文献类型：期刊文献

英文题名：Peculiarities of Ethylene Polymerization Kinetics with an Imido-Vanadium/Silyl-Chromate Bimetallic Catalyst: Effect of Polymerization Conditions

作者：Liu, Bao[1];Tian, Zhou[2];Zhao, Ning[1];Liu, Zhen[1];Liu, Boping[1]

机构：[1]East China Univ Sci & Technol, State Key Lab Chem Engn, Meilong Rd 130, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Minist Educ, Key Lab Adv Control & Optimizat Chem Proc, Meilong Rd 130, Shanghai 200237, Peoples R China

年份：2017

卷号：56

期号：21

起止页码：6164

外文期刊名：INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH

收录：;EI(收录号：20172503805806);WOS:【SCI-EXPANDED(收录号:WOS:000402690800008)】；

基金：This work is financially supported by the National Natural Sciehce Foundation of China (21406061 and 21674036) and the Fundamental Research Funds for the Central Universities.

语种：英文

外文关键词：Catalysts - Molecular weight distribution - Ethylene - Chromates - Homopolymerization - Ultrahigh molecular weight polyethylenes

摘要：The effects of various polymerization conditions [GRAPHIC] such as cocatalyst concentration, pressure, temperature, and reaction time on ethylene homopolymerization over a SiO2-supported imido-vanadium/silyl-chromate (Cr-iV) bimetallic catalyst were systematically investigated. The monometallic silyl-chromate (S-2) and imido-vanadium (iV) catalyst were also employed for comparison. It was found that the S-2 catalyst produced a polymer with relatively low molecular weight, while the iV catalyst produced ultrahigh-molecular-weight polyethylene (UHMWPE). The bimetallic catalyst was capable of producing reactor blends, with bimodal molecular weight distribution (MWD) and a considerable amount of UHMWPE. Increasing and decreasing polymerization temperature both enhanced the high molecular weight part of the bimodal MWD while the position of the two peaks remained unchanged. The polymerization rates all showed first-order dependences with respect to ethylene pressure for the three catalysts. Ethylene pressure variations caused no changes in the MIND of polymers made by the three catalysts, indicating that transfer to the monomer is the main chain transfer mechanism.