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CN-121988321-A - Method for preparing ethylbenzene by catalytic hydrogenolysis of polystyrene mediated by alcohol and catalyst thereof

CN121988321ACN 121988321 ACN121988321 ACN 121988321ACN-121988321-A

Abstract

The invention discloses a method for preparing ethylbenzene by catalytic hydrogenolysis of polystyrene mediated by alcohol and a catalyst thereof. Comprises mixing copper salt solution with alkaline oxide dispersion liquid, adding alkaline precipitant dropwise under heating to adjust pH to 4-10, centrifuging, washing, drying and calcining to obtain the catalyst. The catalytic hydrogenolysis method comprises adding polystyrene, catalyst and alcohol into a reactor, and reacting at 300-500 deg.C under inert atmosphere for 1-24 h to obtain ethylbenzene. The invention has the core that alcohol is used as a reaction medium and an in-situ hydrogen source, the hydrogenolysis reaction of polystyrene is realized under the catalysis, the dependence on high-risk and high-pressure external hydrogen supply in the traditional process is avoided, and the process safety is obviously improved. The preparation process is simple, the cost is low, and the recycling is easy. By using the method, the light aromatic hydrocarbon yield can reach more than 70 percent, the ethylbenzene yield can reach more than 42 percent, and a novel and efficient solution is provided for the safe and high-valued recovery of polystyrene waste.

Inventors

  • ZHOU XIANTAI
  • LI HUILIN
  • WEI XINCHENG
  • XUE CAN
  • WANG HUI

Assignees

  • 中山大学

Dates

Publication Date
20260508
Application Date
20260205

Claims (10)

  1. 1. A copper-based catalyst for catalytic hydrogenolysis of polystyrene, characterized in that it consists of a copper species supported on a basic oxide support, prepared by the process comprising the steps of: S1, adding copper salt into deionized water, and uniformly stirring at 25-90 ℃ to obtain a solution A, dispersing alkaline oxide into the deionized water to obtain a suspension B, adding sodium salt into the deionized water, and stirring to obtain a solution C; s2, mixing the solution A and the suspension B, and dropwise adding the solution C into the mixture under the conditions of 25-90 ℃ and stirring until the pH value of the system is 4-10 to obtain mixed slurry D; And S3, after the reaction is finished, centrifuging, solid-liquid separating, washing and drying the mixed slurry D to obtain a catalyst precursor, and calcining for 2-8 hours in an air atmosphere at 200-500 ℃ to obtain the copper-based catalyst.
  2. 2. The method for preparing the copper-based catalyst according to claim 1, wherein in the step S1, the liquid-solid ratio of deionized water to copper salt in the solution A is (100-500): 1 mL/g, the mass ratio of copper salt to alkaline oxide is (0.25-1): 1, and the liquid-solid ratio of deionized water to sodium salt in the solution C is (10-30): 1 mL/g.
  3. 3. The method for preparing a copper-based catalyst according to claim 1, wherein in the step S1, the copper salt is at least one selected from copper acetate, copper nitrate, copper chloride and copper sulfate, the basic oxide is at least one selected from zirconium oxide, cerium oxide, lanthanum oxide and molybdenum oxide, and the sodium salt is at least one selected from sodium carbonate, sodium sulfate, sodium chloride and sodium bicarbonate.
  4. 4. The method for preparing a copper-based catalyst according to claim 1, wherein in the step S3, the calcination temperature is 300 to 500 ℃ and the calcination time is 2 to 8 hours.
  5. 5. A process for the preparation of ethylbenzene by alcohol-mediated catalytic hydrogenolysis of polystyrene, characterized in that a copper-based catalyst according to any one of claims 1-4 is used, comprising the following steps: And (3) placing polystyrene, the copper-based catalyst and alcohol in a pressure-resistant reaction kettle together, and reacting for 3-24 hours at 300-450 ℃ after air in the reaction kettle is replaced by inert atmosphere to obtain the product ethylbenzene.
  6. 6. The method of claim 5, wherein the alcohol is a C2-C6 aliphatic or cycloaliphatic alcohol, preferably at least one of ethanol, ethylene glycol, isopropanol or cyclohexanol.
  7. 7. The method of claim 5, wherein the inert atmosphere is a nitrogen or argon atmosphere and the initial pressure of the reaction system is 0.1-2 MPa.
  8. 8. The method according to claim 5, wherein the mass ratio of the alcohol to the polystyrene is (2-20): 1, and the mass ratio of the copper-based catalyst to the polystyrene is (0.2-3): 1.
  9. 9. The method of claim 5, wherein the reaction temperature is 360-410 ℃ and the reaction time is 4-24 hours.
  10. 10. The method of claim 5, further comprising separating and recovering the copper-based catalyst after the reaction is completed, and using it for the next batch reaction directly or after regeneration.

Description

Method for preparing ethylbenzene by catalytic hydrogenolysis of polystyrene mediated by alcohol and catalyst thereof Technical Field The invention relates to the technical field of catalyst preparation and plastic recycling, in particular to a copper-based catalyst for catalytic hydrogenolysis of polystyrene, a preparation method thereof and a method for preparing ethylbenzene by catalytic hydrogenolysis of polystyrene under the mediation of alcohol without external hydrogen supply. Background Polystyrene (PS) is one of the general plastics with huge yield, and has stable chemical properties and difficult natural degradation. Traditional recycling methods of polystyrene include incineration, landfill and mechanical recycling. However, in the incineration or landfill process, the natural environment is polluted, which not only causes resource waste, but also causes secondary pollution. Therefore, the development of a chemical recovery technology of polystyrene waste, which can be efficiently converted into high-value basic chemicals such as styrene, ethylbenzene and the like, is a key path for realizing plastic recycling economy. Currently, the routes for catalytic conversion of polystyrene to chemicals are largely divided into catalytic cracking and catalytic hydrogenolysis. However, these prior art techniques generally suffer from the limitations of complex processes, poor selectivity, or high safety requirements. In the catalytic cleavage pathway, the technical core is to cleave the long chain of polystyrene by catalysis to obtain styrene monomer. For example, chinese patent No. 117185890a discloses a method for producing styrene and ethylbenzene by thermal cracking waste polystyrene in a semi-batch or continuous manner in a steam environment, and although the use of an organic solvent is avoided, steam has a corrosive effect on reaction equipment at a high temperature, and equipment maintenance cost is high. The patent CN111100325A discloses a method for cracking waste polystyrene at high temperature by microwaves, which is characterized in that the waste polystyrene is contacted with a porous composite material, and a microwave field is applied to quickly reach high temperature, so that the waste polystyrene is cracked, and the polystyrene can be quickly recovered in a short time. However, the method has high energy consumption and large catalyst consumption, and is unfavorable for large-scale application. The common problem of the catalytic cracking technology is that the reaction process lacks active intervention of active hydrogen and random cleavage of C-C bonds mainly occurs, so that the product distribution is wider, and the selectivity of high-added-value products such as ethylbenzene and the like is not high. Catalytic hydrogenolysis is a more potential route to higher selectivity ethylbenzene and improved product quality. However, the prior art has a precondition that hydrogen must be supplied to the reaction system to effect hydrogenolysis. For example, most of the literature and patent technologies need to be matched with a hydrogen supply system such as a high-pressure hydrogen cylinder and the like, and operate at high temperature and high pressure (for example, the reaction pressure is usually 2-5 MPa or even higher). This clearly increases the complexity and safety risk of the process, puts stringent requirements on the pressure-resistant level and safety protection of the reaction equipment, also increases the investment and operation cost of the device, and limits the application of the device in wider scenes. In conclusion, a novel catalytic hydrogenolysis technology which does not depend on external hydrogen supply, is simple and safe in process, can efficiently and highly selectively convert polystyrene into ethylbenzene is developed, and has important practical significance and economic value. Disclosure of Invention In view of the drawbacks of the prior art described in the background, a primary object of the present invention is to provide a copper-based catalyst for catalytic hydrogenolysis of polystyrene. The catalyst has the advantages of simple preparation method, low cost and even dispersion of active components. The invention aims at providing a method for preparing ethylbenzene by catalytic hydrogenolysis of polystyrene mediated by alcohol. The method takes alcohol as a reaction medium and an in-situ hydrogen source, realizes high-efficiency and high-selectivity conversion of polystyrene under the condition of not additionally introducing high-pressure hydrogen, fundamentally avoids the safety risk and equipment cost caused by externally supplying hydrogen, and provides a brand new solution for safe and high-value recycling of polystyrene waste. The above object of the present invention is achieved by the following technical solutions: A copper-based catalyst for catalytic hydrogenolysis of polystyrene, said catalyst consisting of copper species supported on a basic oxide