单、多活性中心种类聚丙烯催化剂的Monte Carlo模拟

MONTE CARLO SIMULATION OF SINGLE-/MULTI-ACTIVE SITE CATALYSTS FOR PROPYLENE POLYMERIZATION

采用Monte Carlo模拟技术研究了在不考虑聚合物颗粒内物料与热量传递效应及不存在氢气作用下的单、多活性种类催化剂催化的丙烯聚合动力学。探讨了聚合产率、催化剂活性中心分率以及多分散指数随时间的变化规律,并对单、多活性中心种类催化的反应体系分别作了比较。基于Monte Carlo方法的模型得出的聚合动力学结果与文献相一致。此外,由Monte Carlo模拟也得到,催化剂多活性中心种类的性质对聚合产物的分布性质有很大影响;以多分散指数而言,多活性中心种类催化剂催化得到的聚丙烯多分散指数要比单活性中心种类催化剂催化得到的产物多分散指数宽。

A Monte Carlo model was established to describe the propylene polymerization kinetics catalyzed by single- or multi-active site catalyst, ignoring the effects of intraparticle mass and heat transfer and the effect of hydrogen. Corresponding propylene polymerization kinetic data, including polymerization yield, concentration transformation of catalyst active sites, polydispersity etc. , were obtained via the model. Comparisons of the kinetic results between the polymerization catalyzed by the single-active site catalyst and the multi-active site type catalyst were conducted via the model. The simulated kinetic results are found to be in agreement with the reference ones obtained experimentally. The studied results showed that nature of multi-active site type could have a significant influence on polymer distribution properties. As of the polydispersity （PDI）, polypropylene catalyzed by multi-active site type catalyst has a broader PDI than the one catalyzed by the single-site catalyst, under the same reaction circumstance.