A low-loading pt-based catalyst, its preparation method and application

Abstract

The application discloses a low-loading Pt-based catalyst, which comprises a carrier, a transition metal oxide and Pt; the transition metal oxide is dispersed on the carrier in the form of nano-islands; the Pt is selectively deposited and dispersed on the transition metal oxide nano-islands under the action of a coupling agent; and the content of the Pt and the transition metal is 0.05-0.5 wt% and 0.5-5 wt% respectively based on the mass of the low-loading Pt-based catalyst. The application further discloses a preparation method of the low-loading Pt-based catalyst and application of the low-loading Pt-based catalyst in CO preferential oxidation reaction and formaldehyde elimination reaction in a hydrogen-rich atmosphere. The preparation method has the advantages of mild conditions, simple operation and environmental protection, and the low-loading Pt-based catalyst has a wide CO conversion temperature window in the CO preferential oxidation reaction in the hydrogen-rich atmosphere, and can completely eliminate formaldehyde at room temperature.

Description

Technical Field

[0001] This invention relates to the field of solid catalyst technology, and in particular to a low-loading Pt-based catalyst, its preparation method, and its application. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) using high-purity hydrogen as fuel have broad application prospects due to their advantages such as small size, low operating temperature, high energy density, and fast start-up rate. However, trace amounts of CO in hydrogen-rich gas can poison the electrodes. Preferential oxidation of CO in hydrogen-rich gas (CO-PROX) is the most direct and effective method for eliminating CO from a practical and economic perspective; however, it often requires temperatures above 100°C to reduce CO to below the ppm level due to insufficient activity (Chinese patent document CN114515580A). Therefore, developing a high-performance CO-PROX catalyst that can meet the operating temperature (≤80°C) of PEMFCs is imperative.

[0003] Formaldehyde is one of the main pollutants in enclosed spaces, especially in newly renovated homes. Long-term exposure to trace amounts of formaldehyde can cause diseases such as pharyngitis, bronchitis, pneumonia, and even lung cancer. Therefore, the elimination of formaldehyde at room temperature is of great significance to human health and social development.

[0004] Pt-based catalysts have wide applications in oxidation reactions (including CO-PROX and formaldehyde oxidation). In CO preferential oxidation reactions, the choice of support mainly falls into two categories: one is reducible metal oxides such as iron oxide, and the other is inert supports such as silica and activated carbon. When using metal oxides as supports, high activity can be obtained by adjusting the valence state of the reducible metal oxides through heat treatment of the catalyst to enhance the activation ability of O2. However, when the temperature reaches above 100℃, excessive activated oxygen causes the activation oxidation of H2, resulting in a significant decrease in CO conversion rate. Zhang et al. prepared Pt / CeO2 catalysts using CeO2 as supports for preferential oxidation reactions, but when the temperature reached above 120℃, the intensified H2 oxidation led to a rapid decrease in CO conversion rate, and the CO conversion temperature window was far from sufficient [Appl. Catal. B-Environ. 2013, 615-625]. When using inert materials as supports, the catalyst's ability to activate oxygen is insufficient due to the poisoning effect of CO on Pt. As a result, achieving high activity often requires higher temperatures or higher Pt loading. Jie Donglai et al. modified Pt / Al2O3 catalysts with A-type additives such as Ag and Fe and B-type additives such as K and Na for CO removal from reformed gas. Achieving CO reduction to below ppm level requires temperatures above 100℃ (Chinese patent document with publication number CN101879453A).

[0005] Using inert materials with high specific surface area as a substrate can promote metal dispersion, enhance the strong interaction between Pt and metal oxides, and regulate oxygen activation capacity. To effectively construct the interfacial effect between Pt and metal oxides, a one-pot method is generally used to prepare catalysts. However, high-temperature treatment is often required during the activation of metal oxide properties, which can lead to Pt sintering. Chen et al.'s one-pot Pt-Fe / CNTs catalyst can completely eliminate CO at 40℃ [Int. J. Hydrogen Energy, 2016, 14079-14087], but the high-temperature treatment of the Pt-Fe component during preparation causes Pt agglomerates with particle sizes exceeding 7 nm, resulting in low Pt atom utilization and requiring high Pt loading, leading to high preparation costs. Therefore, avoiding Pt sintering remains a challenge. Wang Hongjuan et al. prepared Cu / PtM / CNTs (where M is Fe, Co, or Ni) for use as cathode catalysts in methanol fuel cells by coating with Cu. This metal coating method prevents the sintering of Pt particles. However, the preparation process is cumbersome, and the Cu coating of Pt covers most of the active sites, resulting in a Pt loading as high as 10 wt.%, far from meeting the requirements of practical applications (Chinese patent document CN101380584A). Lu et al. obtained Fe-Pt / SiO2 catalysts using atomic layer deposition, avoiding high-temperature Pt agglomeration and completely eliminating CO at room temperature. However, this preparation method has high equipment requirements, making industrial application difficult [Nature, 2019, 565: 631-635].

[0006] In catalytic reactions, chloride ions can poison the catalytic active center, destroy the catalyst structure and cause catalyst deactivation. Therefore, in the preparation of Pt-based catalysts, more expensive chlorine-free platinum reagents are generally required, or chloride ions are removed by a large amount of washing, which generates a large amount of chlorine-containing wastewater, which to some extent limits the preparation of catalysts [Appl. Catal. A-Gen. 638 (2022), 118636].

[0007] Currently reported Pt-based catalysts still suffer from problems such as low activity, cumbersome preparation steps, weak intermetallic interactions leading to easy sintering of Pt, and chloride ion poisoning, which hinder their practical industrial application. Summary of the Invention

[0008] In view of the problems existing in the prior art, the present invention provides a low-loading Pt-based catalyst, its preparation method and application. The preparation method is simple, the preparation conditions are mild, and the high-temperature sintering of the noble metal Pt is avoided during the preparation process. The prepared catalyst has high catalytic activity on the basis of low Pt loading.

[0009] The technical solution of the present invention is as follows:

[0010] A low-loading Pt-based catalyst includes a support, a transition metal oxide, and Pt;

[0011] Transition metal oxides are dispersed on a support in the form of nano islands; Pt is selectively deposited and dispersed on the transition metal oxide nano islands under the action of a coupling agent;

[0012] Based on the mass of the low-load Pt-based catalyst, the contents of Pt and transition metals, expressed in atomic mass, are 0.05–0.5 wt% and 0.5–5 wt%, respectively.

[0013] Preferably, the carrier is a carbon nanotube; the transition metal oxide is at least one of Fe, Ce, Co, and Mn oxides.

[0014] More preferably, the carbon nanotubes are multi-walled carbon nanotubes.

[0015] Preferably, Pt is dispersed in clusters of 1–2 nm in transition metal oxide nanoislands.

[0016] Using carbon nanotubes as a support to load transition metal oxides MO x Furthermore, Pt is selectively deposited on transition metal oxide nanoislands using a coupling agent, promoting strong interactions between Pt and transition metal oxides, and fostering the generation of oxygen vacancies. This facilitates the adsorption and activation of O2 by the catalyst, effectively improving the catalytic performance of the oxidation reaction. Compared with existing technologies, the low-loading Pt-based catalyst Pt-MO of this invention... x / CNTs are prepared under mild conditions, avoiding the high-temperature sintering of the precious metal Pt, and have the advantages of low loading and high activity.

[0017] The low-loading Pt-based catalyst of the present invention is applicable to, but not limited to, the preferential oxidation reaction of CO in a hydrogen-rich atmosphere. It can completely eliminate CO within a wide CO conversion temperature window (20-200°C), thereby purifying the hydrogen source in a proton exchange membrane fuel cell. It can also be used to completely eliminate formaldehyde at room temperature, converting it into carbon dioxide and water, thereby purifying the air.

[0018] The present invention also provides the application of the low-loading Pt-based catalyst in the preferential oxidation of CO in a hydrogen-rich atmosphere, at a reaction temperature of 20–200 °C.

[0019] Preferably, the application includes: passing the CO-containing hydrogen-rich gas to be treated through a fixed-bed reactor loaded with the low-load Pt-based catalyst, at a mass hourly space velocity of 1.8 × 10⁻⁶. 3 ~3.6×10 5 mL g cat -1 h -1 The reaction temperature is 20–200℃.

[0020] The present invention also provides the application of the low-loading Pt-based catalyst in formaldehyde elimination, with a reaction temperature of 20–80 °C.

[0021] Preferably, the application includes: passing the formaldehyde-containing gas to be treated through a fixed-bed reactor loaded with a low-loading Pt-based catalyst at a mass hourly space velocity (MSV) of 6 × 10⁻⁶. 3 ~6×10 5 mL g cat -1 h -1 The reaction temperature is 20–80℃.

[0022] More preferably, the formaldehyde-containing gas has a formaldehyde concentration of 100-500 ppm and also contains 5-20 vol.% O2.

[0023] This invention also provides a method for preparing a low-loading Pt-based catalyst, comprising the following steps:

[0024] Step 1: The support is immersed in a transition metal M source solution, the pH value is adjusted, and the mixture is stirred, aged, filtered, washed, dried, and calcined under an inert atmosphere to obtain MO. x carrier;

[0025] Step 2: Dissolve the Pt source in a low-carbon alcohol, mix it with a strong base low-carbon alcohol solution, and reduce it under an inert atmosphere to obtain Pt sol;

[0026] Step 3: Disperse the Pt sol in the coupling agent and react it with MO. x The carrier is mixed, stirred, impregnated, dried, and reduced to obtain a low-loading Pt-based catalyst;

[0027] The transition metal M includes at least one of Fe, Ce, Co, and Mn.

[0028] The transition metal M source is a water-soluble compound of the transition metal M.

[0029] Preferably, in step 1, the concentration of the transition metal M source solution is 0.5–10 × 10⁻⁶. -3 mol L -1 .

[0030] When the concentration of the transition metal M source solution is too low, MO is obtained. x The fewer transition metal oxide nanoislands in the support result in a lower concentration of Pt-MO in the final catalyst. x Insufficient structure leads to inadequate catalytic activity; when the concentration of the transition metal M source solution is too high, the final catalyst also exhibits poor catalytic activity.

[0031] More preferably, in step 1, the concentration of the transition metal M source solution is 1–2 × 10⁻⁶.-3 mol L -1 .

[0032] In step 1, adjust the pH value to 8-10. An alkali can be used to adjust the pH value; the alkali can be at least one of NaOH, Na₂CO₃, or NH₃·H₂O.

[0033] In step 1, the stirring time is 1-3 hours; the aging time is 1-3 hours; the drying temperature is 80-120℃; the calcination temperature is 300-500℃; and the calcination time is 3-5 hours.

[0034] In step 2, the lower alcohol is at least one of ethylene glycol, glycerol, and 1,4-butanediol; the strong base is NaOH and / or KOH; and the inert atmosphere is at least one of N2, He, and Ar.

[0035] In step 3, the coupling agent is at least one of aminosilane, carboxysilane, and triethanolamine. Coupling agents such as triethanolamine, aminosilane, and carboxysilane contain two chemical groups with different properties, which can form chemical bonds or complex structures with the target metal through ionic or coordinate bonds. Therefore, coupling agents of the same type should have the same effect.

[0036] Coupling agents promote the bonding of Pt in transition metal oxides MO via metal-ligand bonds. x Selective deposition and dispersion.

[0037] In step 3, the volume fraction of Pt sol in both the Pt sol and the coupling agent is 1-15%.

[0038] In step 3, the stirring time is 0.5–3 h; the impregnation time is 12–24 h; the drying is vacuum drying for 12–24 h at a temperature of 80–120 °C; the reducing atmosphere is 10–100 vol% H₂ with Ar as the equilibrium atmosphere; the reduction time is 0.5–2 h, and the reducing atmosphere flow rate is 20–50 mL / min. -1 .

[0039] Compared with existing technologies, the beneficial effects of the present invention are as follows:

[0040] 1. The preparation method of the present invention selectively deposits Pt onto the metal oxide MO using a coupling agent. x Pt-MO was avoided on the nanoisland. x The agglomeration of Pt during calcination enhances the interaction between Pt and the metal oxide MO. x The strong interactions between them make the preparation method simple and easy to operate.

[0041] 2. The preparation method of the present invention is simple and requires low-end synthesis equipment. It uses chloroplatinic acid, the most economical platinum source, which reduces the preparation cost. During the preparation of the sol, chloride ions are stripped from the Pt coordination structure, eliminating the poisoning of chloride ions during the catalytic reaction of the Pt active center. There is no need to wash off chloride ions, which reduces the generation of wastewater.

[0042] 3. The catalyst prepared by the method of the present invention exhibits good catalytic performance in oxidation reactions with oxygen as the reaction atmosphere (including CO oxidation reaction under hydrogen-rich atmosphere and formaldehyde elimination reaction at room temperature), and the Pt loading is much lower than that of currently reported noble metal-based catalysts. Attached Figure Description

[0043] Figure 1 The diagram shows the structure of the catalyst, where (a) is the catalyst prepared in Comparative Example 3 and (b) is the low-loading Pt-based catalyst of the present invention.

[0044] Figure 2 (a) HAADF-STEM image and particle size distribution of the catalyst prepared in Example 1 of this invention, and (b) Pt-FeO x Location distribution (circles).

[0045] Figure 3 The above are H2-TPR diagrams of the catalysts prepared in Example 1 and Comparative Examples 1 and 2 of this invention.

[0046] Figure 4 The graphs show the performance of the catalysts prepared in Examples 1, 2, and 3 of this invention in the CO preferential oxidation reaction test.

[0047] Figure 5 The figures show the performance test results of the catalysts prepared in Examples 1, 4, and 5 of this invention for the preferential oxidation of CO.

[0048] Figure 6 The graphs show the performance of the catalysts prepared in Example 1 and Comparative Examples 1 and 2 of this invention in the CO preferential oxidation reaction test.

[0049] Figure 7 The graphs show the performance of the catalysts prepared in Examples 1, 6, 7, 8 and Comparative Example 3 of this invention in the CO preferential oxidation reaction test.

[0050] Figure 8 The graphs show the formaldehyde elimination performance test results of the catalysts prepared in Example 1 and Comparative Examples 1 and 2 of this invention. Detailed Implementation

[0051] Example 1:

[0052] 1.0 g of CNTs was dispersed in 100 mL of a solution with a concentration of 1.8 × 10⁻⁶. -3 mol L -1In a ferric nitrate solution, the mixture was stirred for 3 hours in an 80°C water bath at pH 9, allowed to stand for 1 hour, filtered while hot, and washed. The filter cake was dried in an oven at 110°C for 12 hours and calcined in a tube furnace at 350°C for 4 hours under an Ar atmosphere to obtain 1FeO. x / CNTs.

[0053] 50 mL of 0.04 mol L -1 A solution of H₂PtCl₆·6H₂O in ethylene glycol was placed in a 250 mL three-necked flask, and 50 mL of a 0.25 mol / L solution was added. -1 A NaOH-ethylene glycol solution was mixed at room temperature for 1 hour and then transferred to a 160°C oil bath for 3 hours to obtain a Pt colloidal solution.

[0054] Take 0.54 mL of Pt colloidal solution and dilute it to 10 mL with triethanolamine. Add 1.0 g of 1FeO x / CNTs were added and impregnated, dried at room temperature for 12 h, then dried in a vacuum oven at 120 °C for 12 h, and reduced for 0.5 h under a 20 vol.% H2 / Ar atmosphere to obtain a 0.2 wt% Pt-1 wt% Fe / CNTs catalyst, denoted as 0.2Pt-1FeO. x / CNTs.

[0055] Example 2:

[0056] The preparation process was the same as in Example 1. The difference was that the volume of the Pt colloidal solution used was 0.14 mL, and it was diluted to 10 mL with triethanolamine. All other steps were identical, yielding a 0.05 wt% Pt-1 wt% Fe / CNTs catalyst, denoted as 0.05Pt-1FeO. x / CNTs.

[0057] Example 3:

[0058] The preparation process was the same as in Example 1. The difference was that the volume of the Pt colloidal solution used was 1.35 mL, and triethanolamine was added to dilute it to 10 mL. All other steps were identical, yielding a 0.5 wt% Pt-1 wt% Fe / CNTs catalyst, denoted as 0.5Pt-1FeO. x / CNTs.

[0059] Example 4:

[0060] The preparation process is the same as in Example 1. The difference is that the concentration of the ferric nitrate solution used is 9 × 10⁻⁶. -4 molL -1 The remaining steps were the same, yielding a 0.2wt% Pt-0.5wt% Fe / CNTs catalyst, denoted as 0.2Pt-0.5FeO. x / CNTs.

[0061] Example 5:

[0062] The preparation process is the same as in Example 1. The difference is that the concentration of the ferric nitrate solution used is 9 × 10⁻⁶. -3 molL -1 The remaining steps were the same, yielding a 0.2 wt% Pt-5 wt% Fe / CNTs catalyst, denoted as 0.2Pt-5FeO. x / CNTs.

[0063] Example 6:

[0064] The preparation process is the same as in Example 1. The difference between Example 1 and Example 2 is that the salt solution used is 7.2 × 10⁻⁶. -4 mol L -1 Using a cerium nitrate solution, and following the same steps, a 0.2 wt% Pt-1 wt% Ce / CNTs catalyst was obtained, denoted as 0.2Pt-1CeO. x / CNTs.

[0065] Example 7:

[0066] The preparation process was the same as in Example 1, except that the salt solution used was manganese nitrate solution. All other steps were identical, yielding a 0.2 wt% Pt-1 wt% Mn / CNTs catalyst, denoted as 0.2Pt-1MnO. x / CNTs.

[0067] Example 8:

[0068] The preparation process is the same as in Example 1. The difference between Example 1 and Example 2 is that the salt solution used is 1.7 × 10⁻⁶. -3 mol L -1 Using cobalt nitrate solution, and following the same steps, a 0.2 wt% Pt-1 wt% Co / CNTs catalyst was obtained, denoted as 0.2Pt-1CoO. x / CNTs.

[0069] Comparative Example 1:

[0070] Take 0.54 mL of Pt sol from Example 1, dilute it to 10 mL with ethylene glycol, add 1.0 g of CNTs to impregnate it, dry it at room temperature for 12 h, then place it in a vacuum oven at 120 °C for 12 h, and reduce it for 0.5 h under a 20 vol% H2 / Ar atmosphere to obtain a 0.2 wt% Pt / CNTs catalyst, denoted as 0.2 Pt / CNTs.

[0071] Comparative Example 2:

[0072] The preparation process was the same as in Example 1, except that no Pt sol was added. All other steps were identical, yielding a 1 wt% Fe / CNTs catalyst, denoted as 1FeO. x / CNTs. Comparative Example 3:

[0073] The preparation process was the same as in Example 1. The difference was that the Pt sol was not diluted with triethanolamine; all other steps were identical, yielding a 0.2 wt% Pt-1 wt% Fe / CNTs-N catalyst, denoted as 0.2Pt-1FeO. x / CNTs-N.

[0074] To evaluate the catalytic performance of the prepared catalyst, its performance in the preferential CO oxidation reaction was tested using a microreactor evaluation device. A fixed-bed reactor was used; 100 mg of catalyst was weighed and loaded into a U-shaped reaction tube, and the flow rate was 30 mL / min. -1 The reacting gases consist of 1 vol.% CO, 1 vol.% O2, and 40 vol.% H2, with Ar as the equilibrium gas and a mass hourly space velocity (WHSV) of 1.8 × 10⁻⁶. 4 mL·g cat -1 h -1 The catalyst was subjected to a programmed temperature activity test. The test temperature range was 20–200℃, and samples were collected and recorded at each temperature for 20 minutes to determine the CO concentration at the reactor outlet using chromatographic analysis.

[0075] The method for calculating CO conversion rate is as follows:

[0076] CO Conversion (%) = ([CO] in -[CO] out ) / [CO] in ×100%;

[0077] Among them: [CO] in The peak area corresponding to CO at the reactor inlet;

[0078] [CO] out This represents the chromatographic peak area of ​​CO at the reactor outlet at different reaction temperatures.

[0079] To evaluate the catalytic performance of the prepared catalyst, its formaldehyde elimination performance was tested using a microreactor evaluation device. A fixed-bed reactor was used, with 50 mg of catalyst loaded into a U-shaped reaction tube at a flow rate of 100 mL / min. -1 The reactant gas composition is 400 ppm HCHO, 20 vol.% O2, with Ar as the equilibrium gas, and a mass hourly space velocity (WHSV) of 6 × 10⁻⁶. 4 mLg cat -1 h-1 The catalyst was subjected to a temperature-programmed activity test. The test temperature range was 20–80 °C, with samples taken every 20 minutes, three times at each temperature point. The concentration of CO2 at the reactor outlet was recorded by chromatography. Since the CO2 concentration during the experiment was in the ppm range, a nickel conversion furnace was installed in the FID detector of the chromatography system to capture the CO2 concentration. The generated CO2 was then completely converted to CH4 by hydrogenation in an H2 atmosphere, and the concentration of CO2 in the product was quantified by the concentration of CH4.

[0080] The calculation method for HCHO conversion rate is as follows:

[0081] HCHO Conversion(%)=[CO2] / [CO2] A ×100%;

[0082] Among them: [CO2] A This represents the peak area of ​​CH4 when formaldehyde is completely converted into CO2.

[0083] [CO2] represents the CH4 chromatographic peak area corresponding to CO2 generated under different reaction temperature conditions.

[0084] result

[0085] Depend on Figure 1 It can be seen that, compared with catalysts prepared by existing methods ( Figure 1 Compared to (a)), the low-loading Pt-based catalyst prepared in this invention exhibits more uniform Pt nanoclusters in size and, under the action of a coupling agent, selectively deposits and highly disperses them in the metal oxide MO. x Nano Island ( Figure 1 (b)

[0086] Depend on Figure 2 HAADF-STEM images of the catalyst show that in the catalyst prepared in Example 1, Pt is uniformly and highly dispersed in FeO as nanoparticles with an average particle size of 1.8 nm. x On the island of Namibia.

[0087] Figure 3 This indicates that Pt-FeO loaded on CNTs x There are strong interactions between them, which promote the growth of FeO. x The reduction of oxygen vacancies generates more oxygen vacancies, thereby enhancing the catalyst's ability to adsorb and activate O2.

[0088] Figure 4 This indicates that 0.05Pt-1FeO x / CNTs catalysts show a gradual increase in CO conversion with increasing temperature, achieving complete CO conversion at 120℃; 0.2Pt-1FeO x / CNTs and 0.5Pt-1FeO x / CNTs catalysts exhibit excellent catalytic performance in the preferential oxidation of CO, and CO can be completely eliminated in the temperature range of 20 to 200 °C.

[0089] Figure 5 This indicates that different FeO x The content of different elements has varying effects on catalyst performance. Results show that 0.2Pt-1FeO... x / CNTs catalysts exhibit the best activity and can completely eliminate CO within a temperature range of 20–200℃.

[0090] Figure 6 This indicates that 1FeO x / CNTs are almost inactive in the preferential oxidation of CO; 0.2Pt / CNTs only achieve complete CO conversion at 140–160℃, and 0.2Pt-1FeO x / CNTs exhibit the best activity and can completely eliminate CO within a temperature range of 20–200℃.

[0091] Figure 7 This indicates that 0.2Pt-1FeO with added coupling agent... x / CNTs catalysts show a significant improvement in CO preferential oxidation performance, and other transition metals also show varying degrees of performance improvement.

[0092] Figure 8 This indicates that 1FeO x / CNTs are inactive in the formaldehyde elimination reaction; the 0.2Pt / CNTs catalyst only achieves 100% formaldehyde conversion at 40℃. 0.2Pt-1FeO x / CNTs catalysts exhibit excellent formaldehyde removal performance at room temperature, achieving 100% formaldehyde conversion within a temperature range of 20–80°C, and completely eliminating ppm-level formaldehyde at room temperature.

[0093] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Pt-based catalyst, characterized in that, Including supports, transition metal oxides, and Pt; Transition metal oxides are dispersed on a support in the form of nano islands; Pt is selectively deposited and dispersed on the transition metal oxide nano islands under the action of a coupling agent; Based on the mass of the Pt-based catalyst, the contents of Pt and transition metals, expressed as atomic masses, are 0.2–0.5 wt% and 1 wt%, respectively. The carrier is carbon nanotubes; the transition metal oxide is Fe oxide. The preparation method of the Pt-based catalyst includes the following steps: Step 1: The support is immersed in a transition metal Fe source solution, the pH value is adjusted, and after stirring, aging, filtration, washing, drying, and calcination under an inert atmosphere, FeO is obtained. x carrier; Step 2: Dissolve the Pt source in a low-carbon alcohol, mix it with a low-carbon alcohol solution containing a strong base, and reduce it under an inert atmosphere to obtain Pt sol; the low-carbon alcohol is at least one of ethylene glycol, glycerol, and 1,4-butanediol; the strong base is NaOH and / or KOH; Step 3: Disperse the Pt sol in the coupling agent triethanolamine, and then react it with FeO. x The carrier is mixed, stirred, impregnated, dried, and reduced to obtain a Pt-based catalyst.

2. The Pt-based catalyst according to claim 1, characterized in that, The carbon nanotubes mentioned are multi-walled carbon nanotubes.

3. The Pt-based catalyst according to claim 1, characterized in that, Pt is dispersed in clusters of 1 to 2 nm in transition metal oxide nanoislands.

4. The Pt-based catalyst according to claim 1, characterized in that, In step 1, the concentration of the transition metal Fe source solution is (0.5~10)×10⁻⁶. -3 mol L -1 .

5. The application of a Pt-based catalyst as described in any one of claims 1-4 in the preferential oxidation of CO in a hydrogen-rich atmosphere, characterized in that, The reaction temperature is 20~200℃.

6. The application of a Pt-based catalyst as described in any one of claims 1-4 in the oxidative elimination of formaldehyde, characterized in that, The reaction temperature is 20~80℃.

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