MgCl_2-SiO_2复合载体Ti系催化剂的制备及其催化乙烯/1-己烯共聚

在SiO2载体中引入分子状态的MgCl2后再负载TiCl4,制备了高活性的用于乙烯与1-己烯淤浆共聚的双载体Ziegler-Natta催化剂TiCl4/SiO2-MgCl2。催化剂的最佳制备条件:n(TiCl4)∶n(MgCl2)=10,滴加TiCl4温度为-25℃,n(C2H5OH)∶n(MgCl2)=2.4,m(SiO2)∶m(MgCl2)=1。用激光粒度分析仪、SEM和WAXD等手段对催化剂的粒径分布、颗粒形态和结晶情况进行表征的结果显示,催化剂的粒径在20～45μm之间,较均匀;且颗粒形态呈球形。当催化剂中Ti的质量分数为5.1%时,该催化剂可高效催化乙烯与1-己烯进行淤浆共聚,催化效率达1.59kg/g,乙烯-1-己烯共聚物的数均相对分子质量为3.1×104g/mol,相对分子质量分布为16.3,呈宽分布。

Preparation and Characterization of TiCl4/MgCl2-SiO2 Di-Support Catalyst System for Copolymerization of Ethylene with 1-Hexene

A novel di-support Ziegler-Natta catalyst TiCl4/SiO2-MgCl2 with high activity was prepared and used in copolymerization of ethylene with 1-hexene.The optimum catalyst preparation conditions were: n(TiCl4)∶n(MgCl2) 10,adding TiCl4 temperature-25 ℃,n(C2H5OH)∶n(MgCl2) 2.4 and m(SiO2)∶m(MgCl2) 1.The particle shape,size distribution and crystalline morphology of the catalyst were determined by means of laser granulometer,SEM and WAXD.The results showed that the catalyst particles were spherical with the 20-45 μm particle diameter.When mass fraction of Ti in the catalyst was 5.1%,the catalyst could effectively catalyze the copolymerization.The catalytic efficiency was 1.59 kg/g,number-average relative molecular mass of the obtained ethylene-1-hexene copolymer was 3.1×104 g/mol and its relative molecular mass distribution was 16.3.