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CN-121988309-A - Solid base catalyst and preparation method and application thereof

CN121988309ACN 121988309 ACN121988309 ACN 121988309ACN-121988309-A

Abstract

The invention discloses a solid base catalyst, a preparation method and application thereof, and relates to the technical field of catalysts. The solid base catalyst provided by the invention comprises a gamma crystal form alumina carrier with an average pore diameter of 8-12 nm and active component cesium loaded on the carrier, and the pore volume of the whole catalyst is 0.1-0.45 cc/g. In the catalyst, cs species can occupy Lewis acidic sites on the surface of a gamma-crystal alumina carrier and form strong alkaline sites with Al and O, so that the cleavage of silicon rubber from Si-O bonds of a main chain can be promoted when the silicon rubber is catalytically cured, the cleavage rate of the silicon rubber and the DMC (siloxane ring body) in the product, especially the high-value D4, are improved, and meanwhile, the catalyst has stable structure and longer service life.

Inventors

  • PENG XIANGYANG
  • FAN YAZHOU
  • WANG ZHENG
  • LIU LIN
  • WU JI
  • QIAN YIHUA
  • HUANG DENGCHENG
  • YU XIN
  • WANG CHUNJIE

Assignees

  • 广东电网有限责任公司电力科学研究院
  • 广东电网有限责任公司汕尾供电局

Dates

Publication Date
20260508
Application Date
20260402

Claims (10)

  1. 1. The solid base catalyst is characterized by comprising a carrier and an active component supported on the carrier, wherein the carrier comprises gamma-crystal alumina with an average pore diameter of 8-12 nm, the active component comprises cesium, and the pore volume of the solid base catalyst is 0.1-0.45 cc/g.
  2. 2. The solid base catalyst of claim 1, wherein the solid base catalyst has a pore volume of 0.2 to 0.3 cc/g; and/or the loading of the active component on the carrier is 20-40 wt%.
  3. 3. The solid base catalyst according to claim 1 or 2, characterized in that the specific surface area of the solid base catalyst is 60-150 m 2 /g, preferably the specific surface area of the solid base catalyst is 95-120 m 2 /g.
  4. 4. A solid base catalyst according to claim 3, wherein the gamma crystalline form of alumina has a particle size of 0.3 to 0.6 mm.
  5. 5. The method for preparing a solid base catalyst according to any one of claims 1 to 4, comprising the steps of: Mixing cesium source and gamma-crystal alumina uniformly under the condition of solution, impregnating and loading 1-3 h, drying and calcining to obtain the product.
  6. 6. The method for preparing the solid base catalyst according to claim 5, wherein the method for preparing the gamma-alumina comprises the following steps: s1, dispersing pseudo-boehmite into water to prepare alumina sol, and dropwise adding a nitric acid solution into the alumina sol under the stirring condition to make the alumina sol sticky until a magnet cannot be stirred to obtain sticky sol; S2, uniformly mixing a template agent with the tetrahydroxy aluminate solution, then injecting an oil phase, and standing to obtain a phase-separated oil-water mixture, wherein the upper layer of the oil-water mixture is an oil phase, and the lower layer of the oil-water mixture is a water phase; S3, instilling the tacky sol obtained in the step S1 into the oil-water mixture obtained in the step S2 to obtain alumina gel spheres, then removing an upper oil phase of the oil-water compound, sequentially aging, crystallizing and calcining the alumina gel spheres under the condition that a lower water phase exists, and thus obtaining the gamma-crystal alumina.
  7. 7. The method for preparing a solid base catalyst according to claim 6, wherein the method for preparing gamma-alumina comprises at least one of the following (a) to (j): (a) The dispersing in the step S1 comprises stirring and standing, wherein the stirring speed is 100-150 rpm, the time is 10-15 h, and the standing time is 20-30 h; (b) The rotation speed of the stirring condition in the step S1 is 200-300 rpm; (c) The concentration of the nitric acid solution in the step S1 is 65-68 wt%, and the mass ratio of the nitric acid solution to the pseudo-boehmite is (0.0303-0.048): 1; (d) Step S2, the template agent comprises cetyl trimethyl ammonium bromide; (e) The tetrahydroxy aluminate solution in the step S2 is prepared by uniformly mixing sodium hydroxide and sodium metaaluminate with the mass ratio of (0.8-1.2) in water, wherein the concentration of the sodium hydroxide in the water is 50-150 g/L; (f) The oil phase in the step S2 comprises kerosene; (g) The instillation speed in the step S3 is 200-400 drops/min; (h) The aging temperature in the step S3 is 30-60 ℃ and the time is 4-8 h; (i) The crystallization temperature in the step S3 is 80-120 ℃ and the time is 20-30 h; (j) The calcination temperature in the step S3 is 550-800 ℃ and the time is 1-5 h.
  8. 8. The method for preparing a solid base catalyst according to claim 7, wherein the method for preparing gamma-crystalline form of alumina comprises at least one of the following (k) - (l): (k) The height of the upper oil phase of the oil-water mixture in the step S2 is 1-1.5 cm, and the height of the lower water phase is 5-7 cm; (l) The instillation in step S3 is performed by using a needle with a diameter of 0.2-0.5 mm, and the height of the needle from the liquid level is 10-30 cm.
  9. 9. Use of the solid base catalyst of any one of claims 1-4 for catalytic degradation of silicone rubber umbrella sleeves in retired composite insulators.
  10. 10. A method for catalyzing degradation of cured silicone rubber, comprising the steps of: mixing the solid base catalyst according to any one of claims 1-4 and the cured silicone rubber according to the mass ratio of (1-1.5): 1, and carrying out catalytic degradation at 400-600 ℃ for 0.1-1 h.

Description

Solid base catalyst and preparation method and application thereof Technical Field The invention relates to the technical field of catalysts, in particular to a solid base catalyst and a preparation method and application thereof. Background The composite insulator is widely applied to power transmission networks by virtue of excellent insulating property, ageing resistance, corrosion resistance and good pollution flashover resistance. However, the service life of most composite insulators is only 15-20 years, and as the service time is increased, how to recover and process retired composite insulators becomes an urgent technical problem. The silicone rubber umbrella cover is a key component for realizing insulation of the composite insulator and has an electric field regulation function, and is mainly prepared by vulcanizing and crosslinking preparation raw materials such as methyl vinyl silicone rubber raw rubber, reinforcing filler, vulcanizing agent, modified additive and the like, and has stable chemical property in natural environment and extremely difficult degradation, so that the silicone rubber umbrella cover is required to be processed before recycling. At present, the recycling utilization of the waste umbrella cover silicon rubber material mainly comprises four modes, namely an energy recovery method, a biological recovery method, a physical recovery method and a chemical recovery method. The method is characterized in that an energy recovery method and a biological recovery method are adopted to recover the retired composite insulator, the obtained effects are not ideal, the physical recovery method is mainly to crush and graded screen the retired umbrella cover and then directly carry out secondary utilization, the chemical structure of the silicon rubber and filler components in the silicon rubber are not changed, but the economic value of preparing a new product is generally low, the chemical recovery method is mainly a chemical cracking method, namely the silicon rubber is decomposed into DMC (Dimethylcyclosiloxane, dimethyl cyclosiloxane mixture) under specific conditions, and meanwhile, the filler filled in the umbrella cover is separated, so that the chemical structure of the silicon rubber is changed. Compared with the physical recovery method, the chemical recovery method has higher economic value for recovering the product. However, the DMC obtained by recycling the umbrella cover through the chemical cracking method comprises four products, namely D3 (hexamethyl cyclotrisiloxane), D4 (octamethyl cyclotetrasiloxane), D5 (decamethyl cyclopentasiloxane) and D6 (decamethyl cyclopentasiloxane), wherein D3 has excessive ring tension and is not easy to store and transport, D5 and D6 have small ring tension and reduced reactivity, D4 is the only product which has the reactivity and easy storage property, and D4 is the DMC variety which is the best balance among performance, safety and economy when the silicone rubber polymerized monomer is produced in a large-scale industrial manner. The prior art generally only focuses on the yield of DMC, does not focus on the selectivity of D4 in DMC, and leads to the reduction of the recycling value of the silicone rubber umbrella cover, and meanwhile, the degradation activity of the prior art on the silicone rubber umbrella cover still needs to be improved. In view of this, it is desirable to provide a method that can fully degrade a waste silicone rubber umbrella cover into a D4 silicone ring. Disclosure of Invention In order to solve the defects in the prior art, the invention provides a solid base catalyst, and a preparation method and application thereof. The above object of the present invention is achieved by the following technical scheme: A solid base catalyst comprises a carrier and an active component supported on the carrier, wherein the carrier comprises gamma-crystal alumina with an average pore diameter of 8-12 nm, the active component comprises cesium, and the pore volume of the solid base catalyst is 0.1-0.45 cc/g. The solid base catalyst provided by the application can occupy and neutralize Lewis acidic sites on the surface of gamma-crystal alumina carrier, so as to form a catalytic active site with strong basicity. Meanwhile, oxygen atoms (O 2-) and aluminum atoms (Al 3+) on the surface of the alumina carrier can have strong interaction with Cs species, wherein Cs have extremely low binding energy of 6s orbit electrons and extremely strong ionization tendency, and electrons are easy to lose to form Cs + ions. Cs + and the carrier surface O 2- form a Cs-O structure through strong electrostatic and ionic bond interaction, and meanwhile, cs + can be bridged on the [ Al-O ] units on the carrier surface to form a Cs-O-Al bridging structure. The Cs-O structure can be regarded as Lewis basic sites capable of providing lone pair electrons, and O in the Cs-O-Al bridging structure can be expressed as Bronsted basic sites due to the increa