Oil film-wrapped in-situ reduced noble metal catalyst, preparation method and application thereof
The in-situ reduction method with oil film encapsulation solves the problem of precious metal particle aggregation in the preparation of precious metal catalysts, realizes uniform distribution and efficient utilization of precious metals, simplifies the preparation process, and improves catalytic activity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- PETROCHINA CO LTD
- Filing Date
- 2023-06-02
- Publication Date
- 2026-07-03
AI Technical Summary
Existing precious metal catalysts are prone to particle aggregation during preparation, resulting in low utilization and requiring additional reduction and activation processes, which affects efficiency.
An in-situ reduction method using oil film encapsulation is employed. During the drying process, nanoparticles are formed by the reducing agent and stabilizer in the impregnation solution. The oil film seals the pores, achieving in-situ reduction and uniform distribution of precious metals, avoiding the volatilization of the reducing agent, and simplifying the preparation process.
It improves the dispersion and utilization of precious metals, simplifies the preparation process, and enhances catalytic activity and the efficiency of precious metal utilization.
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Abstract
Description
Technical Field
[0001] This invention relates to an oil film-encapsulated in-situ reduction catalyst for noble metals, its preparation method, and its application, belonging to the field of VOCs waste gas purification. Background Technology
[0002] Currently, VOCs treatment technologies mainly include direct oxidation, adsorption, absorption, catalytic oxidation, and biological methods. Among these technologies, each has its own advantages and disadvantages in terms of applicability and removal efficiency. Catalytic oxidation technology is one of the most promising and efficient chemical treatment technologies, possessing advantages such as low-temperature catalytic activity (200-500℃), no secondary pollution (avoiding the generation of nitrogen oxides), high treatment efficiency (removal efficiency is mostly above 95%), and wide applicability. In catalytic oxidation technology, the catalyst is the core technology. Currently, industrially used catalysts mainly use precious metals as active components, with honeycomb ceramics or corrugated metal plates as the matrix. Due to the high cost of precious metal catalysts, it is necessary to improve the utilization rate of precious metals in the catalyst, reduce the amount of precious metals used, and improve catalyst activity.
[0003] CN201310453379.7 discloses a catalyst for exhaust gas purification and its preparation method. The catalyst comprises an alumina support, cerium dioxide supported on the alumina, and a noble metal active component supported on the surface of the cerium dioxide. The alumina support and cerium dioxide are prepared using a precipitation-hydrothermal method, and the noble metal active component is loaded using a hydrothermal in-situ reduction deposition method. The catalyst exhibits strong interaction between CeO2 and the noble metal species; the CeO2 support generates more oxygen vacancies, activating oxygen molecules into active oxygen species and improving catalytic oxidation activity. The alumina and cerium dioxide are dispersed and in contact, acting as a barrier to prevent sintering with pure cerium oxide as the support, while significantly improving the thermal stability of alumina at high temperatures.
[0004] CN201610281077.X discloses a catalyst for the room-temperature catalytic decomposition of formate to produce hydrogen, specifically a titanium dioxide nanorod-supported palladium (Pd) nanoparticle catalyst for formate decomposition. This patent document uses titanium dioxide nanorods as a support, employing an in-situ reduction method with surface modification to load nano-Pd onto the support surface, thus obtaining a supported catalyst. Using this supported catalyst for the room-temperature decomposition of formate to produce hydrogen, highly efficient catalytic decomposition of formate can be achieved entirely at room temperature, producing pure H2 without the presence of other gases. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides an oil film-encapsulated in-situ reduction catalyst for noble metals, its preparation method, and its application.
[0006] As one aspect of the present invention, an oil film-encapsulated in-situ reduction catalyst for noble metals is disclosed. The oil film-encapsulated in-situ reduction catalyst for noble metals comprises a support and nano-noble metal particles loaded on the support. The support is divided into a first support and a second support. The inner surface of the pores of the first support is coated with the second support, and the nano-noble metal particles are distributed on the inner surface of the pores of the second support.
[0007] In a possible specific implementation, the first carrier has a porosity of 20% to 95%, a positive compressive strength > 0.5 MPa, and a lateral compressive strength > 0.2 MPa.
[0008] It should be noted that although a large porosity results in good gas permeability, it may affect its strength. Preferably, the porosity can be between 20% and 90%, and more preferably between 60% and 95%, which can balance strength and gas permeability.
[0009] In a possible specific implementation, the first carrier is honeycomb ceramic and / or honeycomb metal.
[0010] In a possible specific embodiment, the second carrier is one of TiO2, cerium-zirconium solid solution, γ-Al2O3 and ZSM-5 molecules or any mixture thereof;
[0011] In a possible specific implementation, the nano-precious metal includes at least one of gold, silver, ruthenium, rhodium, palladium, osmium, iridium, and platinum.
[0012] In another aspect, the present invention relates to a method for preparing the above-mentioned oil film-encapsulated in-situ reduction noble metal catalyst, the method comprising the following steps:
[0013] S1: Mix the second carrier powder additive with the organic additive and ball mill it to obtain a coated catalyst slurry;
[0014] S2: The coated catalyst slurry of S1 is coated onto the support, then dried and calcined to obtain the catalyst support;
[0015] S3: Dissolve and mix the noble metal precursor, reducing agent, buffer and stabilizer in deionized water, and impregnate it onto the catalyst support of S2 using the equal volume impregnation method, so that the impregnation solution completely enters the micropores of the support, and then add a coating agent to cover the surface of the support.
[0016] S4: Place the impregnated carrier obtained in S3 into an N2 atmosphere for reaction;
[0017] S5: Slowly release N2 under the N2 atmosphere of S4 and then dry;
[0018] S6: The dried support is placed in a muffle furnace for calcination to obtain an oil film-encapsulated in-situ reduction of the noble metal catalyst.
[0019] In a possible specific implementation, the coating agent is an alkane-based oily coating agent with a boiling range of 120 to 290°C or a non-water-soluble organic substance within this boiling point range.
[0020] Preferred are n-decane, n-octane, n-dodecane, or n-hexadecane.
[0021] In a possible specific embodiment, the organic auxiliary agent is one of alcohols, aldehydes, organic acids, and sodium borohydride;
[0022] Organic additives are used as a second carrier to improve the coating effect; PEG or leveling agents are preferred.
[0023] In a possible specific implementation, the reducing agent is methanol or ethylene glycol.
[0024] In a possible specific implementation, the stabilizer is a water-soluble polymer, preferably polyvinylpyrrolidone, polyethylene glycol, or F123.
[0025] In a possible specific embodiment, the buffer is a weak organic acid-organic acid salt system with pH=3 to 7, preferably citric acid-citrate, EDTA or polyacrylate-polyacrylate.
[0026] In a possible specific implementation, the ball milling time in step S1 is 0.1 to 30 hours.
[0027] In a possible specific implementation, in step S4, the pressure of the N2 atmosphere is 0.18 MPa to 0.65 MPa, the volume percentage of O2 is less than 1%, the reaction time is 2 to 4 hours, and the reaction temperature is 80 to 95°C.
[0028] In a possible specific implementation, in step S5, the drying is a two-stage drying process, with the first stage drying temperature being 120℃~300℃ and the second stage drying temperature being 300℃.
[0029] In a possible specific implementation, in step S6, the baking temperature is 500-600°C and the baking time is 2-4 hours.
[0030] As another aspect of the present invention, the application of the above-mentioned oil film-encapsulated in-situ reduction noble metal catalyst or the oil film-encapsulated in-situ reduction noble metal catalyst prepared by the above-mentioned preparation method in the catalytic oxidation treatment of volatile organic compounds is discussed.
[0031] Based on the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows:
[0032] The oil film-encapsulated in-situ reduction noble metal catalyst of the present invention has a reducing agent, a stabilizer and a buffer added to the impregnation solution, which is conducive to the reduction reaction during the drying process. Under the action of the stabilizer, nanoparticles are formed and attached to the carrier.
[0033] Furthermore, the oil film-encapsulated in-situ reduction catalyst for noble metals described in this invention has a layer of high-boiling-point oily substance attached to the outside of the carrier impregnated with the noble metal solution, forming an oil film that blocks the pores of the catalyst and seals the impregnation solution inside the pores of the carrier. This can prevent the low-boiling-point reducing agent from evaporating and overflowing, which would cause the reducing agent to evaporate completely when the temperature reaches the reduction temperature, making it difficult to complete the reduction of the noble metal. Most of the noble metal still exists in an ionic state, causing the ions to migrate and aggregate with the solvent, resulting in uneven distribution of the noble metal. At the same time, it has not been reduced and activated, and it needs to be reduced and activated again in subsequent use.
[0034] In addition, the oil film-encapsulated in-situ reduction process of the precious metal catalyst described in this invention occurs during the catalyst drying step, eliminating the need for a pre-reduction treatment process of the impregnation solution.
[0035] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained in accordance with the structures particularly pointed out in the description and claims. Detailed Implementation
[0036] The present invention will be further described below with reference to specific embodiments. The scope of protection of the present invention is not limited by the following embodiments.
[0037] Traditional methods for developing precious metal catalysts include impregnation, pre-reduction impregnation, and co-impregnation. These methods require reduction and activation with hydrogen or hydrazine hydrate before use. During the reduction process, the precious metals aggregate to form larger particles, resulting in low utilization rates.
[0038] In their practical work, the inventors discovered that in-situ reduction during catalyst drying results in small, uniformly distributed particles, effectively simplifying the preparation process of precious metal catalysts and improving the utilization rate of precious metals.
[0039] To achieve the above objectives, and in order to simplify the reduction process of noble metal catalysts, reduce the particle size of noble metals in the catalyst, improve the dispersion of noble metals, and thus enhance catalytic activity, the inventors of this case have adopted the following technical solution:
[0040] This invention employs a common impregnation method to prepare the catalyst. After impregnation, the reducing agent is protected by an attached oil film, while the active component is dispersed in the micropores of the support. During drying, the active component is reduced and activated. The reduced nano-noble metal particles generated by the reaction are directly loaded onto the surface of the support pores. The support powder has abundant pores. Since the support powder is impregnated in the noble metal precursor solution, the solute in the solution is distributed throughout the pores of the support. Therefore, the reduction reaction is also widespread throughout the pores of the support. The reduced metal particles are distributed on various surfaces inside and outside the pores of the support, further improving the dispersion of the noble metal, thereby improving the activity and metal utilization of the obtained noble metal catalyst.
[0041] A 0.5%–2% solution (based on elemental Pt and Pd) of Pt and Pd precursors was prepared, and methanol, citric acid, PVP, and deionized water were added. This solution was then impregnated onto a pre-treated support. A layer of alkane-based oily coating agent (C8–C16) with a boiling range of 120–290℃ was then impregnated onto the support impregnated with the precious metal solution. The mixture was placed in a drying oven and reacted at 80–95℃ for 2–4 hours under 0.4 MPa N2 protection to reduce the precious metal to elemental form. The protective gas was slowly released to prevent surface cracking caused by violent volatilization until atmospheric pressure was reached. N2 protection was continued, and the temperature was raised to 120–300℃ for 4 hours to allow the reducing agent, water, and oily coating agent to completely volatilize. After drying, the mixture was placed in a muffle furnace and calcined at 500–600℃ for 2–4 hours to crystallize the oxide additives and form the desired catalyst.
[0042] This invention does not impose any particular limitation on the noble metal in the noble metal precursor, which can be Pt or Pd. The noble metal precursor is a Pt-containing compound or a Pd-containing compound, and the aqueous solution of the noble metal precursor is an aqueous solution containing a Pt compound or an aqueous solution containing a Pd compound.
[0043] The present invention does not particularly limit the ball milling method; ball milling can be carried out in a ball mill, and the ball milling time is, for example, 0.1 to 30 hours, preferably 0.5 to 3 hours.
[0044] Furthermore, the inventors of this case discovered that in the preparation of nano-precious metals, the precious metal particles produced by thermal reduction using methanol as a reducing agent are smaller, exhibit better catalytic performance, and a reduction reaction temperature of 80–120°C is optimal. However, methanol has a boiling point of 65°C, and under normal pressure, the reducing agent completely evaporates before reaching the reduction reaction temperature. This invention employs an oil film sealing method, using an oil film to seal the reaction system solution containing the reducing agent within the carrier pores under positive pressure nitrogen sealing conditions. This allows the reduction reaction to complete within the carrier pores, and the generated precious metal nanoparticles are uniformly adsorbed within the carrier pores. Based on the saturated vapor pressure of methanol (180.667 kPa at 80°C and 637.67 kPa at 120°C), the reaction system pressure is controlled between 0.18 MPa and 0.65 MPa.
[0045] Example
[0046] Source of raw materials or equipment:
[0047]
[0048]
[0049] Evaluation and analysis methods:
[0050] Analytical instruments: Agilent 8860 gas chromatograph with FID detector for quantitative analysis of reactants.
[0051] With 1000mg / m 3 Using air as the evaluation gas source, isothermal evaluation was conducted in a fixed-bed reactor at a reaction space velocity of 20,000 h⁻¹. -1 Conversion rate = (1 - benzene content at reaction outlet / benzene content at reaction inlet) × 100%, T 90 It is the reaction temperature at which the benzene conversion rate reaches 90%, expressed in °C.
[0052] Example 1
[0053] Dissolve 0.44g citric acid and 8.5g PVP in 40ml deionized water. Add 12.5ml methanol, 48g chloroplatinic acid solution (2% platinum content), and 12g palladium chloride solution (2% palladium content) to the solution, and bring the volume to 120ml to form an impregnation solution ① with a total precious metal content of 10g / L. Add 120ml deionized water to a mixed powder of 25g γ-Al2O3 and 5g cerium-zirconium solid solution, and ball mill at 400 rpm for 1 hour to form an active slurry with a solid content of 20%. Then coat the slurry onto a cordierite honeycomb ceramic carrier with a coating amount of 25g / L, and obtain the carrier ② after drying and calcination. Take 10ml of impregnation solution ① and impregnate it in a 100cm... 3 On the support, n-decane was added dropwise to cover the catalyst surface, and the reaction was carried out at 80°C for 2 hours in a 0.4 MPa N2 atmosphere. After drying at 160°C under nitrogen protection and calcination at 550°C, a VOCs catalytic oxidation catalyst with a noble metal content of 1 g / L was obtained.
[0054] The obtained catalyst was evaluated according to the above evaluation method, and the evaluation results were obtained by benzene T. 90 =192℃.
[0055] Comparative Example 1
[0056] Dissolve 0.44g citric acid and 8.5g PVP in 40ml deionized water. Add 12.5ml methanol, 48g chloroplatinic acid solution (2% platinum content), and 12g palladium chloride solution (2% palladium content) to the solution, and bring the volume to 120ml to form an impregnation solution ① with a total precious metal content of 10g / L. Add 120ml deionized water to a mixed powder of 25g γ-Al2O3 and 5g cerium-zirconium solid solution, and ball mill at 400 rpm for 1 hour to form an active slurry with a solid content of 20%. Then coat the slurry onto a cordierite honeycomb ceramic carrier with a coating amount of 25g / L, and obtain the carrier ② after drying and calcination. Take 10ml of impregnation solution ① and impregnate it in a 100cm... 3 On the support, the reaction was carried out at 80℃ for 2 hours in a 0.4MPaN2 atmosphere, dried at 160℃ under nitrogen protection, and calcined at 550℃ to obtain a VOCs catalytic oxidation catalyst with a noble metal content of 1g / L.
[0057] The catalyst reduction activation was not evaluated, and the evaluation result was benzene T. 90 =358℃.
[0058] After activating the catalyst by introducing 5% H2 and 95% N2 at 200℃ for 1 hour, the catalyst was evaluated. The evaluation results showed that benzene T 90 =264℃.
[0059] Example 2
[0060] Dissolve 0.44g citric acid and 8.5g PVP in 40ml deionized water. Add 12.5ml methanol, 48g chloroplatinic acid solution (2% platinum content), and 12g palladium chloride solution (2% palladium content) to the solution, and bring the volume to 120ml to form an impregnation solution ① with a total precious metal content of 10g / L. Add 120ml deionized water to a mixed powder of 25g γ-Al2O3 and 5g cerium-zirconium solid solution, and ball mill at 400 rpm for 1 hour to form an active slurry with a solid content of 20%. Then coat the slurry onto a cordierite honeycomb ceramic carrier with a coating amount of 25g / L, and obtain the carrier ② after drying and calcination. Take 10ml of impregnation solution ① and impregnate it in a 100cm... 3 On the support, n-octane was added dropwise to cover the catalyst surface, and the reaction was carried out at 80°C for 2 hours in a 0.18 MPa N2 atmosphere. After drying at 160°C under nitrogen protection, drying at 120°C and calcining at 550°C, a VOCs catalytic oxidation catalyst with a noble metal content of 1 g / L was obtained.
[0061] The obtained catalyst was evaluated according to the above evaluation method, and the evaluation results were obtained by benzene T. 90 =196℃.
[0062] Example 3
[0063] Dissolve 0.44g citric acid and 8.5g PVP in 40ml deionized water. Add 12.5ml methanol, 48g chloroplatinic acid solution (2% platinum content), and 12g palladium chloride solution (2% palladium content) to the solution, and bring the volume to 120ml to form an impregnation solution ① with a total precious metal content of 10g / L. Add 120ml deionized water to a mixed powder of 25g γ-Al2O3 and 5g cerium-zirconium solid solution, and ball mill at 400 rpm for 1 hour to form an active slurry with a solid content of 20%. Then coat the slurry onto a cordierite honeycomb ceramic carrier with a coating amount of 25g / L, and obtain the carrier ② after drying and calcination. Take 10ml of impregnation solution ① and impregnate it in a 100cm... 3 On the support, n-hexadecane was added dropwise to cover the catalyst surface, and the reaction was carried out at 120℃ for 2 hours in a 0.65MPa N2 atmosphere. After drying at 160℃ under nitrogen protection, the catalyst was dried at 300℃ and calcined at 550℃ to obtain a VOCs catalytic oxidation catalyst with a noble metal content of 1g / L.
[0064] The obtained catalyst was evaluated according to the above evaluation method, and the evaluation results were obtained by benzene T. 90 =192℃.
[0065] Example 4
[0066] Dissolve 0.44g EDTA and 8.5g ammonium polyacrylate in 40ml deionized water. Add 12.5ml methanol, 48g platinum nitrate solution (2% platinum content), and 12g palladium nitrate solution (2% palladium content) to the solution, and bring the volume to 120ml to form an impregnation solution ① with a total precious metal content of 10g / L. Add 120ml deionized water to a mixed powder of 25g γ-Al2O3 and 5g cerium-zirconium solid solution, and ball mill at 400 rpm for 1 hour to form an active slurry with a solid content of 20%. Then, coat the slurry onto a cordierite honeycomb ceramic carrier with a coating amount of 25g / L, and obtain the carrier ② after drying and calcination. Take 10ml of impregnation solution ① and impregnate it in a 100cm... 3 On the support, n-decane was added dropwise to cover the catalyst surface, and the reaction was carried out at 85°C for 2 hours in a 0.4 MPa N2 atmosphere. After drying at 160°C under nitrogen protection and calcination at 550°C, a VOCs catalytic oxidation catalyst with a noble metal content of 1 g / L was obtained.
[0067] The obtained catalyst was evaluated according to the above evaluation method, and the evaluation results were obtained by benzene T. 90 =174℃.
[0068] Example 5
[0069] Dissolve 8.4g of ammonium polyacrylate and 3.6g of polyacrylic acid in 40ml of deionized water. Add 12.5ml of ethylene glycol, 48g of a 2% platinum nitrate solution, and 12g of a 2% palladium nitrate solution to the solution, and bring the volume to 120ml to form an impregnation solution ① with a total precious metal content of 10g / L. Add 50ml of deionized water to a mixed powder of 25g TiO2 and 5g cerium-zirconium solid solution, and ball mill at 400 rpm for 3 hours to form an active slurry with a solid content of 37.5%. Then, coat the slurry onto a cordierite honeycomb ceramic carrier with a coating amount of 75g / L, and obtain the carrier ② after drying and calcination. Take 10ml of impregnation solution ① and impregnate it into a 100cm... 3 On the support, n-dodecane was added dropwise to cover the catalyst surface, and the reaction was carried out at 95°C for 2 hours in a 0.4 MPa N2 atmosphere. After drying at 220°C under nitrogen protection and calcination at 550°C, a VOCs catalytic oxidation catalyst with a noble metal content of 1 g / L was obtained.
[0070] The obtained catalyst was evaluated according to the above evaluation method, and the evaluation results were obtained by benzene T. 90 =188℃.
[0071] Example 6
[0072] Dissolve 0.44g EDTA and 8.5g ammonium polyacrylate in 40ml deionized water. Add 12.5ml methanol, 48g platinum nitrate solution (1% platinum content), and 12g palladium nitrate solution (1% palladium content) to the solution, and bring the volume to 250ml to form an impregnation solution ① with a total precious metal content of 2.4g / L. Add 120ml deionized water to a mixed powder of 25g γ-Al2O3 and 5g cerium-zirconium solid solution, and ball mill at 600 rpm for 0.5 hours to form an active slurry with a solid content of 20%. Then coat the slurry onto a cordierite honeycomb ceramic carrier with a coating amount of 50g / L, and obtain the carrier ② after drying and calcination. Take 20ml of impregnation solution ① and impregnate it in a 100cm... 3 On the support, n-decane was added dropwise to cover the catalyst surface, and the reaction was carried out at 85℃ for 2 hours in a 0.4MPa N2 atmosphere. After drying at 160℃ under nitrogen protection and calcination at 550℃, a VOCs catalytic oxidation catalyst with a noble metal content of 0.48 g / L was obtained.
[0073] The obtained catalyst was evaluated according to the above evaluation method, and the evaluation results were obtained by benzene T. 90 =195℃.
[0074] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All modifications or applications made in accordance with the above embodiments are within the scope of protection of this technical solution.
[0075] Although specific embodiments of the invention have been described in detail, those skilled in the art will understand that various modifications and substitutions can be made to those details based on all the teachings disclosed, and all such changes are within the scope of protection of this invention. The full scope of this invention is given by the appended claims and any equivalents thereof.
Claims
1. A method for preparing an in-situ reduction catalyst of noble metals encapsulated in an oil film, characterized in that, The preparation method includes the following steps: S1: Mix the second carrier powder additive with the organic additive and ball mill it to obtain a coated catalyst slurry; S2: The coated catalyst slurry of S1 is coated onto the first support, then dried and calcined to obtain the catalyst support; S3: Dissolve and mix the noble metal precursor, reducing agent, buffer and stabilizer in deionized water, and impregnate it onto the catalyst support of S2 using the equal volume impregnation method, so that the impregnation solution completely enters the micropores of the catalyst support, and then add a coating agent to cover the surface of the catalyst support. S4: Place the impregnated carrier obtained in S3 into an N2 atmosphere for reaction; S5: Slowly release N2 under the N2 atmosphere of S4 and then dry; S6: The dried support is placed in a muffle furnace for calcination to obtain an oil film-encapsulated in-situ reduction of the noble metal catalyst. The encapsulating agent is n-decane, n-octane, n-dodecane, or n-hexadecane; The oil film-encapsulated in-situ reduction noble metal catalyst includes a support and nano-noble metal particles supported on the support. The support is divided into a first support and a second support. The inner surface of the pores of the first support is coated with the second support, and the nano-noble metal particles are distributed on the inner surface of the pores of the second support. The first carrier is honeycomb ceramic and / or honeycomb metal; the second carrier is one or more of TiO2, cerium-zirconium solid solution, and γ-Al2O3; the nano-noble metal includes at least one of gold, silver, ruthenium, rhodium, palladium, osmium, iridium, and platinum.
2. The preparation method according to claim 1, characterized in that, The first carrier has a porosity of 20%~95%, a positive compressive strength >0.5MPa, and a lateral compressive strength >0.2MPa.
3. The preparation method according to claim 1, characterized in that, The organic additive is one of alcohols, aldehydes, or organic acids.
4. The preparation method according to claim 1, characterized in that, The reducing agent is methanol or ethylene glycol; And / or, the stabilizer is polyvinylpyrrolidone or polyethylene glycol.
5. The preparation method according to claim 1, characterized in that, In step S1, the ball milling time is 0.1 to 30 hours.
6. The preparation method according to claim 1, characterized in that, In step S4, the pressure of the N2 atmosphere is 0.18 MPa to 0.65 MPa, the volume percentage of O2 is less than 1%, the reaction time is 2 to 4 hours, and the reaction temperature is 80 to 95°C.
7. The preparation method according to claim 1, characterized in that, In step S5, the drying process is divided into two stages: the first stage drying temperature is 120℃~160℃, and the second stage drying temperature is 300℃.
8. The preparation method according to claim 1, characterized in that, In step S6, the calcination temperature is 500~600℃ and the calcination time is 2~4h.
9. The application of the oil film-encapsulated in-situ reduction noble metal catalyst prepared by the preparation method according to any one of claims 1 to 8 in the catalytic oxidation treatment of volatile organic compounds.