Method for recovering styrene and other aromatic hydrocarbon raw materials by catalyzing and cracking waste polystyrene

Abstract

The invention relates to a new method for catalyzing and cracking waste polystyrene (PS) to generate aromatic hydrocarbon raw materials, such as styrene and the like, so as to realize chemical recycling of the polystyrene. The method is characterized by adopting a mesoporous molecular sieve MxO/MCM-41 carrying alkali metals and/or alkaline-earth metals as a catalyst (wherein M is an alkali metal and an alkaline-earth metal, such as Li, Na, K, Mg, Ca, Ba and the like, or a compound thereof, and x is 1 or 2) and comprising the steps of: carrying out cracking reaction at 300-450 DEG C in the presence of normal pressures, or pressure reduction or nitrogen introduction; and obtaining aromatic hydrocarbon compounds, such as toluene, ethylbenzene, styrene and the like, by operations of rectification and the like after reaction. The catalyst can be recycled directly without any processing. The cracking rate of the polystyrene is greater than or equal to 98%, the yield of a liquid product is greater than or equal to 95%, and the content of styrene in the liquid product is above 80%. Compared with the prior art, the method has the characteristics that the yield of liquid and the selectivityof styrene are higher, the reaction temperature is mild, and the recycling property of the catalyst is good.

Description

technical field [0001] The invention relates to a new method for using MCM-41 mesoporous molecular sieve modified by alkali metal and / or alkaline earth metal as a catalyst to catalyze and crack waste polystyrene to generate styrene and other aromatic hydrocarbon raw materials to realize their chemical cycle recovery. Background technique [0002] Polystyrene refers to a polymer made from styrene monomer through free radical polymerization, referred to as PS. It is a thermoplastic that is widely used as shock-resistant, heat-insulating, and packaging materials, among others. With the rapid development of industries such as home appliances, instruments, electronics, and food, the amount of polystyrene plastics has increased rapidly, and its production and consumption have increased year by year. At the same time, the extensive use of PS has also led to the generation of a large amount of waste PS. Since PS is difficult to degrade by itself in the natural environment, it will ...

AI Technical Summary

Problems solved by technology

[0006] The purpose of this invention is to provide a new method for catalytic cracking of waste polystyrene to reclaim aromatic hydrocarbon raw materials such as styrene monomer, which overcomes the problems of the traditional method of cracking waste polystyrene or the high reaction temperature or the yield of liquid products and styrene Disadvantages such as low selectivity or poor catalyst reuse performance

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