Oxygen Vacancy-Regulated Platinum-Supported Alumina Catalysts, Their Preparation Methods and Applications

Abstract

This invention relates to an oxygen vacancy-controlled platinum-supported alumina catalyst, its preparation method, and its application. The catalyst uses defective alumina obtained by organic acid treatment and heat treatment under an inert atmosphere as a support, loads platinum nanoparticles, and then reduces them with hydrogen. The preparation method includes: dispersing alumina in an organic acid solution and refluxing it to form acetate-containing coordination species on the alumina surface; washing and drying, followed by heat treatment under an inert atmosphere to thermally decompose the surface organic ligands and induce the formation of oxygen vacancies and coordinated unsaturated aluminum sites; loading a platinum precursor using an impregnation method, followed by hydrogen reduction to obtain the oxygen vacancy-controlled platinum-supported alumina catalyst. The oxygen vacancy-controlled platinum-supported alumina catalyst possesses abundant oxygen vacancies, electron-rich platinum sites, and a high proportion of bibridged hydroxyl species, which can synergistically promote water molecule activation, oxygen activation, and surface hydroxyl regeneration, thereby significantly improving the complete oxidation efficiency of formaldehyde under room temperature and low temperature conditions.

Description

Technical Field

[0001] This invention belongs to the field of environmental catalysis and indoor air purification technology, specifically relating to platinum-supported alumina catalysts with oxygen vacancy regulation, their preparation methods, and applications. Background Technology

[0002] Formaldehyde is one of the most common and toxic indoor air pollutants. Exposure to environments with excessive formaldehyde levels can trigger various serious diseases, such as asthma, nasopharyngeal carcinoma, and leukemia, posing a significant threat to human health. Therefore, developing safe and efficient formaldehyde removal technologies is crucial for improving indoor air quality and reducing health risks. Among existing formaldehyde removal technologies, catalytic oxidation is the preferred option due to its high removal efficiency, non-toxic products, and energy efficiency. The core of developing catalytic oxidation for formaldehyde removal lies in researching and developing efficient and low-cost formaldehyde oxidation catalysts to achieve the oxidation and degradation of formaldehyde into CO2 and H2O at room temperature.

[0003] Formaldehyde oxidation catalysts have undergone more than 20 years of research and development, forming two main branches: supported noble metals (Pt, Au, Pd, and Ag, etc.) and non-noble metal oxides (MnO2, CeO2, and Co3O4, etc.). While non-noble metal oxides are inexpensive, their activity is generally low, typically requiring temperatures above 60°C for complete formaldehyde oxidation. In contrast, noble metal catalysts mostly exhibit excellent low-temperature catalytic activity, and some supported noble metal catalysts can catalyze complete formaldehyde oxidation at room temperature; however, their commercial application is limited by high material costs. Given the significant difference in activity between the two, supported noble metal catalysts remain the most promising formaldehyde oxidation catalysts (Appl. Surf. Sci. 475 (2019) 237-255). Existing platinum-based formaldehyde oxidation catalysts mostly use reducible oxides such as TiO2, CeO2, MnO2, and Fe2O3 as supports, utilizing the oxygen vacancies and oxygen migration capabilities of the support to promote the reaction. However, such reducible supports have complex structures and compositions, and may face challenges in practical applications, including stability, humidity tolerance, or production costs. In contrast, non-reducible oxides such as Al2O3 offer advantages such as low cost, good thermal stability, high specific surface area, and a mature industrial application foundation. However, traditional Al2O3 supports lack tunable active defect structures on their surface, resulting in weak interactions with platinum, which limits the performance improvement of the catalyst in formaldehyde oxidation at room temperature.

[0004] Previous studies have shown that platinum sites are primarily responsible for oxygen activation during formaldehyde oxidation, while hydroxyl species on the carrier surface can participate in formaldehyde adsorption, intermediate transformation, and hydroxyl recycling. In particular, certain types of surface hydroxyl groups, such as bridged hydroxyl groups, may play a crucial role in the formaldehyde oxidation reaction. However, effective methods for controllably constructing oxygen vacancies, regulating the platinum electronic structure, and enriching favorable hydroxyl species on the surface of the non-reducible oxide Al₂O₃ remain lacking.

[0005] Therefore, there is an urgent need to develop a simple, controllable method for preparing platinum-supported alumina catalysts suitable for low precious metal loading, so as to achieve efficient and stable catalytic oxidation of formaldehyde at room temperature and in humid environments. Summary of the Invention

[0006] To address the shortcomings and deficiencies of the existing technologies, the present invention aims to provide an oxygen vacancy-controlled platinum-supported alumina catalyst, its preparation method, and its application. Oxygen vacancies and coordinated unsaturated aluminum sites are constructed on the alumina surface through organic acid treatment and inert atmosphere heat treatment. Furthermore, the electronic state of platinum nanoparticles and the distribution of surface hydroxyl species are regulated, thereby improving the catalyst's activity, stability, and humidity tolerance in formaldehyde oxidation at room temperature.

[0007] The preparation method provided by this invention uses readily available raw materials, is easy to operate, and is convenient for mass production.

[0008] The objective of this invention is achieved through the following technical solution: This invention provides an oxygen vacancy-regulated platinum-supported alumina catalyst, comprising: a defective alumina support and platinum nanoparticles supported on the surface of the defective alumina support; Among them, the defective alumina carrier is obtained by heat treatment of alumina under an inert atmosphere after treatment with organic acid; the surface of the defective alumina carrier contains five-coordinate aluminum species, oxygen vacancies and double-bridged hydroxyl species; platinum nanoparticles work synergistically with oxygen vacancies and double-bridged hydroxyl species to promote the formaldehyde oxidation reaction, and the double-bridged hydroxyl species are the key active hydroxyl species in the formaldehyde oxidation reaction.

[0009] Furthermore, the alumina is γ-Al2O3; the morphology of γ-Al2O3 is nanoparticles with a particle size of 3-20 nm.

[0010] Furthermore, the organic acid is one or more of the carboxylic acid organic acids; the concentration of the organic acid solution is 0.01-10.0 mol / L, and the amount of organic acid added is calculated as 0.15-150 mmol of carboxyl groups per 1g of alumina.

[0011] Furthermore, the organic acid is a C1-C6 carboxylic acid, preferably acetic acid.

[0012] Furthermore, when the organic acid is one or more of acetic acid, formic acid, and propionic acid, the concentration of the organic acid solution is 0.1-5.0 mol / L.

[0013] Furthermore, when the organic acid is one or more of citric acid and oxalic acid, the concentration of the organic acid solution is 0.01-2.0 mol / L.

[0014] Furthermore, the loading of platinum nanoparticles, based on the total mass of the oxygen vacancy-regulated platinum-supported alumina catalyst, is 0.1-3.0 wt%; the average particle size of the platinum nanoparticles is 0.5-10 nm.

[0015] Furthermore, the platinum loading is 1.0 wt%.

[0016] This invention also provides a method for preparing the above-mentioned platinum-supported alumina catalyst with oxygen vacancy regulation, comprising the following steps: S1. Disperse alumina in an organic acid solution and reflux it to allow the organic acid to coordinate with the aluminum hydroxyl or aluminum oxide structure on the surface of alumina, forming surface organic acid anion coordination species or aluminum organic acid hydroxyl intermediates, thus obtaining alumina treated with organic acid. S2. After solid-liquid separation, washing, and drying, the alumina treated with organic acid is then heat-treated in an inert atmosphere. During the heat treatment, the organic ligands on the alumina surface undergo thermal decomposition and react with surface hydroxyl groups or lattice oxygen, releasing CO. x H2O is reacted with the alumina to form oxygen vacancies, coordinated unsaturated aluminum sites, and localized free electrons on the alumina surface. After cooling to room temperature, a defect alumina support is obtained. S3. Disperse the defective alumina support in a solvent, add a platinum precursor solution for impregnation treatment, so that the platinum species are uniformly loaded on the alumina surface, collect the solid sample and dry it to obtain the impregnated sample. S4. The impregnated sample is subjected to reduction heat treatment in a hydrogen-containing atmosphere to convert the platinum precursor into metallic platinum nanoparticles. After cooling to room temperature, an oxygen vacancy-regulated platinum-supported alumina catalyst is obtained.

[0017] Furthermore, in step S1, the reflux temperature is 80-130℃; the reflux time is 0.5-5h.

[0018] Furthermore, the reflux temperature is 110℃ and the reflux time is 1 hour. Furthermore, in step S2, the inert atmosphere is one or more of argon, nitrogen, or helium, and the inert atmosphere flow rate is 5-500 mL / h.

[0019] Furthermore, in step S2, the heat treatment temperature is 200-500℃; the heat treatment time is 0.1-5h.

[0020] Furthermore, the heat treatment temperature is 350℃, and the heat treatment time is 2 hours. Further, in step S3, the platinum precursor is at least one of the following: platinum tetraammine nitrate [Pt(NH3)4](NO3)2, sodium hexahydroxyplatinate (IV) Na2[Pt(OH)6], potassium hexahydroxyplatinate (IV) K2[Pt(OH)6], sodium chloroplatinate (Na2PtCl6), platinum nitrate (Pt(NO3)2), platinum hydroxide (Pt(OH)4), hexahydroxyplatinate (IV) acid (H2) [Pt(OH)6], and chloroplatinic acid (H2PtCl6); Furthermore, in step S3, the immersion treatment time is 0.1-5 hours; Furthermore, in step S3, the solid sample is collected by rotary evaporation at a temperature of 50-80℃; Furthermore, in step S3, the drying is carried out under vacuum at a temperature of 60-150℃ for 3-24 hours.

[0021] Furthermore, in step S4, the temperature of the reduction heat treatment is 100-400℃, and the time of the reduction heat treatment is 0.5-5h.

[0022] Furthermore, the reduction heat treatment temperature is 300℃, and the reduction heat treatment time is 1 hour.

[0023] Furthermore, in step S4, the hydrogen-containing atmosphere is a hydrogen / argon mixture containing 1%-100% hydrogen by volume.

[0024] This invention also provides the application of the above-mentioned oxygen vacancy-regulated platinum-supported alumina catalyst in the catalytic oxidation of formaldehyde, characterized in that the catalytic oxidation of formaldehyde is used for indoor air purification, air purifier filters, formaldehyde release treatment from building materials, air purification in enclosed spaces, or purification of low-concentration volatile organic compounds.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) This invention introduces oxygen vacancies and coordinated unsaturated aluminum sites on the surface of Al2O3 by acetic acid treatment and inert atmosphere heat treatment, thus overcoming the limitation of traditional Al2O3 in terms of defect control. (2) Local free electrons on the surface of defective alumina can be transferred to platinum nanoparticles, making the platinum sites exhibit electron-rich characteristics, which is conducive to oxygen adsorption and activation.

[0026] (3) By adjusting the process conditions, the proportion of double-bridged hydroxyl species on the surface of the platinum-supported alumina catalyst with oxygen vacancy regulation is increased, and these hydroxyl species are beneficial to formaldehyde adsorption, intermediate conversion and hydroxyl recycling.

[0027] (4) The synergistic effect of oxygen vacancies, electron-rich platinum sites and double-bridged hydroxyl species promotes the activation of water molecules, oxygen activation and surface hydroxyl regeneration, enabling formaldehyde to be efficiently converted into CO2 and H2O at room temperature.

[0028] (5) The platinum-supported alumina catalyst with oxygen vacancy regulation can still maintain stable formaldehyde conversion capacity in a water-containing atmosphere and a wide humidity range, making it suitable for actual indoor air purification environments.

[0029] (6) The present invention adopts conventional impregnation, heat treatment and reduction processes, which do not require complex equipment, the raw materials are readily available, and have good industrial scale-up potential.

[0030] Chart Explanation Figure 1 The X-ray diffraction patterns are those of commercial γ-Al2O3, organic acid-treated Al2O3, and Al2O3-1.0HAc in Example 1 of this invention.

[0031] Figure 2 The X-ray photoelectron spectra of commercial γ-Al2O3 and Al2O3-1.0HAc in the O 1s region are shown in Example 1 of this invention.

[0032] Figure 3 The commercial γ-Al2O3 and Al2O3-1.0HAc in Example 1 of this invention 27 Al solid NMR image.

[0033] Figure 4 This is a high-angle annular dark-field scanning transmission electron micrograph of Pt / Al2O3-1.0HAc obtained in Example 2 of the present invention.

[0034] Figure 5 This is a graph showing the effect of different acetic acid concentrations on the formaldehyde oxidation rate of the oxygen vacancy-regulated catalyst obtained in Example 3 of the present invention.

[0035] Figure 6 The images show in-situ infrared spectroscopy of ammonia adsorption on the Pt / Al2O3, Pt / Al2O3-0.2HAc, Pt / Al2O3-0.5HAc, Pt / Al2O3-1.0HAc and Pt / Al2O3-2.0HAc catalysts obtained in Example 3 and Comparative Example 1 of this invention.

[0036] Figure 7 The graph shown in Example 5 of this invention illustrates the effect of different Pt loadings on the formaldehyde oxidation rate of the oxygen vacancy-regulated catalyst.

[0037] Figure 8 The graph shows the formaldehyde catalytic oxidation performance of the commercial γ-Al2O3, Al2O3-1.0HAc catalysts in Example 1 of this invention, as well as the catalysts obtained in Examples 2, 3 and Comparative Example 1.

[0038] Figure 9 The graph shows the stability test results of Pt / Al2O3-1.0HAc obtained in Example 2 of this invention.

[0039] Figure 10 The graph shows the moisture resistance test results of Pt / Al2O3-1.0HAc obtained in Example 2 of this invention. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation methods and protection scope of the present invention are not limited thereto.

[0041] Example 1 Preparation of defective alumina supports: Weigh 1.0 g of commercial γ-Al₂O₃ (particle size approximately 20-50 nm) and add it to 15 mL of 1.0 mol / L acetic acid solution. Reflux at 110 °C for 1 h under stirring. After the reaction is complete, organic acid-treated alumina is obtained. The alumina treated with organic acid was centrifuged to separate the solid and liquid phases, and repeatedly washed with deionized water to remove residual acetic acid and soluble impurities. It was then dried at 80°C for 12 hours and ground into powder. The resulting powder was placed in a tube furnace and calcined at 350°C for 2 hours under an argon atmosphere (flow rate of 50 mL / min). After natural cooling to room temperature, the defective alumina support was obtained, denoted as Al2O3-1.0HAc.

[0042] Figure 1 The X-ray diffraction patterns of commercial γ-Al2O3, organic acid-treated Al2O3, and Al2O3-1.0HAc in Example 1 are shown. As can be seen from the figure, basic aluminum acetate intermediate species are generated on the surface after organic acid treatment, which disappear after argon heat treatment.

[0043] Figure 2 The X-ray photoelectron spectra of commercial γ-Al2O3 and Al2O3-1.0HAc in the O 1s region are shown in Example 1. Figure 3 The commercial γ-Al₂O₃ and Al₂O₃-1.0HAc in Example 1 are shown. 27 Al solid NMR image.

[0044] X-ray photoelectron spectroscopy and solid-state nuclear magnetic resonance results show that the surface of the support has a large number of oxygen vacancies, five-coordinate aluminum species and local free electrons. The local free electrons can be transferred to platinum nanoparticles, making the platinum sites exhibit electron-rich characteristics, providing active sites for subsequent platinum species anchoring and electronic regulation.

[0045] Example 2 Preparation of oxygen vacancy-regulated platinum-supported alumina catalysts: 100 mg (0.1 g) of Al2O3-1.0HAc prepared in Example 1 and 78 μL of [Pt(NH3)4](NO3)2 (64.6 mM) were dispersed in 10 mL of deionized water and stirred for 1 h for impregnation treatment. The solid sample was collected by rotary evaporation (60 °C), and after vacuum drying at 80 °C for 6 h, it was cooled to room temperature to obtain the impregnated sample. The impregnated sample was heated to 300℃ under H2 atmosphere at a heating rate of 5℃ / min. -1 After a 1-hour reduction heat treatment, the catalyst was naturally cooled to room temperature to obtain an oxygen vacancy-regulated platinum-supported alumina catalyst, denoted as Pt / Al2O3-1.0HAc.

[0046] Figure 4 A high-angle annular dark-field-scanning transmission electron micrograph of Pt / Al2O3-1.0HAc obtained in Example 2 is shown. As can be seen from the figure, the platinum nanoparticles in the obtained oxygen vacancy-regulated platinum-supported alumina catalyst are uniformly dispersed on the surface of the alumina support, with an average particle size of about 1.7-1.9 nm. Platinum mainly exists in the metallic state.

[0047] Example 3 Preparation of platinum-supported alumina catalysts with oxygen vacancy regulation under different acetic acid concentrations: Following the methods of Examples 1 and 2, only the concentration of the acetic acid solution was changed. γ-Al2O3 was treated with acetic acid solutions of 0.01 mol / L, 0.2 mol / L, 0.5 mol / L, 2.0 mol / L, and 10.0 mol / L to prepare alumina supports with different defect levels. Platinum was then further loaded onto these supports to obtain platinum-supported alumina catalysts with oxygen vacancy regulation: Pt / Al2O3-0.01HAc; Pt / Al2O3-0.2HAc; Pt / Al2O3-0.5HAc; Pt / Al2O3-2.0HAc; Pt / Al2O3-10.0HAc.

[0048] Table 1. In-situ infrared fitting results of ammonia adsorption on the oxygen vacancy-regulated platinum-supported alumina catalysts obtained in Example 3 and Comparative Example 1.

[0049] Figure 5 The graph shows the effect of different acetic acid concentrations obtained in Example 3 on the formaldehyde oxidation rate of the oxygen vacancy-regulated catalyst. Figure 6The in-situ infrared spectra of ammonia adsorption of the Pt / Al2O3, Pt / Al2O3-0.2HAc, Pt / Al2O3-0.5HAc, Pt / Al2O3-1.0HAc and Pt / Al2O3-2.0HAc catalysts obtained in Example 3 and Comparative Example 1 are shown.

[0050] Depend on Figure 5 , 6 As shown in Table 1, the acetic acid concentration has a significant impact on the formaldehyde oxidation performance of the catalyst and the types of surface hydroxyl species. As the acetic acid concentration increases from 0.01 M to 1.0 M, the catalyst reaction rate gradually increases, reaching a maximum of 77.7 μmol g at 1.0 M. Pt -1 s -1 When the acetic acid concentration was further increased to 2.0 M and 10.0 M, the reaction rate decreased. This indicates that treatment with an appropriate concentration of acetic acid is beneficial for regulating the defect structure and the proportion of double-bridged hydroxyl species on the alumina surface, thereby improving catalytic activity; however, excessively high acetic acid concentrations may lead to excessive modulation of the surface structure, which is detrimental to performance improvement. Therefore, the preferred acetic acid concentration is 0.2-2.0 M, more preferably 1.0 M.

[0051] Example 4 Preparation of platinum-supported alumina catalysts with oxygen vacancy regulation by different organic acids: 1.0 g of γ-Al₂O₃ was weighed and added to 15 mL of aqueous solutions of organic acids, namely formic acid, propionic acid, citric acid, and oxalic acid. The concentrations of the formic acid and propionic acid aqueous solutions were 1.0 mol / L, and the concentrations of the citric acid and oxalic acid aqueous solutions were 0.5 mol / L. Each system was refluxed at 110 °C for 1 h under stirring, followed by centrifugation, washing, and drying at 80 °C for 12 h.

[0052] The dried solids were calcined at 350°C for 2 hours under an argon atmosphere to obtain defective alumina supports treated with different organic acids. Subsequently, platinum precursors were loaded and reduced with hydrogen using the same method as in Example 2 to obtain platinum-supported alumina catalysts treated with different organic acids.

[0053] This embodiment illustrates that, in addition to acetic acid, carboxylic acid organic acids such as formic acid, propionic acid, citric acid, and oxalic acid can also form organic acid anion coordination species and / or aluminum organic acid hydroxyl intermediates by reacting with aluminum sites on the alumina surface, and then induce the formation of defective alumina carriers through heat treatment in an inert atmosphere.

[0054] Example 5 Preparation of oxygen vacancy-controlled platinum-supported alumina catalysts with platinum loading in the range of 0.1-3.0 wt%: Following the method of Example 2, only the volume of the added 64.6 mmol / L tetraammineplatinum nitrate aqueous solution was changed. Volumes of 8 μL, 78 μL, and 234 μL of 64.6 mmol / L tetraammineplatinum nitrate aqueous solution were added respectively, so that the theoretical loading of Pt in the obtained catalyst, based on the final total mass of the catalyst, were 0.1 wt%, 1.0 wt%, and 3.0 wt%, respectively, to obtain impregnated samples; Figure 7 The graph shown in Example 5 illustrates the effect of different Pt loadings on the formaldehyde oxidation rate of the oxygen vacancy-regulated catalyst.

[0055] Depend on Figure 7 It can be seen that the Pt loading has a significant impact on the formaldehyde oxidation performance of the catalyst. When the Pt loading increases from 0.1 wt% to 1.0 wt%, the reaction rate increases from 28.2 μmol g / L. Pt -1 s -1 Increased to 77.7 μmol g Pt -1 s -1 When the Pt loading continued to increase to 3.0 wt%, the reaction rate decreased to 26.3 μmol g. Pt -1 s -1 This indicates that an appropriate amount of Pt is beneficial for improving activity, but excessive loading may lead to a decrease in Pt utilization efficiency. Therefore, the preferred Pt loading is 1.0 wt%.

[0056] Comparative Example 1 Preparation of comparative catalysts: Commercial γ-Al₂O₃ was weighed and treated at 350°C for 2 hours under an argon atmosphere. After cooling, it was used as a comparative support. Subsequently, a platinum precursor was loaded and reduced in hydrogen at 200°C according to the same method as in Example 2 to obtain the comparative catalyst Pt / Al₂O₃.

[0057] Example 6 Catalysts for formaldehyde oxidation at room temperature: γ-Al₂O₃, Al₂O₃-1.0HAc, and the catalysts obtained in Examples 2, 3, and Comparative Example 1 were loaded into a fixed-bed continuous flow reactor. The gas composition was a mixture of 80 ppm formaldehyde and synthesis air, with a relative humidity of 50% and a gas hourly space velocity of 500 L / g. cat -1 h -1 .

[0058] The reaction gas was introduced at room temperature, and the formaldehyde CO2 concentration at the reaction outlet was measured.

[0059] Figure 8The formaldehyde catalytic oxidation performance of the catalysts obtained in Examples 1 (Pt / Al2O3, Al2O3-1.0HAc, Example 2 (Pt / Al2O3-1.0HAc), Example 3 (Pt / Al2O3-0.01HAc; Pt / Al2O3-0.2HAc; Pt / Al2O3-0.5HAc; Pt / Al2O3-2.0HAc; Pt / Al2O3-10.0HAc) and Comparative Example 1 (Pt / Al2O3) is shown in the diagram.

[0060] Catalytic activity of Pt / Al2O3-1.0HAc at different temperatures as follows: Figure 8 As shown, under high airspeed conditions (400L g) cat - 1 h -1 The reaction can completely degrade 80 ppm formaldehyde into CO2 and H2O at a reaction temperature of 20℃, indicating that it has excellent low-temperature catalytic activity. Furthermore, under room temperature (25℃) reaction conditions, the mass ratio reaction rate of Pt / Al2O3-1.0HAc is as high as 77.7 μmol / g. Pt -1 s -1 This catalytic activity is among the highest reported formaldehyde oxidation catalysts and is superior to the catalyst obtained in Example 3. This further illustrates that treatment with an appropriate concentration of acetic acid is beneficial for regulating the defect structure and double-bridged hydroxyl species on the alumina surface, thereby enhancing catalytic activity. Compared to the untreated Pt / Al2O3 catalyst, Pt / Al2O3-1.0HAc exhibits a higher formaldehyde conversion rate.

[0061] Example 7 Catalyst stability and humidity tolerance tests: The Pt / Al2O3-1.0HAc catalyst was used for continuous formaldehyde oxidation reaction under high space velocity conditions (500 Lg). cat -1 h -1 Long-term stability testing was conducted.

[0062] Figure 9 The stability test results of Pt / Al2O3-1.0HAc obtained in Example 2 are shown in the figure. As can be seen from the figure, the oxygen vacancy-regulated platinum-supported alumina catalyst can maintain a relatively stable formaldehyde conversion capacity during continuous operation.

[0063] The catalytic performance was tested by further varying the relative humidity of the reaction gas within a range of 30%-70% relative humidity (30%, 40%, 50%, 60%, 70%RH).

[0064] Figure 10The results of the humidity resistance test of Pt / Al2O3-1.0HAc obtained in Example 2 are shown in the figure. As can be seen from the figure, Pt / Al2O3-1.0HAc still maintains stable activity under different humidity conditions, indicating that it has good humidity resistance and is suitable for practical indoor air purification scenarios.

[0065] The above embodiments are some implementations of the present invention, but the implementation of the present invention is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A platinum-supported alumina catalyst with oxygen vacancy regulation, characterized in that, include: Defective alumina carrier and platinum nanoparticles loaded on the surface of the defective alumina carrier; The defective alumina support is obtained by heat treatment of alumina under an inert atmosphere after treatment with organic acid; the surface of the defective alumina support contains five-coordinated aluminum species, oxygen vacancies and double-bridged hydroxyl species.

2. The oxygen vacancy-regulated platinum-supported alumina catalyst according to claim 1, characterized in that, The alumina is γ-Al2O3; the morphology of γ-Al2O3 is nanoparticles with a particle size of 3-20 nm.

3. The oxygen vacancy-regulated platinum-supported alumina catalyst according to claim 1, characterized in that, The organic acid is one or more of the carboxylic acid organic acids; the concentration of the organic acid solution is 0.01-10.0 mol / L, and the amount of organic acid added is 0.15-150 mmol of carboxyl groups per 1g of alumina, calculated as carboxyl groups.

4. The oxygen vacancy-regulated platinum-supported alumina catalyst according to claim 1, characterized in that, When the organic acid is one or more of acetic acid, formic acid, and propionic acid, the concentration of the organic acid solution is 0.1-5.0 mol / L; when the organic acid is one or more of citric acid and oxalic acid, the concentration of the organic acid solution is 0.01-2.0 mol / L.

5. The oxygen vacancy-regulated platinum-supported alumina catalyst according to claim 1, characterized in that, The loading of the platinum nanoparticles, based on the total mass of the oxygen vacancy-regulated platinum-supported alumina catalyst, is 0.1-3.0 wt%; the average particle size of the platinum nanoparticles is 0.5-10 nm.

6. A method for preparing an oxygen vacancy-regulated platinum-supported alumina catalyst as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Disperse alumina in an organic acid solution and reflux it to obtain organic acid-treated alumina. S2. After solid-liquid separation, washing and drying, the alumina treated with organic acid is heat-treated in an inert atmosphere and cooled to room temperature to obtain a defective alumina carrier. S3. Disperse the defective alumina support in a solvent, add a platinum precursor solution for impregnation treatment, collect the solid sample, dry it, and cool it to room temperature to obtain the impregnated sample. S4. The impregnated sample is subjected to reduction heat treatment in a hydrogen-containing atmosphere to obtain an oxygen vacancy-controlled platinum-supported alumina catalyst.

7. The preparation method according to claim 6, characterized in that, In step S1, the reflux treatment temperature is 80-130℃; the reflux treatment time is 0.5-5h.

8. The preparation method according to claim 6, characterized in that, In step S2, the inert atmosphere is one or more of argon, nitrogen, or helium, the inert atmosphere flow rate is 5-500 mL / min, the heat treatment temperature is 200-500℃, and the heat treatment time is 0.1-5 h.

9. The preparation method according to claim 6, characterized in that, In step S3, the platinum precursor is at least one of the following: platinum tetraammine nitrate [Pt(NH3)4](NO3)2, sodium hexahydroxyplatin(IV) acid Na2[Pt(OH)6], potassium hexahydroxyplatin(IV) acid K2[Pt(OH)6], sodium chloroplatinate Na2PtCl6, platinum nitrate Pt(NO3)2, platinum hydroxide Pt(OH)4, hexahydroxyplatin(IV) acid H2[Pt(OH)6], and chloroplatinic acid H2PtCl6; the impregnation treatment time is 0.1-5 h; the solid sample is collected by rotary evaporation at a temperature of 50-80 °C; the drying is performed by vacuum drying at a temperature of 60-150 °C for 3-24 h; In step S4, the temperature of the reduction heat treatment is 100-400℃, and the time of the reduction heat treatment is 0.5-5h; the hydrogen-containing atmosphere is a hydrogen / argon mixture containing 1%-100% hydrogen by volume.

10. The application of the oxygen vacancy-regulated platinum-supported alumina catalyst according to any one of claims 1-5 in the catalytic oxidation of formaldehyde, characterized in that, The formaldehyde catalytic oxidation is used for indoor air purification, air purifier filters, formaldehyde release treatment from building materials, air purification in enclosed spaces, or purification of low-concentration volatile organic compounds.

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