Preparation method and application of ceria-supported bimetallic catalyst

Abstract

The application belongs to the field of carbon monoxide treatment and catalytic oxidation in sintering flue gas, and discloses a preparation method and application of a ceria-supported bimetallic catalyst. A cerium source, a surfactant, a complexing agent and a crosslinking agent solution are mixed, and the pH is adjusted to make metal ions form hydroxide precipitates to obtain a precursor turbid solution. After hydrothermal reaction, the precursor turbid solution is filtered, washed, dried, ground and calcined to obtain a precursor powder. The precursor powder is dispersed, and a bimetallic solution is gradually added dropwise. The ceria-supported bimetallic catalyst is obtained through drying and calcination treatment. 3+ The surfactant, the complexing agent and the crosslinking agent are introduced to synergistically regulate Ce Hydrolysis, inhibit grain growth and construct three-dimensional network limited space, obtain small grain, large specific surface area, rich in defects of ceria carrier, make it uniform dispersion, enhance metal-support interaction, promote alloy phase or hetero-interface formation, so as to significantly improve the stability of catalytic active center, selectivity.

Description

Technical Field

[0001] This invention belongs to the field of carbon monoxide treatment and catalytic oxidation in sintering flue gas, and specifically relates to a method for preparing and applying a cerium dioxide-supported bimetallic catalyst. Background Technology

[0002] Catalytic oxidation is a typical end-of-pipe treatment technology for CO. This technology primarily converts CO into CO2 under the action of a catalyst, offering advantages such as low reaction temperature (120~300℃) and no secondary pollution. Furthermore, the catalytic oxidation of CO in sintering flue gas can usually be achieved by simply loading a catalyst into an SCR reactor, making it easy to operate. Therefore, CO catalytic oxidation is considered the most promising CO purification pathway. The application efficiency of CO catalytic oxidation technology is highly dependent on the catalyst activity, selectivity, and stability. Currently, industrial catalysts are mainly noble metal catalysts. Although noble metal catalysts have high reactivity and can achieve excellent CO catalytic oxidation performance, their scarcity leads to high costs (Pt loading is typically 0.1%~0.5%), and the high concentrations of SO2 and H2O in sintering flue gas easily compete with active sites for adsorption, causing irreversible poisoning and deactivation, thus limiting their application. While non-noble metal catalysts have lower application costs, they generally have lower catalytic efficiency for carbon monoxide and poor stability. Therefore, the rational design of catalyst structure and composition, and the improvement of catalyst selectivity and stability have become important issues that urgently need to be addressed. This is of great significance for promoting the purification of sintering flue gas in the iron and steel industry and achieving the "dual carbon" strategic goal. Summary of the Invention

[0003] This application provides a highly efficient and stable defect-rich cerium dioxide-supported bimetallic catalyst, its preparation method, and its application. Through the coupling of the support and active sites, this catalyst exhibits a significantly beneficial effect on the oxidation and removal of carbon monoxide from sintering flue gas. It has high application value for treating low-concentration carbon monoxide in sintering flue gas.

[0004] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, this application provides a method for preparing a cerium dioxide-supported bimetallic catalyst, comprising the following steps: S1. Dissolve the cerium source in water and stir until homogeneous. Add a certain amount of crosslinking agent, surfactant, and complexing agent, and stir until homogeneous to obtain a mixed solution. Then, add an alkaline solution dropwise to adjust the pH of the solution to 10-12, causing the metal ions to form hydroxide precipitates, resulting in a turbid precursor solution. S2, the turbid precursor liquid obtained from S1 is poured into a hydrothermal reactor and heated in a sealed environment at 100~150℃ for 1~10h. The reaction product is then filtered, washed, dried and ground to obtain precursor powder. The precursor powder is then calcined at 400~600℃ for 0.5~5h to obtain cerium dioxide support. The calcination process is carried out in an air atmosphere. S3, add the cerium dioxide powder obtained in S2 to water and disperse it by ultrasonication to obtain a cerium dioxide dispersion. Place the cerium dioxide dispersion in a water bath and gradually add the prepared bimetallic solution while stirring. Continue stirring and react for 1 to 5 hours. Then heat to 60 to 80°C and continue stirring until the material is completely dry to obtain a solid substance. S4. The solid material obtained in S3 is heated to 400~600℃ and calcined for 0.5~5h under an inert atmosphere to obtain a cerium dioxide supported bimetallic catalyst.

[0005] Optionally, in step S1, the cerium source is one or a mixture of two of cerium nitrate, cerium acetate, cerium carbonate, cerium sulfate, and cerium oxalate, and after dissolution, Ce... 3+ The molar concentration range is 0.5 ~ 1.5 mol / L.

[0006] Optionally, in step S1, the crosslinking agent is one or a mixture of two of α-cyclodextrin, γ-cyclodextrin, polyethylene glycol (PEG), and chitosan, and the molar concentration of the crosslinking agent in water ranges from 0.001 to 0.01 mol / L.

[0007] Optionally, in step S1, the surfactant is one of hexadecyltrimethylammonium bromide (CTAB), hexadecyltrimethylammonium chloride, and dodecyltrimethylammonium chloride, and the molar concentration of the surfactant is 0.002~0.01mol / L.

[0008] Optionally, in step S1, the complexing agent is one of citric acid, malic acid, ethylenediaminetetraacetic acid, and phytic acid, and the molar concentration of the complexing agent is 0.1~0.5 mol / L.

[0009] Optionally, in step S1, the alkaline solution is a sodium hydroxide or potassium hydroxide solution with a molar concentration of 0.5~3 mol / L.

[0010] Optionally, in step S1, the stirring speed is 300-500 r / min, the alkaline solution is added at a rate of 1-15 mL / min, until the pH reaches 10-12, then the addition of alkaline solution is stopped, and stirring is continued for 1-2 hours to allow the reaction to proceed fully.

[0011] Optionally, in step S2, the particle size distribution of the cerium dioxide support is D50≤0.5μm and D90≤5μm.

[0012] Optionally, in step S3, the bimetallic solution is any combination of two metal salts selected from nickel nitrate, cobalt nitrate, copper nitrate, and manganese nitrate, and the molar concentration of the bimetallic solution is 0.1~0.9 mol / L.

[0013] Secondly, a cerium dioxide-supported bimetallic catalyst prepared by the above method.

[0014] Thirdly, this application provides the application of the above-mentioned cerium dioxide-supported bimetallic catalyst as a catalytically active material in the oxidation of CO in sintering flue gas.

[0015] Optionally, 0.5-3g of the cerium dioxide-supported bimetallic catalyst is packed into a catalytic oxidation fixed reaction bed for sintering flue gas, and sintering flue gas containing CO is introduced, with a CO content of 1.0-3.0% (by volume). The flow rate of the sintering flue gas is 20-300 mL / min, and the temperature of the heating catalytic reaction is 180-300℃.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention introduces a crosslinking agent, a surfactant, and a complexing agent during the preparation stage of the cerium dioxide support. By introducing the surfactant, the crosslinking of cerium dioxide is controlled. 3+ The hydrolysis rate is improved, the precursor is promoted to be uniformly dispersed, and the aggregation of nanoparticles is effectively inhibited, thereby obtaining cerium dioxide nano-precursors with uniform size and controllable morphology; at the same time, by adding a complexing agent and Ce 3+ The formation of stable complexes by ions achieves uniform mixing of metal ions at the atomic level, effectively inhibiting excessive growth of cerium dioxide grains during precipitation and calcination, thus obtaining nano-cerium dioxide particles with fine grains and narrow particle size distribution. Furthermore, the introduction of a crosslinking agent constructs a three-dimensional network gel framework in the synthesis system, forming a nano-confined space that effectively restricts the growth and aggregation of cerium dioxide nanoparticles, achieving a spatial confinement effect. Finally, through the synergistic effect of the surfactant, complexing agent, and crosslinking agent, a cerium dioxide carrier with fine grain size, large specific surface area, and abundant defect sites is obtained. Based on this, when bimetals are loaded within the three-dimensional network confinement space formed by the crosslinking agent, the confinement space can effectively limit the migration and aggregation of bimetallic nanoparticles through the steric hindrance effect, so that their size is controlled in the sub-nanometer to several nanometer range and highly uniformly dispersed. At the same time, the confinement environment and the defect-rich surface of the cerium dioxide support synergistically induce strong metal-support interactions, promote the formation of more alloy phases or heterogeneous interfaces between the bimetals to enhance the electronic synergistic effect, thereby significantly improving the reaction selectivity and stability of the catalytic active center, and effectively inhibiting the sintering and loss of bimetallic nanoparticles during the reaction process. Attached Figure Description

[0017] Figure 1 These are results figures under some of the embodiment and comparative examples; Figure 2 These are SEM and TEM images of the catalyst prepared in Example 1. A is the SEM image and B is the TEM image. Detailed Implementation

[0018] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0019] Example 1 (1) Weigh 26.05g of cerium nitrate hexahydrate and add it to 60g of water, stirring to dissolve. 3+ The concentration of the substance was 1 mol / L. α-Cyclodextrin was used as a cross-linking agent; 0.3 g of α-cyclodextrin was weighed and added to the solution, and the mixture was stirred until homogeneous. The concentration of the cross-linking agent was 0.005 mol / L. Hexadecyltrimethylammonium bromide (CTAB) was used as a surfactant; 0.175 g of CTAB was weighed and added to the solution, and the mixture was stirred until homogeneous. The concentration of the surfactant was 0.008 mol / L. Citric acid was used as a complexing agent; 3.458 g of citric acid was weighed and added to the solution, and the mixture was stirred until homogeneous. The concentration of the complexing agent was 0.3 mol / L. A mixed solution was then prepared with a concentration of 0.5 mol / L sodium hydroxide solution. The sodium hydroxide solution was gradually added dropwise at a rate of 10 mL / min to the mixed solution while stirring at 400 r / min until the pH of the solution reached 10. Stirring was continued for 1 hour to ensure the reaction proceeded completely.

[0020] (2) Pour the turbid precursor liquid after the reaction in step 1 into a hydrothermal reactor, seal and heat at 120°C for 8 hours. After cooling, filter, wash, dry and grind the product in the hydrothermal reactor to obtain precursor powder. Then place the precursor powder in a muffle furnace in an air atmosphere and calcine at 550°C for 2 hours to obtain cerium dioxide support.

[0021] (3) Weigh 5.0 g of the obtained cerium dioxide powder and add it to 15 g of water for ultrasonic dispersion to obtain a cerium dioxide dispersion. Place the cerium dioxide dispersion in a water bath. The copper / manganese bimetallic solution is prepared using two salts: copper nitrate trihydrate and manganese nitrate tetrahydrate. The solution contains Cu 2+ and Mn 2+The calculated concentration of the bimetallic substance was 0.5 mol / L. 9 mL of bimetallic solution was measured and the prepared copper / manganese bimetallic solution was gradually added dropwise while stirring. The reaction was continued for 2 hours with stirring. Then, the mixture was heated to 80°C and stirred continuously until the material was completely dried to obtain a solid substance.

[0022] (4) The solid material obtained in step 3 is heated to 550°C and calcined for 2 hours under a nitrogen atmosphere to obtain a cerium dioxide-supported bimetallic catalyst.

[0023] The prepared cerium dioxide-supported iron / nickel bimetallic catalyst was packed into a fixed reaction bed for catalytic oxidation of sintering flue gas. Sintering flue gas containing CO (2.0% by volume) was introduced at a flow rate of 200 mL / min. The catalytic reaction was carried out at 180–300 °C. The conversion rate of CO catalytic oxidation by the cerium dioxide-supported bimetallic catalyst was tested, and the CO conversion rates at 180 °C, 210 °C, 240 °C, 270 °C, and 300 °C were recorded.

[0024] CO conversion rate = 1 - (CO concentration in the exhaust gas after reaction / CO concentration in the sintering flue gas) × 100%.

[0025] Example 2 The process and conditions are the same as in Example 1, the difference being that Ce in this example... 3+ The concentration differs from that in step (1) of the implementation process, as follows: (1) Weigh 31.26g of cerium nitrate hexahydrate and add it to 60g of water, stirring to dissolve. 3+ The molar concentration is 1.2 mol / L.

[0026] The remaining steps are the same as in Example 1. The cerium dioxide-supported bimetallic catalyst prepared in Example 2 is used to test the conversion rate of CO oxidation catalyzed by the catalyst. The test content and conditions are the same as in Example 1.

[0027] Example 3 The process and conditions are the same as in Example 1, the difference being that Ce in this example... 3+ The concentration differs from that in step (1) of the implementation process, as follows: (1) Weigh 15.63g of cerium nitrate hexahydrate and add it to 60g of water, stirring to dissolve. 3+ The concentration is 0.6 mol / L.

[0028] The remaining steps are the same as in Example 1. The cerium dioxide-supported bimetallic catalyst prepared in Example 3 is used to test the conversion rate of CO oxidation catalyzed by the catalyst. The test content and conditions are the same as in Example 1.

[0029] Example 4 The process and conditions are the same as in Example 1, except that the crosslinking agent used in this example is different, and step (1) is different, as follows: (1) Polyethylene glycol (PEG) was used as a crosslinking agent. 0.3g of PEG was weighed and added to the solution and stirred evenly. The molar concentration of the crosslinking agent was 0.008mol / L.

[0030] The remaining steps are the same as in Example 1. The cerium dioxide-supported bimetallic catalyst prepared in Example 4 is used to test the conversion rate of CO oxidation catalyzed by the catalyst. The test content and conditions are the same as in Example 1.

[0031] Example 5 The process and conditions are the same as in Example 1, except that the concentration of the surfactant used in this example is different, and step (1) is different, as follows: (1) Using cetyltrimethylammonium bromide (CTAB) as a surfactant, weigh 0.219 g of CTAB and add it to the solution and stir until homogeneous. The molar concentration of the surfactant is 0.01 mol / L.

[0032] The remaining steps are the same as in Example 1. The cerium dioxide-supported bimetallic catalyst prepared in Example 5 is used to test the conversion rate of CO oxidation catalyzed by the catalyst. The test content and conditions are the same as in Example 1.

[0033] Example 6 The process and conditions are the same as in Example 1, except that the concentration of the complexing agent used in this example is different, and step (1) is different, as follows: (1) Citric acid was used as a complexing agent. 1.15g of citric acid was weighed and added to the solution and stirred evenly. The molar concentration of the complexing agent was 0.1mol / L.

[0034] The remaining steps are the same as in Example 1. The cerium dioxide-supported bimetallic catalyst prepared in Example 6 is used to test the conversion rate of CO oxidation catalyzed by the catalyst. The test content and conditions are the same as in Example 1.

[0035] Example 7 The process and conditions are the same as in Example 1, except that the concentration of the complexing agent used in this example is different, and step (1) is different, as follows: (1) Citric acid was used as a complexing agent. 4.61 g of citric acid was weighed and added to the solution and stirred evenly. The molar concentration of the complexing agent was 0.4 mol / L.

[0036] The remaining steps are the same as in Example 1. The cerium dioxide-supported bimetallic catalyst prepared in Example 7 is used to test the conversion rate of CO oxidation catalyzed by the catalyst. The test content and conditions are the same as in Example 1.

[0037] Example 8 The process and conditions are the same as in Example 1, except that the bimetal used in this example is different, and step (3) in the implementation steps is different, as follows: (3) The nickel / cobalt bimetallic solution is prepared using two salts: nickel nitrate hexahydrate and cobalt nitrate hexahydrate. The solution contains Ni. 2+ and Co 2+ The calculated concentration of the bimetallic substance is 0.5 mol / L.

[0038] The remaining steps are the same as in Example 1. The cerium dioxide-supported bimetallic catalyst prepared in Example 8 is used to test the conversion rate of CO oxidation catalyzed by the catalyst. The test content and conditions are the same as in Example 1.

[0039] Example 9 The process and conditions are the same as in Example 1, except that the bimetal used in this example is different, and step (3) in the implementation steps is different, as follows: (3) The iron / manganese bimetallic solution is prepared using two salts: ferric nitrate nonahydrate and manganese nitrate tetrahydrate. The solution contains Fe 3+ and Mn 2+ The calculated concentration of the bimetallic substance is 0.5 mol / L.

[0040] The remaining steps are the same as in Example 1. The cerium dioxide-supported bimetallic catalyst prepared in Example 9 is used to test the conversion rate of CO oxidation catalyzed by the catalyst. The test content and conditions are the same as in Example 1.

[0041] Example 10 The process and conditions are the same as in Example 1, except that the concentration of the bimetallic solution used in this example is different, and step (3) in the implementation steps is different, as follows: (3) The copper / manganese bimetallic solution is prepared using two salts: copper nitrate trihydrate and manganese nitrate tetrahydrate. The solution contains Cu 2+ and Mn 2+ The calculated concentration of the bimetallic substance is 0.7 mol / L.

[0042] The remaining steps are the same as in Example 1. The cerium dioxide-supported bimetallic catalyst prepared in Example 10 is used to test the conversion rate of CO oxidation catalyzed by the catalyst. The test content and conditions are the same as in Example 1.

[0043] Example 11 The process and conditions are the same as in Example 1, except that the concentration of the bimetallic solution used in this example is different, and step (3) in the implementation steps is different, as follows: (3) The copper / manganese bimetallic solution is prepared using two salts: copper nitrate trihydrate and manganese nitrate tetrahydrate. The solution contains Cu 2+ and Mn 2+ The calculated concentration of the bimetallic substance is 0.3 mol / L.

[0044] The remaining steps are the same as in Example 1. The cerium dioxide-supported bimetallic catalyst prepared in Example 11 is used to test the conversion rate of CO oxidation catalyzed by the catalyst. The test content and conditions are the same as in Example 1.

[0045] To further illustrate the beneficial effects of the present invention, the following comparative analysis was conducted.

[0046] Comparative Example 1 The process and conditions are the same as in Example 1, except that no cross-linking agent is used in this example and no α-cyclodextrin is added in step (1).

[0047] The remaining steps are the same as in Example 1. The catalyst prepared in Comparative Example 1 is used to test the conversion rate of CO oxidation by the catalyst. The test content and conditions are the same as in Example 1.

[0048] Comparative Example 2 The process and conditions are the same as in Example 1. The difference is that the crosslinking agent used in this example has a low concentration. In step (1), 0.018g of α-cyclodextrin is added and the molar concentration of the crosslinking agent is 0.0003 mol / L.

[0049] The remaining steps are the same as in Example 1. The catalyst prepared in Comparative Example 2 is used to test the conversion rate of CO oxidation by the catalyst. The test content and conditions are the same as in Example 1.

[0050] Comparative Example 3 The process and conditions are the same as in Example 1, except that no surfactant is used in this example and no surfactant CTAB is added in step (1).

[0051] The remaining steps are the same as in Example 1. The catalyst prepared in Comparative Example 3 is used to test the conversion rate of CO oxidation by the catalyst. The test content and conditions are the same as in Example 1.

[0052] Comparative Example 4 The process and conditions are the same as in Example 1, except that no complexing agent is used in this example and no complexing agent citric acid is added in step (1).

[0053] The remaining steps are the same as in Example 1. The catalyst prepared in Comparative Example 4 is used to test the conversion rate of CO oxidation by the catalyst. The test content and conditions are the same as in Example 1.

[0054] Comparative Example 5 The process and conditions are the same as in Example 1, except that the concentration of the complexing agent in this comparative example is too high, and the concentration of the complexing agent citric acid added in step (1) is too high, as detailed below: (1) Citric acid was used as a complexing agent. 9.221 g of citric acid was weighed and added to the solution and stirred evenly. The molar concentration of the complexing agent was 0.8 mol / L.

[0055] The remaining steps are the same as in Example 1. The catalyst prepared in Comparative Example 5 is used to test the conversion rate of CO oxidation by the catalyst. The test content and conditions are the same as in Example 1.

[0056] Comparative Example 6 The process and conditions are the same as in Example 1, except that no bimetal is added in this comparative example, and no bimetal solution is added in step (3) of the implementation process, as follows: (3) Weigh 5.0 g of the obtained cerium dioxide powder and add it to 15 g of water for ultrasonic dispersion to obtain a cerium dioxide dispersion. Place the cerium dioxide dispersion in a water bath. Stir for the same duration as in Example 1, then heat to 80°C and continue stirring until the material is completely dry to obtain a solid substance.

[0057] The remaining steps were the same as in Example 1. The catalyst prepared in Comparative Example 6 was used to test the conversion rate of CO oxidation by the catalyst. The test content and conditions were the same as in Example 1.

[0058] Comparative Example 7 The process and conditions are the same as in Example 1, except that only a single metal is used in this comparative example. In step (3), a single metal solution is added, as follows: (3) The single metal solution is a copper metal solution, prepared using copper nitrate, and the Cu in the solution is... 2+ The molar concentration is 0.5 mol / L. 9 mL of a single metal solution is measured and gradually added dropwise while stirring. The reaction is continued for 2 hours with stirring. Then, the mixture is heated to 80°C and stirred continuously until the material is completely dry to obtain a solid substance.

[0059] The remaining steps were the same as in Example 1. The catalyst prepared in Comparative Example 7 was used to test the conversion rate of CO oxidation by the catalyst. The test content and conditions were the same as in Example 1.

[0060] Table 1. CO conversion rates under different temperature conditions in the examples and comparative examples. Comparative analysis of the examples and comparative examples revealed that, under optimal conditions, the cerium dioxide-supported bimetallic catalyst prepared with the crosslinking agent, surfactant, and complexing agent achieved a catalytic conversion rate of up to 100% for CO in flue gas. The results from Examples 1-3 show that different Ce... 3+ The concentration of cerium dioxide-supported bimetallic catalysts has a relatively small effect on the catalytic conversion of CO in flue gas. However, the catalytic effect of cerium dioxide-supported bimetallic catalysts is significantly better than that of catalysts supported by single metals. Comparing the results of Examples 5, 10, and 11, the higher the cerium dioxide-supported bimetallic loading, the better its performance in catalyzing CO in flue gas. Comparing the results of Example 1 and Comparative Examples 1, 3, and 4, it was found that the addition of crosslinking agent, surfactant, and complexing agent all effectively improved the catalytic conversion of CO in flue gas by cerium dioxide-supported bimetallic catalysts, and the effects of the concentrations of the three substances on the catalytic effect were different. For example, the results of Examples 4 and 5 showed that the catalytic conversion ability of cerium dioxide-supported bimetallic catalysts increased with the increase of surfactant concentration. The results of Examples 5, 6, and 7 showed that within a certain concentration range, the catalytic performance of the catalyst improved significantly with the increase of complexing agent concentration, but excessively high concentrations of complexing agent would reduce its catalytic performance. Furthermore, the results of Examples 3 and 4 show that the type of crosslinking agent affects the catalytic conversion of CO in flue gas by the cerium dioxide-supported bimetallic catalyst. Under the same concentration conditions, the catalyst prepared by α-cyclodextrin as a crosslinking agent has a better catalytic effect than the catalyst prepared by PEG as a crosslinking agent.

[0061] In summary, this application introduces crosslinking agents, surfactants, and complexing agents during the preparation stage of the cerium dioxide support to enhance its CO conversion efficiency in bimetallic catalytic flue gas. The conversion efficiency of CO in the supported flue gas is improved by introducing surfactants to regulate the cerium dioxide content. 3+ The hydrolysis rate is improved, the precursor is promoted to be uniformly dispersed, and the aggregation of nanoparticles is effectively inhibited; at the same time, the addition of a complexing agent and Ce... 3+Ions form stable complexes, achieving uniform mixing of metal ions at the atomic level and effectively suppressing excessive growth of cerium dioxide grains during precipitation and calcination. Furthermore, a crosslinking agent is introduced into the synthesis system to construct a three-dimensional network gel framework, forming a nanoscale confinement space that effectively restricts the growth and aggregation of cerium dioxide nanoparticles, achieving a spatial confinement effect. Ultimately, through the synergistic effect of the surfactant, complexing agent, and crosslinking agent, a cerium dioxide support with uniform grain size, large specific surface area, and abundant defect sites is obtained. Based on this, when bimetals are loaded within the three-dimensional network confinement space formed by the crosslinking agent, this confinement space effectively restricts the migration and aggregation of bimetallic nanoparticles through steric hindrance, controlling their size to the sub-nanometer to several-nanometer range and achieving highly uniform dispersion. Simultaneously, the confinement environment and the defect-rich surface of the cerium dioxide support synergistically induce strong metal-support interactions, promoting the formation of more alloy phases or heterogeneous interfaces between the bimetals to enhance electronic synergistic effects. This significantly improves the reaction selectivity and stability of the catalytic active centers and effectively suppresses the sintering and loss of bimetallic nanoparticles during the reaction process. Therefore, the cerium dioxide-supported bimetallic catalyst proposed in this application has the advantage of high catalytic conversion efficiency for CO in sintering flue gas.

[0062] The above description is merely an embodiment of this application and does not constitute any limitation on this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a ceria-supported bimetallic catalyst, characterized by, Includes the following steps: S1, dissolve the cerium source in water and stir evenly, add a certain amount of crosslinking agent, surfactant and complexing agent, stir evenly to obtain a mixed solution, then add alkaline solution dropwise to adjust the pH value of the solution to 10~12, so that the metal ions form hydroxide precipitates to obtain a precursor turbid liquid; S2, the precursor turbid liquid obtained in S1 is poured into a hydrothermal reactor and heated in a sealed manner at 100~150℃ for 1~10h. After the reaction product is filtered, washed, dried and ground to obtain precursor powder, the precursor powder is then calcined at 400~600℃ for 0.5~5h to obtain cerium dioxide support. The calcination process is carried out in an air atmosphere. S3, add the cerium dioxide powder obtained in S2 to water and disperse it by ultrasonication to obtain a cerium dioxide dispersion. Place the cerium dioxide dispersion in a water bath and gradually add the prepared bimetallic solution while stirring. Continue stirring and react for 1 to 5 hours. Then heat to 60 to 80°C and continue stirring until the material is completely dry to obtain a solid substance. S4. The solid material obtained in S3 is heated to 400~600℃ and calcined for 0.5~5h under an inert atmosphere to obtain a cerium dioxide supported bimetallic catalyst.

2. The method for preparing a ceria-supported bimetallic catalyst according to claim 1, characterized in that, In step S1, the cerium source is one of cerium nitrate, cerium acetate, cerium carbonate, cerium sulfate, cerium oxalate or a mixture of two. After dissolution, the concentration of Ce 3+ ranges from 0.5 to 1.5 mol / L.

3. The method of claim 1, wherein the ceria-supported bimetallic catalyst is prepared by the steps of: In step S1, the crosslinking agent is one or a mixture of two of α-cyclodextrin, γ-cyclodextrin, polyethylene glycol, and chitosan, and the molar concentration of the crosslinking agent in water ranges from 0.001 to 0.01 mol / L.

4. The method for preparing the cerium dioxide-supported bimetallic catalyst according to claim 1, characterized in that, In step S1, the surfactant is one of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and dodecyltrimethylammonium chloride, and the molar concentration of the surfactant is 0.002~0.01 mol / L.

5. The method of claim 1, wherein the ceria-supported bimetallic catalyst is prepared by the steps of: In step S1, the complexing agent is one of citric acid, malic acid, ethylenediaminetetraacetic acid, and phytic acid, and the molar concentration of the complexing agent is 0.1~0.5 mol / L.

6. The method of claim 1, wherein the ceria-supported bimetallic catalyst is prepared by the steps of: In step S1, the alkaline solution is a sodium hydroxide or potassium hydroxide solution with a molar concentration of 0.5~3 mol / L. The stirring speed is 300~500 r / min, and the alkaline solution is added at a dropping rate of 1~15 mL / min until the pH reaches 10~12. Then, the addition of the alkaline solution is stopped, and stirring is continued for 1~2 hours to allow the reaction to proceed fully.

7. The method of claim 1, wherein the ceria-supported bimetallic catalyst is prepared by the steps of: In step S2, the particle size distribution of the cerium dioxide support is D50≤0.5μm and D90≤5μm.

8. The method of claim 1, wherein the ceria-supported bimetallic catalyst is prepared by the steps of: In step S3, the bimetallic solution is any combination of two metal salts selected from nickel nitrate, cobalt nitrate, copper nitrate, and manganese nitrate, and the molar concentration of the bimetallic solution is 0.1~0.9 mol / L.

9. A cerium dioxide-supported bimetallic catalyst prepared by the method according to any one of claims 1-8.

10. Use of the ceria-supported bimetallic catalyst according to claim 9 for the oxidation of CO in sintering flue gases, characterized in that, The cerium dioxide-supported bimetallic catalyst is loaded into a sintering flue gas catalytic oxidation fixed reaction bed at a concentration of 0.5-3g. Sintering flue gas containing CO is introduced, with a CO volume percentage of 1.0-3.0%. The flow rate of the sintering flue gas is 20-300 mL / min, and the temperature of the heating catalytic reaction is 180-300℃.

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