用TiCl_4修饰非茂金属催化剂制备宽相对分子质量分布的聚乙烯

将TiCl_4与CpTi(dbm)Cl_2非茂金属催化剂(Cp表示环戊二烯基,dbm表示二苯甲酰甲烷)通过原位反应负载到MgCl_2-SiO_2复合载体上,制备了一种新型双中心非茂金属催化剂TiCl_4-CpTi(dbm)Cl_2-MgCl_2-SiO_2(简称Ti/dbm-Ti)。通过调节TiCl_4与CpTi(dbm)Cl_2的配比,可以达到增宽聚乙烯相对分子质量分布的目的。在H_2压力0.15MPa、总压力0.80MPa、聚合温度70℃、聚合时间1h、1-己烯80mL、正己烷1L的条件下,用n(TiCl_4):n(CpTi(dbm)Cl_2)=1:10的Ti/dbm-Ti催化剂催化乙烯与1-己烯共聚时,催化活性为4.05×10~6g/(mol·h),共聚物的相对分子质量分布可达17.22,达到了提高共聚物加工性能的目的。

Preparation of Polyethylene with Broad Relative Molecular Mass Distribution Catalyzed by Non-Metallocene Catalyst Modified with TiCl4

A dual-site non-metallocene catalyst TiC14-CpTi(dbm)Cl_2-MgCl_2-SiO_2(Ti/dbm-Ti) (Cp:cyclopentadiene;dbm:dibenzoylmethane)was prepared through an in-situ reaction of TiCl_4 with CpTi(dbm)Cl_2 non-metallocene catalyst and through supporting the reaction product onto MgCl_2-SiO_2 support,which was used in ethylene polymerization.By controlling the mole ratio of TiCl_4 to CpTi(dbm)Cl_2 in the prepared catalyst,relative molecular mass distribution of the obtained polyethylene could be broadened.And catalytic activity of the bimetallic catalyst Ti/dbm-Ti in ethylene polymerization was high.Under following polymerization conditions:70℃,1h,H_2 pressure 0.15 MPa,total pressure 0.80 MPa,n(TiCl_4):n(CpTi(dbm)Cl_2)1:10,n-hexane 1Land 1- hexene 80 mL,the catalyst activity could reach 4.05×10~6 g/(mol·h)and copolymer of ethylene and 1-hexene with relative molecular mass distribution 17.22 could be obtained,which was beneficial for improvement of processing properties of the copolymer.