CN-121990868-A - Method for producing monocyclic aromatic hydrocarbon by using solvent to promote polystyrene hydropyrolysis

Abstract

The invention relates to the field of plastic degradation, in particular to a method for carrying out hydrogenation pyrolysis on polystyrene. The method comprises the steps of adding solvent and polystyrene into a suspension bed reactor respectively, sealing the suspension bed reactor, and introducing hydrogen with a certain pressure to start the reaction. The method for the hydropyrolysis of the polystyrene provided by the invention does not need a catalyst and a solvent to be recycled, and has more economical efficiency and environmental protection. The invention solves the problem of forming polycyclic aromatic hydrocarbon by thermally induced self-cyclization of polystyrene, and solves the problems of benzene ring hydrogenation and aromatic hydrocarbon selectivity reduction. Can realize complete degradation of waste polystyrene and has good economic benefit.

Inventors

• MA HUAIJUN
• SONG HUAN
• Gong shuxin
• TIAN ZHIJIAN
• QU WEI
• HAN JIANQIANG
• CHEN XIN

Assignees

• 中国科学院大连化学物理研究所

Dates

Publication Date

20260508

Application Date

20241105

Claims (8)

1. 1. The method for preparing the monocyclic aromatic hydrocarbon by hydrogenating the polystyrene through the solvent is characterized by comprising the following steps of: The polystyrene is hydropyrolyzed under the action of a solvent and H 2 .
2. 2. The method for preparing monocyclic aromatic hydrocarbon by hydrogenating polystyrene according to claim 1, wherein the solvent is at least one or two or more of a hydrogen-donating solvent and a non-hydrogen-donating solvent.
3. 3. The method for preparing monocyclic aromatic hydrocarbon by hydrogenating polystyrene according to claim 1, wherein, The non-hydrogen-supplying solvent is at least one or more than two of decalin, n-tridecane and the like; Preferably, the solvent is a hydrogen-supplying solvent, and the hydrogen-supplying solvent is at least one or more of hydrogenated aromatic hydrocarbon, such as tetrahydronaphthalene, dihydroanthracene, dihydrophenanthrene and tetrahydroanthracene.
4. 4. The method for preparing monocyclic aromatic hydrocarbon by hydrogenating polystyrene according to claim 1, characterized in that the mass ratio of polystyrene to solvent is 1:100 to 2:1, preferably the mass ratio of polystyrene to solvent is 1:50 to 1:1, more preferably the mass ratio of catalyst to polystyrene is 1:20 to 1:1.
5. 5. The process for the hydrogenation of polystyrene to produce monocyclic aromatic hydrocarbon according to claim 1, characterized in that the molar ratio of H 2 to benzene in polystyrene is from 30:1 to 1:2, preferably the molar ratio of H 2 to benzene in polystyrene is from 10:1 to 1:2, more preferably the molar ratio of H 2 to benzene in polystyrene is from 10:1 to 2:1.
6. 6. The method for preparing monocyclic aromatic hydrocarbon by hydrogenating polystyrene according to claim 1, wherein the specific process is that the solvent and the polystyrene are respectively added into a suspension bed reactor, the suspension bed reactor is sealed, and the reaction is started after hydrogen with a certain pressure is introduced, wherein the reaction pressure is 2MPa to 20MPa, preferably 6MPa to 15MPa, more preferably 8MPa to 12MPa.
7. 7. The method for preparing monocyclic aromatic hydrocarbon by hydrogenating polystyrene according to any one of claims 1 to 6, wherein the polystyrene is hydropyrolyzed at a temperature of 300 ℃ to 450 ℃, preferably at a hydropyrolyzing temperature of 380 ℃ to 420 ℃, more preferably at a temperature of 400 ℃, and the polystyrene is hydropyrolyzed for 0.5h to 12h, preferably for 2h to 12h, more preferably for 4h to 8h.
8. 8. The method for preparing monocyclic aromatic hydrocarbon by hydrogenating polystyrene according to claim 7, wherein said polystyrene is waste polystyrene plastic.

Description

Method for producing monocyclic aromatic hydrocarbon by using solvent to promote polystyrene hydropyrolysis Technical Field The invention relates to the field of plastic degradation, in particular to a method for producing monocyclic aromatic hydrocarbon by utilizing solvent to promote the hydro-pyrolysis of waste polystyrene. Background Polystyrene is widely used in the fields of packaging, household appliances, consumer electronics, building materials, medical supplies and the like. Polystyrene has good weather resistance, and the accumulation of the polystyrene can cause various environmental damages such as visual pollution, soil pollution, water pollution and the like, thereby bringing persistent harm to the ecological environment. There is a need to develop efficient recycling methods to reuse polystyrene waste plastics. The current treatment modes of the recycled waste polystyrene mainly comprise mechanical recovery, energy recovery and landfill treatment. The above disposal of waste polystyrene has great economic and environmental negative effects. In the developed route, the traditional pyrolysis and catalytic degradation processes of polystyrene are simple, but the utilization rate of carbon resources of pyrolysis is low, carbon deposition of a catalytic degradation catalyst is serious, and light gases and solid residues are generated by the two methods. In addition, there are plasma-assisted fast hydropyrolysis of polystyrene, photocatalytic oxidation of polystyrene, azide-assisted polystyrene degradation routes which, although possible at lower temperatures, have low yields of high value oil products and poor practical availability. The hydropyrolysis of polystyrene can be almost completely converted into aromatics and alkanes. At present, fewer reports of the hydropyrolysis of polystyrene are made. Patent 202311617793.7 discloses a route for hydropyrolysis of polystyrene to monocyclic aromatic and monocyclic alkane under the action of a metal sulfide catalyst. Patent 202310316107.6 discloses a route for hydrocracking polystyrene into monocyclic aromatic hydrocarbon and monocyclic alkane under the action of supported ruthenium catalyst and methanol. The polystyrene hydropyrolysis mainly uses noble metals such as Pt, ru and the like as catalysts, and has excellent catalytic performance, but the noble metal catalysts are extremely easy to poison. The waste plastics contain a large amount of impurities and are extremely easy to poison noble metals. Although the metal sulfide catalyst is low in price and good in toxicity resistance, the stability of the catalyst needs to be further improved. There is therefore an urgent need to develop a practical method for recycling waste polystyrene, which focuses on finding suitable hydropyrolysis conditions, and which can thoroughly upgrade waste polystyrene into valuable monocyclic aromatic hydrocarbons under severe conditions. The invention provides a method for producing monocyclic aromatic hydrocarbon by utilizing solvent to promote the hydropyrolysis of waste polystyrene, wherein the solvent is divided into a hydrogen-supplying solvent and a non-hydrogen-supplying solvent, and the hydrogen-supplying solvent has stronger dissolving, swelling and dispersing capacities and more critical is good hydrogen transferring and hydrogen supplying capacities. From the structural point of view, the hydrogen-supplying solvent is rich in polycyclic aromatic hydrocarbon, especially hydrogenated aromatic hydrocarbon (such as tetrahydronaphthalene, dihydroanthracene, dihydrophenanthrene and tetrahydroanthracene) with strong hydrogen-supplying performance, while the non-hydrogen-supplying solvent is linear alkane and cycloalkane with weaker hydrogen-supplying capability. Various solvents are widely applied in the hydrogenation degradation process of heavy carbon resources in coal chemical industry, oil refining industry and the like. At present, no report exists that a solvent promotes the hydrogenation pyrolysis of polystyrene to produce light aromatic hydrocarbon. Disclosure of Invention The invention provides a method for producing monocyclic aromatic hydrocarbon by utilizing solvent to promote the hydro-pyrolysis of waste polystyrene, which can effectively solve the problems of low polystyrene conversion rate, coking, reactor bed blockage and catalyst deactivation in the polystyrene degradation process. The invention provides a method for preparing monocyclic aromatic hydrocarbon by polystyrene hydrogenation, which comprises the following steps: the solvent and the polystyrene are respectively added into a suspension bed reactor, the suspension bed reactor is sealed, and hydrogen with certain pressure is introduced. The solvent is at least one of hydrogen-supplying solvent and non-hydrogen-supplying solvent. The hydrogen-supplying solvent is at least one of tetrahydronaphthalene, tetrahydroanthracene, octahydroanthracene and the like. The non-hydrogen-supplying solvent i