Metal auxiliary agent modified Pt loaded CeO2 catalyst, preparation and application thereof in CO oxidation

Abstract

The invention relates to a metal additive modified Pt-loaded CeO2 catalyst, preparation and application thereof in CO oxidation, and belongs to the technical field of industrial catalysis. The preparation process of the catalyst mainly comprises the following steps: respectively dissolving cerium salt, platinum salt and auxiliary metal salt in deionized water to prepare corresponding precursor solutions; then, mixing the three solutions, and dropwise adding ammonia water under a stirring condition until yellow precipitates are generated; and finally, drying and washing the precipitate, and calcining the solid powder in a proper atmosphere to obtain the assistant metal modified Pt / CeO2 catalyst. La, Pr, Nd or Sm auxiliary metal is introduced into the Pt / CeO2 catalyst, so that the CO catalytic oxidation performance of the catalyst can be improved, and the poisoning resistance of the catalyst in an SO2-containing environment can be enhanced. The method has important significance in the actual industrial application, especially in the catalytic oxidation process under the condition of treating complex flue gas.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial catalysis, and more specifically to a Pt-loaded CeO2 catalyst modified by a metal promoter, and its preparation and application in CO oxidation. Background Art

[0002] Carbon monoxide (CO) is a colorless, odorless and toxic gas with stable chemical properties. It is not easy to react with other components in the atmosphere. Therefore, it can exist in the environment for a long time and has become a pollutant that needs to be focused on. The main sources of CO emissions include diesel vehicle exhaust and incomplete combustion of fossil fuels. In recent years, although the emission of CO in diesel vehicle exhaust has been significantly reduced, the problem caused by incomplete combustion of fossil fuels, especially CO produced during the sintering process of the steel industry, has gradually become a focus of attention. In this process, the volume fraction of CO in the exhaust gas emitted is about 1%. Despite the continuous advancement of combustion technology, the emission problem of fuel residues has not been completely solved and continues to affect the environment. Therefore, it is particularly urgent to develop efficient CO treatment technology. Among the many CO treatment technologies, catalytic oxidation is regarded as one of the most promising technologies due to its high efficiency and low economic cost. Through the action of catalysts, CO can be oxidized to harmless carbon dioxide (CO2) at a lower temperature, thereby effectively reducing the impact on the environment. Research and development of new and efficient catalysts to improve the performance of catalytic oxidation processes is the key to achieving CO pollution control.

[0003] As a typical heterogeneous catalytic material, Pt / CeO2 catalyst is widely used in CO catalytic oxidation reaction due to its excellent catalytic performance. However, even if the catalytic unit is placed after the desulfurization device, industrial flue gas will still contain a certain concentration of SO2. Therefore, the tolerance of the catalyst under the coexistence of SO2 is very important. Although the precious metal Pt is not easy to directly combine with SO2 to form sulfate, SO2 can be formed on Pt 0 The surface of the PtO2 is oxidized and transferred to the CeO2 support to form sulfate. 0 The adsorption on Pt is reversible, but the adsorption of SO2 will still occupy these active sites, thereby inhibiting the catalytic activity. Therefore, reducing the adsorption and oxidation of SO2 is of great significance to improving the SO2 resistance of Pt-based catalysts.

[0004] In the prior art, the Chinese patent with publication number CN 116393164 A discloses the application of Fe-SSZ-13 molecular sieve modified with additive metal in denitration reaction. The patent shows that the introduction of additive metal effectively improves the denitration performance of Fe-SSZ-13. Although the research has made certain progress, it has not deeply explored the poisoning mechanism and SO2 resistance of the catalyst in the presence of SO2. Therefore, considering the ubiquitous presence of SO2 in industrial flue gas, the present invention aims at this problem and proposes a preparation method of Pt / CeO2 catalyst modified with additive metal, aiming to improve the catalyst's resistance to sulfur poisoning in CO catalytic oxidation reaction and enhance the application life and stability of the catalyst in complex atmosphere. This research not only provides a new solution for the industrial application of Pt-based catalysts, but also provides valuable ideas for improving the anti-sulfur poisoning performance of catalysts. Summary of the invention

[0005] In view of the limitations of the prior art, the present invention proposes a method for preparing a Pt / CeO2 catalyst modified with an auxiliary metal. The preparation method has a simple process, is easy to repeat, and has good consistency. The Pt-M / CeO2 catalyst prepared by this method exhibits excellent CO catalytic oxidation performance and excellent resistance to sulfur poisoning, and is suitable for CO catalytic oxidation treatment of mobile sources and fixed sources. Thereby solving the technical problems of poor sulfur resistance and catalytic performance of CO catalytic oxidation reaction catalysts in the prior art.

[0006] According to a first aspect of the present invention, there is provided a method for preparing a Pt-supported CeO2 catalyst modified with an additive metal using a one-pot process, comprising the following steps:

[0007] (1) dissolving a cerium salt, a platinum salt and an auxiliary metal salt in deionized water respectively to prepare a cerium precursor solution, a platinum precursor solution and an auxiliary metal precursor solution, and mixing the three solutions to obtain a mixed solution; the auxiliary metal salt is a lanthanum salt, a praseodymium salt, a neodymium salt or a samarium salt;

[0008] (2) adding alkaline solution dropwise to the mixed solution obtained in step (1) to adjust the pH to alkaline until a yellow precipitate is generated;

[0009] (3) The precipitate obtained in step (2) is washed and dried, and then calcined to obtain a Pt-loaded CeO2 catalyst modified with an auxiliary metal.

[0010] Preferably, the mass ratio of the platinum salt to the auxiliary metal salt is 0.1 to 5.

[0011] Preferably, in step (2), a reducing agent is added before adding the alkali solution.

[0012] Preferably, the reducing agent is sodium borohydride, ethylene glycol, sodium citrate or ascorbic acid.

[0013] Preferably, in step (3), the calcination temperature is 300-650° C., the time is 4-8 hours, and the calcination atmosphere is ammonia, carbon monoxide, air or argon.

[0014] According to another aspect of the present invention, a prepared promoter metal-modified Pt-supported CeO2 catalyst is provided.

[0015] Preferably, the loading amount of the active component Pt in the promoter metal-modified Pt-loaded CeO2 catalyst is 0.2wt.% to 5wt.%, and the doping amount of the promoter metal is 0.2wt.% to 2wt.%.

[0016] According to another aspect of the present invention, there is provided the use of the promoter metal-modified Pt-loaded CeO2 catalyst in CO catalytic oxidation reaction.

[0017] According to another aspect of the present invention, a CO catalytic oxidizer is provided, comprising the above-mentioned promoter metal-modified Pt-loaded CeO2 catalyst.

[0018] According to another aspect of the present invention, there is provided a system for treating tail gas from a mobile source or a fixed source, comprising the CO catalytic oxidizer.

[0019] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0020] (1) The present invention proposes a method for preparing a Pt / CeO2 catalyst modified with an additive metal. The method is simple in process, easy to repeat, and has good consistency, and is intended to optimize the CO catalytic oxidation performance. Compared with the Pt / CeO2 catalyst, its T 90 The T of the Pt-M / CeO2 (M = La, Pr, Nd or Sm) catalyst provided by the present invention is 209°C. 90 The T values ​​of Pt / CeO2 and Pt-M / CeO2 (M=La, Pr, Nd or Sm) catalysts were 204℃, 195℃, 199℃ and 188℃ respectively, indicating that the introduction of the promoter metal significantly improved the CO catalytic oxidation activity of Pt / CeO2 catalyst. 90They are 258℃, 224℃, 204℃, 214℃ and 194℃ respectively, indicating that the CO catalytic oxidation activity of all catalysts decreases in the presence of SO2. Among them, the activity of Pt / CeO2 catalyst decreases most significantly. In contrast, the decrease in CO catalytic oxidation performance of Pt-M / CeO2 (M=La, Pr, Nd or Sm) catalyst is relatively small, showing better resistance to sulfur poisoning. This result shows that by introducing additive metals such as La, Pr, Nd or Sm into Pt / CeO2 catalyst, not only the CO catalytic oxidation performance of the catalyst can be improved, but also its anti-poisoning ability in an environment containing SO2 can be enhanced. This is of great significance for practical industrial applications, especially in the catalytic oxidation process under complex flue gas conditions.

[0021] (2) The introduction of rare earth metals (La, Pr, Nd or Sm) into Pt / CeO2 catalysts can change the electronic structure of Pt, resulting in changes in the electron density of Pt atoms, improving the adsorption and activation ability of Pt for CO molecules, and thus improving the CO catalytic oxidation activity of the catalyst. Rare earth metals such as La, Pr, Nd and Sm show good stability in the catalyst and can prevent the aggregation and sintering of Pt particles. The good compatibility of these metals with CeO2 helps to maintain the high specific surface area of ​​the catalyst, thereby improving its catalytic activity. In addition, the introduction of additive metals can also form solid solutions or mixed oxides to enhance the structural stability of the catalyst. In terms of sulfur poisoning resistance, the presence of rare earth metals (La, Pr, Nd or Sm) helps to weaken the sulfation effect of SO2 on the catalyst, thereby reducing the sulfur poisoning effect. Specifically, rare earth metals (La, Pr, Nd or Sm) can change the electronic structure of the catalyst, making it more difficult for SO2 to adsorb on the active sites. In addition, rare earth metals (La, Pr, Nd or Sm) can accelerate the decomposition of sulfate formed on the catalyst surface, maintain the high valence state of the active sites, and further improve its redox ability. These mechanisms work together to make the modified catalyst show better catalytic performance, excellent stability and stronger resistance to sulfur poisoning in complex atmospheres.

[0022] (3) In the present invention, the reducing agent used is preferably sodium borohydride, ethylene glycol, sodium citrate or ascorbic acid. Sodium borohydride has a strong reducing ability and can effectively reduce Pt ions to nano-sized Pt particles, provide uniform dispersion, and enhance the activity and anti-aggregation ability of the catalyst. Ethylene glycol, as a mild reducing agent, can reduce metal ions at a relatively low temperature and form an organic coating layer during the reaction, further improving the structural stability of the catalyst. In addition to the reducing effect, sodium citrate can also inhibit the aggregation of Pt particles through complexation, enhance the specific surface area of ​​the catalyst, and improve its catalytic activity. As a biological reducing agent, ascorbic acid can provide a good reducing environment under relatively mild conditions, while inhibiting the excessive growth of Pt particles and maintaining its catalytic activity. The selection of various reducing agents is closely related to the performance improvement of the catalyst and can be optimized according to specific application requirements.

[0023] (4) In the present invention, the calcination atmosphere is preferably ammonia, carbon monoxide, air or argon. By selecting different calcination atmospheres, the metal oxidation state, surface properties and microstructure of the Pt / CeO2 catalyst can be precisely controlled, thereby optimizing the performance of the catalyst and making it more suitable for specific CO catalytic oxidation reactions and application conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 X-ray diffraction (XRD) patterns of Pt-M / CeO2 (M=La, Pr, Nd or Sm) and Pt / CeO2 catalysts prepared in Examples 1 to 4 and Comparative Example 1.

[0025] Figure 2 Graph showing the CO catalytic oxidation conversion of Pt-M / CeO2 (M = La, Pr, Nd or Sm) and Pt / CeO2 catalysts prepared in Examples 1 to 4 and Comparative Example 1.

[0026] Figure 3 This is a graph showing the CO catalytic oxidation conversion rate of Pt-M / CeO2 (M=La, Pr, Nd or Sm) and Pt / CeO2 catalysts prepared in Examples 1 to 4 and Comparative Example 1 in the presence of 200 ppm SO2. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] In a first aspect of the present invention, there is provided a method for preparing a Pt / CeO2 catalyst modified with a promoter metal using a one-pot process, comprising the following steps:

[0029] (1) Dissolve appropriate amounts of Ce salt, Pt salt and auxiliary metal salt in deionized water to prepare Ce precursor solution, Pt precursor solution and auxiliary metal precursor solution. Mix the three solutions in the required proportions and stir at 30-80° C. for 0.5-3 hours to prepare a uniform mixed solution.

[0030] (2) Under stirring conditions, add ammonia water dropwise to adjust the pH to 8-10 until a yellow precipitate is generated. At the same time, use an ultrasonic cleaner to ultrasonically treat the solution for 0.5-1 hour to ensure that the formed precipitate is evenly dispersed.

[0031] (3) Wash the precipitate repeatedly with deionized water until the washing liquid is neutral. Dry the washed precipitate at 80-120°C for 12 hours to obtain a dry solid powder. Place the dried solid powder in a muffle furnace and calcine it at 300-650°C in an atmosphere of ammonia, carbon monoxide, air or argon for 4-8 hours, then cool it naturally to room temperature to obtain a Pt / CeO2 catalyst modified with an additive metal.

[0032] Preferably, the auxiliary metal salt in step (1) is La salt, Pr salt, Nd salt or Sm salt, and the mass ratio of the Pt salt to the mass of the auxiliary metal salt is 0.1 to 5.

[0033] Preferably, in step (2), a reducing agent is added before adding the alkali solution, and the reducing agent is preferably sodium borohydride, ethylene glycol, sodium citrate or ascorbic acid.

[0034] Preferably, the calcination temperature in step (3) is 300-650° C., the time is 4-8 hours, and the calcination atmosphere is ammonia, carbon monoxide, air or argon.

[0035] In some embodiments, the auxiliary metal salt used in step (1) is La salt, Pr salt, Nd salt or Sm salt.

[0036] In some embodiments, the reducing agent used in step (2) is sodium borohydride, ethylene glycol, sodium citrate or ascorbic acid.

[0037] In some embodiments, the calcination atmosphere in step (3) is ammonia, carbon monoxide, air or argon; the calcination temperature is 300-650° C., and the calcination time is 4-8 hours.

[0038] In a second aspect, the present invention provides a Pt / CeO2 catalyst for CO catalytic oxidation, comprising an active component and a promoter metal; the active component is a Pt species, and the promoter metal is La, Pr, Nd or Sm.

[0039] In some embodiments, the loading amount of the active component Pt in the carrier is 0.2 wt.% to 5 wt.%, more preferably 0.6 wt.%.

[0040] In some embodiments, the Pt / CeO2 catalyst is further doped with a promoter metal, wherein the promoter metal is at least one of La, Pr, Nd or Sm.

[0041] In some embodiments, the doping amount of the promoter metal in the Pt / CeO2 catalyst is 0.2 wt.% to 2 wt.%, and more preferably 0.8 wt.%.

[0042] In a third aspect, the present invention provides a CO catalytic oxidizer comprising the above-mentioned auxiliary metal-modified Pt / CeO2 catalyst.

[0043] According to a fourth aspect of the present invention, there is provided a mobile source and a fixed source exhaust gas treatment system comprising the above-mentioned CO catalytic oxidizer.

[0044] The following are specific embodiments

[0045] Example 1

[0046] A method for preparing a Pt-La / CeO2 catalyst comprises the following steps:

[0047] 4.5 g of cerium nitrate, 0.055 g of chloroplatinic acid and 0.07 g of lanthanum nitrate were dissolved in 100 mL of deionized water to prepare cerium precursor solution, platinum precursor solution and lanthanum precursor solution. The three solutions were mixed and stirred at 60 ° C for 2 hours to prepare a uniform mixed solution. 0.15 g of sodium borohydride was added to the mixed solution as a reducing agent and continued to stir for 1 hour. Under stirring conditions, an appropriate amount of ammonia water was added dropwise to adjust the pH to 9 until a yellow precipitate was generated. At the same time, the solution was ultrasonically treated for 0.5 hours using an ultrasonic cleaner to ensure that the formed precipitate was uniformly dispersed. The precipitate was repeatedly washed with deionized water until the washing solution was neutral. The washed precipitate was placed in an oven at 110 ° C and dried for 12 hours to obtain a dry solid powder. The dried solid powder was placed in a muffle furnace and calcined at 500 ° C in an ammonia atmosphere for 4 hours. After calcination, the sample was cooled naturally to room temperature to obtain a Pt-La / CeO2 catalyst with a Pt loading of 0.5 wt.% and a La doping of 0.6 wt.%.

[0048] Comparative Example 1

[0049] The difference between this comparative example and Example 1 is that lanthanum nitrate is not added. The other conditions are exactly the same as those in Example 1, and finally a Pt / CeO2 catalyst containing no metal additive and having a Pt loading of 0.5 wt.% is obtained.

[0050] Example 2

[0051] A method for preparing a Pt-Pr / CeO2 catalyst comprises the following steps:

[0052] 4.5 g of cerium nitrate, 0.077 g of chloroplatinic acid and 0.12 g of praseodymium nitrate were dissolved in 100 mL of deionized water to prepare a cerium precursor solution, a platinum precursor solution and a praseodymium precursor solution. The three solutions were mixed and stirred at 70 ° C for 1 hour to prepare a uniform mixed solution. 15 mL of ethylene glycol was added to the mixed solution as a reducing agent and continued to stir for 1 hour. Under stirring conditions, an appropriate amount of ammonia water was added dropwise to adjust the pH to 9 until a yellow precipitate was generated. At the same time, the solution was ultrasonically treated with an ultrasonic cleaner for 1 hour to ensure that the formed precipitate was uniformly dispersed. The precipitate was repeatedly washed with deionized water until the washing solution was neutral. The washed precipitate was placed in an oven at 90 ° C and dried for 12 hours to obtain a dry solid powder. The dried solid powder was placed in a muffle furnace and calcined at 450 ° C in an argon atmosphere for 4 hours. After calcination, the sample was cooled naturally to room temperature to obtain a Pt-Pr / CeO2 catalyst with a Pt loading of 0.7 wt.% and a Pr doping of 0.8 wt.%.

[0053] Example 3

[0054] A method for preparing a Pt-Nd / CeO2 catalyst comprises the following steps:

[0055] 5 g of cerium nitrate, 0.12 g of chloroplatinic acid and 0.2 g of neodymium nitrate were dissolved in 100 mL of deionized water to prepare a cerium precursor solution, a platinum precursor solution and a neodymium precursor solution. The three precursor solutions were mixed and stirred at 80 ° C for 2 hours to prepare a uniform mixed solution. 0.4 g of ethylene glycol was added to the mixed solution as a reducing agent and continued to stir for 1 hour. Under stirring, an appropriate amount of ammonia water was added dropwise to adjust the pH to 10 until a yellow precipitate was generated. At the same time, the solution was ultrasonically treated with an ultrasonic cleaner for 1 hour to ensure that the formed precipitate was uniformly dispersed. The precipitate was repeatedly washed with deionized water until the washing solution was neutral. The washed precipitate was placed in an oven at 100 ° C and dried for 12 hours to obtain a dry solid powder. The dried solid powder was placed in a muffle furnace and calcined at 550 ° C in an air atmosphere for 5 hours. After calcination, the sample was cooled naturally to room temperature to obtain a Pt-Nd / CeO2 catalyst with a Pt loading of 1.0 wt.% and a Nd doping of 1.2 wt.%.

[0056] Example 4

[0057] A method for preparing a Pt-Sm / CeO2 catalyst comprises the following steps:

[0058] 5.4 g of cerium nitrate, 0.079 g of chloroplatinic acid and 0.14 g of samarium nitrate were dissolved in 100 mL of deionized water to prepare a cerium precursor solution, a platinum precursor solution and a samarium precursor solution. The three precursor solutions were mixed and stirred at 60 ° C for 1 hour to prepare a uniform mixed solution. 0.3 g of ascorbic acid was added to the mixed solution as a reducing agent and continued to stir for 2 hours. Under stirring conditions, an appropriate amount of ammonia water was added dropwise to adjust the pH to 9 until a yellow precipitate was generated. At the same time, the solution was ultrasonically treated for 1 hour using an ultrasonic cleaner to ensure that the formed precipitate was uniformly dispersed. The precipitate was repeatedly washed with deionized water until the washing solution was neutral. The washed precipitate was placed in an oven at 80 ° C and dried for 12 hours to obtain a dry solid powder. The dried solid powder was placed in a muffle furnace and calcined at 450 ° C in a carbon monoxide atmosphere for 5 hours. After calcination, the sample was cooled naturally to room temperature to obtain a Pt-Sm / CeO2 catalyst with a Pt loading of 0.6 wt.% and a Sm doping of 0.8 wt.%.

[0059] XRD tests were performed on the Pt / CeO2 and Pt-M / CeO2 catalysts prepared in Examples 1 to 4 and Comparative Example 1. The results are as follows: Figure 1 As shown, this indicates that the Pt / CeO2 modified by the additive metal (La, Pr, Nd, or Sm) still maintains the crystal structure of CeO2. At the same time, no diffraction peaks of the metal additives were observed, indicating that the metal additives were evenly distributed on the catalyst, or their particle size was small, beyond the detection range of XRD.

[0060] Embodiments 5 to 8

[0061] The preparation method of Pt-Sm / CeO2 catalysts with different Pt loadings and Sm loadings comprises the following steps:

[0062] 4.5 g of cerium nitrate, 0.044 g of chloroplatinic acid (0.077 g of chloroplatinic acid, 0.11 g of chloroplatinic acid or 0.14 g of chloroplatinic acid) and 0.044 g of samarium nitrate (0.074 g of samarium nitrate, 0.10 g of samarium nitrate or 0.13 g of samarium nitrate) were dissolved in 100 mL of deionized water to prepare a cerium precursor solution, a platinum precursor solution and a samarium precursor solution. The three precursor solutions were mixed and stirred at 60 ° C for 2 hours to prepare a uniform mixed solution. 0.1 g of sodium borohydride (0.3 g of ethylene glycol, 0.5 g of sodium citrate or 0.3 g of ascorbic acid) was added to the mixed solution as a reducing agent and continued to stir for 2 hours. Under stirring, an appropriate amount of ammonia water was added dropwise and the pH was adjusted to 9 until a yellow precipitate was generated. At the same time, the solution was ultrasonically treated for 1 hour using an ultrasonic cleaner to ensure that the formed precipitate was evenly dispersed. The precipitate was repeatedly washed with deionized water until the washing liquid was neutral. The washed precipitate was placed in an oven at 80°C and dried for 12 hours to obtain a dry solid powder. The dried solid powder was placed in a muffle furnace and calcined at 500°C in an ammonia atmosphere for 5 hours. After calcination, the sample was cooled naturally to room temperature to obtain Pt-Sm / CeO2 catalysts with Pt loadings of 0.4wt.%, 0.7wt.%, 1.0wt.% and 1.3wt.%, respectively, and Sm doping amounts of 0.3wt.%, 0.5wt.%, 0.7wt.% and 0.9wt.%, respectively.

[0063] Examples 9 to 12

[0064] A method for preparing a Pt-Sm / CeO2 catalyst comprises the following steps:

[0065] 4.5g of cerium nitrate, 0.086g of platinum chloride (0.082g of platinum nitrate, 0.11g of platinum acetate or 0.084g of dichloroethylenediamine platinum) and 0.089g of samarium nitrate were dissolved in 100mL of deionized water to prepare cerium precursor solution, platinum precursor solution and samarium precursor solution. The three precursor solutions were mixed and stirred at 60°C for 2 hours to prepare a uniform mixed solution. 0.3g of ethylene glycol was added to the mixed solution as a reducing agent and continued to stir for 2 hours. Under stirring conditions, an appropriate amount of ammonia water was added dropwise to adjust the pH to 9 until a yellow precipitate was generated. At the same time, an ultrasonic cleaner was used to ultrasonically treat the solution for 1 hour to ensure that the formed precipitate was uniformly dispersed. The precipitate was repeatedly washed with deionized water until the washing solution was neutral. The washed precipitate was placed in an oven at 90°C and dried for 12 hours to obtain a dry solid powder. The dried solid powder was placed in a muffle furnace and calcined at 550°C in an ammonia atmosphere for 5 hours. After calcination, when the sample is naturally cooled to room temperature, Pt-Sm / CeO2 catalysts with Pt loading of 1.0wt.% and Sm doping of 0.6wt.% can be obtained. The samples are marked as Pt-Sm / CeO2-1, Pt-Sm / CeO2-2, Pt-Sm / CeO2-3 and Pt-Sm / CeO2-4.

[0066] Embodiment 13

[0067] The Pt / CeO2 and Pt-M / CeO2 catalysts prepared in Examples 1 to 4 and Comparative Example 1 were tested for CO catalytic oxidation performance and sulfur resistance. The test conditions were: catalyst dosage 0.2 g (60-80 mesh), simulated flue gas composition of 1000 ppm CO, 15% H2O, 10% O2, 200 ppm SO2 (introduced when needed), reaction space velocity of 150000 h -1 .

[0068] The results of CO catalytic oxidation performance test and sulfur resistance test are as follows Figure 2 and Figure 3 As shown. Figure 2It can be seen that the introduction of an appropriate amount of auxiliary metal La, Pr, Nd or Sm into the Pt / CeO2 catalyst can significantly improve its CO catalytic oxidation activity. This is because the auxiliary metals La, Pr, Nd and Sm have incompletely occupied 4f orbitals and empty 5d orbitals. Their outer electrons will undergo electronic deviation when interacting with atoms in CeO2. This adjustment of the electronic structure can affect the valence state of CeO2, increase the active oxygen and lattice defects on its surface, and thus improve the redox ability and catalytic activity of the catalyst. After the introduction of SO2 in the reaction atmosphere, the CO catalytic oxidation activity of Pt / CeO2 and Pt-M / CeO2 (M=La, Pr, Nd or Sm) catalysts decreased. Among them, the activity of Pt / CeO2 catalyst decreased most significantly. In contrast, the decrease in CO catalytic oxidation performance of Pt-M / CeO2 (M=La, Pr, Nd or Sm) catalysts is relatively small, showing better resistance to sulfur poisoning. This is because the additive metal can react with SO2 preferentially to generate metal sulfate, thereby protecting the active sites of the catalyst from being poisoned by SO2. In addition, the addition of additive metal can also increase the content of active oxygen on the catalyst surface, accelerate the decomposition of sulfate, and further improve the sulfur resistance of the catalyst.

[0069] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a Pt-loaded CeO2 catalyst modified with an auxiliary metal using a one-pot process, characterized in that: The following steps are involved: (1) dissolving a cerium salt, a platinum salt and an auxiliary metal salt in deionized water to prepare a cerium precursor solution, a platinum precursor solution and an auxiliary metal precursor solution, respectively, and mixing the three solutions to obtain a mixed solution; The auxiliary metal salt is a lanthanum salt, a praseodymium salt, a neodymium salt or a samarium salt; (2) adding alkaline solution dropwise to the mixed solution obtained in step (1) to adjust the pH to alkaline until a yellow precipitate is generated; (3) The precipitate obtained in step (2) is washed and dried, and then calcined to obtain a Pt-loaded CeO2 catalyst modified with an auxiliary metal.

2. The method for preparing a Pt-supported CeO2 catalyst modified with an auxiliary metal using a one-pot process as claimed in claim 1, characterized in that: The mass of the platinum salt is 0.1 to 5 times the mass of the auxiliary metal salt.

3. The method for preparing a Pt-supported CeO2 catalyst modified with an auxiliary metal using a one-pot process as claimed in claim 1, characterized in that: In step (2), a reducing agent is added before adding the alkali solution.

4. The method for preparing a Pt-supported CeO2 catalyst modified with an auxiliary metal using a one-pot process as claimed in claim 3, characterized in that: The reducing agent is sodium borohydride, ethylene glycol, sodium citrate or ascorbic acid.

5. The method for preparing a Pt-supported CeO2 catalyst modified with an auxiliary metal using a one-pot process as claimed in claim 1, characterized in that: In step (3), the calcination temperature is 300-650° C., the time is 4-8 hours, and the calcination atmosphere is ammonia, carbon monoxide, air or argon.

6. A Pt-supported CeO2 catalyst modified with an auxiliary metal prepared by the method of any one of claims 1 to 5.

7. The promoter metal-modified Pt-supported CeO2 catalyst according to claim 6, characterized in that: The loading amount of the active component Pt in the Pt-loaded CeO2 catalyst modified by the auxiliary metal is 0.2 wt.% to 5 wt.%, and the doping amount of the auxiliary metal is 0.2 wt.% to 2 wt.%.

8. Use of the Pt-supported CeO2 catalyst modified with an auxiliary metal as claimed in claim 6 or 7 in a CO catalytic oxidation reaction.

9. A CO catalytic oxidizer, characterized in that: The invention comprises the Pt-loaded CeO2 catalyst modified with the auxiliary metal as claimed in claim 6 or 7.

10. A system for treating tail gas from a mobile source or a fixed source, characterized in that: Comprising the CO catalytic oxidizer as described in claim 9.

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