Toward the Optimization of a Cr-V Bimetallic Catalyst for Producing Bimodal Polyethylene: Effect of Vanadium Content and Calcination Temperature
Toward the Optimization of a Cr-V Bimetallic Catalyst for Producing Bimodal Polyethylene: Effect of Vanadium Content and Calcination Temperature
复制标题
用于生产双峰聚乙烯的 Cr-V 双金属催化剂的优化：钒含量和煅烧温度的影响
DOI：
10.1002/macp.201800021
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发表时间：
2018
影响因子：
2.5
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
本工作涵盖了用SiO2负载的氧化钒/铬酸硅酯（Cr-V）双金属催化剂合成双峰聚乙烯，该催化剂通过使用VOx/SiO2催化剂前体上的残余羟基来负载铬物种而制备。考察了载体钒含量和焙烧温度对催化剂活性和聚合物性能的影响。结果表明，随着催化剂中钒含量的增加，催化剂活性下降，聚乙烯分子量增加。另一方面，通过降低载体的焙烧温度可以弥补Cr-V催化剂在高钒含量下催化活性的下降，同时降低聚合物的分子量。然而，太低的煅烧温度不利于催化剂的活性，因为过量的羟基对活性中心的毒化作用，并且这也会导致分子量的增加。
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/SiO2catalyst 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.