文献类型：期刊文献

英文题名：Toward the Optimization of a Cr-V Bimetallic Catalyst for Producing Bimodal Polyethylene: Effect of Vanadium Content and Calcination Temperature

作者：Liu, Bao[1];Tian, Zhou[2];Jin, Yulong[3];Zhao, Ning[1];Liu, Boping[1,3]

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;[3]South China Agr Univ, Coll Mat & Energy, Guangzhou 510642, Guangdong, Peoples R China

年份：2018

卷号：219

期号：12

外文期刊名：MACROMOLECULAR CHEMISTRY AND PHYSICS

收录：;EI(收录号：20182005194103);WOS:【SCI-EXPANDED(收录号:WOS:000435641200006)】；

基金：This work was financially supported by the National Natural Science Foundation of China (grant nos. 21406061 and 21674036), and the Shanghai Municipal Natural Science Foundation (grant no. 14ZR1410600).

语种：英文

外文关键词：bimetallic catalysts; bimodal MWD; calcination temperature; ethylene polymerization; vanadium content

摘要：This work covers the synthesis of bimodal polyethylene with a SiO2-supported vanadium-oxide/silyl-chromate (Cr-V) bimetallic catalyst, which is prepared by using the residual hydroxyl groups on the VOx/SiO2 catalyst precursor to support chromium species. The effects of vanadium content and calcination temperature of the support on catalyst activity and polymer properties are investigated in detail. It is found that increasing vanadium content in the Cr-V catalyst leads to the decline of catalyst activity, while the molecular weight of the resulting polyethylene is raised. On the other hand, the decline of catalytic activity at high vanadium content in the Cr-V catalyst can be remedied by decreasing the calcination temperature of the support, and the molecular weight of the polymers is reduced at the same time. However, too low a calcination temperature is not beneficial for catalyst activity due to the poisoning effect of the excess hydroxyl groups on the active sites, and this would cause the increase of molecular weight as well.