A metal-supported catalyst and its use in high flash point insulating oils
By using a metal-supported catalyst with a metal oxide carrier and a composite mesoporous layer in the synthetic ester insulating oil, the problems of low catalyst reaction efficiency and short lifespan were solved, achieving efficient preparation of high-ignition-point and low-pour-point insulating oil with excellent catalyst stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LANZHOU INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2026-05-13
- Publication Date
- 2026-06-23
AI Technical Summary
Existing catalysts have unsatisfactory reaction efficiency in the preparation of synthetic ester insulating oils, short cycle life, and pose environmental pollution risks. They also cannot guarantee the high flash point, low pour point, and low viscosity properties of the insulating oil.
Metal oxides are used as supports to load transition metals and composite metal oxide mesoporous layers, combined with fluorination modification and organic carbon precursors to form stable metal-supported catalysts. Mesoporous structures are constructed using surfactant templates, and ultrathin amorphous carbon layers are formed at high temperatures to enhance the hydrophobicity, acidity, and structural stability of the catalysts.
The catalytic efficiency and yield have been significantly improved. The synthetic ester insulating oil has a high flash point, low pour point and low viscosity. The catalyst activity has almost no decay during multiple cycles of use, ensuring the comprehensive performance and safety of the insulating oil.
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Abstract
Description
Technical Field
[0001] This application relates to the field of high flash point insulating oil technology, and more specifically, it relates to a metal-supported catalyst and its application in high flash point insulating oil. Background Technology
[0002] Insulating oil is a crucial medium for ensuring the insulation and heat dissipation of electrical equipment. Its performance directly determines the operational safety, stability, and service life of the equipment. While traditional mineral insulating oils are inexpensive, their inherent low ignition point and poor biodegradability pose safety and environmental risks. Natural ester insulating oils, although offering improved ignition point and environmental friendliness, suffer from limitations in oxidation resistance, low-temperature fluidity, and performance consistency due to their molecular structure. Synthetic ester insulating oils, prepared through chemical synthesis, possess strong molecular designability and combine advantages such as high ignition point, low pour point, low viscosity, and environmental friendliness, making them the most promising high-end insulating oils for meeting demanding operating conditions.
[0003] However, regarding the aforementioned technologies, the inventors discovered that the core of preparing synthetic ester insulating oil lies in the efficient esterification catalysis of long-chain fatty acids and polyols. In existing technologies, the reaction efficiency of synthetic ester oils is often unsatisfactory. While using some ultra-strong solid acid catalysts can improve reaction efficiency and yield, the catalyst preparation process causes significant environmental pollution, and the acidic sites are easily lost during use, making recycling impossible. Ordinary tin-based compound catalysts and p-toluenesulfonic acid catalysts leave significant residues in the oil, requiring large amounts of adsorbents or alkaline washing for treatment, generating substantial solid waste or wastewater. These residues also severely degrade the electrical properties of the insulating oil. Although supported metal catalysts possess the potential for both high activity and easy separation, in the high-temperature, acidic, and water-containing esterification reaction environment, the active metal components easily dissolve from the support, leading not only to rapid catalyst deactivation and short cycle life but also potential contamination of the insulating oil product, endangering the safe operation of electrical equipment. Summary of the Invention
[0004] To improve the cycle stability of the catalyst, enhance its catalytic efficiency and yield for insulating oil, and ensure the high flash point, low pour point, and low viscosity of the insulating oil, this application provides a metal-supported catalyst and its application in high flash point insulating oil.
[0005] In a first aspect, this application provides a metal-supported catalyst, employing the following technical solution:
[0006] A metal-supported catalyst includes a support, an active metal supported on the support, and a composite metal oxide mesoporous layer. The support is a metal oxide selected from at least one of MoO2, Al2O3, ZrO2, MgO, TiO2, and SnO2. The active metal is a transition metal selected from at least one of Fe, Co, Cu, Ni, Ti, Zr, Mn, V, and Zn. The raw materials for the composite metal oxide mesoporous layer include SiO2, ZrO2, and a carbon precursor.
[0007] Optionally, the loading of the active metal is 15-50% of the mass of the carrier.
[0008] Optionally, the carbon precursor is selected from phenolic resins.
[0009] By adopting the above technical solution, metal oxides such as MoO2, Al2O3, ZrO2, MgO, TiO2 and SnO2 are used as supports. These supports have high surface hydroxyl density and high mechanical strength, as well as high chemical stability, which can provide stable loading sites for active metals and prevent structural collapse of the support.
[0010] Using SiO2 and ZrO2 synergistically as raw materials for the composite metal oxide mesoporous layer, a highly ordered or interconnected mesoporous composite metal oxide layer is constructed through a surfactant template method. This provides a rapid diffusion channel for reactants and products, effectively blocking the dissolution of active metals while also reducing the catalytic efficiency caused by the dense protective layer of traditional catalysts blocking active sites. ZrO2 provides high chemical stability and mechanical strength, and can maintain the stability of the composite layer mesoporous structure even after high-temperature calcination, effectively maintaining the stability of the catalyst structure.
[0011] Furthermore, during the preparation of SiO2-ZrO2 coated sol, a carbonizable organic carbon precursor is introduced and carbonized during subsequent calcination, thereby forming an ultrathin amorphous carbon layer inside the pores. On the one hand, this effectively enhances the hydrophobicity and acid-phobicity of the catalyst, repelling the water generated in the reaction and reducing the attack and hydrolysis of the metal-support bonds by water molecules generated during the insulating oil reaction, thus physically blocking the dissolution pathway and mitigating hydrothermal erosion of the support and active metal. At the same time, it provides effective physical protection for the active metal supported on the catalyst, further fixing the active metal, strengthening the interfacial bonding, and ensuring the activity and stability of the active metal. On the other hand, the amorphous carbon layer formed after carbonization fills the defects in the mesopore walls, enhances the stability of the mesopore structure, further prevents the catalyst from collapsing during recycling, and enhances the catalyst's cycle stability.
[0012] Secondly, this application provides a method for preparing a metal-supported catalyst, which adopts the following technical solution:
[0013] A method for preparing a metal-supported catalyst includes the following steps:
[0014] S1: The carrier is mixed with a precursor solution of an active metal, and the mixture is sonicated to obtain a blend. After standing at room temperature, the blend is dried to obtain solid A.
[0015] S2: Calcine the solid A at 800-900℃ for 3-5 hours to obtain solid B;
[0016] S3: Tetraethyl orthosilicate is added to ethanol, water and catalyst are added, and the mixture is stirred for pre-hydrolysis to obtain silicon source solution; zirconium oxychloride is added to a mixed solution of ethanol and acetylacetone to obtain zirconium source solution; hexadecyltrimethylammonium bromide and carbon precursor are added to ethanol to obtain a mixed solution, and then the zirconium source solution and silicon source solution are added dropwise to the mixed solution under stirring to form a composite coated sol;
[0017] S4: Disperse the solid B in the composite coated gel, stir and react at 50-60℃, let stand, wash, dry, grind, then heat to 500-600℃ at 2-5℃ / min, keep warm for 2-3h, then continue to heat to 750-800℃, keep warm for 3-4h, and the product is obtained.
[0018] Optionally, the carrier described in step S1 undergoes the following pretreatment before being mixed with the precursor solution of the active metal:
[0019] The carrier was impregnated in a 0.2-0.4 mol / L ammonium bifluoride solution, then washed with deionized water, dried, and calcined at 480-500℃ for 4-5 hours to obtain a pretreated carrier.
[0020] By employing the above technical solution, ammonium bifluoride is used to fluorinate and modify the support. After calcination, the ammonium bifluoride decomposes, and F ions replace the hydroxyl groups on the support surface, forming stable active metal-F bonds, such as Ti-F. Fluorine atoms have strong electronegativity, and after connecting with the metal ions on the support, they can make the metal ions on the support surface very strong Lewis acid sites through a strong electron-withdrawing inductive effect. When the active metal ions approach the F-modified support surface sites, the oxygen on the active metal ions can act as electron donors, generating a strong interaction with the extremely electron-deficient Lewis acid sites on the support. In addition, water is generated during the preparation of esterified oil, which can cause the active metal to dissolve. Fluorination modification can replace the hydrophilic groups, reduce the surface energy, and reduce the attack and hydrolysis of the metal-support bonds by water molecules during the reaction, physically blocking the dissolution pathway. Fluorination treatment can also increase the phase transition temperature of the support, inhibit its transformation to a lower specific surface area during use, maintain the high specific surface area and pore structure of the support, suppress the damage of sintering to the support, and help prevent the migration and aggregation of highly dispersed active metals during sintering.
[0021] Optionally, the solid B described in step S4 may undergo the following pretreatment before being added to the composite coating gel:
[0022] The solid B was dispersed in an aqueous ethanol solution, the pH was adjusted, and then an aminosilane coupling agent was added. Under nitrogen protection, the mixture was stirred in an oil bath at 70-80°C to obtain a suspension. After centrifugation, washing, and drying, the pretreated solid B was obtained.
[0023] By adopting the above technical solution, before coating the composite oxide mesoporous layer, an aminosilane coupling agent is used for surface modification. During the subsequent in-situ growth of the mesoporous layer, a covalent bond is formed between the agent and the catalyst support, which effectively enhances the interfacial bonding strength between the catalyst core and the outer composite metal oxide mesoporous layer. This enhances the resistance of the mesoporous structure to long-term thermal cycling, acid and alkali environments, or mechanical stress, effectively preventing the catalyst structure from collapsing, clogging, or deactivating, and achieving a long cycle life for the catalyst.
[0024] Secondly, this application provides the application of a metal-supported catalyst in the preparation of high flash point insulating oil, wherein the amount of the metal-supported catalyst is 0.02-1%.
[0025] Optionally, the method for preparing the high flash point insulating oil includes the following steps:
[0026] (1) Add acid, polyol and catalyst to reaction vessel, heat and stir to react;
[0027] (2) Vacuum stripping deacidification and filtration to recover catalyst;
[0028] (3) Dehydration and degassing are used to obtain synthetic ester insulating oil.
[0029] Optionally, the polyol is at least one of trimethylolpropane and pentaerythritol.
[0030] Optionally, the acid includes an ortho-acid and an iso-acid, wherein the ortho-acid is selected from heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid, and the iso-acid is selected from isooctanoic acid.
[0031] Optionally, the molar ratio of the polyol to the acid is 1:(3.06-4.2).
[0032] Optionally, the mass ratio of the ortho-acid to the iso-acid is (4-8):(2-6).
[0033] By adopting the above technical solution, the method for preparing high flash point insulating oil based on the metal supported catalyst of this application has a simple synthesis process, significantly improved catalytic efficiency and yield, and the prepared synthetic ester insulating oil has the advantages of high flash point, low pour point and low viscosity, with excellent comprehensive performance.
[0034] In summary, this application has the following beneficial effects:
[0035] 1. This application utilizes active metals such as Fe, Co, Cu, Ni, Ti, Zr, Mn, V, and Zn to form strong active bonds with metal oxide supports such as MoO2, Al2O3, ZrO2, MgO, TiO2, and SnO2. The active metals have extremely low solubility in the esterification reaction, and a small amount can produce a highly efficient catalytic effect on the synthesis of synthetic ester insulating oil. The outer layer is coated with a composite metal oxide mesoporous layer, and the catalyst activity hardly decreases after multiple cycles, exhibiting excellent cycle stability.
[0036] 2. In this application, SiO2-ZrO2 coated sol is preferred, and a carbonizable organic carbon precursor is introduced as a mesoporous layer of composite metal oxide. A highly ordered or interconnected mesoporous composite metal oxide layer is constructed by surfactant template method, which provides a channel for rapid diffusion of reactants and products. An ultrathin amorphous carbon layer is formed inside the pores, which on the one hand effectively enhances the hydrophobicity and acid-phobicity of the catalyst and effectively protects the activity and loading stability of the active metal. On the other hand, it fills the pore wall defects of the mesoporous layer, enhances the stability of the mesoporous structure, and enhances the recycling stability of the catalyst.
[0037] 3. This application uses ammonium bifluoride solution to pretreat the support, which effectively enhances the hydrophobicity of the support and reduces the dissolution effect of water molecules on the active metal during the synthesis of ester insulating oil. In synergy with the organic amorphous carbon layer in the mesoporous layer of the composite metal oxide, it further ensures the cycle stability of the metal-supported catalyst. Detailed Implementation
[0038] The present application will be further described in detail below with reference to embodiments and comparative examples.
[0039] Example
[0040] Example 1
[0041] A metal-supported catalyst, the preparation method of which includes the following steps:
[0042] S1: Al2O3 was impregnated in 0.2 mol / L ammonium bifluoride solution for 4 h, filtered after standing, washed 3 times with deionized water, dried at 120 °C, and calcined at 500 °C for 4 h to obtain pretreated Al2O3 support.
[0043] S2: FeCl3 was dissolved in deionized water to prepare a 5% active metal precursor solution. 50g of pretreated Al2O3 support was added, and the mixture was sonicated at 300W for 20min to obtain a blend. The blend was allowed to stand at room temperature for 12h, and then dried at 100℃ for 12h to obtain solid A.
[0044] S3: Grind solid A into powder, and then calcine it at 900℃ for 3 hours to obtain solid B with Al2O3 as support and Fe loading of 50%;
[0045] S4: Solid B was dispersed in an ethanol solution with a volume ratio of 3 / 1 to 7 and an ethanol / water ratio of 1:7. After stirring, the pH was adjusted to 4±0.5 with hydrochloric acid. Then, 2.5 wt% of γ-aminopropyltriethoxysilane was added. The mixture was stirred in an oil bath at 80°C for 3 hours under nitrogen protection to obtain a suspension. After centrifugation, washing and drying, pretreated solid B was obtained.
[0046] S5: Dissolve 28 mL of tetraethyl orthosilicate in 60 mL of anhydrous ethanol, add 5 mL of deionized water and 2 mL of 0.1 M hydrochloric acid, and stir at room temperature to pre-hydrolyze to obtain a silicon source solution; dissolve 9.5 g of zirconium oxychloride in a mixture of 40 mL of anhydrous ethanol and 3 mL of acetylacetone, and stir at 60 °C to obtain a zirconium source solution; add 2 g of hexadecyltrimethylammonium bromide and 1.2 g of phenolic resin to 200 mL of anhydrous ethanol, and stir to obtain a mixture. Under stirring conditions, add the silicon source solution and zirconium source solution to the mixture, and stir to form a composite coating gel. The phenolic resin is boron-modified phenolic resin, selected from Jining Fangyu Chemical Co., Ltd., fy-03;
[0047] S6: Heat the composite coated gel in a water bath to 50°C, disperse the pretreated solid B in the composite coated gel at a material-to-liquid ratio of 1:20, stir and react for 12 hours, let it stand and age for 12 hours, filter, wash, dry at 100°C for 12 hours, grind, heat to 600°C at 5°C / min, keep at 600°C for 2 hours, then continue to heat to 800°C, keep at 800°C and calcine for 3 hours to obtain the final product.
[0048] Example 2
[0049] A metal-supported catalyst, the preparation method of which includes the following steps:
[0050] S1: Al2O3 was impregnated in 0.3 mol / L ammonium bifluoride solution for 3.5 h, filtered after standing, washed 3 times with deionized water, dried at 120 °C, and calcined at 480 °C for 5 h to obtain pretreated Al2O3 support.
[0051] S2: Dissolve Zn(NO3)2 in deionized water to prepare a 5% active metal precursor solution, add 65g of pretreated Al2O3 support, sonicate at 300W for 20min to obtain a blend, let stand at room temperature for 12h, and then dry at 100℃ for 12h to obtain solid A.
[0052] S3: Grind solid A into powder, and then calcine it at 800℃ for 5 hours to obtain solid B with Al2O3 as support and Zn loading of 35%;
[0053] S4: Solid B was dispersed in an ethanol solution with a volume ratio of ethanol / water of 3 / 1 at a material-to-liquid ratio of 1:7. After stirring, the pH was adjusted to 4±0.5 with hydrochloric acid. Then, 2.5wt% of γ-aminopropyltriethoxysilane was added. The mixture was stirred in an oil bath at 70°C for 4 hours under nitrogen protection to obtain a suspension. After centrifugation, washing and drying, pretreated solid B was obtained.
[0054] S5: Dissolve 28 mL of tetraethyl orthosilicate in 60 mL of anhydrous ethanol, add 5 mL of deionized water and 2 mL of 0.1 M hydrochloric acid, and stir at room temperature to pre-hydrolyze to obtain a silicon source solution; dissolve 9.5 g of zirconium oxychloride in a mixture of 40 mL of anhydrous ethanol and 3 mL of acetylacetone, and stir at 60 °C to obtain a zirconium source solution; add 2 g of hexadecyltrimethylammonium bromide and 1.2 g of phenolic resin to 200 mL of anhydrous ethanol, and stir to obtain a mixture. Under stirring conditions, add the silicon source solution and zirconium source solution to the mixture, and stir to form a composite coating gel. The phenolic resin is boron-modified phenolic resin, selected from Jining Fangyu Chemical Co., Ltd., fy-03;
[0055] S6: Heat the composite coated gel in a water bath to 60°C, disperse the pretreated solid B in the composite coated gel at a material-to-liquid ratio of 1:20, stir and react for 12 hours, let it stand and age for 12 hours, filter, wash, dry at 100°C for 12 hours, grind, heat to 500°C at 2°C / min, keep at that temperature for 3 hours, then continue to heat to 750°C, keep at that temperature and calcine for 4 hours to obtain the final product.
[0056] Example 3
[0057] A metal-supported catalyst, the preparation method of which includes the following steps:
[0058] S1: Al2O3 was impregnated in 0.4 mol / L ammonium bifluoride solution for 2.5 h, filtered after standing, washed 3 times with deionized water, dried at 120 °C, and calcined at 500 °C for 4.5 h to obtain pretreated Al2O3 support.
[0059] S2: Dissolve TiCl4 in deionized water to prepare a 5% active metal precursor solution, add 85g of pretreated Al2O3 support, sonicate at 300W for 20min to obtain a blend, let stand at room temperature for 12h, and then dry at 100℃ for 12h to obtain solid A.
[0060] S3: Grind solid A into powder, and then calcine it at 850℃ for 4 hours to obtain solid B with Al2O3 as support and Ti loading of 15%.
[0061] S4: Solid B was dispersed in an ethanol solution with a volume ratio of ethanol / water of 3 / 1 at a material-to-liquid ratio of 1:7. After stirring, the pH was adjusted to 4±0.5 with hydrochloric acid. Then, 2.5wt% of γ-aminopropyltriethoxysilane was added. Under nitrogen protection, the mixture was stirred in an oil bath at 80℃ for 4 hours to obtain a suspension. After centrifugation, washing and drying, pretreated solid B was obtained.
[0062] S5: Dissolve 28 mL of tetraethyl orthosilicate in 60 mL of anhydrous ethanol, add 5 mL of deionized water and 2 mL of 0.1 M hydrochloric acid, and stir at room temperature to pre-hydrolyze to obtain a silicon source solution; dissolve 9.5 g of zirconium oxychloride in a mixture of 40 mL of anhydrous ethanol and 3 mL of acetylacetone, and stir at 60 °C to obtain a zirconium source solution; add 2 g of hexadecyltrimethylammonium bromide and 1.2 g of phenolic resin to 200 mL of anhydrous ethanol, and stir to obtain a mixture. Under stirring conditions, add the silicon source solution and zirconium source solution to the mixture, and stir to form a composite coating gel. The phenolic resin is boron-modified phenolic resin, selected from Jining Fangyu Chemical Co., Ltd., fy-03;
[0063] S6: Heat the composite coated gel in a water bath to 55°C, disperse the pretreated solid B in the composite coated gel at a material-to-liquid ratio of 1:20, stir and react for 12 hours, let it stand and age for 12 hours, filter, wash, dry at 100°C for 12 hours, grind, heat to 600°C at 3°C / min, keep it at that temperature for 3 hours, then continue to heat to 750°C and keep it at that temperature for 3 hours to obtain the final product.
[0064] Example 4
[0065] A metal-supported catalyst, differing from Example 1 only in that Al2O3 is used as the support, Zn and Cu are the active metals, the loading is 50%, and the active metal precursor solution in step S2 is Zn(NO3)2 and Cu(NO3)2 in a mass ratio of 1:1.
[0066] Example 5
[0067] A metal-supported catalyst, differing from Example 1 only in that Al2O3 is used as the support, Ni and Co are the active metals with a loading of 50%, and the active metal precursor solution in step S2 is NiSO4 and CoSO4 with a mass ratio of 1:1.
[0068] Example 6
[0069] A metal-supported catalyst, differing from Example 1 only in that Al2O3 is used as the support, the active metals are Zn and Mn, the loading is 50%, and the active metal precursor solution in step S2 is Zn(NO3)2 and Mn(NO3)2 in a mass ratio of 1:1.
[0070] Example 7
[0071] A metal-supported catalyst, differing from Example 1 only in that the support is MoO2.
[0072] Example 8
[0073] A metal-supported catalyst, differing from Example 1 only in that the support is ZrO2.
[0074] Example 9
[0075] A metal-supported catalyst, differing from Example 1 only in that the support is MgO.
[0076] Example 10
[0077] A metal-supported catalyst, differing from Example 1 only in that the support is TiO2.
[0078] Example 11
[0079] A metal-supported catalyst, differing from Example 1 only in that the support is SnO2.
[0080] Example 12
[0081] A metal-supported catalyst, differing from Example 1 only in that the Al2O3 support was not pretreated with ammonium bifluoride solution in step S1.
[0082] Comparative Example
[0083] Comparative Example 1
[0084] A metal-supported catalyst, differing from Example 1 in that steps S5-S6 specifically include the following steps:
[0085] S5: Dissolve 28 mL of tetraethyl orthosilicate in 60 mL of anhydrous ethanol, add 5 mL of deionized water and 2 mL of 0.1 M hydrochloric acid, and stir at room temperature to pre-hydrolyze to obtain a silicon source solution; dissolve 9.5 g of zirconium oxychloride in a mixture of 40 mL of anhydrous ethanol and 3 mL of acetylacetone, and stir at 60 °C to obtain a zirconium source solution; add 1.2 g of phenolic resin to 200 mL of anhydrous ethanol, and stir to obtain a mixture. Under stirring conditions, add the silicon source solution and zirconium source solution to the mixture, and stir to form a composite coating gel;
[0086] S6: Heat the composite coated gel in a water bath to 50°C, disperse the pretreated solid B in the composite coated gel at a material-to-liquid ratio of 1:20, stir and react for 12 hours, let it stand and age for 12 hours, filter, wash, dry at 100°C for 12 hours, grind, heat to 800°C at 5°C / min, and calcine for 5 hours to obtain the final product.
[0087] Comparative Example 2
[0088] A metal-supported catalyst, differing from Example 1 in that steps S5-S6 specifically include the following steps:
[0089] S5: Dissolve 28 mL of tetraethyl orthosilicate in 60 mL of anhydrous ethanol, add 5 mL of deionized water and 2 mL of 0.1 M hydrochloric acid, and stir at room temperature to pre-hydrolyze to obtain a silicon source solution; dissolve 9.5 g of zirconium oxychloride in a mixture of 40 mL of anhydrous ethanol and 3 mL of acetylacetone, and stir at 60 °C to obtain a zirconium source solution; add 2 g of hexadecyltrimethylammonium bromide to 200 mL of anhydrous ethanol, and stir to obtain a mixture. Under stirring conditions, add the silicon source solution and zirconium source solution to the mixture, and stir to form a composite coating gel;
[0090] S6: Heat the composite coated gel in a water bath to 50°C, disperse the pretreated solid B in the composite coated gel at a material-to-liquid ratio of 1:20, stir and react for 12 hours, let it stand and age for 12 hours, filter, wash, dry at 100°C for 12 hours, grind, heat to 600°C at 5°C / min, keep at 600°C for 2 hours, then continue to heat to 800°C, keep at 800°C and calcine for 3 hours to obtain the final product.
[0091] Comparative Example 3
[0092] A metal-supported catalyst, differing from Example 1 in that steps S5-S6 specifically include the following steps:
[0093] S5: Add 4g of lanthanum nitrate to water to prepare a 3wt% solution, add 4g of zirconium oxychloride to water to prepare a 3wt% solution, mix well to obtain a composite oxide precursor solution;
[0094] S6: Disperse the pretreated solid B in the composite oxide precursor solution at a material-to-liquid ratio of 1:20, impregnate for 4 hours, let stand for aging for 12 hours, filter, wash, dry at 100℃ for 12 hours, grind into powder, heat to 800℃ at 5℃ / min, and calcine for 5 hours to obtain the final product.
[0095] Application examples
[0096] Application Example 1
[0097] A high flash point insulating oil, the preparation method of which includes the following steps:
[0098] (1) Pentaerythritol, heptanoic acid, decanoic acid, isooctanoic acid, and the metal-supported catalyst prepared in Example 1 were added to a reaction vessel, stirred, and heated to 220°C for 20 h. The molar ratio of alcohol to acid was 1:4.2, the mass ratio of heptanoic acid, decanoic acid, and isooctanoic acid was 5:2:3, and the amount of metal-supported catalyst was 0.02%.
[0099] (2) After the reaction is complete, nitrogen gas is introduced, vacuum is turned on, 220°C is maintained, nitrogen flow rate is adjusted, vacuum degree is maintained at 500-800 Pa, deacidification is carried out under reduced pressure for 12 hours, and after the depressurization is completed, the temperature is lowered, filtered, and the metal supported catalyst is recovered.
[0100] (3) Place the filtered clear oil in a clean flask and dehydrate and degas it at 70°C for 2 hours to obtain the final product.
[0101] Application Example 2-12
[0102] A high flash point insulating oil, the only difference between Application Example 2-12 and Application Example 1 is that the metal-supported catalyst used in its preparation method is prepared by Example 2-12.
[0103] Comparative application examples
[0104] Comparative Application Examples 1-3
[0105] A high flash point insulating oil, the only difference between Comparative Application Examples 1-3 and Application Example 1 is that the metal-supported catalyst used in its preparation method is prepared by Comparative Examples 1-3 respectively.
[0106] Performance testing
[0107] Test Example 1: Activity Test of Metal-Supported Catalysts
[0108] For the corresponding use case 1-12 and comparative application example 1-3, (1) samples were taken before and after the reaction, the acid value was determined by acid-base titration, and the esterification rate of the insulating oil preparation reaction was calculated. The kinematic viscosity (GB / T 265), flash point (GB / T 3536) and pour point (GB / T 3535) of the insulating oil obtained in use case 1-12 and comparative application example 1-3 were tested. Each group of tests was performed 3 times, and the average value of the 3 test results was taken as the final result and recorded in Table 1.
[0109] Table 1
[0110]
[0111] As shown in Table 1, the performance test results demonstrate that this application utilizes active metals such as Fe, Co, Cu, Ni, Ti, Zr, Mn, V, and Zn supported on metal oxide supports of MoO2, Al2O3, ZrO2, MgO, TiO2, and SnO2, followed by coating with a composite oxide mesoporous layer of SiO2-ZrO2 with an amorphous carbon structure. A relatively small amount of catalyst (0.2%) is sufficient to produce highly efficient catalytic activity in the preparation of synthetic ester insulating oil. The prepared synthetic ester insulating oil exhibits advantages such as low viscosity, high flash point, and low pour point, with a kinematic viscosity range of 28.5-30.2 (40℃) / mm. 2 ·s -1 It has an ignition point of 306-314℃ and a pour point of -55 to -45℃.
[0112] Test Example 2: Cyclic Stability Test of Metal-Supported Catalyst
[0113] The metal-supported catalysts recovered by filtration during the preparation of high-flash-point insulating oil in Application Examples 1-12 and Comparative Application Examples 1-3 were reused in the reaction of pentaerythritol, heptanoic acid, decanoic acid, and isooctanoic acid to prepare insulating oil. The application method was the same, and a cyclic test was conducted using this method. The reaction conditions and the yield test method for the catalytic products were the same as the activity test method. The yield after 20 hours of cyclic reaction was recorded. The standard for recycling was that the difference between the yield after 20 hours of the first reaction and the yield after 20 hours of cyclic use was <5%. The maximum number of times each group of metal-supported catalysts could be recycled was recorded.
[0114] Table 2
[0115]
[0116] In Table 2, " / " indicates that the product does not meet the recycling standard and will no longer be tested for recycling.
[0117] As can be seen from the performance test results in Table 2, this application uses SiO2-ZrO2 to coat the sol and introduces a carbonizable organic carbon precursor as a mesoporous layer of the composite metal oxide. A highly ordered or interconnected mesoporous composite metal oxide layer is constructed by the surfactant template method. Compared with the group coated with La2O3 and ZrO2 composite metal oxide layers, the metal-supported catalyst is usable from 11 cycles to more than 16 cycles, and the cycle stability of the catalyst is significantly improved. Moreover, the prepared insulating oil has excellent performance.
[0118] In Comparative Example 1, the composite metal oxide layer of the metal-supported catalyst lacks a mesoporous structure. This results in decreased esterification efficiency and reduced catalyst cycle stability. Because of the lack of a mesoporous structure, the composite metal oxide layer can only prevent the dissolution of the active metal and enhance the catalyst's chemical stability by forming a dense or disordered physical barrier layer. However, the composite metal oxide mesoporous layer used in this application possesses strong hydrophobicity, protecting the catalyst's active metal from dissolution during the reaction. With the mesoporous structure optimizing mass transfer efficiency, it avoids catalyst activity degradation due to localized encapsulation or physical blockage of active sites by reactants. Furthermore, the formation of an ultrathin amorphous carbon layer endows the catalyst with stronger resistance to mechanical / thermal shock, enhancing the overall structural stability of the catalyst.
[0119] In Comparative Example 2, the composite metal oxide mesoporous layer of the metal-supported catalyst does not have an amorphous carbon layer. It can be seen that the catalyst cycle count decreases and the catalyst stability decreases. This is because the ultrathin carbon layer can effectively enhance the hydrophobicity and acid-phobicity of the catalyst, thereby protecting the activity and loading stability of the active metal. On the other hand, it also fills the pore wall defects of the mesoporous layer, enhancing the stability of the mesoporous structure, thereby enhancing the catalyst's cycle stability.
[0120] Only by introducing a carbonizable organic carbon precursor while preparing a composite metal oxide layer with a mesoporous structure, and then carbonizing it in the pores during the subsequent calcination process to form an ultrathin amorphous carbon layer, can the metal-loaded oxide achieve the best stability retention effect.
[0121] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A metal-supported catalyst, characterized in that, The device includes a support, an active metal supported on the support, and a composite metal oxide mesoporous layer. The support is a metal oxide selected from at least one of MoO2, Al2O3, ZrO2, MgO, TiO2, and SnO2. The active metal is a transition metal selected from at least one of Fe, Co, Cu, Ni, Ti, Zr, Mn, V, and Zn. The raw materials for the composite metal oxide mesoporous layer include SiO2, ZrO2, and a carbon precursor.
2. The metal-supported catalyst according to claim 1, characterized in that, The loading of the active metal is 15-50% of the mass of the carrier.
3. The metal-supported catalyst according to claim 1, characterized in that, The carbon precursor is selected from phenolic resin.
4. The method for preparing the metal-supported catalyst according to any one of claims 1-3, characterized in that, Includes the following steps: S1: The carrier is mixed with a precursor solution of an active metal, and the mixture is sonicated to obtain a blend. After standing at room temperature, the blend is dried to obtain solid A. S2: Calcine the solid A at 800-900℃ for 3-5 hours to obtain solid B; S3: Tetraethyl orthosilicate is added to ethanol, water and catalyst are added, and the mixture is stirred for pre-hydrolysis to obtain silicon source solution; zirconium oxychloride is added to a mixed solution of ethanol and acetylacetone to obtain zirconium source solution; hexadecyltrimethylammonium bromide and carbon precursor are added to ethanol to obtain a mixed solution, and then the zirconium source solution and silicon source solution are added dropwise to the mixed solution under stirring to form a composite coated sol; S4: Disperse the solid B in the composite coated gel, stir and react at 50-60℃, let stand, wash, dry, grind, then heat to 500-600℃ at 2-5℃ / min, keep warm for 2-3h, then continue to heat to 750-800℃, keep warm for 3-4h, and the product is obtained.
5. The method for preparing the metal-supported catalyst according to claim 4, characterized in that, The carrier described in step S1 undergoes the following pretreatment before being mixed with the precursor solution of the active metal: The carrier was impregnated in a 0.2-0.4 mol / L ammonium bifluoride solution, then washed with deionized water, dried, and calcined at 480-500℃ for 4-5 hours to obtain a pretreated carrier.
6. The method for preparing the metal-supported catalyst according to claim 4, characterized in that, Before adding the composite coating gel, the solid B described in step S4 undergoes the following pretreatment: The solid B was dispersed in an aqueous ethanol solution, the pH was adjusted, and then an aminosilane coupling agent was added. Under nitrogen protection, the mixture was stirred in an oil bath at 70-80°C to obtain a suspension. After centrifugation, washing, and drying, the pretreated solid B was obtained.
7. The application of the metal-supported catalyst according to any one of claims 1-3 or the metal-supported catalyst prepared by the preparation method according to any one of claims 4-6 in the preparation of high flash point insulating oil, characterized in that, The amount of the metal-supported catalyst used is 0.02-1%.
8. The application according to claim 7, characterized in that, The method for preparing the high flash point insulating oil includes the following steps: (1) Add acid, polyol and catalyst to reaction vessel, heat and stir to react; (2) Vacuum stripping deacidification and filtration to recover catalyst; (3) Dehydration and degassing are used to obtain synthetic ester insulating oil.