超临界甲苯降解聚苯乙烯反应动力学模型

引言 聚苯乙烯是一种性能优良、应用广泛的通用塑料,且可降解回收苯乙烯单体,因此废聚苯乙烯的回收利用受到广泛关注.但聚苯乙烯热降解高温熔融时黏度很大,造成温度分布不均和局部过热,容易发生二次反应并导致结炭,同时降低了苯乙烯单体收率,因此近年来发展了各种热解技术以抑制结炭、提高苯乙烯收率.超临界降解技术利用超临界流体优异的扩散性能和溶解性能,具有加快聚苯乙烯降解速率,提高反应转化率,抑制结炭等优点1-4].

Kinetic model of polystyrene degradation in supercritical toluene

The degradation of polystyrene in supercritical toluene was studied at 310—370℃, 3.6—5.2 MPa by using a novel fast reactor. Supercritical solvents have unique properties such as excellent heat and mass transfer. Compared with thermal degradation without solvents, supercritical degradation obtains high conversion in a very short reaction time. The supercritical degradation of polystyrene is a typical free radical reaction mechanism, including chain fission, disproportionation, radical recombination, β-scission, intermolecular abstraction and intramolecular abstraction. Based on the reaction mechanism, the process of polystyrene degradation in supercritical toluene was modeled at the mechanistic level by using population balance equations formulated via the method of moments. The predictions of the degradation conversion of polystyrene were compared with experimental results, and the agreement was good.