Effect of Alkyl Aluminums on Ethylene Polymerization Reactions with a Cr-V Bimetallic Catalyst
Effect of Alkyl Aluminums on Ethylene Polymerization Reactions with a Cr-V Bimetallic Catalyst
复制标题
烷基铝对 Cr-V 双金属催化剂乙烯聚合反应的影响
DOI：
10.1002/mren.201700059
复制
发表时间：
2018
影响因子：
1.5
通讯作者：
Liu Boping
中科院分区：
文献类型：
--
作者：
Liu Bao;Tian Zhou;Jin Yulong;Zhao Ning;Liu Boping
系统地研究了在催化剂中直接和/或在聚合过程中引入不同类型的烷基铝作为助催化剂对铬钒双金属催化剂催化乙烯聚合效率的影响。结果表明，由于两种金属中心对烷基铝的不同响应和敏感性，在聚合的不同阶段使用烷基铝对铬钒催化剂的聚合活性、动力学行为和聚合物性能有很大的影响。当使用三异丁基铝作为助催化剂时，三异丁基铝的活性较高，而聚乙烯的相对分子质量较低，而二乙基氯化铝作为助催化剂时，可以生成超高相对分子质量的聚乙烯，但活性很低。另一方面，烷基铝对双金属催化剂的预还原对催化剂效率有显著的促进作用。结果表明，在催化剂中加入烷基铝和在反应器中加入助催化剂，对提高聚合活性的效果基本相同，但对聚合物性能的影响不同。
The effect of introducing various types of alkyl aluminums directly into the catalyst and/or in the polymerization process as cocatalyst on the efficiency of a Cr‐V bimetallic catalyst for ethylene polymerization is systematically investigated. Results indicate that polymerization activity, kinetic behavior, and polymer properties of the Cr‐V catalyst are strongly affected by using alkyl aluminums in different stages of polymerization, due to the different responses and sensitivities of the two metal centers to alkyl aluminum. When employed as cocatalyst, triisobutyl aluminum gives high activity and polyethylene with relatively low molecular weight, while diethylaluminum chloride cocatalyzes the production of ultra‐high molecular weight polyethylene but with very low activity. On the other hand, the pre‐reduction of the bimetallic catalyst by alkyl aluminums has a marked promotion effect on catalyst efficiency. It is suggested that the addition of alkyl aluminum to the catalyst and to the reactor as cocatalyst are more or less equivalent in their effects on the improvement of polymerization activity, but they behave in different ways to affect polymer properties.