Preparation method and application of surface defect-rich catalyst for catalytic oxidation of VOCs (Volatile Organic Compounds)

Abstract

The invention belongs to the technical field of VOCs catalytic oxidation catalysts, and particularly relates to a preparation method and application of a surface defect-rich catalyst for VOCs catalytic oxidation, and the preparation method comprises the following steps: (1) uniformly mixing heteropolyacid, pseudo-boehmite and water, grinding, carrying out vacuum drying, and calcining to obtain catalyst carrier powder; (2) preparing a manganese precursor saline solution, adding the catalyst carrier powder into the manganese precursor saline solution, and loading manganese precursor salt on the catalyst carrier; performing vacuum drying and calcining the obtained product to obtain a manganese oxide loaded catalyst; and (3) reducing the supported catalyst in a mixed reducing atmosphere containing CO / inert gas to obtain the catalyst with rich surface defects. According to the method, rich defect sites are constructed on the surface of the catalyst, the catalytic combustion activity is promoted, and the conversion temperature of the catalyst is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of VOCs catalytic oxidation catalysts, and in particular relates to a preparation method and application of a catalyst with surface defects rich in VOCs catalytic oxidation. Background Art

[0002] Volatile Organic Compounds (VOCs) are a general term for organic compounds with a melting point below room temperature and a boiling point below 200-260°C under standard atmospheric pressure, mainly including alkanes, hydrocarbons, esters, alcohols, benzene series, etc. Volatile organic compounds (VOCs) are an important factor causing air pollution. Direct emissions not only directly pollute the atmosphere, but also form secondary pollutants such as haze, photochemical fumes and ozone under certain conditions, causing serious air pollution.

[0003] There are many VOCs emission reduction treatment technologies. Among them, catalytic combustion technology (catalytic oxidation method to treat VOCs) as one of the VOCs waste gas treatment processes has the advantages of low operating cost, no secondary pollution, small combustion equipment size, low reaction temperature, wide application range and high VOCs removal rate. Therefore, it has good application prospects for the purification of VOCs generated by industrial processes.

[0004] The core of catalytic oxidation technology is the oxidation catalyst. Currently, precious metal system catalysts are basically used. Although they have good low-temperature activity, they are relatively expensive and have poor resistance to poisoning.

[0005] In addition, the existing non-precious metal system VOCs catalytic oxidation catalysts have a high complete combustion temperature (≥300°C) and consume a lot of energy in the actual application process.

[0006] Patent document CN109248691A discloses a VOCs elimination catalyst containing oxygen defects and a preparation method thereof. The method uses cobalt salt, cerium salt, urea and tetraethoxysilane as raw materials, and adopts a sol-gel method and a programmed temperature controllable hydrogen reduction method to prepare a supported catalyst with silicon dioxide as a carrier and cobalt oxide / cerium oxide containing oxygen defects as an active ingredient; the cobalt oxide / cerium oxide catalyst containing oxygen defects has a higher electron cloud density, which is conducive to the adsorption of oxygen-containing compounds formaldehyde and oxygen, and can promote the catalytic combustion activity of the catalyst.

[0007] Therefore, developing low-cost and highly active oxidation catalysts is an urgent problem to be solved in the field of VOCs emission reduction. Summary of the invention

[0008] The purpose of the present invention is to provide a method for preparing a surface defect-rich catalyst for catalytic oxidation of VOCs and its application, in view of the problems existing in the prior art for preparing oxidation catalysts. An acidic Al2O3 carrier with a high specific surface area is prepared by doping with heteropolyacids and combining with mechanical ball milling, and a transition metal manganese oxide is loaded on the modified carrier. While increasing the specific surface area of ​​the catalyst, the surface acidity can also be adjusted. After high-temperature reduction treatment in a mixed atmosphere of CO / inert gas, abundant defect sites are constructed on the catalyst surface, which is beneficial to promoting the catalytic combustion activity of the catalyst and reducing the conversion temperature of the catalyst (such as the intermediate conversion temperature and the complete conversion temperature).

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] In a first aspect, a method for preparing a surface defect-rich catalyst for catalytic oxidation of VOCs is provided, comprising the following steps:

[0011] (1) Preparation of catalyst carrier

[0012] The heteropoly acid, pseudo-boehmite and deionized water are uniformly mixed to obtain a mixture, and the mixture is ground (placed in a ball mill, such as a zirconia ball mill, with a certain amount of zirconia grinding balls added); the wet powder mixture obtained by grinding is vacuum dried, and then the dried powder is calcined in an inert atmosphere (for example, placed in a tube furnace and programmed to heat) to obtain a catalyst carrier powder;

[0013] (2) Preparation of Catalyst

[0014] Weigh a manganese precursor salt and dissolve it in water to prepare a manganese precursor salt solution; then add the catalyst support powder obtained in step (1) to the manganese precursor salt solution (for example, by one or more methods selected from the group consisting of impregnation, coprecipitation, and citric acid method) to load the manganese precursor salt on the catalyst support; then vacuum dry the catalyst support; and then calcine the dried product under an inert atmosphere to obtain a supported catalyst containing manganese oxide;

[0015] (3) Reduction of supported catalyst

[0016] The supported catalyst obtained in step (2) is placed in a mixed reducing atmosphere containing CO / inert gas for reduction to obtain the catalyst with rich surface defects.

[0017] According to the preparation method provided by the present invention, in some embodiments, in step (1), the mass ratio of pseudo-boehmite: heteropolyacid: deionized water is 1:(0.003-0.01):(0.8-1.6), for example, 1:0.004:1, 1:0.006:1, 1:0.008:1, 1:0.01:1, 1:0.006:1.2, 1:0.008:1.2, 1:0.01:1.2, 1:0.006:1.5, 1:0.008:1.5, 1:0.01:1.5, preferably 1:(0.005-0.008):(1-1.2).

[0018] In some embodiments, the heteropoly acid is selected from one or more of phosphomolybdic acid, phosphotungstic acid and silicotungstic acid. The pseudo-boehmite is commercially available, for example but not limited to, from SASOL in South Africa.

[0019] In some embodiments, in step (1), the mass ratio of the mixture to be ground: grinding porcelain balls is (1-5):1, for example, 1.2:1, 1.5:1, 2.2:1, 2.5:1, 3:1, 3.5:1, 4.2:1, 4.5:1, preferably (2-4):1.

[0020] In some embodiments, the grinding process conditions include: a grinding speed of 350 to 450 r / min (e.g., 370 r / min, 390 r / min, 400 r / min, 440 r / min), preferably 380-420 r / min; a grinding time of 30-60 min (e.g., 35 min, 45 min, 55 min), preferably 40-50 min.

[0021] In some embodiments, in step (1), the process conditions of vacuum drying include: time of 12-24h (e.g., 15h, 18h, 20h), temperature of 50-80°C (e.g., 55°C, 70°C, 75°C), and vacuum degree of ≤50Pa (e.g., 1Pa, 5Pa, 10Pa, 20Pa, 30Pa, 40Pa).

[0022] In some embodiments, in step (1), the calcination process conditions (using a programmed temperature curve) include: heating to 200°C at a heating rate of 5°C / min at room temperature and maintaining for 1-2h (e.g., 1.5h); heating to 350°C at a heating rate of 5°C / min at 200°C and maintaining for 0.5-2h (e.g., 1.0h, 1.5h); heating to 500°C at a heating rate of 10°C / min at 350°C and maintaining for 1-2h (e.g., 1.5h). During the calcination process, the inert atmosphere may be, for example, a nitrogen atmosphere.

[0023] In some embodiments, in step (1), the specific surface area of ​​the catalyst carrier is ≥ 400 m 2 / g, for example, 420m 2 / g, 450m 2 / g、500m 2 / g, 550m 2 / g.

[0024] According to the preparation method provided by the present invention, in some embodiments, in step (2), the manganese precursor salt is a water-soluble manganese precursor salt selected from one or more of manganese acetate, manganese nitrate and manganese sulfate.

[0025] In some embodiments, the loaded catalyst containing manganese oxide has a loading amount of manganese oxide of 1-30 wt% (e.g., 2 wt%, 4 wt%, 8 wt%, 12 wt%, 15 wt%, 20 wt%, 25 wt%), preferably 1-10 wt%, of the total mass of the loaded catalyst.

[0026] In step (2), the catalyst support is added to an aqueous solution containing a manganese precursor salt, and the active component can be loaded on the support by one or more methods of impregnation, coprecipitation, and citric acid method. The process conditions of the impregnation method, coprecipitation method, and citric acid method are conventional operations in the art and will not be repeated here.

[0027] In some embodiments, in step (2), the process conditions for vacuum drying include: temperature of 50-80°C (e.g., 55°C, 75°C), preferably 60-70°C, time of 12-24h (e.g., 15h, 22h), preferably 18-20h, vacuum degree of ≤50Pa (e.g., 1Pa, 5Pa, 10Pa, 20Pa, 35Pa, 40Pa), preferably ≤30Pa.

[0028] In some embodiments, in step (2), the calcination process conditions include: calcination temperature of 400-550° C. (e.g., 420° C., 480° C., 540° C.), preferably 450-500° C.; calcination time of 3-6 h (e.g., 3.5 h, 4.5 h, 5.5 h), preferably 4-5 h. During the calcination process, the inert atmosphere, for example, can be a nitrogen atmosphere.

[0029] According to the preparation method provided by the present invention, in some embodiments, in step (3), the inert gas is selected from one or more of nitrogen, helium and argon.

[0030] In some embodiments, the total flow rate of the mixed reducing atmosphere is 120 to 280 L / h·g -1 Catalyst (e.g., 130 L / h·g -1Catalyst, 160L / h·g -1 Catalyst, 180L / h·g -1 Catalyst, 200L / h·g -1 Catalyst, 240L / h·g -1 Catalyst), preferably 150 to 250 L / h·g -1 Catalyst; based on the total volume of the mixed reducing atmosphere, wherein the amount of CO added accounts for 0.1 to 6 vol% (for example, 0.5 vol%, 1 vol%, 2.5 vol%, 4 vol%, 5.5 vol%) of the total volume of the mixed reducing atmosphere, preferably 2 to 5 vol%.

[0031] In some embodiments, in step (3), the reduction process conditions include: the reduction temperature is 450-600°C (for example, 480°C, 520°C, 580°C), preferably 500-550°C; the reduction time is 6-24h (for example, 8h, 12h, 18h, 22h), preferably 10-20h.

[0032] In a second aspect, there is provided a use of the catalyst having surface defects rich in surface defects prepared by the preparation method as described above in the catalytic oxidation reaction of VOCs.

[0033] VOCs mainly include alkanes, hydrocarbons, esters, alcohols, and benzene series. The surface defect-rich catalyst prepared by the present invention can be used, for example but not limited to, in the catalytic oxidation reaction of VOCs such as alkanes, hydrocarbons, esters, alcohols, and benzene series.

[0034] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0035] (1) In the step of preparing the catalyst carrier of the present invention, pseudo-boehmite is used as a precursor, a certain amount of heteropoly acid is doped for modification, and a mechanical ball milling method is used to make the pseudo-boehmite and heteropoly acid particles both in a high-energy unstable state by mechanical force, fully fuse, reduce the particle size, create internal lattice defects or distortions, increase the specific surface area and surface acidity of the carrier, promote the formation of defect sites of the carrier to a certain extent, and improve the low-temperature catalytic activity of the catalyst in the catalytic oxidation reaction of VOCs;

[0036] (2) At the same time, after calcination under an inert atmosphere, the present invention can obtain a catalyst carrier with both high specific surface area and high surface acidity; and by subjecting the catalyst carrier with high specific surface area and high surface acidity to a high-temperature reduction treatment of a manganese oxide-loaded catalyst in a mixed atmosphere containing CO / inert gas, abundant defect sites can be constructed on the catalyst surface; the defect sites of the carrier can anchor the active components and prevent the active components from agglomerating, so that the active components are well dispersed on the surface of the carrier, promoting oxygen conduction and electron transfer of the catalyst, improving the unit specific surface activity and the utilization efficiency of the active sites, which is beneficial to promoting the catalytic combustion activity of the catalyst, thereby improving the low-temperature activity of the catalyst and reducing the conversion temperature of the catalyst (such as the intermediate conversion temperature and the complete conversion temperature); especially for oxidation reactions, and reaction environments in which O2 is also used as a reaction gas, the low-temperature activity of the catalyst in the catalytic oxidation reaction of VOCs is improved, and the conversion temperature of VOCs is effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a graph showing the relationship between the oxidation rate of ethylene and temperature when the catalyst prepared in Example 1 of the present invention is used in a catalytic oxidation experiment of ethylene. DETAILED DESCRIPTION

[0038] In order to understand the technical features and contents of the present invention in detail, the preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described in the embodiments, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described here.

[0039] <Source of raw materials>

[0040] Pseudoboehmite, commercially available;

[0041] Phosphomolybdic acid, commercially available;

[0042] Manganese acetate salt, commercially available.

[0043] Example 1

[0044] (1) Preparation of catalyst carrier

[0045] Add 50g of pseudo-boehmite into a beaker, then add phosphomolybdic acid and deionized water, adjust the mass ratio of pseudo-boehmite: phosphomolybdic acid: deionized water to 1:0.008:1 and mix them. After stirring and mixing with a glass rod, place the entire mixture in a zirconia ball mill, add 40g of zirconia grinding balls, and grind at a grinding speed of 400r / min for 40min.

[0046] The wet powder mixture obtained after grinding was placed in a vacuum dryer for vacuum drying (drying temperature of 70°C, vacuum degree of 20Pa) for 24 hours, and then the dried powder was calcined at high temperature in a tube furnace under a nitrogen atmosphere. The calcination temperature program was as follows:

[0047] At room temperature, the temperature was raised to 200°C at a rate of 5°C / min and maintained for 2 h. At 200°C, the temperature was raised to 350°C at a rate of 5°C / min and maintained for 1 h. At 350°C, the temperature was raised to 500°C at a rate of 10°C / min and maintained for 2 h. The specific surface area was 423 m 2 / g of catalyst carrier;

[0048] (2) Preparation of Catalyst

[0049] Weighing manganese acetate salt (manganese precursor salt) and dissolving it in water to prepare a manganese precursor salt solution, then immersing the catalyst support obtained in step (1) in the manganese precursor salt solution, and loading the manganese acetate salt on the catalyst support by an immersion method, wherein the immersion temperature is 80° C. and the immersion time is 6 hours;

[0050] The wet catalyst powder obtained by impregnation is then placed in a vacuum dryer and vacuum dried at 80°C for 12 hours with a vacuum degree of 20Pa; the dried powder is placed in a tubular furnace under a nitrogen atmosphere for high-temperature calcination at a calcination temperature of 500°C for 4 hours to obtain a supported catalyst containing manganese oxide, wherein the supported amount of manganese oxide is controlled to account for 10wt% of the total mass of the supported catalyst;

[0051] (3) Catalyst reduction

[0052] Weigh 5 g of the supported catalyst containing manganese oxide obtained in step (2), and place it in a mixed reducing atmosphere containing CO / nitrogen gas for high-temperature reduction to obtain a catalyst with rich surface defects; wherein:

[0053] The total flow rate of the mixed reducing atmosphere is 200L / h·g -1 Catalyst, CO accounts for 5 vol% of the total volume of the mixed reducing atmosphere; the reduction temperature is 500°C, and the reduction time is 15 h.

[0054] Example 2

[0055] The preparation method of the catalyst with rich surface defects is as follows:

[0056] In step (1), the mass ratio of pseudo-boehmite: heteropoly acid: deionized water is 1:0.003:1, and the other process conditions are the same as those in Example 1; the specific surface area of ​​the obtained catalyst carrier is 440m 2 / g;

[0057] Step (2) is the same as in Example 1;

[0058] Step (3) is the same as in Example 1.

[0059] Example 3

[0060] The preparation method of the catalyst with rich surface defects is as follows:

[0061] In step (1), the mass ratio of pseudo-boehmite: heteropoly acid: deionized water is 1:0.01:1.2, and the other process conditions are the same as those in Example 1; the specific surface area of ​​the obtained catalyst carrier is 409m 2 / g;

[0062] Step (2) is the same as in Example 1;

[0063] Step (3) is the same as in Example 1.

[0064] Example 4

[0065] The preparation method of the catalyst with rich surface defects is as follows:

[0066] In step (2), the amount of manganese acetate added is changed so that the loading amount of manganese oxide accounts for 5 wt% of the total mass of the supported catalyst;

[0067] Step (1) is the same as in Example 1;

[0068] Step (3) is the same as in Example 1.

[0069] Example 5

[0070] The preparation method of the catalyst with rich surface defects is as follows:

[0071] In step (3), the total flow rate of the mixed reducing atmosphere is 150 L / h·g -1 Catalyst, CO added in an amount of 2 vol% of the total volume of the mixed reducing atmosphere;

[0072] Step (1) is the same as in Example 1;

[0073] Step (2) is the same as in Example 1.

[0074] Example 6

[0075] The preparation method of the catalyst with rich surface defects is as follows:

[0076] In step (3), the total flow rate of the mixed reducing atmosphere is 280 L / h·g -1Catalyst, CO accounts for 6 vol% of the total volume of the mixed reducing atmosphere; the reduction temperature is 550°C, and the reduction time is 10 h;

[0077] Step (1) is the same as in Example 1;

[0078] Step (2) is the same as in Example 1.

[0079] Comparative Example 1

[0080] The preparation method of the catalyst for catalytic oxidation of VOCs refers to Example 1, except that step (3) is not performed, that is, the obtained supported catalyst containing manganese oxide is not placed in a mixed reducing atmosphere containing CO / inert gas for high-temperature reduction.

[0081] Comparative Example 2

[0082] A method for preparing a catalyst for catalytic oxidation of VOCs comprises the following steps:

[0083] (1) weighing manganese acetate salt (manganese precursor salt) and dissolving it in water to prepare a manganese precursor salt solution, then directly using commercially available aluminum oxide as a catalyst carrier, immersing the commercially available aluminum oxide carrier in the manganese precursor salt solution, and loading the manganese acetate salt on the aluminum oxide carrier by an immersion method; wherein the immersion temperature is 80° C. and the immersion time is 6 hours;

[0084] The wet catalyst powder obtained by impregnation is then placed in a vacuum dryer and vacuum dried at 80°C for 12 hours with a vacuum degree of 20Pa; the dried powder is placed in a tubular furnace under a nitrogen atmosphere for high-temperature calcination at a calcination temperature of 500°C for 4 hours to obtain a supported catalyst containing manganese oxide, wherein the supported amount of manganese oxide is controlled to account for 10wt% of the total mass of the supported catalyst;

[0085] (2) Weighing 5 g of the supported catalyst containing manganese oxide obtained in step (1), placing it in a mixed reducing atmosphere containing CO / nitrogen gas for high-temperature reduction, to obtain a catalyst for catalytic oxidation of VOCs; wherein:

[0086] The total flow rate of the mixed reducing atmosphere is 200L / h·g -1 Catalyst, CO accounts for 5 vol% of the total volume of the mixed reducing atmosphere; the reduction temperature is 500°C, and the reduction time is 15 h.

[0087] The catalysts prepared in the examples and comparative examples were used in the catalytic oxidation experiment of ethylene:

[0088] Using ethylene as a probe molecule, the catalysts prepared in the examples and comparative examples were applied to the catalytic oxidation experiment of ethylene. The simulated atmosphere contained: 10 vol% O2, 0.7 vol% ethylene, and the rest nitrogen. The reaction space velocity was 150,000 h -1 , and the catalytic performance of each catalyst was examined by continuous online monitoring; the ethylene conversion rate of the catalyst at each temperature can be calculated by the initial and post-reaction tail gas ethylene concentrations, and the calculation formula is as follows:

[0089]

[0090] Where: X 乙烯 Indicates ethylene conversion rate (%); C in With C out They represent the ethylene concentration in the initial intake air and the ethylene concentration in the exhaust gas after reaction at each temperature point, in ppm.

[0091] Ethylene conversion rate X 乙烯 The reaction temperature T corresponding to 50% and 90% 50 and T 90 The test results are shown in Table 1. The relationship between the oxidation rate of ethylene and the temperature when the catalysts prepared in the examples and comparative examples are used in the catalytic oxidation experiment of ethylene is shown in Table 1. Figure 1 shown.

[0092] Table 1 Catalytic performance test results of the catalysts of various embodiments and comparative examples

[0093] serial number <![CDATA[T 50 (℃)]]> <![CDATA[T 90 (℃)]]> Example 1 131.5 164.0 Example 2 141.5 172.2 Example 3 147.5 171.7 Example 4 154.5 191.0 Example 5 147.0 180.1 Example 6 134.3 170.2 Comparative Example 1 198.3 248.4 Comparative Example 2 190.9 233.4

[0094] Table 1 and Figure 1 The test results show that the present invention significantly promotes the catalytic oxidation activity of non-precious metal system VOCs catalysts and reduces the conversion temperature of the catalyst (such as intermediate conversion temperature and complete conversion temperature) by in-situ modification of alumina carriers by heteropolyacids, loading a specific amount of active components, and reducing them at high temperature in an inert atmosphere to obtain a VOCs catalytic oxidation catalyst with abundant defect sites on the surface. Compared with Comparative Example 1, the ethylene complete conversion temperature of the catalyst can be reduced to below 200°C after high-temperature reduction in an inert atmosphere in the methods of each embodiment; compared with Comparative Example 2, the catalysts prepared by heteropolyacid modification of the carriers of each embodiment can achieve the same ethylene catalytic conversion rate at a lower conversion temperature.

[0095] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing a surface defect-rich catalyst for catalytic oxidation of VOCs, characterized in that: The following steps are involved: (1) Preparation of catalyst carrier The heteropoly acid, pseudo-boehmite and deionized water are uniformly mixed to obtain a mixture, and the mixture is ground; the wet powder mixture obtained by grinding is vacuum dried, and then the dried powder is calcined under an inert atmosphere to obtain a catalyst carrier powder; (2) Preparation of Catalyst Weighing a manganese precursor salt and dissolving it in water to prepare a manganese precursor salt solution; then adding the catalyst support powder obtained in step (1) to the manganese precursor salt solution to load the manganese precursor salt on the catalyst support; Then, the product is vacuum dried; and the dried product is calcined under an inert atmosphere to obtain a supported catalyst containing manganese oxide; (3) Reduction of supported catalyst The supported catalyst obtained in step (2) is placed in a mixed reducing atmosphere containing CO / inert gas for reduction to obtain the catalyst with rich surface defects.

2. The preparation method according to claim 1, characterized in that: In step (1), the mass ratio of pseudo-boehmite: heteropoly acid: deionized water is 1: (0.003-0.01): (0.8-1.6), preferably 1: (0.005-0.008): (1-1.2); The heteropoly acid is selected from one or more of phosphomolybdic acid, phosphotungstic acid and silicotungstic acid.

3. The preparation method according to claim 1, characterized in that: In step (1), the mass ratio of the mixture to be ground: grinding ceramic balls is (1-5):1, preferably (2-4):1; The grinding process conditions include: a grinding speed of 350-450 r / min, preferably 380-420 r / min; a grinding time of 30-60 min, preferably 40-50 min.

4. The preparation method according to claim 1, characterized in that: In step (1), the process conditions of vacuum drying include: time of 12-24h, temperature of 50-80°C, vacuum degree of ≤50Pa; and / or The calcination process conditions include: heating to 200°C at a heating rate of 5°C / min at room temperature and maintaining for 1-2 hours; heating to 350°C at a heating rate of 5°C / min at 200°C and maintaining for 0.5-2 hours; heating to 500°C at a heating rate of 10°C / min at 350°C and maintaining for 1-2 hours.

5. The preparation method according to claim 1, characterized in that: In step (1), the specific surface area of ​​the catalyst carrier is ≥400m 2 / g.

6. The preparation method according to claim 1, characterized in that: In step (2), the manganese precursor salt is selected from one or more of manganese acetate, manganese nitrate and manganese sulfate; In the supported catalyst containing manganese oxide, the supported amount of manganese oxide accounts for 1-30wt% of the total mass of the supported catalyst, preferably 1-10wt%.

7. The preparation method according to claim 1, characterized in that: In step (2), the process conditions of vacuum drying include: temperature of 50-80°C, preferably 60-70°C, time of 12-24h, preferably 18-20h, vacuum degree of ≤50Pa, preferably ≤30Pa; and / or The calcination process conditions include: calcination temperature of 400-550° C., preferably 450-500° C.; calcination time of 3-6 hours, preferably 4-5 hours.

8. The preparation method according to any one of claims 1 to 7, characterized in that: In step (3), the inert gas is selected from one or more of nitrogen, helium and argon; The total flow rate of the mixed reducing atmosphere is 120 to 280 L / h·g -1 Catalyst, preferably 150 to 250 L / h·g -1 Catalyst; based on the total volume of the mixed reducing atmosphere, wherein the amount of CO added accounts for 0.1 to 6 vol%, preferably 2 to 5 vol%, of the total volume of the mixed reducing atmosphere.

9. The preparation method according to any one of claims 1 to 8, characterized in that: In step (3), the reduction process conditions include: reduction temperature of 450-600°C, preferably 500-550°C; reduction time of 6-24h, preferably 10-20h.

10. Use of the catalyst with surface defects obtained by the preparation method according to any one of claims 1 to 9 in the catalytic oxidation reaction of VOCs.

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