Abstract:

According to the mechanism of propylene polymerization, the process simulation for liquid phase bulk propylene polymerization in loop reactor was carried out by using Polymers Plus of ASPEN with the method of response surface methodology(RSM). The method of Levenberg-Marguardt was used in the GPC (Gel Permeation Chromatography) curve deconvolution of the polypropylene sample to calculate the active sites of Ziegler-Natta catalyst. The result showed that the catalyst was characterized by assuming existence of five active sites. By using Monte Carlo method, the multi-site's dynamic data was gotten on the base of a new model in which the catalyst was assumed as uniform sphere and the integral was made. The individual and interactive effects of temperature, pressure, mass flow of catalyst, mass flow of propylene, and volume fraction of hydrogen on M_w of PP was investigated and a quadratic model was developed for the prediction of M_w of PP. The M_w predicted by quadratic model was 2.142×10⁵ very close to the experimental data with the deviation of 1.25%. The quadratic model and 3D tendency curves can be used to optimize operation and to improve PP quality conveniently.

Key words: polymerization, simulation, reaction kinetics, loop reactor, response surface methodology

摘要：

采用响应曲面法(RSM),利用Aspen Polymers Plus软件对环管工艺丙烯液相本体聚合过程进行了模拟。利用基于Newton-Raphson逐步逼近法对聚丙烯样品的GPC曲线进行解析,得到所用催化剂有5个活性中心;建立催化剂均匀球体模型并对其进行球积分,利用Monte Carlo随机模拟法,计算得到了聚合动力学参数;利用Box-Behnken Design方法进行实验设计,探讨了聚合温度、压力、丙烯质量流量、催化剂用量、氢气用量等主要因素对环管反应器出口聚丙烯(PP)分子质量的影响,建立了以环管反应器出口聚丙烯分子质量为响应函数的数学模型。利用模型计算出的聚丙烯相对分子质量为2.142×10⁵,与实测值的误差为1.25%;利用数学模型和3D响应曲面趋势图,可以方便地调整装置操作,改进产品质量。

关键词: 聚合, 模拟, 反应动力学, 环管反应器, 响应曲面