rac-Me_2Si(Ind)_2ZrCl_2负载型催化剂催化丙烯等规聚合的研究

STUDY ON PROPYLENE ISOSPECIFIC POLYMERIZATION USING SUPPORTED METALLOCENE CATALYST rac-Me_2Si(Ind)_2ZrCl_2

将rac Me2 Si(Ind) 2 ZrCl2 与甲基铝氧烷 (MAO)预络合后负载于SiO2 上得到了高活性的负载型茂金属催化剂 ,并用于丙烯等规聚合 ,研究了 [Al]/ [Zr]比、聚合温度对聚合活性、产物分子量、聚合动力学的影响 ,同时与相应的均相体系进行比较 .结果表明 ,负载化后 ,活性中心的稳定性提高 ,所得聚合物的分子量也明显高于均相体系 .同时用13 C NMR测定了两种催化体系所制备的等规聚丙烯的微结构 .结果发现 ,负载型茂金属催化剂制得的聚丙烯立构选择性高于均相体系 ,其五元组立构序列 [mmmm]从均相的 82 0 %提高到负载的 86 3 % .同时区域选择性也有所改进 ,2 ,1 插入、1 ,3 插入分别从均相体系的 4 4‰和 1 9‰降到负载体系的 3 7‰和 0 5‰ .

A highly active supported metallocene catalyst for propylene isospecific polymerization was prepared by immobilization of SiO\-2 with precontacted compounds of rac Me\-2Si(Ind)\-2ZrCl\-2 and methylaluminoxane (MAO).The influence of \/\ ratio and polymerization temperature on the activity,molecular weight ( M \-W) and polymerization kinetics was investigated.The behavior of this catalyst was also compared with its corresponding homogeneous catalytic system.It was demonstrated that the active site of heterogeneous systems was more stable,and the M W of the obtained polymer improved apparently in parallel.The microstructure of i PP produced by two types of catalysts was determined by 13 C\|NMR spectra.It was found that the isotacticity of i PP obtained by heterogeneous systems was higher,its pentad sequence \ increased to 86 3% from 82 0% for homogeneous systems.Moreover,the regioselectivity of polymers produced by heterogeneous systems was also improved,the 2,1\|insertion and 1,3\|insertion decreased to 3 7‰ and 0 5‰ from the values of 4 4‰ and 1 9‰,respectively for those produced by homogeneous systems.