A method for preparing a VOCs oxidation catalyst

Abstract

The application discloses a preparation method of a VOCs oxidation catalyst, which comprises the following steps: (1) immersing a spherical molecular sieve into a mixed solution of alkali and sodium silicate to perform a hydrothermal reaction, obtaining a spherical molecular sieve carrier with a multi-level pore structure and drying the same; (2) immersing the spherical molecular sieve carrier obtained in the step (1) into an active component-containing precursor salt aqueous solution to obtain a molecular sieve carrier loaded with the precursor salt; (3) drying and calcining the molecular sieve carrier loaded with the precursor salt obtained in the step (2) to obtain the VOCs oxidation catalyst; wherein the active component is one or more of manganese, cobalt, iron and copper. When used for VOCs oxidation catalysis, the method can improve the reaction activity, selectivity and water resistance of the catalyst.

Description

Technical Field

[0001] This invention relates to the technical fields of environmental protection and air pollution control, and also to the technical fields of catalysts, specifically to a method for preparing a VOCs oxidation catalyst. Background Technology

[0002] Volatile organic compounds (VOCs) are organic compounds with a saturated vapor pressure greater than 70 Pa at room temperature and a boiling point below 260℃ at normal pressure. VOCs are a common air pollutant, mainly originating from industries such as printing, coating, pharmaceuticals, furniture manufacturing, and petrochemicals. Most of these organic waste gases are flammable and explosive, and often emit unpleasant odors and foul smells into the air. Even at low concentrations, they can irritate the eyes, nose, and respiratory system, and may even induce cancer and mutations in humans.

[0003] Commonly used VOCs emission reduction technologies include adsorption condensation, direct oxidation, catalytic combustion, photocatalytic oxidation, and biofiltration membranes. Catalytic combustion refers to the flameless combustion of VOCs components in waste gas at a relatively low ignition temperature (<500℃) in the presence of a catalyst, completely oxidizing them into CO2 and H2O. This method features low auxiliary fuel costs, low operating temperature, small equipment size, high purification efficiency, low energy consumption, and no secondary pollution, making it one of the most promising VOCs pollution control technologies currently available. Developing highly efficient catalytic combustion catalysts is one of the keys to the widespread application of this technology in VOCs pollution treatment.

[0004] CN113401918A relates to an Ag-based method for removing sulfur-containing volatile organic compounds. + Multi-level porous molecular sieves, their preparation methods, and applications. Alkali treatment is used to modify microporous molecular sieves to form mesoporous structures within them. Ion exchange-loaded Ag. + It possesses both mesoporous and microporous structures and is loaded with Ag. + In USY molecular sieves, the silica-alumina molar ratio is 10-30, and the specific surface area is 500-1000 m². 2 ·g -1 The ratio of mesoporous pore volume to microporous pore volume is 0.5-2.5.

[0005] CN104174425A relates to a catalyst for the catalytic oxidation of volatile organic compounds and a method for preparing the same. The active component of the catalyst is Pd or Pt, and the support is a hierarchical porous molecular sieve such as SBA-15 or KIT-6 with a macroporous-mesoporous structure.

[0006] CN113184878A relates to a hierarchical porous zeolite molecular sieve, its preparation method, and its application. Na-SSZ-13 zeolite is first treated with an alkaline solution, followed by acid washing to obtain a hierarchical porous zeolite molecular sieve. Small molecule amine compounds pre-adsorb and occupy the interior of the zeolite channels, forming an "internal protective" layer to resist the rapid diffusion and disordered etching of the alkali within the zeolite micropores. This achieves good protection of the zeolite framework while constructing the hierarchical channels through alkaline treatment of SSZ-13 zeolite.

[0007] There is a continuous need for improvement in VOCs oxidation catalysts in this field, especially in terms of improving the catalyst's reactivity and water resistance, as well as its selective catalytic oxidation capability for macromolecular and small molecular components when facing different VOCs pollution sources. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides a method for preparing a VOCs oxidation catalyst. The catalyst prepared by the method of this invention has improved reactivity and water resistance, and achieves efficient removal of specific volatile organic compounds.

[0009] To achieve its purpose, the present invention adopts the following technical solution:

[0010] In one aspect of the present invention, a method for preparing a VOCs oxidation catalyst is provided, comprising the following steps:

[0011] (1) The spherical molecular sieve was immersed in a mixed solution of alkali and sodium silicate for hydrothermal reaction to obtain a spherical molecular sieve support with a hierarchical pore structure and then dried.

[0012] (2) The spherical molecular sieve support obtained in step (1) is immersed in a precursor salt solution containing active components to obtain a molecular sieve support loaded with precursor salt.

[0013] (3) The molecular sieve support loaded with precursor salt obtained in step (2) is dried and calcined to obtain the VOCs oxidation catalyst.

[0014] The active component is one or more of manganese, cobalt, iron and copper.

[0015] In a specific embodiment of the present invention, in step (1), the spherical molecular sieve is one or more of CHA type zeolite molecular sieve, MFI type zeolite molecular sieve and BEA type zeolite molecular sieve.

[0016] In a preferred embodiment of the present invention, the CHA type zeolite molecular sieve is SSZ-13 zeolite molecular sieve and / or SAPO zeolite molecular sieve, the MFI type zeolite molecular sieve is ZSM-5 zeolite molecular sieve and / or S-1 zeolite molecular sieve, and the BEA type zeolite molecular sieve is Beta zeolite molecular sieve (β molecular sieve).

[0017] In a specific embodiment of the present invention, in step (1), the diameter of the spherical molecular sieve is 2-5 mm, for example, about 2 mm, about 3 mm, about 4 mm, about 5 mm, etc.

[0018] In a preferred embodiment of the present invention, the spherical molecular sieve is ultrasonically washed with water to remove surface impurities before use.

[0019] In a specific embodiment of the present invention, in step (1), the base is one or more of organic amines (e.g., methylamine, ethanolamine, aniline, ethylenediamine, etc.), sodium hydroxide, and potassium hydroxide.

[0020] In a specific embodiment of the present invention, in step (1), the mass fraction of alkali in the mixed solution is 1-5%, for example 2%, 3%, 4%, etc.; the mass fraction of sodium silicate is 2-10%, for example 3%, 4%, 5%, 6%, 7%, 8%, 9%, etc.; and the mass ratio of spherical molecular sieve to mixed solution is 1-1:3, for example 1:2.

[0021] In a preferred embodiment of the present invention, in step (1), the pH value of the mixed solution is 11-14, for example 12, 13, etc.

[0022] In a specific embodiment of the present invention, in step (1), the temperature of the hydrothermal reaction is 80-200℃, for example 100℃, 120℃, 140℃, 160℃, 180℃, etc.; the time is 5-168h, for example 10h, 25h, 50h, 75h, 100h, 125h, 150h, etc.

[0023] In a specific embodiment of the present invention, in step (1), the mass loss of the spherical molecular sieve is controlled to be 1-3%, for example, 2%.

[0024] In a specific embodiment of the present invention, in step (1), the silicon-to-aluminum ratio of the obtained spherical molecular sieve support is 100-300, for example 150, 200, 250, etc.

[0025] In a specific embodiment of the present invention, in step (1), the intermediate pore volume of the obtained spherical molecular sieve carrier accounts for 10%-50% of the total pore volume, for example, 15%, 20%, 25%, 30%, 35%, 40%, 45%, etc.

[0026] In a specific embodiment of the present invention, in step (2), the manganese salt in the precursor salt solution is one or more of manganese nitrate, manganese chloride, manganese acetate and manganese sulfate; the cobalt salt is one or more of cobalt nitrate, cobalt chloride, cobalt acetate and cobalt sulfate; the iron salt is one or more of ferric nitrate, ferric chloride, ferrous chloride, ferrous sulfate, ferric acetate and ferric sulfate; and the copper salt is one or more of copper nitrate, copper chloride, copper acetate and copper sulfate.

[0027] In a specific embodiment of the present invention, in step (2), the concentration of the precursor salt solution is 0.001-0.03M, more preferably 0.0025-0.005M, such as 0.0015M, 0.002M, 0.0035M, 0.004M, 0.0045M, 0.0055M, 0.01M, 0.015M, 0.02M, 0.025M, etc.

[0028] In a specific embodiment of the present invention, in step (2), the mass ratio of the precursor salt solution to the spherical molecular sieve support is 15-40:1, preferably 20-30:1, for example 25:1.

[0029] In a specific embodiment of the present invention, in step (2), the soaking time is 0.5-5h, for example 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, etc.; the temperature of the soaking solution is 40-80℃, for example 50℃, 60℃, 70℃, etc.

[0030] In a specific embodiment of the present invention, in step (3), the drying temperature is 50-120℃ and the drying time is 2-10h; the calcination temperature is 400-600℃ and the calcination time is 3-8h.

[0031] In another aspect of the invention, there is a VOCs oxidation catalyst obtained according to the preparation method described above.

[0032] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in the following aspects:

[0033] The catalyst prepared by this invention, using molecular sieves with meso-micro hierarchical porous structure as a support, can improve catalyst reactivity, increase VOCs removal efficiency, and significantly reduce T90.

[0034] Microporous channels can achieve selective adsorption and removal of VOCs, and improve the dispersibility of active components by anchoring them, thereby improving the VOCs removal efficiency; mesoporous channels can shorten the mass transfer path, increase the specific surface area and pore volume, improve the VOCs adsorption rate, and increase the adsorption capacity.

[0035] Unbound by any theory, the inventors discovered that a higher pore volume ratio between mesopores and micropores and / or a higher valence state of the metal results in a higher removal efficiency for large organic molecules such as toluene; a lower pore volume ratio between mesopores and micropores and / or a lower valence state of the metal results in a higher removal efficiency for small organic molecules such as ethylene. The process of this invention can achieve adjustment of the pore volume ratio between mesopores and micropores and / or the valence state of the metal.

[0036] Micropores facilitate the desorption of water molecules within the micropores, enhancing the moisture resistance of the molecular sieve and enabling its use for VOC removal in high-humidity environments. Furthermore, the introduction of sodium silicate further increases the silica-to-alumina ratio, thereby enhancing the moisture resistance of the molecular sieve and making it suitable for the selective removal of VOCs from high-humidity flue gas. Detailed Implementation

[0037] The present invention will be further described below with reference to the embodiments. However, the present invention is not limited to the listed embodiments, but should also include equivalent improvements and modifications of the technical solutions defined in the appended claims of the present invention.

[0038] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0039] raw material

[0040] Molecular sieves were purchased from Tianjin Nanhua Catalyst Co., Ltd. ZSM-5 zeolite molecular sieve was selected for MFI type, and Beta zeolite molecular sieve was selected for BEA type. Organic amines (including ethanolamine H₂NCH₂CH₂OH and ethylenediamine H₂NCH₂CH₂NH₂), sodium silicate, sodium hydroxide, and inorganic salts (such as manganese nitrate, ferric nitrate, and copper nitrate) were all purchased from Sinopharm Chemical Reagent Co., Ltd. Unless otherwise specified, all raw materials mentioned in this article are commercially available.

[0041] Test methods

[0042] Silicon-to-aluminum ratio test: using high-resolution solid-state MAS 29 The Si-NMR method is used to determine the silicon-to-aluminum ratio of the molecular sieve framework, and the solid-state nuclear magnetic resonance spectroscopy simulation program can automatically calculate the framework silicon-to-aluminum ratio.

[0043] Mesopore and micropore volume testing of molecular sieves: Micropores and mesopores were measured using N2 as the adsorption medium and a BET physical adsorption instrument.

[0044] Valence state analysis of metal elements: The valence state of metal elements on the catalyst surface was analyzed by X-ray photoelectron spectroscopy (XPS).

[0045] Catalyst composition analysis: The content of metal oxides in the catalyst was analyzed by X-ray fluorescence spectroscopy (XRF).

[0046] Detection of ethylene and toluene concentrations at the inlet and outlet of the reaction unit: The concentrations of ethylene and toluene at the inlet and outlet of the reaction unit are detected by a Fourier transform infrared multi-component gas analyzer.

[0047] Example

[0048] Example 1

[0049] (1) 10g of spherical molecular sieve (ZSM-5, silicon-to-aluminum ratio of 20) with 2mm diameter was ultrasonically washed with water to remove surface impurities; the washed spherical molecular sieve was immersed in a mixed solution of sodium hydroxide (mass fraction of 1%) and sodium silicate (mass fraction of 2%), and the mixed solution was placed in a reaction vessel for hydrothermal reaction at 80℃ for 5h. The mass ratio of spherical molecular sieve to mixed solution was 1:1 to obtain a spherical molecular sieve carrier with a multi-level pore structure, which was then dried for later use; the mass loss of the obtained spherical molecular sieve carrier was about 1%, the silicon-to-aluminum ratio was about 100, and the mesoporous pore volume accounted for about 10% of the total pore volume;

[0050] (2) The above-mentioned spherical molecular sieve support with multi-level pore structure was immersed in 200 mL of manganese nitrate (molar concentration of 0.0025 M) aqueous solution for 30 min. The temperature of the immersion solution was 40 °C. The mass ratio of manganese nitrate aqueous solution to spherical molecular sieve support was 20:1. The molecular sieve support loaded with precursor salt was obtained.

[0051] (3) The molecular sieve support loaded with precursor salt was placed in an oven and dried at 50°C for 10 hours, and then placed in a tube furnace and calcined at 400°C for 3 hours to obtain a VOCs oxidation catalyst.

[0052] XRF composition analysis showed that MnO x Mn accounts for 2% of the catalyst mass and is determined by XPS. 4+ / Mn (total) is 30%, Mn 3+ / Mn (total) is 40%, Mn 2+ The total Mn content is 30%.

[0053] Example 2

[0054] (1) 10g of spherical molecular sieve (Beta molecular sieve, silicon-to-aluminum ratio of 20) with 2mm diameter was ultrasonically washed with water to remove surface impurities; the washed spherical molecular sieve was immersed in a mixed solution of sodium hydroxide (mass fraction of 5%) and sodium silicate (mass fraction of 10%), and the mixed solution was placed in a reactor for hydrothermal reaction at 200℃ for 168h, wherein the mass ratio of spherical molecular sieve to mixed solution was 1:3, and a spherical molecular sieve carrier with a multi-level pore structure was obtained, which was then dried for later use; the mass loss of the obtained spherical molecular sieve carrier was about 3%, the silicon-to-aluminum ratio was about 300, and the mesoporous pore volume accounted for about 50% of the total pore volume;

[0055] (2) The above-mentioned spherical molecular sieve support with multi-level pore structure was immersed in 200 mL of manganese nitrate (molar concentration of 0.005 M) aqueous solution for 5 h. The temperature of the immersion solution was 80 °C. The mass ratio of manganese nitrate aqueous solution to spherical molecular sieve support was 30:1. The molecular sieve support loaded with precursor salt was obtained.

[0056] (3) The molecular sieve support loaded with precursor salt was placed in an oven and dried at 120°C for 2 hours, and then placed in a tube furnace and calcined at 600°C for 8 hours to obtain a VOCs oxidation catalyst.

[0057] XRF composition analysis showed that MnO x Mn, accounting for 5% of the catalyst mass, was analyzed by XPS. 4+ / Mn (total) is 50%, Mn 3 + / Mn (total) is 30%, Mn 2+ / Mn (total) is 20%.

[0058] Example 3

[0059] The catalyst was prepared using the same method as in Example 1, except that:

[0060] The washed spherical molecular sieve and the mixed solution were placed in a reaction vessel for hydrothermal reaction at a temperature of 150℃ for 80 hours.

[0061] The above-mentioned spherical molecular sieve support with a hierarchical porous structure was immersed in 200 mL of an aqueous solution of manganese nitrate (0.0025 M molar concentration) and ferric nitrate (0.0025 M molar concentration) for 30 min. The temperature of the immersion solution was 40 °C, and the mass ratio of the aqueous solution to the spherical molecular sieve support was 20:1. The molecular sieve support loaded with precursor salt was then obtained.

[0062] The obtained spherical molecular sieve support has a mass loss of about 1.5%, a silica-to-alumina ratio of about 120, and a mesoporous pore volume of about 15%.

[0063] XRF composition analysis showed that MnO x FeO accounts for 2.5% of the catalyst mass. x Mn, comprising 0.5% of the catalyst mass, was analyzed by XPS. 4+ / Mn (total) is 30%, Mn 3+ / Mn (total) is 40%, Mn 2+ The total Mn content is 30%.

[0064] Example 4

[0065] The catalyst was prepared using the same method as in Example 2, except that the washed spherical molecular sieve was immersed in a mixed solution of ethanolamine (4% by mass) and sodium silicate (8% by mass); the mass ratio of manganese nitrate aqueous solution to the spherical molecular sieve support was 28:1.

[0066] The obtained spherical molecular sieve support has a mass loss of about 2.8%, a silica-to-alumina ratio of about 270, and a mesoporous pore volume of about 45%.

[0067] XRF composition analysis showed that MnO x Mn accounts for 4.5% of the catalyst mass and, according to XPS analysis, is... 4+ / Mn (total) is 50%, Mn 3+ / Mn (total) is 30%, Mn 2+ / Mn (total) is 20%.

[0068] Example 5

[0069] The catalyst was prepared using the same method as in Example 1, except that the washed spherical molecular sieve was immersed in a mixed solution of ethylenediamine (3% by mass) and sodium silicate (5% by mass).

[0070] The obtained spherical molecular sieve support has a mass loss of about 1.2%, a silicon-to-aluminum ratio of about 110, and a mesoporous pore volume of about 12%.

[0071] XRF composition analysis showed that MnO x It accounts for 2.0% of the catalyst mass, and after XPS analysis, Mn 4+ / Mn (total) is 50%, Mn 3+ / Mn (total) is 30%, Mn 2+ / Mn (total) is 20%.

[0072] Example 6

[0073] The catalyst was prepared using the same method as in Example 2, except that:

[0074] (2) The above-mentioned spherical molecular sieve support with multi-level pore structure was immersed in 200 mL of aqueous solution of manganese nitrate (molar concentration of 0.003 M) and copper nitrate (molar concentration of 0.003 M) for 2 h. The temperature of the immersion solution was 60 °C. The mass ratio of manganese nitrate aqueous solution to spherical molecular sieve support was 30:1. The molecular sieve support loaded with precursor salt was obtained.

[0075] (3) The molecular sieve support loaded with precursor salt was placed in an oven and dried at 120°C for 2 hours, and then placed in a tube furnace and calcined at 600°C for 5 hours to obtain a VOCs oxidation catalyst.

[0076] The obtained spherical molecular sieve support has a mass loss of about 3%, a silica-alumina ratio of about 300, and a mesoporous pore volume of about 50%.

[0077] XRF composition analysis showed that MnO x CuO accounts for 4.6% of the catalyst mass. x Mn, accounting for 1.0% of the catalyst mass, was analyzed by XPS. 4+ / Mn (total) is 40%, Mn 3+ / Mn (total) is 32%, Mn 2+ The total percentage of Mn is 28%.

[0078] Comparative Example 1

[0079] The preparation of spherical molecular sieve supports with hierarchical porous structures is not carried out.

[0080] (1) 10g of spherical molecular sieve (ZSM-5, silicon-to-aluminum ratio of 20) with a diameter of 2mm was immersed in 200mL of manganese nitrate (molar concentration of 0.0025M) aqueous solution for 30min. The temperature of the immersion solution was 40℃. The mass ratio of manganese nitrate aqueous solution to spherical molecular sieve support was 20:1. The molecular sieve support loaded with precursor salt was obtained. The silicon-to-aluminum ratio was 20. The mesoporous pore volume was 0%.

[0081] (2) The molecular sieve support loaded with precursor salt was dried at 100°C for 2 hours and then calcined at 400°C for 3 hours in a tube furnace to obtain the catalyst.

[0082] XRF composition analysis showed that MnO x Mn accounts for 2% of the catalyst mass and was analyzed by XPS. 4+ / Mn (total) is 30%, Mn 3 + / Mn (total) is 40%, Mn 2+ The total Mn content is 30%.

[0083] Comparative Example 2

[0084] The catalyst was prepared using the same method as in Example 1, except that only a sodium hydroxide solution (1% by mass) was used in the hydrothermal reaction in step (1), without sodium silicate. The resulting spherical molecular sieve support had a mass loss of approximately 1%, a silica-to-alumina ratio of approximately 20, and a mesoporous pore volume of approximately 10% of the total pore volume. XRF composition analysis showed that MnO x Mn accounts for 2% of the catalyst mass and is determined by XPS. 4+ / Mn (total) is 30%, Mn 3+ / Mn (total) is 40%, Mn 2+ The total Mn content is 30%.

[0085] After obtaining the catalysts in the above examples and comparative examples, the catalyst performance was tested under the following test conditions.

[0086] Test conditions:

[0087] The VOCs in the flue gas consist of 800 ppm ethylene, 800 ppm toluene, 3% O2, 5% H2O, and the remainder is nitrogen. Space velocity: 20000 h⁻¹ -1 The removal rate of VOCs at 200℃, 250℃, and 300℃ was measured. Sampling points were set at the inlet and outlet of the reaction unit, and the ethylene and toluene concentrations at the inlet and outlet were measured to calculate the removal rate. Calculation formula: Ethylene removal rate = 1 - (C 进口C2H4 -C 出口C2H4 ) / C 进口C2H4 Toluene removal rate = 1 - (C 进口C7H8 -C 出口C7H8 ) / C 进口C7H8 The results are shown in Table 1 below.

[0088] Table 1

[0089]

[0090] Although the invention has been described in detail above for illustrative purposes, it should be understood that such detailed description is merely for illustration, and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention, which is defined only by the claims.

Claims

1. A method for preparing a VOCs oxidation catalyst, comprising the following steps: (1) The spherical molecular sieve was immersed in a mixed solution of alkali and sodium silicate to carry out a hydrothermal reaction, and the spherical molecular sieve support with a hierarchical pore structure was obtained and then dried. (2) The spherical molecular sieve support obtained in step (1) is immersed in a precursor salt solution containing active components to obtain a molecular sieve support loaded with precursor salt. (3) The molecular sieve support loaded with precursor salt obtained in step (2) is dried and calcined to obtain the VOCs oxidation catalyst; The active component is one or more of manganese, cobalt, iron, and copper; In step (1), the intermediate pore volume of the obtained spherical molecular sieve support accounts for 10%-50% of the total pore volume; In step (1), the spherical molecular sieve is one or more of CHA type zeolite molecular sieve, MFI type zeolite molecular sieve and BEA type zeolite molecular sieve; In step (1), the base is one or more of organic amines, sodium hydroxide and potassium hydroxide, and the organic amine is methylamine, ethanolamine, aniline or ethylenediamine; In step (1), the mass fraction of alkali in the mixed solution is 1-5%, the mass fraction of sodium silicate is 2-10%, and the mass ratio of spherical molecular sieve to mixed solution is 1-1:

3. In step (1), the hydrothermal reaction temperature is 80-200℃ and the time is 5-168 h; wherein, in step (1), the obtained spherical molecular sieve support has a silica-alumina ratio of 100-300, and the silica-alumina ratio is tested by high-resolution solid MAS 29 Si The silica-alumina ratio of the molecular sieve framework is determined by NMR method.

2. The preparation method according to claim 1, wherein, The CHA type zeolite molecular sieve is SSZ-13 zeolite molecular sieve and / or SAPO zeolite molecular sieve, the MFI type zeolite molecular sieve is ZSM-5 zeolite molecular sieve and / or S-1 zeolite molecular sieve, and the BEA type zeolite molecular sieve is Beta zeolite molecular sieve.

3. According to the preparation method of claim 1, the diameter of the spherical molecular sieve is 2-5 mm.

4. According to the preparation method of claim 3, the spherical molecular sieve is ultrasonically washed with water to remove surface impurities before use.

5. The preparation method according to any one of claims 1-4, wherein, In step (2), The manganese salt in the precursor salt solution is one or more of manganese nitrate, manganese chloride, manganese acetate, and manganese sulfate; the cobalt salt is one or more of cobalt nitrate, cobalt chloride, cobalt acetate, and cobalt sulfate; the iron salt is one or more of ferric nitrate, ferric chloride, ferrous chloride, ferrous sulfate, ferric acetate, and ferric sulfate; and the copper salt is one or more of copper nitrate, copper chloride, copper acetate, and copper sulfate. The concentration of the precursor salt solution was 0.001-0.03 M; The mass ratio of the precursor salt solution to the spherical molecular sieve support is 15-40:

1.

6. The preparation method according to claim 5, wherein, The concentration of the precursor salt solution is 0.0025-0.005M; the mass ratio of the precursor salt solution to the spherical molecular sieve support is 20-30:

1.

7. The preparation method according to any one of claims 1-4, wherein, In step (2), the soaking time is 0.5-5h and the temperature of the soaking solution is 40-80℃.

8. The preparation method according to any one of claims 1-4, wherein, In step (3), the drying temperature is 50-120℃ and the drying time is 2-10 h; the calcination temperature is 400-600℃ and the calcination time is 3-8 h.

9. The VOCs oxidation catalyst obtained by the preparation method according to any one of claims 1-8.

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