新型高效催化剂气相聚合制备聚乙烯

Preparation of Polyethylene With MG - type Highly Active Catalysts

综合报道了新型乙烯气相聚合MG型催化剂的制备及其聚合反应性能。研究了采用浸渍反应法制备含TiCl_4/MgCl_2/ZnCl_2/SiO_2/醇/Al(i-Bu)_3的MG-4型高效催化剂。在压力1.0MPa下,乙烯聚合催化效率高达445～884 kg PE/g Ti,制得了表观密度≥0.37 g/cm^3、重均颗粒分布(20～200目)≥97.7％、颗粒状态良好的聚乙烯。用DSC、SEM、WAXD对聚合产物进行了表征。发现制得了双峰分布的聚乙烯。这可归因于催化剂中锌化合物存在而生成多种活性中心。

MG - type highly active catalysts prepared with various supports and gaseous phase polymerization of ethylene with MG - type catalysts were studied. Novel highly active catalysts(MG - 4 type) containing ingredients of TiCl4/ MgCl2/SiO2/alcohol/Al(i - Bu)3 were prepared by precipitation reaction approach. The catalytic efficiency was as high as 445 - 884 kg PE / g Ti for the ethylene polymerization under the pressure of 1.0 MPa. The yielding polyethylene with bulk density ≥ 0.37 g/ cm3 and weight distribution (20-200 mesh) ≥97.7% possessed excellent morphology. The polymerization products were characterized by DSC, SEM and WAXD.The results showed double melting peak PE in DSC curves, which was ascribed to the formation of two or more kinds of active centers due to the existence of Zn compounds.