is because excessively high concentrations of the palladium precursor solution lead to greater Pd aggregation on the catalyst surface, while excessively low concentrations result in a decrease in the content of active sites on the catalyst surface, leading to a decline in catalyst activity.

[0082] In addition, the catalysts in Example 1 and Comparative Example 3 were subjected to sulfur resistance testing experiments in flue gas containing 50 ppm SO2. Electron microscopy analysis before and after sulfur resistance was performed, such as... Figures 2-3 As shown; from Figure 2 (a) It can be seen that the morphological changes of the catalyst used in Example 1 before and after sulfur resistance are not significant. From Figure 2 (b) It can be seen that the morphology of the catalyst used in Comparative Example 3 changed significantly before and after the sulfur resistance test; the electron microscopy of the catalyst in Comparative Example 3 after the sulfur resistance test showed ( Figure 3 (b) The presence of irregular small particles on the catalyst surface indicates that SO2 reacts with the active species on the catalyst surface to form sulfates, which cover the active sites and lead to a decrease in catalyst activity.

[0083] Comparing Example 1 and Comparative Examples 5-6, it can be seen that excessively high molar concentrations of the platinum precursor solution (above 0.06 mol / L) significantly increase the catalyst's activity decay rate, and also raise the ignition temperature at which the catalyst achieves a 90% carbon monoxide conversion. Conversely, excessively low molar concentrations of the palladium precursor solution (below 0.04 mol / L) also increase the catalyst's activity decay rate, and further raise the ignition temperature at which the catalyst achieves a 90% carbon monoxide conversion. This is because excessively high platinum precursor solution concentrations lead to greater Pt aggregation on the catalyst surface, while excessively low concentrations result in a decrease in the content of active sites on the catalyst surface, leading to a decline in catalyst activity.

[0084] In summary, this invention provides a carbon monoxide oxidation catalyst and its preparation method. Regarding the design of the active components, the catalyst employs a palladium-platinum bimetallic synergistic effect, where palladium dominates carbon monoxide adsorption and activation, while platinum promotes oxygen dissociation. In terms of the support structure, vanadium pentoxide is doped with titanium dioxide to form a solid solution complex, which can generate more oxygen vacancies. The preparation method involves dissolving vanadium and titanium sources in a solution of alcohol and citric acid, followed by aging, drying, and step-calcination treatments, and then performing multiple impregnation treatments to obtain a catalyst support loaded with noble metals. Finally, the catalyst support loaded with noble metals is subjected to reduction calcination treatment, thus constructing a synergistic mechanism of "dual active sites - gradient support - dynamic sulfur resistance." When applied to iron and steel smelting flue gas, in an iron and steel flue gas environment (1% carbon monoxide, 15% oxygen, 200 ppm sulfur dioxide, 300°C), the ignition temperature reaches as low as 130°C with a carbon monoxide conversion rate of 90%.

[0085] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.

Claims

1. A carbon monoxide oxidation catalyst, characterized in that, The catalyst comprises an active component and a support; The active components include palladium and platinum; The carrier comprises vanadium pentoxide-titanium dioxide composite oxide.

2. The carbon monoxide oxidation catalyst according to claim 1, characterized in that, The molar ratio of vanadium to titanium in the vanadium pentoxide-titanium dioxide composite oxide is (1:5) to (1:3); and / or, In the catalyst, the palladium has a mass percentage of 0.2% to 0.6%; and / or, In the catalyst, the platinum mass percentage is 0.1% to 0.4%; and / or, The molar ratio of palladium to platinum in the active component is (1.5:1) to (3:1).

3. A method for preparing the carbon monoxide oxidation catalyst according to claim 1 or 2, characterized in that, Includes the following steps: We provide vanadium sources, titanium sources, alcohol solvents, citric acid solutions, and precursor mixed solutions. The alcohol solvent and the citric acid solution are mixed to obtain a first mixture; the vanadium source and the titanium source are dissolved in the first mixture to obtain a vanadium-titanium mixture. The vanadium-titanium mixture was aged to obtain a gel carrier; The gel support was subjected to a first drying treatment and a step-by-step calcination treatment in sequence to obtain a catalyst support; The catalyst support is placed in the precursor mixture solution for impregnation treatment to obtain a catalyst support loaded with noble metals. The catalyst support loaded with noble metals is subjected to reduction roasting treatment to obtain the carbon monoxide oxidation catalyst.

4. The method for preparing the carbon monoxide oxidation catalyst according to claim 3, characterized in that, The impregnation process includes: The catalyst support is placed in a precursor mixture solution for a first impregnation treatment to obtain a catalyst support impregnated with noble metals; the catalyst support impregnated with noble metals is then subjected to a second drying treatment to obtain a catalyst support loaded with noble metals; the second drying treatment includes: placing the catalyst support impregnated with noble metals under vacuum conditions of 90℃~110℃ for 1.5h~3h; the vacuum degree of the vacuum conditions during the second drying treatment is -0.07MPa~-0.09 MPa; The catalyst support one loaded with noble metal is placed in the precursor mixture solution two for a second impregnation treatment to obtain the catalyst support two impregnated with noble metal; the catalyst support two impregnated with noble metal is then subjected to a third drying treatment to obtain the catalyst support two loaded with noble metal; the third drying treatment includes: placing the catalyst support two impregnated with noble metal in an inert atmosphere at 140℃~160℃ for 1.5h~3h; the gas flow rate of the inert gas in the inert atmosphere is 40mL / min~60mL / min; The catalyst support second loaded with noble metals is placed in the precursor mixed solution third for a third impregnation treatment to obtain the catalyst support loaded with noble metals. The first, second, and third impregnation treatments all meet the following conditions: the impregnation time is 8 min to 15 min; the impregnation temperature is 25℃ to 40℃; ultrasonic-assisted impregnation is used; the frequency of the ultrasonic waves is 30 kHz to 50 kHz, and the power of the ultrasonic waves is 150 W to 250 W; in the first impregnation treatment, the mass of the first precursor mixed solution is 30% to 40% of the saturated adsorption mass of the catalyst support; in the second impregnation treatment, the mass of the second precursor mixed solution is 30% to 40% of the saturated adsorption mass of the first catalyst support loaded with noble metals; in the third impregnation treatment, the mass of the third precursor mixed solution is 30% to 40% of the saturated adsorption mass of the second catalyst support loaded with noble metals.

5. The method for preparing the carbon monoxide oxidation catalyst according to claim 3, characterized in that, The reduction roasting process includes: heating the catalyst support loaded with noble metal to 300℃~400℃ and holding it at that temperature for 2h~4h; the roasting atmosphere during the reduction roasting process consists of hydrogen gas accounting for 3%~7% by volume and inert gas accounting for 93%~97% by volume.

6. The method for preparing the carbon monoxide oxidation catalyst according to claim 3, characterized in that, The vanadium source includes ammonium metavanadate; and / or, The titanium source includes tetrabutyl titanate; and / or, The alcohol solvent includes any one or more of ethanol, methanol, and isopropanol; and / or, The citric acid solution has a mass concentration of 15% to 25%; and / or, In the vanadium-titanium mixture, the volume ratio of the alcohol solvent to the citric acid solution is (3:1) to (5:1); and / or, In the vanadium-titanium mixture, the molar ratio of vanadium in the vanadium source to titanium in the titanium source is (1:5) to (1:3); and / or, In the vanadium-titanium mixture, the ratio of the molar mass of citric acid in the citric acid solution to the total molar mass of vanadium in the vanadium source and titanium in the titanium source is (1:1) to (1.5:1).

7. The method for preparing the carbon monoxide oxidation catalyst according to claim 3, characterized in that, The aging process includes aging the vanadium-titanium mixture in a water bath for 18 to 30 hours; the water bath temperature is 70°C to 90°C.

8. The method for preparing the carbon monoxide oxidation catalyst according to claim 3, characterized in that, The first drying process includes drying the gel carrier at 100°C to 150°C for 10 to 15 hours, and then cooling it to 10°C to 30°C; and / or, The stepped calcination process includes sequentially performing a first calcination and a second calcination on the gel carrier after the first drying treatment. The first calcination includes: heating the gel carrier after the first drying treatment to 300℃~400℃ and holding it at that temperature for 1h~3h; the heating rate during the first calcination is 1℃ / min~3℃ / min; The second calcination includes: heating the gel carrier after the first calcination treatment to 550℃~650℃ and holding it at that temperature for 3h~5h; the heating rate during the second calcination is 3℃ / min~8℃ / min.

9. The method for preparing the carbon monoxide oxidation catalyst according to claim 3, characterized in that, The precursor mixture solution comprises a mixture of palladium precursor solution and platinum precursor solution; the palladium precursor solution is selected from palladium chloride solution, palladium nitrate solution, and palladium acetate solution; the platinum precursor solution is selected from chloroplatinic acid solution, ammonium chloroplatinate solution, and platinum nitrate solution; the molar concentration of the palladium precursor solution is 0.08 mol / L to 0.12 mol / L; the molar concentration of the platinum precursor solution is 0.04 mol / L to 0.06 mol / L.

10. The application of the carbon monoxide oxidation catalyst according to claim 1 or 2, characterized in that, The carbon monoxide oxidation catalyst is used for the purification of carbon monoxide in iron and steel smelting flue gas, carbon monoxide in coke oven gas, and carbon monoxide in automobile exhaust.

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