Preparation method of a cobalt tetraoxide supported noble metal catalyst and application thereof

Abstract

This invention belongs to the field of preparation of catalytic materials for the oxidative decomposition of gaseous carbon-containing compounds, and particularly relates to a method for preparing a cobalt tetroxide-supported noble metal catalyst and its application in the catalytic oxidation of gaseous carbon-containing compounds. The preparation method includes the following steps: S1. Dissolving a soluble cobalt salt in water, mixing it with an alkaline reagent, and reacting to obtain a cobalt salt precipitate; S2. Calcining the cobalt salt precipitate to obtain a support Co3O4; S3. Dissolving the support Co3O4 and a soluble noble metal salt in a solvent, mixing them, adding H2O2, reacting, and calcining to obtain Pd / Co3O4. The catalyst prepared by this invention exhibits good catalytic activity and stability.

Description

Technical Field

[0001] This invention belongs to the field of preparation of catalytic materials for the oxidative decomposition of gaseous carbon-containing compounds, and particularly relates to a method for preparing a cobalt tetroxide-supported noble metal catalyst and its application in the catalytic oxidation of gaseous carbon-containing compounds. Background Technology

[0002] The ozone pollution, greenhouse effect, and indoor air pollution caused by gaseous pollutants such as VOCs (volatile organic compounds) and CH4 are gradually becoming more prominent and replacing the original air pollution problems, attracting widespread attention.

[0003] In addition to impacting the atmospheric environment, most VOCs also have serious biological toxicity. Long-term exposure to VOC-polluted environments poses a huge threat to human health. For example, benzene compounds, which are widely used in industrial production processes, have long been certified as Group 1 carcinogens by the International Agency for Research on Cancer (IARC), a branch of the World Health Organization (WHO).

[0004] Methane, as the most promising clean energy alternative, is also a potential greenhouse gas. Compared to carbon dioxide (CO2), a greenhouse gas we are familiar with, an equal amount of methane will absorb more infrared radiation than CO2, and its greenhouse effect is about 30 times that of CO2. The long-term accumulation of CH4 directly causes a 16% greenhouse effect.

[0005] Strengthening the coordinated control of the aforementioned gaseous pollutants is key to promoting the continuous improvement of air quality in my country. Compared with other gaseous pollutant treatment technologies, catalytic oxidation technology can oxidize and decompose gaseous carbonaceous compounds such as CH4 and VOCs into CO2 and H2O at relatively low temperatures (200-600℃), and is considered one of the most effective technologies for solving air pollution problems, thus receiving widespread attention and application.

[0006] As is well known, catalysts are the core materials in catalytic oxidation technology, playing a crucial role in the catalytic oxidation degradation of gaseous pollutants. Cobalt tetroxide (Co3O4), as an important industrial material, has wide applications in energy storage, metallurgy, and catalysis. Cobalt (Co) exhibits diverse metallic valence states (2... + 3 +Cobalt oxide (CO) plays an important role in the activation of gaseous O2 and the cleavage of organic compounds (CH), thus exhibiting excellent catalytic oxidation function in the degradation of gaseous carbon-containing compounds. Although CO has a wide range of applications in the catalytic oxidation and degradation of gaseous carbon-containing compounds, its performance is slightly inferior to that of noble metal catalysts. In recent years, the research and development of noble metal catalysts with cobalt oxide as the support and their application in the field of environmental catalysis have continued to grow, which has to some extent made up for the lack of related research. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for preparing a Co3O4-supported noble metal catalyst and its application, wherein the catalyst exhibits good catalytic activity and stability.

[0008] In a first aspect, the present invention provides a method for preparing a Co3O4-supported noble metal catalyst for the catalytic oxidation of gaseous carbon-containing compounds, the preparation method comprising the following steps:

[0009] S1. Dissolve soluble cobalt salt in water, mix with an alkaline reagent, and react to obtain a cobalt salt precipitate;

[0010] S2. Calcine the cobalt salt precipitate to obtain the support Co3O4;

[0011] S3. Dissolve the carrier Co3O4 and the soluble salt corresponding to the noble metal M in a solvent, mix them, add H2O2 to react, and calcine to obtain M / Co3O4.

[0012] According to an embodiment of the present invention, the mixing of the soluble cobalt salt aqueous solution and the alkaline reagent in step S1 includes the following steps: adding the alkaline reagent to the soluble cobalt salt aqueous solution and stirring at room temperature for 0.1 to 1 h to obtain a mixed solvent, for example, stirring for 0.5 h.

[0013] According to an embodiment of the present invention, the alkaline reagent is an aqueous solution of an alkaline substance.

[0014] According to an embodiment of the present invention, the concentration of the alkaline reagent is 1 to 3 times the concentration of the soluble cobalt salt aqueous solution.

[0015] According to an embodiment of the present invention, the reaction example in step S1 is a solvothermal reaction, which includes the following steps: reacting a mixed solvent at a temperature of 100-200°C for 4-24 hours.

[0016] Preferably, the temperature of the solvothermal reaction is 120–180°C, and the reaction time is 8–20 h.

[0017] According to an embodiment of the present invention, the calcination temperature in step S2 is 300-800℃ and the calcination time is 2-12h, preferably the calcination temperature is 400-600℃ and the calcination time is 5-8h.

[0018] According to an embodiment of the present invention, the carrier Co3O4 has an amorphous structure or a crystalline structure.

[0019] As an example, the calcination temperature is 400℃, the calcination time is 4 hours, the Co3O4 support is a sheet-like amorphous structure, and the size of the nanosheets is 50–500 nm.

[0020] As another example, the calcination temperature is 650°C, the calcination time is 4 hours, and the carrier Co3O4 has a particulate nanocrystalline structure with a nanoparticle size of 100–250 nm.

[0021] According to an embodiment of the present invention, in step S2, the microstructure and crystallization degree of the support Co3O4 are controlled by the calcination temperature. When the calcination temperature increases, the crystallization degree of the support Co3O4 crystal increases, the size of the support Co3O4 crystal increases, the porosity decreases, and the interaction with the noble metal M weakens.

[0022] According to an embodiment of the present invention, after step S1 and before step S2, the following steps are further included: filtering, washing and drying the cobalt salt precipitate.

[0023] According to an embodiment of the present invention, the washing includes water washing and / or ethanol washing, for example, water washing followed by ethanol washing in sequence.

[0024] According to an embodiment of the present invention, the drying includes the following steps: drying the washed cobalt salt precipitate at a temperature of 50-100°C for 10-20 hours, for example, drying at a temperature of 80°C for 12 hours.

[0025] According to an embodiment of the present invention, the soluble cobalt salt is selected from at least one of Co(NO3)2, CoCl2 and Co(CH3COO)2.

[0026] According to an embodiment of the present invention, the alkaline substance is selected from at least one of NaOH, Na2CO3, and NaHCO3.

[0027] According to an embodiment of the present invention, the step S3 of dissolving the support Co3O4 and the soluble noble metal salt in a solvent includes the following steps: dispersing the support Co3O4 in a solvent, adding the soluble salt of the noble metal M, and stirring at room temperature for 0.1 to 1 h to obtain a mixed solution.

[0028] According to an embodiment of the present invention, the noble metal M is selected from at least one of Pd, Pt, Au, and Ru, for example, Pd.

[0029] According to an embodiment of the present invention, the loading of the noble metal is 0.1 to 5% of the carrier Co3O4 by weight, preferably 1 to 3% of the carrier Co3O4.

[0030] According to an embodiment of the present invention, the reaction of the mixed solution with the redox-driven hydrolysis precipitant includes the following steps: heating the mixed solution to 20-100°C, adding the redox-driven hydrolysis precipitant H2O2, and reacting for 2-10 hours to obtain a solid reactant.

[0031] According to an embodiment of the present invention, the concentration of H2O2 in the aqueous solution of H2O2 is 20-30%, for example, 30%.

[0032] According to an embodiment of the present invention, the amount of H2O2 is more than 50 times that of the precious metal, by molar weight.

[0033] According to an embodiment of the present invention, the calcination in step S3 includes the following steps: calcining the solid reactant at a temperature of 200 to 400°C for 2 to 12 hours, for example, calcining at a temperature of 400°C for 4 hours.

[0034] According to an embodiment of the present invention, after obtaining the solid reactant in step S3 and before calcination, the following steps are further included: filtering the reaction solution, washing and drying the solid reactant.

[0035] According to an embodiment of the present invention, the washing includes water washing and / or ethanol washing, for example, water washing followed by ethanol washing in sequence.

[0036] According to an embodiment of the present invention, the drying includes the following steps: drying the washed solid reactants at a temperature of 50-100°C for 10-20 hours, for example, drying at a temperature of 80°C for 12 hours.

[0037] According to embodiments of the present invention, catalysts with lower Co3O4 support crystallinity exhibit better catalytic degradation activity for gaseous carbon-containing compounds than catalysts with higher support crystallinity.

[0038] According to an embodiment of the present invention, catalysts with lower Co3O4 support crystallinity have poorer high-temperature stability.

[0039] According to an embodiment of the present invention, after Co3O4 is loaded with noble metals, the catalytic activity of oxidizing gaseous carbon-containing compounds is significantly improved. At the same time, the noble metal loading can be used to suppress the crystallization of the support under high temperature conditions to a certain extent.

[0040] According to an embodiment of the present invention, the Co3O 4(400C) Co3O 4(650C) 3% Pd / Co3O 4(400C) 3% Pd / Co3O 4(650C) Having basic such as Figure 1 The TEM image shown.

[0041] According to an embodiment of the present invention, the Co3O 4(400C) Co3O 4(650C) 3% Pd / Co3O 4(400C) 3% Pd / Co3O 4(650C) Having basic such as Figure 2 The XRD pattern shown.

[0042] According to an embodiment of the present invention, the Co3O 4(400C) Co3O 4(650C) 3% Pd / Co3O 4(400C) 3% Pd / Co3O 4(650C) Having basic such as Figure 3 The BET chart shown.

[0043] According to an embodiment of the present invention, the Co3O 4(400C) Co3O 4(650C) 3% Pd / Co3O 4(400C) 3% Pd / Co3O 4(650C) Having basic such as Figure 4 The graph shown is a test chart of methane conversion rate.

[0044] According to an embodiment of the present invention, the Co3O 4(400C) Co3O 4(650C) 3% Pd / Co3O 4(400C) 3% Pd / Co3O 4(650C) Having basic such as Figure 5 The graph shown is a stability test chart for methane conversion.

[0045] According to an embodiment of the present invention, Co3O 4(400c) At 500℃ and 3% Pd / Co3O 4(400C) Before and after 24 hours of catalytic methane oxidation reaction at 600℃, it exhibits essentially the following characteristics: Figure 6 The XRD pattern shown.

[0046] According to an embodiment of the present invention, the Co3O 4(400C) Co3O 4(650C) 3% Pd / Co3O 4(400C) 3% Pd / Co3O 4(650C) Having basic such as Figure 4The graph shown is a test result for toluene conversion rate.

[0047] Secondly, the present invention provides a Co3O4 supported noble metal catalyst prepared by the above method, wherein the catalyst has an amorphous structure or a crystalline structure, wherein the amount of noble metal in the catalyst is 0.1-5% of the Co3O4 support, and the noble metal M is at least one of Pd, Pt, Au, and Ru.

[0048] According to an embodiment of the present invention, the catalyst is a nanostructure, such as a nanosheet, nanorod, nanoparticle, or nanocluster structure.

[0049] According to an embodiment of the present invention, the catalyst has a specific surface area greater than 5 m². 2 / g, preferably the catalyst has a specific surface area greater than 6m². 2 / g.

[0050] Thirdly, the present invention also provides the application of the above-mentioned Co3O4 supported noble metal catalyst in the catalytic oxidation of gaseous carbon-containing compounds, such as VOCs or methane.

[0051] Beneficial effects

[0052] (1) The preparation method of the present invention prepares Co3O4 support by alkaline precipitation, solvothermal reaction and high temperature calcination. In the reaction, the Co3O4 support with different morphologies and crystal structures is controlled by controlling the raw material ratio, reaction temperature and / or time. The catalytic function of the Co3O4 support drives the H2O2 redox reaction, thereby indirectly driving the deposition of noble metals on the surface of the Co3O4 support. The Co3O4 supported noble metal catalyst prepared by this method can be used for the low-temperature catalytic oxidation of common gaseous carbon compounds. The inventors unexpectedly found that, compared with the catalyst with a higher degree of crystallization, the catalyst with amorphous morphology or low degree of crystallization has more active oxygen species, more defect structures and a larger specific surface area, and exhibits better catalytic oxidation performance after being loaded with noble metals.

[0053] (2) The Co3O4 supported noble metal catalyst prepared in this invention can achieve 100% conversion rate when catalyzing methane reaction at a temperature below 340℃. At the same time, it has good stability at a temperature of 340℃ and can be used as a highly efficient and stable catalyst for catalyzing the oxidation of gaseous carbon compounds. Attached Figure Description

[0054] Figure 1 These are SEM images of the catalysts prepared in Examples 1, 2, 3, and 4 of this invention.

[0055] Figure 2These are the XRD patterns of the catalysts prepared in Examples 1, 2, 3, and 4 of this invention.

[0056] Figure 3 These are BET diagrams of the catalysts prepared in Examples 1, 2, 3, and 4 of this invention.

[0057] Figure 4 The graph shows the methane conversion activity test results of the catalysts prepared in Examples 1, 2, 3, and 4 of this invention.

[0058] Figure 5 The graph shows the methane conversion stability test results of the catalysts prepared in Examples 1, 2, 3, and 4 of this invention.

[0059] Figure 6 These are XRD patterns showing the changes in the catalysts prepared in Examples 1 and 3 of this invention before and after catalytic oxidation of methane at 500℃ and 600℃ for 24 hours.

[0060] Figure 7 The graph shows the methane conversion activity test results of the catalysts prepared in Examples 1, 2, 3, and 4 of this invention. Detailed Implementation

[0061] The catalyst, its preparation method, and its application of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0062] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0063] Example 1 Catalyst Co3O 4(400C) Preparation:

[0064] (1) Weigh 23.2g Co(NO3)2·6H2O and 6.4g NaOH and dissolve them in 200mL and 50mL of secondary water, respectively;

[0065] (2) Quickly mix the Co(NO3)2 aqueous solution and the NaOH aqueous solution, and stir the mixture at room temperature for 0.5 h to obtain the reaction solution;

[0066] (3) Transfer the reaction solution to a 500 mL high-pressure reactor and hydrothermally react at 180 °C for 12 h to obtain the hydrothermal reaction product;

[0067] (4) The hydrothermal reaction product was filtered, washed with water and ethanol in sequence, and then dried at 80°C for 12 hours to obtain the dried product.

[0068] (5) The dried product was calcined in air at 400°C for 4.0 h to obtain the product, which was named Co3O. 4(400C) .

[0069] See Figure 1 As can be seen in the upper left corner, the Co3O prepared in this embodiment 4(400C) It has a sheet-like structure with a size of approximately 50–500 nm. See also Figure 2 It can be seen that the Co3O prepared in this embodiment 4(400C) The diffraction peak intensity at a diffraction angle of 2θ = 36.8° is 400. (See also...) Figure 3 It can be seen that the Co3O prepared in this embodiment 4(400C) Its specific surface area is 32.04 m². 2 / g.

[0070] Example 2 Catalyst Co3O 4(650C) Preparation:

[0071] (1) Weigh 23.2g Co(NO3)2·6H2O and 6.4g NaOH and dissolve them in 200mL and 50mL of secondary water, respectively;

[0072] (2) Quickly mix the Co(NO3)2 aqueous solution and the NaOH aqueous solution, and stir the mixture at room temperature for 0.5 h to obtain the reaction solution;

[0073] (3) Transfer the reaction solution to a 500 mL high-pressure reactor and hydrothermally react at 180 °C for 12 h to obtain the hydrothermal reaction product;

[0074] (4) The hydrothermal reaction product was filtered, washed with water and ethanol in sequence, and then dried at 80°C for 12 hours to obtain the dried product.

[0075] (5) The dried product was calcined in air at 650°C for 4.0 h to obtain the product, which was named Co3O. 4(650C) .

[0076] See Figure 1 As can be seen in the upper right corner, the Co3O prepared in this embodiment 4(650C) It has a nanoparticle structure with a size of 100–250 nm. See [link / reference] Figure 2 It can be seen that the Co3O prepared in this embodiment 4(650C) The diffraction peak intensity at a diffraction angle of 2θ = 36.8° is 1600. (See also...) Figure 3 It can be seen that the Co3O prepared in this embodiment 4(650C) Its specific surface area is 9.54 m². 2 / g.

[0077] Example 3 Catalyst 3% Pd / Co3O 4(400C) Preparation:

[0078] (1) 1.0g of Co3O prepared in Example 1 4(400C) Solid powder was ultrasonically dispersed in 100 mL of deionized water to obtain Co3O. 4(400C) Aqueous solution;

[0079] (2) Adding Co3O under stirring conditions 4(400C) 11.6 mL of H2PdCl4 solution (Pd concentration of 2.57 mg / mL) was added to the aqueous solution, and the mixture was stirred at room temperature for 0.5 h to obtain a mixed solution.

[0080] (3) Heat the mixed solution prepared in step (2) to 80°C, and add 50 mL of an aqueous solution containing 4 mL of 30% H2O2 dropwise to Co3O under the condition of 80°C. 4(400C) The reaction solution was obtained by mixing H2PdCl4 with a mixed solution.

[0081] (4) Stir the reaction solution in step (3) at 80°C for 4 hours to obtain the reaction product;

[0082] (5) The reaction product prepared in step (4) is filtered, washed with water and ethanol in sequence, and then dried at 80°C for 12 hours to obtain the dried product.

[0083] (6) The dried product from step (5) was calcined in air at 200°C for 2.0 h, and the calcined product was named 3% Pd / Co3O 4(400C) .

[0084] See Figure 1 As shown in the lower left corner, the 3% Pd / Co3O prepared in this embodiment... 4(400C) It has a sheet-like structure with a size of approximately 50-500 nm. See also Figure 2 It can be seen that the 3% Pd / Co3O prepared in this embodiment... 4(400C) The diffraction peak intensity at a diffraction angle of 2θ = 36.8° is 300. (See also...) Figure 3 It can be seen that the 3% Pd / Co3O prepared in this embodiment... 4(400C) Its specific surface area is 32.07 m². 2 / g.

[0085] Example 4 Catalyst 3% Pd / Co3O 4(650C) Preparation:

[0086] (1) 1.0g of Co3O prepared in Example 2 4(650C) Solid powder was ultrasonically dispersed in 100 mL of deionized water to obtain Co3O. 4(650C) Aqueous solution;

[0087] (2) Adding Co3O under stirring conditions 4(650C) 11.6 mL of H2PdCl4 solution (Pd concentration of 2.57 mg / mL) was added to the aqueous solution, and the mixture was stirred at room temperature for 0.5 h to obtain a mixed solution.

[0088] (3) Heat the mixed solution prepared in step (2) to 80°C, and add 50 mL of an aqueous solution containing 4 mL of 30% H2O2 dropwise to Co3O under the condition of 80°C. 4(650C) The reaction solution was obtained by mixing H2PdCl4 with a mixed solution.

[0089] (4) Stir the reaction solution prepared in step (3) at 80°C for 4 hours to obtain the reaction product;

[0090] (5) The reaction product prepared in step (4) was filtered, washed with water and ethanol in sequence, and then dried at 80°C for 12 hours to obtain the dried product.

[0091] (6) The dried product prepared in step (5) was calcined in air at 200°C for 2.0 h, and the calcined product was named 3% Pd / Co3O 4(650C) .

[0092] See Figure 1 As shown in the lower right corner, the 3% Pd / Co3O prepared in this embodiment... 4(650C) It has a nanoparticle structure with a size of approximately 100-250 nm. See also Figure 2 It can be seen that the 3% Pd / Co3O prepared in this embodiment... 4(650C) The diffraction peak intensity at a diffraction angle of 2θ = 36.8° is 1500. (See also...) Figure 3 It can be seen that the 3% Pd / Co3O prepared in this embodiment... 4(400C) Its specific surface area is 6.86 m². 2 / g.

[0093] Test case

[0094] Evaluation of the catalyst's activity in catalytic oxidation of gaseous carbon compounds: Methane and toluene (CO) were used as target pollutants to represent common gaseous carbon compounds. The concentrations of methane and toluene were controlled at 1% and 1000 ppm, respectively, and the space velocity of the catalytic reaction was controlled at 20000-80000 ml / (g·h). The catalytic oxidation performance of the catalyst was evaluated by heating.

[0095] Test Example 1: Using Co3O prepared in Examples 1-4 respectively 4(400C) Co3O 4(650C) 3% Pd / Co3O 4(400C) 3% Pd / Co3O 4(650C)As a catalyst, the conversion rate of catalytic oxidation degradation of 1.0% CH4 was tested under a reaction space velocity (GHSV) of 40000 ml / (g·h). See [reference needed]. Figure 4 As shown, Co 3O4(400C) The temperature at which catalytic oxidation degradation of CH4 achieves a 90% conversion rate (T) 90 ) is 415℃, Co 3O4(650C) The temperature at which catalytic oxidation degradation of CH4 achieves a 90% conversion rate (T) 90 ) at 530℃, 3% Pd / Co 3O4(400C) The temperature at which catalytic oxidation degradation of CH4 achieves a 90% conversion rate (T) 90 ) at 335℃, 3% Pd / Co 3O4(650C) The temperature at which catalytic oxidation degradation of CH4 achieves a 90% conversion rate (T) 90 The temperature is 515℃.

[0096] Test Example 2: Using Co3O prepared in Examples 1-4 respectively 4(400C) Co3O 4(650C) 3% Pd / Co3O 4(400C) 3% Pd / Co3O 4(650C) As a catalyst, its stability in the catalytic oxidation and degradation of 1.0% CH4 was tested at different temperatures under a reaction space velocity (GHSV) of 40000 ml / (g·h). See [reference needed]. Figure 5 As shown, Co3O 4(400C) The catalytic performance at 500℃ gradually decreased over time, while Co3O 4(650C) The catalytic performance at 540℃ showed good stability over time, indicating that Co3O 4(650C) Its stability at high temperatures is significantly higher than that of Co3O. 4(400C) That is, Co3O4 with a higher degree of crystallinity has higher stability; 3% Pd / Co3O4 after Pd loading 4(400C) It exhibits good stability at 340℃ and its catalytic performance is also improved. The 3% Pd / Co3O3 after Pd loading... 4(650C) It exhibits high stability at 500℃ and shows some improvement in catalytic performance, but the improvement is significantly less than that of 3% Pd / Co3O. 4(400C) This indicates that Co3O4 synthesized at low temperatures has better catalytic activity but poorer stability. However, when Co3O4 synthesized at low temperatures is combined with noble metals, both its catalytic performance and stability are significantly improved, surpassing that of Co3O4 synthesized at high temperatures with a higher degree of crystallinity.

[0097] Test Example 3: Test the Co3O prepared in Examples 1 and 3 4(400C) and 3% Pd / Co3O 4(400C)As a catalyst, the catalytic oxidation degradation reaction was carried out at reaction temperatures of 500 and 600 °C with a reaction space velocity (GHSV) of 40000 ml / (g·h), a concentration of 1.0% CH4, and a reaction time of 12 h. The XRD changes before and after these reactions are shown in the figure. Figure 6 Co3O shown 4(400C) The diffraction peak at 2θ = 36.8° was significantly enhanced after 12 hours of catalytic oxidation of 1.0% CH4 at 500℃ compared to that of 3% Pd / Co3O. 4(400C) The significant difference in the catalytic oxidation of 1.0% CH4 at 600℃ for 12 hours indicates that the noble metal Pd loading helps to inhibit the growth of Co3O4 on the support to a certain extent. 4(400C) High-temperature crystallization.

[0098] Test Example 4: Using Co3O prepared in Examples 1-4 respectively 4(400C) Co3O 4(650C) 3% Pd / Co3O 4(400C) 3% Pd / Co3O 4(650C) As a catalyst, the conversion rate of catalytic oxidation degradation of 1000 ppm toluene was tested under a reaction space velocity (GHSV) of 40000 ml / (g·h). See [reference needed]. Figure 7 As shown, Co3O 4(400C) The temperature at which catalytic oxidation degradation of toluene achieves a conversion rate of 90% (T) 90 The temperature is 249℃, and the Co3O content is... 4(650C) The temperature at which catalytic oxidation degradation of toluene achieves a conversion rate of 90% (T) 90 The temperature was 254℃, and the concentration of 3% Pd / Co3O was 3%. 4(400C) The temperature at which catalytic oxidation degradation of toluene achieves a conversion rate of 90% (T) 90 The temperature was 213℃, and the concentration of 3% Pd / Co3O was 3%. 4(650C) The temperature at which catalytic oxidation degradation of toluene achieves a conversion rate of 90% (T) 90 The temperature is 24℃.

[0099] The specific embodiments of the present invention have been described above by way of example. However, the scope of protection of the present invention is not limited to the above exemplary embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a Co3O4-supported noble metal catalyst for the catalytic oxidation of gaseous carbon-containing compounds, characterized in that, The preparation method includes the following steps: S1. Dissolve soluble cobalt salt in water, mix with an alkaline reagent, and react to obtain a cobalt salt precipitate; S2. Calcine the cobalt salt precipitate to obtain the support Co3O4; S3. Dissolve the carrier Co3O4 and the soluble salt of noble metal M in a solvent, mix them, add H2O2 to react, and calcine to obtain M / Co3O4; The mixing of the soluble cobalt salt aqueous solution and the alkaline reagent in step S1 includes the following steps: adding the alkaline reagent to the soluble cobalt salt aqueous solution and stirring at room temperature for 0.1 to 1 h to obtain a mixed solvent, wherein the concentration of the alkaline reagent is 1 to 3 times the concentration of the soluble cobalt salt aqueous solution; The reaction described in step S1 is a solvothermal reaction, which includes the following steps: reacting the mixed solvent at a temperature of 100~200 degrees Celsius for 4~24 h; The calcination temperature in step S2 is 300-800 degrees Celsius, and the calcination time is 2-12 hours. Step S3, which involves dissolving the support Co3O4 and the soluble noble metal salt in a solvent, includes the following steps: dispersing the support Co3O4 in a solvent, adding the soluble noble metal salt, and stirring at room temperature for 0.1 to 1 h to obtain a mixed solution; The reaction of the mixed solution with H2O2, by mass percentage, includes the following steps: heating the mixed solution to 20-100 degrees Celsius, adding H2O2, reacting for 2-10 hours to obtain a solid reactant, wherein the amount of H2O2 is more than 50 times that of the precious metal. After obtaining the solid reactant in step S3 and before calcination, the following steps are also included: filtering the reaction solution, washing and drying the solid reactant; The calcination in step S3 includes the following steps: calcining the solid reactants at a temperature of 200-400 degrees Celsius for 2-12 hours.

2. The preparation method according to claim 1, characterized in that: The soluble cobalt salt is selected from at least one of Co(NO3)2, CoCl2, and Co(CH3COO)2; the alkaline substance in the alkaline reagent is selected from at least one of NaOH, Na2CO3, and NaHCO3.

3. The preparation method according to claim 1, characterized in that: The precious metal loading precipitation process mainly uses Co3O4 as a catalyst to promote the redox reaction of H2O2. At the same time, the OH- generated by the redox reaction of H2O2 further reacts with the precious metal to precipitate, which helps to complete the uniform loading of the precious metal.

4. A Co3O4 supported noble metal catalyst prepared by the method according to any one of claims 1-3, characterized in that: The catalyst comprises amorphous or crystalline Co3O4, on which a noble metal with catalytic properties is supported.

5. The Co3O4-supported noble metal catalyst according to claim 4, characterized in that, The Co3O4 has a plate-like or granular structure with a crystal size of 50-500 nm. The noble metal M is at least one of Pd, Pt, Au, and Ru, and the loading of the noble metal is 0.1-5 wt% of the Co3O4 support.

6. The application of a Co3O4 supported noble metal catalyst prepared by the method of any one of claims 1-3 or the Co3O4 supported noble metal catalyst of any one of claims 4-5 in the catalytic oxidation of gaseous carbon-containing compounds.

7. The application according to claim 6, characterized in that, The gaseous carbonaceous compound is VOCs or methane.

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