Ti-Hf双金属高效载体催化剂合成宽分子量分布聚乙烯的研究

乙烯聚合;乙烯-丁烯聚合;双金属催化剂;Ti-Hf双金属高效载体催化剂合成宽分子量分布聚乙烯的研究

MgCl_2-supported Titanium and Hafnium Bimetallic High Activity Catalyst for Ethylene Homo-and Copolymerization

Titanium and hafnium bimetallic catalyst prepared by chemical reaction method using MgCl 2 as support shows a high activity and good polymer particle size distribution. Compared with catalyst containing only titanium, the titanium-hafnium bimetallic catalyst exhibits better performance and produces polyethylenes with higher molecular weight and wider molecular weight distribution and gives lower density copolymer of ethylene with butene-1. The MFR values of polyethylene obtained decrease with increase in partial hydrogen pressure. High molecular weight shoulders in GPC profile demonstrates that moderate or low molecular weight polyethylene is due to the titanium species while the hafnium active species produce high molecular weight polyethylene. This bimetallic catalyst is suggested to have a promising application in production of polyethylenes with broad molecular weight distributions.