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CN-121972175-A - Magnetic easy-to-separate Fe3O4-SnO-SiO2Composite catalyst, preparation and application thereof

CN121972175ACN 121972175 ACN121972175 ACN 121972175ACN-121972175-A

Abstract

The invention discloses a magnetic easy-to-separate Fe 3 O 4 -SnO-SiO 2 composite catalyst and preparation and application thereof, wherein the composite catalyst is of a three-layer core-shell structure of a core, a middle layer and a shell layer, the shell comprises a coating layer, the core comprises a magnetic core, the middle layer comprises an active layer, the active layer is uniformly adsorbed on the surface of the magnetic core, the magnetic core is Fe 3 O 4 , the active layer is any one or more than two of SnO, zrO 2 and TiO 2 , and the coating layer is SiO 2 and is coated on the outer side of the active layer. The invention solves the problems that the prior art cannot synchronously solve the problems of high-efficiency catalysis, convenient magnetic separation, long-acting circulation stability and accurate regulation and control of a product structure. The conversion rate of the catalyst for catalytic synthesis of the trimethylolpropane trioleate reaches 94.32%, the friction coefficient of the product is stabilized at 0.09-0.10, the abrasion volume is reduced by more than 68%, and the magnetic separation recovery rate is 98%.

Inventors

  • LIU JUNMING
  • LAI BINGBING
  • ZHAO GAIQING
  • WANG XIAOBO
  • ZHAO QIN

Assignees

  • 中国科学院兰州化学物理研究所

Dates

Publication Date
20260505
Application Date
20260120

Claims (10)

  1. 1. A magnetic easy-to-separate Fe 3 O 4 -SnO-SiO 2 composite catalyst is characterized in that the composite catalyst has a three-layer core-shell structure of a core-middle layer-shell layer; wherein the shell comprises a cladding layer, the core comprises a magnetic core, the intermediate layer comprises an active layer, and the active layer is uniformly adsorbed on the surface of the magnetic core; The magnetic core is Fe 3 O 4 ; The active layer is any one or more than two of SnO, zrO 2 and TiO 2 ; the coating layer is SiO 2 and is coated on the outer side of the active layer to form a complete core-shell structure.
  2. 2. The composite catalyst according to claim 1, wherein the particle diameter of the magnetic core is 50nm, and the thickness of the coating layer is 15 nm-50 nm.
  3. 3. The composite catalyst according to claim 1, wherein the loading of the active layer is 50% -70% of the mass of the magnetic core, the active layer is SnO, and positive tetravalent tin ions 4+ lewis acid sites are provided.
  4. 4. The composite catalyst according to claim 3, wherein the active layer is anchored on the surface of the Fe 3 O 4 magnetic core by an oleic acid surface modifier, and the SiO 2 is formed by hydrolysis condensation of tetraethyl orthosilicate or a silane coupling agent under alkaline conditions.
  5. 5. A method for preparing the magnetic easy-to-separate Fe 3 O 4 -SnO-SiO 2 composite catalyst according to any one of claims 1 to 3, comprising: (1) Adding Fe 3 O 4 powder into absolute ethyl alcohol, performing ultrasonic dispersion, adding a dispersing agent, and stirring to form a suspension; (2) Adding SnO powder and trimethylolpropane into the suspension, heating to 40-60 ℃, stirring, and slowly dripping oleic acid to obtain a loaded SnO system; (3) Slowly dripping SiO 2 coating layer precursor into a load SnO system, adjusting the pH of the system to 9-10, and heating to 60-80 ℃ for reaction; (4) After the reaction is finished, the product is collected through magnetic separation, and the magnetic easy-to-separate Fe 3 O 4 -SnO-SiO 2 composite catalyst is obtained through washing and freeze drying.
  6. 6. The method of claim 5, wherein in step (1), the dispersant is polyvinylpyrrolidone; the ultrasonic power is 280-320W, the time is 10-20 minutes, and the mass of the dispersing agent is 15-25% of the mass of Fe 3 O 4 .
  7. 7. The preparation method of claim 5, wherein in the step (2), the stirring time is 25-35 minutes, the mass ratio of SnO to Fe 3 O 4 is (0.5-0.7) to 1, the dosage ratio of SnO to oleic acid is (0.5-0.7) g to (0.4-0.6) mL, and in the step (3), the precursor of the SiO 2 coating is tetraethyl orthosilicate or a silane coupling agent.
  8. 8. A method for synthesizing trimethylolpropane trioleate by using the magnetic easy-to-separate Fe 3 O 4 -SnO-SiO 2 composite catalyst according to any one of claims 1-3, which is characterized by comprising the steps of heating and melting trimethylolpropane, adding oleic acid and the magnetic easy-to-separate Fe 3 O 4 -SnO-SiO 2 composite catalyst, reacting at 180-220 ℃, cooling after the reaction, recovering the catalyst by magnetic separation, and collecting the trimethylolpropane trioleate.
  9. 9. The method of claim 8, wherein the mass ratio of the trimethylolpropane to the oleic acid is 1:2.5-3.5, the magnetic easy-to-separate Fe 3 O 4 -SnO-SiO 2 composite catalyst is 8-12% of the trimethylolpropane in mass, the magnetic separation has a magnetic field strength of 0.4-0.6 tesla and a separation time of 3-8 minutes.
  10. 10. An application of the magnetic easy-to-separate Fe 3 O 4 -SnO-SiO 2 composite catalyst according to any one of claims 1-3 in synthesizing trimethylolpropane trioleate.

Description

Magnetic easy-to-separate Fe 3O4-SnO-SiO2 composite catalyst and preparation and application thereof Technical Field The invention relates to a preparation method of a catalyst for synthesizing trimethylolpropane trioleate, in particular to a magnetic easy-to-separate Fe 3O4-SnO-SiO2 composite catalyst and preparation and application thereof. Background Trimethylolpropane trioleate (TMPTO) as high-end lubricating oil, the industrial synthesis of the core base oil of aviation hydraulic oil depends on esterification reaction of Trimethylolpropane (TMP) and Oleic Acid (OA), the existing literature 1（Su H G, Zhao Q, Jiang C, et al. Preparation of highly dispersed SnO/TiO2catalysts and their performances in catalyzing polyol ester[J]. RSC Advances,2023[J]. https://doi.org/10.1039/d2ra07334j） adopts an immersion method to prepare a SnO/TiO 2 catalyst, stannous chloride or stannous oxalate is used as a tin source, tin loading and roasting conditions are optimized, the core base oil is used for catalyzing esterification reaction of the trimethylolpropane and the n-octanoic acid, and esterification conversion rate is improved through Lewis acid sites provided by Sn species. Document 2 (Lu Feiyan. Construction of Fe 3O4@SiO2@Sn-TiO2 composite photocatalyst and research on catalytic degradation of tetracycline hydrochloride [ D ]. University of Guangxi, 2020.DOI:10.27034/d.cnki. Ggxiu. 2020.001841) constructed a catalyst comprising Fe 3O4 as a magnetic core and SiO 2 as an intermediate layer, the Sn-doped TiO 2 is a ternary core-shell structure of an outer shell and is used for photocatalysis. the core defect existing in the prior art is that the integrated design of the multifunctional synergy of the catalyst cannot be realized. Document 1 (SnO/TiO 2) has reached a high level of 99.6% (160 ℃ and 5 hours) in esterification conversion, but its nonmagnetic carrier has to rely on time-consuming and labor-consuming centrifugation or filtration separation after reaction, and has low efficiency and serious catalyst recovery loss, and at the same time, the TiO 2 carrier lacks an effective coating design, so that active Sn species are easy to fall off in circulation, and stability is limited (only 6 times of verification). Although document 2 (Fe 3O4@SiO2@Sn-TiO2) has a core-shell structure and magnetic separation potential, the active component Sn-TiO 2 is specially designed for photocatalytic degradation reaction, the property of an active site is not matched with the function of a Lewis acid center required by esterification reaction, and the synthesis of TMPTO is expected to be difficult to catalyze efficiently. Meanwhile, the structure is designed for adapting to photocatalysis requirements, long-term structural stability in a high-temperature esterification reaction environment is doubtful, and the research target does not relate to molecular structure regulation of a product, and the requirement of high-quality TMPTO synthesis cannot be met. In addition to the closest prior art, the traditional homogeneous acid catalytic system (such as concentrated sulfuric acid and p-toluenesulfonic acid catalysis) can realize esterification reaction, but has the environmental protection and cost problems of serious equipment corrosion, high-salt wastewater generated by post-treatment of products, unrecoverable catalyst and the like, the traditional heterogeneous catalytic system (such as molecular sieve and single metal oxide catalysis) solves the equipment corrosion problem, but still relies on low-efficiency separation modes such as centrifugation, filtration and the like, active sites are easy to agglomerate and lose, and the traditional magnetic catalyst system is mostly loaded with active components by single Fe 3O4 and has the defects of uneven dispersion of the active components, poor magnetic and catalytic activity cooperativity, insufficient circulation stability and the like. In summary, the prior art fails to realize the multi-functional coordination of "high-efficiency catalysis-convenient magnetic separation-long-acting circulation stabilization-accurate regulation of product structure", and fails to synchronously solve four key problems of catalysis efficiency, separation cost, circulation stability and product quality in TMPTO synthesis process, which restricts the green industrial production of high-performance TMPTO, and is also a core technology pain point to be solved urgently. Disclosure of Invention The invention aims to provide a magnetic easy-to-separate Fe 3O4-SnO-SiO2 composite catalyst and preparation and application thereof, which solve the problems that the prior art cannot synchronously solve the problems of high-efficiency catalysis, convenient magnetic separation, long-acting circulation stability and accurate regulation and control of a product structure, the prepared Fe 3O4-SnO-SiO2 core-shell catalyst is synthesized into TMPTO through positive tetravalent tin ion site accurate catalysis,