Cerium oxide size-controllable alumina composite carrier, preparation method and application thereof

Abstract

The present application relates to the controlled size of cerium oxide alumina composite carrier and its preparation method and application. The method takes alumina as carrier, and takes cerium salt as precursor. By controlling the evaporation temperature and evaporation rate of solvent in the impregnation process, the nucleation, migration, growth and aggregation process of cerium species on the surface of alumina is controlled, so as to form the size-controllable and highly dispersed cerium oxide nanometer island on the surface of alumina. The average size of cerium oxide nanometer island can be adjusted by the evaporation temperature. After loading platinum nanoparticles, Pt / Al2O3-CeO2 catalyst rich in Pt-O-Ce interface can be formed. In the catalyst, the smaller size of cerium oxide nanometer island can improve the platinum-cerium oxide interface density, promote the migration of active oxygen species and the regeneration of surface hydroxyl, thereby significantly improving the room temperature formaldehyde oxidation performance. The method is simple, controllable and suitable for building high dispersion rare earth oxide nanometer island modified carrier and high efficiency environmental catalytic material.

Description

Technical Field

[0001] This invention belongs to the field of environmental catalytic materials, specifically relating to alumina composite support with controllable cerium oxide size, its preparation method, and its application. Background Technology

[0002] Cerium oxide, due to its excellent oxygen storage and release capacity, oxygen vacancy regulation ability, and oxygen migration ability, is widely used in catalytic oxidation, automotive exhaust purification, volatile organic compound removal, and indoor air purification. The catalytic performance of cerium oxide is closely related to its size, dispersion state, oxygen vacancy concentration, and interfacial structure. Especially in supported noble metal catalysts, the interfacial sites formed between cerium oxide and noble metals can typically promote oxygen activation, reactive oxygen migration, and the transformation of reaction intermediates.

[0003] However, traditional methods for preparing cerium oxide-modified alumina supports often struggle to precisely control the size and dispersion of cerium oxide species on the alumina surface. Conventional impregnation methods are prone to causing localized enrichment of cerium precursors during rapid solvent evaporation, leading to cerium oxide particle growth or agglomeration, thereby reducing the exposed cerium oxide area and the density of the noble metal-cerium oxide interface. Furthermore, if cerium species cannot nucleate uniformly on the alumina surface, it is difficult to form stable, discrete, and size-controllable cerium oxide nanoisland structures.

[0004] Existing technologies focus more on the effects of cerium oxide loading, calcination temperature, or noble metal particle size on catalytic performance, while research and application on how the solvent evaporation rate during impregnation affects the nucleation, growth, and final size of cerium oxide nanoislands are relatively limited (Environ. Sci. Technol. 55(2021), 7624-7633). Therefore, developing a simple, tunable, and scalable method to achieve controllable preparation of cerium oxide nanoislands is of great significance for constructing efficient composite oxide supports and high-performance supported catalysts. Summary of the Invention

[0005] The purpose of this invention is to provide an alumina composite carrier with controllable cerium oxide nanoislands and its preparation method. The preparation method controls the migration, nucleation, growth, and aggregation of cerium precursors on the alumina surface by adjusting the solvent evaporation temperature and evaporation rate in the impregnation system, thereby obtaining uniformly dispersed cerium oxide nanoislands of different sizes.

[0006] Another objective of this invention is to provide a supported noble metal catalyst prepared from the above-mentioned composite support. This catalyst possesses abundant noble metal-O-Ce interface sites and enhanced reactive oxygen species migration ability, and can be used for the low-temperature catalytic oxidation of formaldehyde or other volatile organic compounds. The preparation method provided by this invention uses readily available raw materials, is simple to operate, and is suitable for mass production.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides an alumina composite carrier with controllable cerium oxide size, wherein the surface of the alumina carrier has highly dispersed cerium oxide nanoislands with controllable size; the average size of the cerium oxide nanoislands is 2-10 nm.

[0008] Furthermore, the mass fraction of cerium oxide in the alumina composite carrier with controllable cerium oxide size is 1-30 wt%.

[0009] This invention also provides a method for preparing the above-mentioned cerium oxide-sized controllable alumina composite carrier, comprising the following steps: S1. Disperse alumina in a cerium salt solution to ensure full contact between the cerium precursor and alumina, thereby obtaining an impregnation system containing alumina and cerium precursor. Cerium ions in the cerium salt solution can be adsorbed near hydroxyl groups, defect sites, or Lewis acid-base sites on the surface of alumina, providing a precursor source for the subsequent nucleation of cerium oxide nanoislands. S2. Provides control over the evaporation temperature of the impregnation system under stirring conditions, allowing the solvent to gradually evaporate, thereby regulating the distribution, nucleation, and growth process of cerium precursors on the alumina surface; S3. After the solvent has completely evaporated, the resulting solid is ground and calcined in an oxygen-containing atmosphere. The cerium precursor is transformed into CeO2 with a fluorite structure and distributed on the surface of alumina in the form of discrete nano-islands, thus obtaining an alumina composite carrier with controllable cerium oxide nano-islands.

[0010] Furthermore, in step S1, the aluminum oxide is γ-Al2O3.

[0011] Furthermore, in step S1, the cerium salt is at least one of cerium nitrate, cerium ammonium nitrate, cerium chloride, cerium acetate, and cerium sulfate.

[0012] Furthermore, the cerium salt is cerium nitrate hexahydrate.

[0013] Furthermore, in step S1, the solvent for the cerium salt solution is water, ethanol, methanol, isopropanol, or a mixture thereof.

[0014] Furthermore, in step S2, the size of the cerium oxide nanoislands increases with the increase of the solvent evaporation rate. When the evaporation temperature is low, the solvent evaporation rate is slow, allowing the cerium precursor to have more time to diffuse and redistribute on the alumina surface, which is conducive to the formation of uniform nucleation sites and inhibits local enrichment and particle growth, thereby forming smaller and more uniformly dispersed cerium oxide nanoislands. When the evaporation temperature is high, the solvent evaporates rapidly, and the local cerium salt concentration increases rapidly, easily forming local supersaturation, which promotes the rapid nucleation, growth, or aggregation of cerium species, thereby forming larger cerium oxide nanoislands. By adjusting the evaporation rate to regulate the spatial distribution and growth behavior of the cerium precursor on the alumina surface, the size of the cerium oxide nanoislands can be controlled. Furthermore, in step S2, the evaporation temperature is 40-100℃.

[0015] Furthermore, the evaporation temperature is 50-90℃.

[0016] Furthermore, in step S3, the calcination temperature is 300-600℃; the calcination time is 0.5-5h.

[0017] Furthermore, the calcination temperature is 350-450℃, preferably 400℃.

[0018] Furthermore, the calcination time is 2 hours.

[0019] The present invention also provides a supported noble metal catalyst, comprising: The above-mentioned alumina composite carrier with controllable cerium oxide size and noble metal nanoparticles loaded on the surface of the alumina composite carrier with controllable cerium oxide size.

[0020] Furthermore, based on the total mass of the supported precious metal catalyst, the content of precious metal elements is 0.1-3.0 wt%.

[0021] Furthermore, based on the total mass of the supported precious metal catalyst, the precious metal element content is 0.5-1.5 wt%. Furthermore, precious metals are provided using precious metal salts or precious metal acids; The noble metal salts are: platinum tetraamminenitrate [Pt(NH3)4](NO3)2, sodium hexahydroxyplatin(IV)ate Na2[Pt(OH)6], potassium hexahydroxyplatin(IV)ate K2[Pt(OH)6], sodium chloroplatinate Na2PtCl6, platinum nitrate Pt(NO3)2, palladium nitrate Pd(NO3)2, iridium chloride IrCl3, platinum hydroxide Pt(OH)4, gold hydroxide Au(OH)3, and platinum acetylacetonate C. 10 H 14 At least one of O4Pt; The noble metal acid is at least one of hexahydroxyplatinic(IV) acid H2[Pt(OH)6], chloroplatinic acid H2PtCl6, chloroauric acid H2AuCl4 and chloroiridium acid H2IrCl6.

[0022] Furthermore, the noble metal salt is at least one of chloroplatinic acid, tetraammineplatinum nitrate, platinum nitrate, and platinum acetylacetonate, preferably chloroplatinic acid hexahydrate.

[0023] The present invention also provides the application of the above-mentioned supported noble metal catalyst in the catalytic oxidation of formaldehyde, the catalytic oxidation of volatile organic compounds, or indoor air purification.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The present invention can control the size of CeO2 nano islands by adjusting the evaporation rate by adjusting the evaporation temperature during the impregnation process, without the need for complex template agents, surfactants or special equipment.

[0025] (2) By changing the evaporation temperature and adjusting the evaporation rate, CeO2 nanoislands of different sizes can be obtained. For example, smaller CeO2 nanoislands can be formed at 50℃, medium-sized CeO2 nanoislands at 70℃, and larger CeO2 nanoislands at 90℃.

[0026] (3) A lower evaporation rate helps the cerium precursor to be evenly distributed on the alumina surface, reducing local agglomeration, thereby obtaining highly dispersed CeO2 nano islands.

[0027] (4) The obtained Al2O3-CeO2 composite support can be used to support precious metals such as Pt, Pd, Au, Ru, and Rh to construct a highly efficient oxidation reaction catalyst, which is especially suitable for the catalytic oxidation of formaldehyde and other low-concentration VOCs.

[0028] (5) Small size and good dispersion of CeO2 nano islands are beneficial to increase the density of noble metal-O-Ce interface and enhance the synergistic effect between noble metal and cerium oxide.

[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. Attached Figure Description

[0030] Figure 1 The images show high-angle annular dark-field scanning transmission electron microscopy (DSE) images and cerium oxide nanoisland size distribution diagrams of the Pt / Al2O3-CeO2-50 catalyst obtained in Example 1 of this invention.

[0031] Figure 2 The images show high-angle annular dark-field scanning transmission electron microscopy (DSE) images and cerium oxide nanoisland size distribution diagrams of the Pt / Al2O3-CeO2-70 catalyst obtained in Example 2 of this invention.

[0032] Figure 3 The images show high-angle annular dark-field scanning transmission electron microscopy (DSE) images and cerium oxide nanoisland size distribution diagrams of the Pt / Al2O3-CeO2-90 catalyst obtained in Example 3 of this invention.

[0033] Figure 4 The graph shows the formaldehyde catalytic oxidation performance of the Al2O3-CeO2-50 composite support obtained in Example 1 of this invention, as well as the catalysts obtained in Examples 1, 2, 3 and Comparative Examples 1 and 2.

[0034] Figure 5The graph shows the stability test results of the Pt / Al2O3-CeO2-50 catalyst obtained in Example 1 of this invention.

[0035] Figure 6 The graph shows the moisture resistance test results of the Pt / Al2O3-CeO2-50 catalyst obtained in Example 1 of this invention. Detailed Implementation

[0036] 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.

[0037] Example 1: Preparation of small-sized CeO2 nanoislands at low evaporation rates (1) Preparation of alumina composite carrier with controllable cerium oxide size Weigh 150 mg of γ-Al2O3 and add it to 10 mL of cerium nitrate hexahydrate aqueous solution (9.7 mmol / L) to obtain an impregnation system containing γ-Al2O3 and cerium nitrate hexahydrate; Under magnetic stirring, the evaporation temperature of the impregnation system was controlled at 50°C, and stirring was maintained until the solvent was completely evaporated; After the solvent has completely evaporated, the resulting solid is thoroughly ground and then calcined at 400°C for 2 hours in air to decompose the cerium precursor and form cerium oxide nano-islands, thus obtaining an alumina composite carrier with controllable cerium oxide size, which is called Al2O3-CeO2-50 composite carrier.

[0038] Under these conditions, the solvent evaporation rate is low, and the cerium precursor can be distributed more uniformly on the alumina surface, eventually forming CeO2 nanoislands with small average size and good dispersion.

[0039] (2) Preparation of supported noble metal catalysts Weigh 100 mg of Al2O3-CeO2-50 composite carrier, disperse it in 10 mL of deionized water, add 0.27 mL of chloroplatinic acid hexahydrate solution (19.3 mmol / L), and stir for 1 h.

[0040] The solvent was then removed by rotary evaporation, and the resulting solid was calcined at 400°C for 1 hour in air and then reduced in hydrogen atmosphere for 1 hour to obtain the Pt / Al2O3-CeO2-50 catalyst.

[0041] Figure 1 High-angle annular dark-field-scanning transmission electron micrographs and cerium oxide nanoisland size distribution diagrams of the obtained Pt / Al2O3-CeO2-50 catalyst are shown.

[0042] Depend on Figure 1It can be seen that in the Pt / Al2O3-CeO2-50 catalyst, Pt nanoparticles are dispersed on the surface of the Al2O3-CeO2 composite support and form a Pt-O-Ce interface structure with CeO2 nano islands; the average size of CeO2 nano islands in the Pt / Al2O3-CeO2-50 catalyst is about 3.8 nm.

[0043] This catalyst exhibits high Pt dispersion and abundant Pt-O-Ce interface sites.

[0044] Example 2: Preparation of medium-sized CeO2 nanoislands at moderate evaporation rates (1) Preparation of alumina composite carrier with controllable cerium oxide size Weigh 150 mg of γ-Al2O3 and add it to 10 mL of cerium nitrate hexahydrate aqueous solution (9.7 mmol / L) to obtain an impregnation system containing γ-Al2O3 and cerium nitrate hexahydrate; Under magnetic stirring, the evaporation temperature of the impregnation system was controlled at 70°C, and stirring was maintained until the solvent was completely evaporated; After the solvent has completely evaporated, the resulting solid is ground and then calcined at 400°C for 2 hours in air to decompose the cerium precursor and form cerium oxide nano-islands, thus obtaining an alumina composite carrier with controllable cerium oxide size, which is called Al2O3-CeO2-70 composite carrier.

[0045] (2) Preparation of supported noble metal catalysts Weigh 100 mg of Al2O3-CeO2-70 composite carrier, disperse it in 10 mL of deionized water, add 0.27 mL of chloroplatinic acid hexahydrate solution (19.3 mmol / L), and stir for 1 h.

[0046] The solvent was then removed by rotary evaporation, and the resulting solid was calcined at 400°C for 1 hour in air and then reduced in hydrogen atmosphere for 1 hour to obtain the Pt / Al2O3-CeO2-70 catalyst.

[0047] Figure 2 High-angle annular dark-field-scanning transmission electron microscopy image and cerium oxide nanoisland size statistical distribution diagram of the obtained Pt / Al2O3-CeO2-70 catalyst are shown.

[0048] Depend on Figure 2 It can be seen that in the Pt / Al2O3-CeO2-70 catalyst, Pt nanoparticles are dispersed on the surface of the Al2O3-CeO2 composite support and form a Pt-O-Ce interface structure with CeO2 nano islands; the average size of CeO2 nano islands in the Pt / Al2O3-CeO2-70 catalyst is about 5.4 nm.

[0049] This embodiment illustrates that by increasing the evaporation temperature, the solvent evaporation rate increases, and the size of the CeO2 nanoislands increases accordingly.

[0050] Example 3: Preparation of large-sized CeO2 nanoislands by high evaporation rate (1) Preparation of alumina composite carrier with controllable cerium oxide size Weigh 150 mg of γ-Al2O3 and add it to 10 mL of cerium nitrate hexahydrate aqueous solution (9.7 mmol / L) to obtain an impregnation system containing γ-Al2O3 and cerium nitrate hexahydrate; Under magnetic stirring, the evaporation temperature of the impregnation system was controlled at 90°C, and stirring was maintained until the solvent was completely evaporated.

[0051] After the solvent has completely evaporated, the resulting solid is ground and then calcined at 400°C for 2 hours in air to decompose the cerium precursor and form cerium oxide nano-islands, thus obtaining an alumina composite carrier with controllable cerium oxide size, which is called Al2O3-CeO2-90 composite carrier.

[0052] (2) Preparation of supported noble metal catalysts Weigh 100 mg of Al2O3-CeO2-90 composite carrier, disperse it in 10 mL of deionized water, add 0.27 mL of chloroplatinic acid hexahydrate solution (19.3 mmol / L), and stir for 1 h.

[0053] The solvent was then removed by rotary evaporation, and the resulting solid was calcined at 400°C for 1 hour in air and then reduced in hydrogen atmosphere for 1 hour to obtain the Pt / Al2O3-CeO2-90 catalyst.

[0054] Figure 3 High-angle annular dark-field-scanning transmission electron microscopy image and cerium oxide nanoisland size statistical distribution diagram of the obtained Pt / Al2O3-CeO2-90 catalyst are shown.

[0055] Depend on Figure 3 It can be seen that in the Pt / Al2O3-CeO2-90 catalyst, Pt nanoparticles are dispersed on the surface of the Al2O3-CeO2 composite support and form a Pt-O-Ce interface structure with CeO2 nano islands; the average size of CeO2 nano islands in the Pt / Al2O3-CeO2-90 catalyst is about 6.7 nm.

[0056] This embodiment illustrates that higher evaporation temperatures lead to rapid solvent evaporation, increasing the local enrichment and rapid growth of cerium precursors, thereby forming larger CeO2 nanoislands.

[0057] Comparative Example 1 Preparation of comparative catalysts: Commercial γ-Al2O3 was weighed, loaded with a platinum precursor, and reduced in hydrogen at 200°C using the same method as in Example 1 to obtain the comparative catalyst Pt / Al2O3.

[0058] Comparative Example 2 Cerium nitrate hexahydrate was weighed and treated at 350°C for 2 h in air atmosphere to obtain cerium oxide support. Platinum precursor was loaded and reduced in hydrogen at 200°C according to the same method as in Example 1 to obtain comparative catalyst Pt / CeO2.

[0059] Example 5 Catalysts for formaldehyde oxidation at room temperature: The Al2O3-CeO2-50 composite support, Pt / Al2O3-CeO2-50 catalyst prepared in Example 1, and the catalysts prepared in Examples 1, 2, and 3 and Comparative Examples 1 and 2 were respectively loaded into a fixed-bed continuous flow reactor. The gas composition was a mixture of 80 ppm formaldehyde and synthesis air, the relative humidity was 50% RH, and the gas hourly space velocity was 500 L / g. cat -1 h -1 .

[0060] The reaction gas was introduced at room temperature, and the formaldehyde CO2 concentration at the reaction outlet was measured.

[0061] Figure 4 The diagram shows the formaldehyde catalytic oxidation performance of the Al2O3-CeO2-50 composite support obtained in Example 1 of the present invention, as well as the catalysts obtained in Examples 1, 2, 3 and Comparative Examples 1 and 2.

[0062] The catalytic activity changes of the Pt / Al2O3-CeO2-50 catalyst (Example 1) at different temperatures are as follows: Figure 4 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; in addition, at room temperature (25℃) it can completely degrade formaldehyde into CO2 and H2O. C) Under the reaction conditions, the mass ratio of this catalyst to the reaction rate is as high as 75.4 μmol g. Pt -1 s -1This catalytic activity is among the highest reported formaldehyde oxidation catalysts, and is superior to both the Pt / Al₂O₃-CeO₂-70 catalyst (Example 2) and the Pt / Al₂O₃-CeO₂-90 catalyst (Example 3). This indicates that the small size and well-dispersed CeO₂ nanoislands are beneficial for increasing the noble metal-O-Ce interface density and enhancing the synergistic effect between the noble metal and cerium oxide. Compared to the catalysts prepared in Comparative Examples 1 and 2, it exhibits a higher formaldehyde conversion rate.

[0063] Example 6 Catalyst stability and humidity tolerance tests: The Pt / Al2O3-CeO2-50 catalyst was used for the continuous formaldehyde oxidation reaction under high space velocity conditions (500 Lg). cat -1 h -1 Long-term stability testing was conducted.

[0064] Figure 5 The stability test results of the Pt / Al2O3-CeO2-50 catalyst obtained in Example 1 of this invention are shown in the figure.

[0065] Depend on Figure 5 It can be seen that the catalyst can maintain a relatively stable formaldehyde conversion capacity during continuous operation.

[0066] The catalytic performance was tested by further varying the relative humidity of the reaction gas within a range of 30%-70%RH (30%, 40%, 50%, 60%, 70%RH).

[0067] Figure 6 The diagram shows the moisture resistance test results of the Pt / Al2O3-CeO2-50 catalyst obtained in Example 1 of the present invention.

[0068] Depend on Figure 6 It can be seen that Pt / Al2O3-CeO2-50 maintains stable activity under different humidity conditions, indicating that it has good humidity tolerance and is suitable for practical indoor air purification scenarios.

[0069] In summary, the controllability of CeO2 nanoisland size in this invention mainly stems from the regulation of the nucleation and growth process of cerium precursors on the alumina surface.

[0070] At lower evaporation temperatures, the solvent evaporates more slowly, allowing for more sufficient diffusion and redistribution of cerium precursors on the alumina surface. Therefore, cerium species are less likely to rapidly accumulate in localized areas, instead forming more uniformly dispersed nucleation sites. During subsequent calcination, these uniformly dispersed cerium species transform into smaller CeO2 nanoislands.

[0071] At higher evaporation temperatures, the solvent evaporates rapidly, causing a rapid increase in cerium salt concentration in localized areas, leading to localized supersaturation. Cerium species rapidly nucleate and grow or aggregate locally. Subsequent calcination results in the formation of large CeO2 nanoislands.

[0072] Therefore, the evaporation rate is a key factor in controlling the size of CeO2 nanoislands. By adjusting the evaporation temperature, the size of CeO2 nanoislands can be continuously controlled without changing the type of support or the cerium loading.

[0073] The size of CeO2 nanoislands affects the interfacial structure of Pt / Al2O3-CeO2 catalysts. Smaller CeO2 nanoislands exhibit higher dispersion and greater interfacial exposure, which is conducive to the formation of more Pt-O-Ce interfacial sites. These interfacial sites can promote the migration of reactive oxygen species and improve the regeneration efficiency of surface hydroxyl groups in catalytic oxidation reactions.

[0074] 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 cerium oxide-sized alumina composite carrier, characterized in that, The alumina carrier surface has cerium oxide nanoislands with controllable size and high dispersion; the average size of the cerium oxide nanoislands is 2-10 nm.

2. The cerium oxide-sized controllable alumina composite carrier according to claim 1, characterized in that, The mass fraction of cerium oxide in the alumina composite carrier with controllable cerium oxide size is 1-30 wt%.

3. The method for preparing the cerium oxide-sized controllable alumina composite carrier according to claim 1, characterized in that, Includes the following steps: S1. Alumina is dispersed in a cerium salt solution to obtain an impregnation system containing alumina and cerium precursor; S2. By controlling the evaporation temperature of the impregnation system under stirring conditions, the solvent is gradually evaporated; S3. After the solvent has completely evaporated, the resulting solid is ground and calcined in an oxygen-containing atmosphere to decompose the cerium precursor into cerium oxide nano-islands, thus obtaining an alumina composite carrier with controllable cerium oxide size.

4. The preparation method according to claim 3, characterized in that, In step S1, the alumina is γ-Al2O3; the cerium salt is at least one of cerium nitrate, cerium ammonium nitrate, cerium chloride, cerium acetate, and cerium sulfate.

5. The preparation method according to claim 3, characterized in that, In step S2, the evaporation temperature is 40-100℃.

6. The preparation method according to claim 3, characterized in that, In step S1, the solvent for the cerium salt solution is water, ethanol, methanol, isopropanol, or a mixture thereof; in step S3, the calcination temperature is 300-600℃; and the calcination time is 0.5-5h.

7. A supported noble metal catalyst, characterized in that, The supported noble metal catalyst includes: The cerium oxide-sized controllable alumina composite carrier and the noble metal nanoparticles loaded on the surface of the cerium oxide-sized controllable alumina composite carrier as described in claim 1.

8. The supported noble metal catalyst according to claim 7, characterized in that, The content of precious metal elements is 0.1-3.0 wt% based on the total mass of the supported precious metal catalyst.

9. The supported noble metal catalyst according to claim 7, characterized in that, The precious metal is provided by a precious metal salt or a precious metal acid; The noble metal salts are: platinum tetraamminenitrate [Pt(NH3)4](NO3)2, sodium hexahydroxyplatin(IV)ate Na2[Pt(OH)6], potassium hexahydroxyplatin(IV)ate K2[Pt(OH)6], sodium chloroplatinate Na2PtCl6, platinum nitrate Pt(NO3)2, palladium nitrate Pd(NO3)2, iridium chloride IrCl3, platinum hydroxide Pt(OH)4, gold hydroxide Au(OH)3, and platinum acetylacetonate C. 10 H 14 At least one of O4Pt; The noble metal acid is at least one of hexahydroxyplatinic(IV) acid H2[Pt(OH)6], chloroplatinic acid H2PtCl6, chloroauric acid H2AuCl4 and chloroiridium acid H2IrCl6.

10. The application of the supported noble metal catalyst according to claim 7 in the catalytic oxidation of formaldehyde, the catalytic oxidation of volatile organic compounds, or indoor air purification.

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