A platinum-based catalyst for preferential CO oxidation in a hydrogen-rich atmosphere, its preparation method and application

Abstract

This invention relates to a platinum-based catalyst for the preferential oxidation of CO in a hydrogen-rich atmosphere, its preparation method, and its applications. The method, starting from an interface design perspective, employs a series of synergistic and innovative preparation steps: "selective adsorption with non-polar solvents + controlled pH in-situ anchored hydrolysis + two-step thermal treatment." This successfully solves the technical challenge of traditional methods in constructing a tight, stable, and efficient interface between platinum clusters and iron oxides. The catalyst prepared by this method exhibits high catalytic activity, excellent selectivity, and stability in the preferential oxidation of CO in a hydrogen-rich atmosphere, demonstrating outstanding technological innovation and application value.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen purification and catalysis technology, specifically relating to a platinum-based catalyst for the preferential oxidation of CO in a hydrogen-rich atmosphere, as well as the preparation method and application of the catalyst. Background Technology

[0002] With the expanding application of proton exchange membrane fuel cells (PEMFCs) in transportation and energy sectors, the requirements for hydrogen purity in hydrogen supply systems are becoming increasingly stringent. Hydrogen obtained from fossil fuel reforming or other hydrogen production processes typically contains a certain amount of CO impurities. Under fuel cell operating conditions, CO undergoes strong adsorption on the platinum electrode surface. Even trace amounts of CO can significantly reduce electrode reactivity and cause irreversible performance degradation. Therefore, the CO concentration in hydrogen must be controlled below 1 ppm before entering the fuel cell to meet the requirements for stable fuel cell operation.

[0003] Among existing hydrogen purification methods, CO-PROX (Co-Proximity Co-oxidation) is considered an effective approach for deep hydrogen purification due to its relatively mild reaction conditions, simple process, and ease of integration with hydrogen production units. Supported platinum-based catalysts have been extensively studied and applied in CO-PROX reactions due to their high catalytic activity for CO. However, under hydrogen-rich atmospheres, platinum also exhibits strong adsorption and activation capabilities for hydrogen, inevitably leading to competitive oxidation of hydrogen during the reaction. This consumes limited oxygen, resulting in incomplete CO oxidation, making it difficult to achieve a balance between catalyst activity and selectivity. Furthermore, platinum resources are scarce and expensive; excessively high precious metal loadings significantly increase catalyst costs, hindering its widespread application in practical systems.

[0004] To address the aforementioned issues, existing research has attempted to improve catalytic performance by introducing a second metal or metal oxide, and by controlling the structural state of platinum and its interaction with the support. Patent (CN 202411864880.7) reports the preparation and application of metallic platinum-based catalysts. The introduction of Ni and Fe improves the catalyst's activity and stability. The prepared Pt / Ni-SiO2 and Pt / Fe-SiO2 catalysts maintain 100% CO conversion within the PEMFC operating temperature range and exhibit good stability over long reaction periods, largely unaffected by water vapor or carbon dioxide. Patent (CN202310506735.0) discloses a ruthenium-based catalyst for preferential CO oxidation. During synthesis, ruthenium is pre-reduced using reducing agents such as NaBH4, effectively improving the catalyst's reaction performance. Patent (CN202111515592.7) reports a platinum catalyst supported on flower-shaped cerium iron oxide. After air pre-oxidation and hydrogen pre-reduction, this catalyst can completely convert CO within the PEMFC operating temperature range. Patent (CN 202410773999.7) describes a gold catalyst supported on a cerium-iron solid solution prepared using a solvothermal and precipitation-deposition method for the preferential oxidation of trace CO in hydrogen gas. The prepared catalyst exhibits excellent low-temperature activity. To date, while this type of catalyst demonstrates high activity within a low-temperature window from room temperature to 100°C, its effective temperature window for complete CO conversion is relatively narrow. Furthermore, to achieve considerable reaction performance, some systems still require a high loading of precious metals, making it difficult to balance performance and cost requirements, thus limiting its application potential under practical conditions. Summary of the Invention

[0005] Based on the above-mentioned situation, this invention provides a platinum-based catalyst for the preferential oxidation of CO in a hydrogen-rich atmosphere, its preparation method, and its application. By constructing an interfacial structure with a stable spatial proximity between platinum and iron oxide on a high specific surface area support, effective control over the oxygen activation pathway and platinum surface adsorption behavior is achieved, thereby obtaining good CO oxidation activity and reaction stability with a relatively low noble metal loading. Although this catalyst is still mainly suitable for CO removal processes within a certain temperature range, it can balance activity and selectivity in a hydrogen-rich atmosphere, providing a technical solution with practical application value for the effective control of CO in fuel cell hydrogen supply systems.

[0006] The technical solution adopted in this invention is: a method for preparing a platinum-based catalyst for the preferential oxidation of CO, comprising the following steps: Step 1: Dissolve platinum salt in deionized water to prepare a platinum precursor solution, immerse it in a high specific surface area silica support, dry it, and then calcine it in air at 300-600℃ for at least 2 h to obtain sample A. Step 2: Dissolve ferrocene in nonpolar alkanes to prepare an iron salt solution with an iron ion concentration of 0.0045-0.0135 mol / L. Add sample A to an excess of the iron salt solution and stir at 25-45℃ for at least 3 h to adsorb. Filter to collect the solid product and dry it to obtain sample B. Step 3: Disperse sample B in ethanol, slowly add dilute hydrochloric acid dropwise under continuous stirring to adjust the pH of the system to 3.0-3.5, stir the reaction at 40-60℃ for at least 1 h, filter to collect the solid product after the reaction is completed and dry it to obtain sample C; Step 4: Replace sample A with sample C and repeat steps 2 and 3 1-3 times to obtain sample D; Step 5: Place sample D in a flowing air atmosphere and calcine at 200-350℃ for at least 1 h, then switch to a reducing atmosphere and heat treat at 200-400℃ for 0.5-1 h. Afterward, purge under an inert atmosphere until the temperature drops to room temperature to obtain the desired platinum-based catalyst.

[0007] Preferably, the high specific surface area silica support in step one is one or more of fumed silica, HMS, MCM-48, MCM-41 or SBA-15.

[0008] Preferably, the platinum salt mentioned in step one is chloroplatinic acid, and the platinum content in sample A accounts for 0.5%-3.0% of the carrier mass.

[0009] Preferably, the nonpolar alkane in step two is one or more of alkane or cycloalkanes with 5-16 carbon atoms.

[0010] Preferably, the excess iron salt solution in step two is a solution with a water absorption rate not less than twice that of sample A.

[0011] Preferably, the reducing atmosphere in step five is high-purity hydrogen or an H2 / Ar mixture.

[0012] A catalyst prepared by a method for the preferential oxidation of CO using a platinum-based catalyst.

[0013] Application of catalysts in preferential CO oxidation.

[0014] Preferably, the prepared catalyst is used at a temperature of 60-160℃, the volume ratio of CO:O2 in the mixed gas is 2-1:1, and the gas space velocity of the mixed gas is 4000-18000 h⁻¹. -1 .

[0015] The catalyst described in this invention has a tight coupling between the active components FeO and Pt, with sufficient exposure of active sites, exhibiting high activity and high selectivity for preferential oxidation of CO in a hydrogen-rich atmosphere, and can maintain stable performance in long-term continuous reactions.

[0016] Compared with the prior art, the outstanding innovations and positive effects of this invention are as follows: (1) Novel FeO-Pt interface structure design and construction strategy: Existing technologies for preparing platinum-iron based catalysts mostly employ traditional methods such as co-impregnation, sequential impregnation, or co-precipitation, which makes it difficult to control the spatial distribution of iron species around the platinum active center. This easily leads to iron oxides randomly covering the support or encapsulating platinum particles, thus obscuring the active sites. This invention innovatively proposes a preparation strategy of "selective molecular adsorption-in-situ hydrolysis": First, utilizing the unique π-metal interaction between the π-electron system of the cyclopentadienyl group in the ferrocene molecule and the d orbitals of the platinum cluster, preferential and directional adsorption of ferrocene on the platinum surface is achieved in a nonpolar solvent; subsequently, in-situ hydrolysis is carried out in an acidic solution with strictly controlled pH, allowing the released iron ions (FeO-Pt) to be released. 3+ Through electrostatic interactions and hydrolysis-condensation reactions, iron species are anchored to the negatively charged SiO2 support surface adjacent to the platinum cluster via Si-O-Fe bonds. This strategy achieves spatial enrichment and localization of iron species around the active sites of the platinum cluster at the molecular level, laying the structural foundation for constructing a highly coupled FeO-Pt interface. (2) Improved solvent system: In the adsorption stage, traditional polar solvents (such as ethanol) are abandoned, and non-polar alkanes (such as cyclohexane) are creatively selected as the solvent for ferrocene. This system maintains the electronic structure integrity of ferrocene molecules to the greatest extent, avoids the problem of Fe-C bond perturbation that may occur in polar solvents for the FeCp2 structure, and thus ensures the effectiveness of subsequent π-metal interactions and adsorption. (3) Flexible and controllable catalyst composition: By introducing the “cyclic adsorption-hydrolysis” step (step four), the loading of iron is gradually increased without destroying the constructed interface structure, thereby realizing flexible control of catalyst composition and interface density and optimizing catalytic activity. (4) Innovative hydrolysis anchoring mechanism: The intermediate loaded with ferrocene is hydrolyzed in a mildly acidic system with pH = 3.0-3.5. The charge characteristics of the silanol groups on the support surface (negatively charged at pH above the isoelectric point) are cleverly utilized to promote the adsorption of the iron hydroxy cations generated by hydrolysis through strong electrostatic interaction, and further condensation to form chemically bonded, amorphous Si-O-Fe surface species. This process realizes the transformation of the iron precursor from "physical adsorption" to "chemical anchoring", which significantly enhances the thermal stability of the iron species and prevents them from migrating long distances during subsequent heat treatment. (5) Improved heat treatment procedure: A two-step heat treatment procedure of "low-temperature oxidation pretreatment" and "medium-temperature reduction" was designed. Low-temperature (200-350℃) air calcination aims to convert the anchored amorphous iron hydroxyl oxide into highly dispersed Fe2O3, while the low temperature can effectively inhibit the sintering of Fe species; subsequently, in a reducing atmosphere (200-400℃), the hydrogen overflow effect of platinum is used to reduce the loaded Fe2O3 into FeO, which has high co-catalytic activity for CO oxidation, effectively avoiding the sintering of Fe. 3+ Excessive reduction to metallic iron or the formation of inert iron silicates ensures the successful construction of the active FeO-Pt interface. (6) Highly Coupled FeO-Pt Interface: Thanks to the innovative interface construction strategy described above, the catalyst obtained in this invention forms a highly dispersed and spatially coupled FeO-Pt interface. Unlike the structural characteristics of platinum-iron catalysts obtained in the prior art, the active iron oxide (Fe2O3) nanoparticles in the catalyst obtained by low-temperature calcination are preferentially located around platinum clusters, rather than randomly distributed. After reduction to form FeO, oxygen can achieve low-energy-barrier dissociation at the FeO sites or FeO-Pt interface. This tight interface structure allows the active oxygen species generated by dissociation to react rapidly with CO adsorbed on the platinum. Attached Figure Description

[0017] Figure 1 HRTEM image of the Fe2O3-Pt / SiO2 catalyst prepared in Example 1 Detailed Implementation

[0018] To better illustrate this patent, the following embodiments are provided. These embodiments are intended to enable those skilled in the art to understand the invention in more detail, or to allow for non-essential improvements and adjustments based on the content of the invention. However, the scope of the invention is not limited to these embodiments. Example 1

[0019] (1) Dissolve chloroplatinic acid in deionized water to prepare a platinum precursor solution, impregnate it in a fumed silica support, the platinum content is 1.0% of the support mass, stir at room temperature for 3 h, dry thoroughly at 80℃, and calcine at 500℃ in air atmosphere for 2 h to obtain sample A. (2) Ferrocene was dissolved in cyclohexane to prepare an iron salt solution with an iron ion concentration of 0.0900 mol / L. The iron salt solution was twice the amount of sample A solution. Sample A was added, and after stirring and adsorption at 45℃ for 3 h, it was thoroughly dried at 80℃ to obtain sample B. (3) Disperse sample B in ethanol, slowly add dilute hydrochloric acid to adjust the pH of the system to 3.0 under continuous stirring, stir the reaction at 40°C for 3 h, filter and collect the solid product after the reaction, dry it at 80°C to obtain sample C; (4) Replace sample A with sample C and repeat steps (2) and (3) 3 times to obtain sample D; (5) Sample D was calcined at 200°C for 1 h in a flowing air atmosphere, then switched to an H2 / Ar mixture and heat-treated at 400°C for 0.5 h. After that, it was purged in an argon atmosphere until the temperature dropped to room temperature to obtain the desired platinum-based catalyst. The obtained catalyst was numbered catalyst-1. Example 2

[0020] The preparation steps of Example 2 are the same as those of Example 1, except that the silica support in step (1) is changed to MCM-41, and the resulting catalyst is numbered catalyst-2. Example 3

[0021] The preparation steps of Example 3 are the same as those of Example 1, except that the silica support in step (1) is changed to MCM-48, and the resulting catalyst is numbered catalyst-3. Example 4

[0022] The preparation steps of Example 4 are the same as those of Example 1, except that the content of platinum in step (1) is changed to 0.5% of the carrier mass, and the resulting catalyst is numbered catalyst-4. Example 5

[0023] The preparation steps of Example 5 are the same as those of Example 1, except that the content of platinum in step (1) is changed to 3.0% of the carrier mass, and the resulting catalyst is numbered catalyst-5. Example 6

[0024] The preparation steps of Example 6 are the same as those of Example 1, except that the air atmosphere calcination temperature in step (1) is changed to 300°C, and the resulting catalyst is numbered Catalyst-6. Example 7

[0025] The preparation steps of Example 7 are the same as those of Example 1, except that the air atmosphere calcination temperature in step (1) is changed to 600°C, and the resulting catalyst is numbered Catalyst-7. Example 8

[0026] The preparation steps of Example 8 are the same as those of Example 1, except that cyclohexane in step (2) is replaced with n-hexane, and the resulting catalyst is numbered catalyst-8. Example 9

[0027] The preparation steps of Example 9 are the same as those of Example 1, except that the stirring and adsorption temperature in step (2) is changed to 25°C, and the resulting catalyst is numbered catalyst-9. Example 10

[0028] The preparation steps of Example 10 are the same as those of Example 1, except that the iron ion concentration in the iron salt solution in step (2) is changed to 0.0045 mol / L, and the resulting catalyst is numbered catalyst-10. Example 11

[0029] The preparation steps of Example 11 are the same as those of Example 1, except that the iron ion concentration in the iron salt solution in step (2) is changed to 0.0135 mol / L, and the resulting catalyst is numbered catalyst-11. Example 12

[0030] The preparation steps of Example 12 are the same as those of Example 1, except that the stirring and adsorption time in step (2) is changed to 4 h, and the resulting catalyst is numbered catalyst-12. Example 13

[0031] The preparation steps of Example 13 are the same as those of Example 1, except that the pH of the system in step (3) is adjusted to 3.5, and the resulting catalyst is numbered catalyst-13. Example 14

[0032] The preparation steps of Example 14 are the same as those of Example 1, except that the stirring reaction temperature in step (3) is changed to 60°C, and the resulting catalyst is numbered catalyst-14. Example 15

[0033] The preparation steps of Example 15 are the same as those of Example 1, except that the stirring reaction time in step (3) is changed to 2 h, and the resulting catalyst is numbered catalyst-15. Example 16

[0034] The preparation steps of Example 16 are the same as those of Example 1, except that in step (4), steps (2) and (3) are repeated once in sequence, and the resulting catalyst is numbered catalyst-16. Example 17

[0035] The preparation steps of Example 17 are the same as those of Example 1, except that the air atmosphere calcination temperature in step (5) is changed to 350°C, and the resulting catalyst is numbered Catalyst-17. Example 18

[0036] The preparation steps of Example 18 are the same as those of Example 1, except that the air atmosphere calcination time in step (5) is changed to 2 hours, and the resulting catalyst is numbered catalyst-18. Example 19

[0037] The preparation steps of Example 19 are the same as those of Example 1, except that the reducing atmosphere heat treatment temperature in step (5) is changed to 200°C, and the resulting catalyst is numbered catalyst-19. Example 20

[0038] The preparation steps of Example 20 are the same as those of Example 1, except that the heat treatment time in the reducing atmosphere in step (5) is changed to 1 h, and the resulting catalyst is numbered catalyst-20. Comparative Example 1

[0039] The purpose is to compare with Example 1 to verify the key role of preferential directional adsorption of ferrocene in nonpolar solvents in constructing the FeO-Pt interface.

[0040] The preparation steps of Comparative Example 1 are the same as those of Example 1, except that steps (2) and (3) are changed to dissolve ferric chloride in deionized water to obtain an iron salt solution with a concentration of 0.0900 mol / L, and dilute hydrochloric acid is slowly added dropwise under continuous stirring to adjust the pH of the system to 3.0. The reaction is stirred at 40°C for 3 h, and step (4) is removed. The resulting catalyst is numbered Catalyst-21. Comparative Example 2

[0041] The purpose is to compare with Example 1 to highlight the inventiveness and advantages of the present invention’s “nonpolar solvent selective adsorption-controllable pH in situ anchored hydrolysis-two-step heat treatment” strategy in controlling the spatial proximity and interaction between FeO and Pt.

[0042] Comparative Example 2 used the traditional co-impregnation method, in which an aqueous solution of chloroplatinic acid and a cyclohexane solution containing ferrocene were simultaneously impregnated on a fumed silica support. After drying, the catalyst was treated under the same conditions as in Example 1, and the resulting catalyst was designated as Catalyst-22. Comparative Example 3

[0043] The purpose is to compare with Example 1 to illustrate that the catalyst prepared with platinum loading within the scope of the claims has good performance. The catalyst with higher platinum loading has higher economic cost, while the catalyst with lower platinum loading has insufficient active metal sites and fewer FeO-Pt effective interfaces.

[0044] The preparation steps of Comparative Example 3 are the same as those of Example 1, except that the platinum loading in step (1) is changed to 0.1%, and the resulting catalyst is numbered Catalyst-23. Comparative Example 4

[0045] The purpose is to compare with Example 1 to illustrate that the high-temperature calcination process of the present invention can construct large-particle platinum clusters, and FeO migrates during the subsequent heating and reduction process, thus solving the problem that small-particle platinum clusters are easily covered, leading to catalyst deactivation.

[0046] The preparation steps of Comparative Example 4 are the same as those of Example 1, except that the air atmosphere calcination temperature in step (1) is changed to 200°C, and the resulting catalyst is numbered Catalyst-24. Comparative Example 5

[0047] The purpose is to compare with Example 1 to illustrate that the catalyst prepared by the ferrocene salt solution at the concentration within the scope of the claims has good catalytic activity. The low iron loading catalyst has too low FeO loading and insufficient interfacial active sites, which affects the catalytic activity.

[0048] The preparation steps of Comparative Example 5 are the same as those of Example 1, except that the iron ion concentration of the iron salt solution in step (2) is changed to 0.0010 mol / L, and the resulting catalyst is numbered Catalyst-25. Comparative Example 6

[0049] The purpose is to compare with Example 1 to illustrate that the catalyst prepared by ferrocene adsorption time on the Pt / SiO2 surface within the scope of the claims has good performance. The low adsorption time is insufficient for ferrocene molecules to reach adsorption-desorption equilibrium and saturation coverage on the platinum surface, resulting in a limited number of iron precursors available for subsequent hydrolysis anchoring.

[0050] The preparation steps of Comparative Example 6 are the same as those of Example 1, except that the adsorption time of ferrocene in step (2) is changed to 1 h, and the resulting catalyst is numbered Catalyst-26. Comparative Example 7

[0051] The purpose is to compare with Example 1 to illustrate the hydrolysis of ferrocene in an acidic solution with pH = 3.0-3.5, releasing Fe. 3+ The necessity of subsequent electrostatic adsorption and anchoring with hydroxyl groups on the carrier surface.

[0052] The preparation steps of Comparative Example 7 are the same as those of Example 1, except that step (3) is changed to adjust the pH of the system to 7.0. The resulting catalysts are numbered Catalyst-27. Comparative Example 8

[0053] The purpose is to compare with Example 1 to illustrate the importance of a stepwise, cyclic loading strategy for uniformly and densely constructing a layer of iron hydroxyl species on the surface of the support and around the platinum particles, thereby increasing the FeO-Pt interface density.

[0054] The preparation steps of Comparative Example 8 are the same as those of Example 1, except that the cyclic adsorption and hydrolysis step in step (4) is skipped, and the resulting catalyst is numbered Catalyst-28. Comparative Example 9

[0055] The purpose is to compare with Example 1 to illustrate that the lack of an oxidation step will prevent iron species from being fixed in the form of highly dispersed Fe2O3, thereby affecting their effective transformation to the active FeO phase and stable binding with Pt in subsequent reduction.

[0056] The preparation steps of Comparative Example 9 are the same as those of Example 1, except that the air atmosphere heating and roasting step (5) is skipped, and the resulting catalyst is numbered Catalyst-29. Comparative Example 10

[0057] The purpose is to compare with Example 1 to illustrate that harsh calcination conditions can cause excessive sintering of Fe2O3, which is not conducive to the formation of an ideal FeO-Pt coupling interface.

[0058] The preparation steps of Comparative Example 10 are the same as those of Example 1, except that step (5) is changed to calcination at 400°C in air atmosphere for 1 hour, and the resulting catalyst is numbered Catalyst-30. Comparative Example 11

[0059] The purpose is to compare with Example 1 to illustrate that high reduction temperature can cause excessive reduction of FeO (such as conversion to metallic Fe), or lead to structural damage at the Pt-FeO interface due to intensified atomic migration, resulting in decreased catalytic activity.

[0060] The preparation steps of Comparative Example 11 are the same as those of Example 1, except that the reducing atmosphere heat treatment temperature in step (5) is changed to 500°C, and the resulting catalyst is numbered Catalyst-31.

[0061] The testing method is as follows: (1) The obtained catalyst was pressed into tablets, crushed and sieved to obtain catalysts with a particle size of 40-60 mesh for CO preferential oxidation activity evaluation; (2) 300 mg of the prepared catalyst was loaded into the reactor. The test temperature range was 60-160℃. Samples were taken every 10℃, and the temperature was maintained at a constant value for 1 h each time. The volume ratio of CO to O2 in the mixed gas was 1:1, and the gas space velocity of the mixed gas was 4000 h⁻¹. -1 ; (3) Qualitative and quantitative analysis of the inlet and outlet gases was performed using a gas chromatograph equipped with TCD and FID detectors; The activity of the prepared catalyst was tested using the above method. The results of CO conversion rate and O2 to CO2 selectivity of the prepared catalyst in the temperature range of 60-160℃ are shown in Table 1.

[0062] Table 1 Catalyst number CO complete conversion temperature window / ℃ Selectivity corresponding to the CO total conversion temperature Catalyst-1 100-150 70.2% Catalyst-2 160 51.9% Catalyst-3 160 53.1% Catalyst-4 150-160 52.9% Catalyst-5 130-160 49.7% Catalyst-6 150-160 54.5% Catalyst-7 160 49.8% Catalyst-8 110-140 55.3% Catalyst-9 110-150 62.5% Catalyst-10 160 52.4% Catalyst-11 160 53.7% Catalyst-12 110-160 62.5% Catalyst-13 120-150 59.4% Catalyst-14 130-160 61.1% Catalyst-15 150-160 66.3% Catalyst-16 130-150 59.4% Catalyst-17 150-160 55.1% Catalyst-18 160 50.6% Catalyst-19 140-160 57.5% Catalyst-20 140-160 53.0% Catalyst-21 No full conversion temperature point / Catalyst-22 No full conversion temperature point / Catalyst-23 No full conversion temperature point / Catalyst-24 160 47.2% Catalyst-25 No full conversion temperature point / Catalyst-26 160 50.4% Catalyst-27 No full conversion temperature point / Catalyst-28 150-160 52.7% Catalyst-29 No full conversion temperature point / Catalyst-30 160 47.9% Catalyst-31 No full conversion temperature point /

Claims

1. A method for preparing a platinum-based catalyst for preferential oxidation of CO in a hydrogen-rich atmosphere, characterized in that: Includes the following steps: Step 1: Dissolve platinum salt in deionized water to prepare a platinum precursor solution, immerse it in a high specific surface area silica support, dry it, and then calcine it in air at 300-600℃ for at least 2 h to obtain sample A. Step 2: Dissolve ferrocene in nonpolar alkanes to prepare an iron salt solution with an iron ion concentration of 0.0045-0.0135 mol / L. Add sample A to an excess of the iron salt solution and stir at 25-45℃ for at least 3 h to adsorb. Filter to collect the solid product and dry it to obtain sample B. Step 3: Disperse sample B in ethanol, slowly add dilute hydrochloric acid dropwise under continuous stirring to adjust the pH of the system to 3.0-3.5, stir the reaction at 40-60℃ for at least 1 h, filter to collect the solid product after the reaction is completed and dry it to obtain sample C; Step 4: Replace sample A with sample C and repeat steps 2 and 3 1-3 times to obtain sample D; Step 5: Place sample D in a flowing air atmosphere and calcine at 200-350℃ for at least 1 h, then switch to a reducing atmosphere and heat treat at 200-400℃ for 0.5-1 h. Afterward, purge under an inert atmosphere until the temperature drops to room temperature to obtain the desired platinum-based catalyst.

2. The method for preparing a platinum-based catalyst according to claim 1, characterized in that: In step one, the high specific surface area silica support is one or more of fumed silica, HMS, MCM-48, MCM-41 or SBA-15.

3. The method for preparing a platinum-based catalyst according to claim 1, characterized in that: In step one, the platinum salt is chloroplatinic acid, and the platinum content in sample A accounts for 0.5%-3.0% of the carrier mass.

4. The method for preparing a platinum-based catalyst according to claim 1, characterized in that: In step two, the nonpolar alkane is one or more of the following: alkane or cycloalkanes with 5-16 carbon atoms.

5. The preparation method according to claim 1, characterized in that: In step two, the excess iron salt solution is a solution with a water absorption rate no less than twice that of sample A.

6. The preparation method according to claim 1, characterized in that: In step five, the reducing atmosphere is high-purity hydrogen or an H2 / Ar mixture.

7. A catalyst prepared by any one of the preparation methods according to claims 1-6.

8. The application of the catalyst according to claim 7 in the preferential oxidation reaction of CO under a hydrogen-rich atmosphere.

9. The application of the catalyst according to claim 7 in the preferential oxidation of CO in a hydrogen-rich atmosphere, characterized in that: The prepared catalyst is used at temperatures of 60-160℃, with a CO:O2 volume ratio of 2-1:1 in the mixed gas and a gas space velocity of 4000-18000 h⁻¹. -1 .

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