Development of novel chromium oxide/metallocene hybrid catalysts for bimodal polyethylene
Development of novel chromium oxide/metallocene hybrid catalysts for bimodal polyethylene
复制标题
DOI：
10.1016/j.polymer.2011.02.048
复制
发表时间：
2011-04
期刊：
影响因子：
4.6
通讯作者：
J. Moreno;R. Grieken;A. Carrero;Beatriz Paredes
中科院分区：
文献类型：
--
作者：
J. Moreno;R. Grieken;A. Carrero;Beatriz Paredes
在聚烯烃领域，多组分催化剂的研究为在恒定反应条件下一步法合成双峰聚合物提供了一种新的途径。在目前的工作中，新的双功能催化剂的制备通过结合铬和茂金属物种在同一个固体和测试在乙烯聚合，以评估生产双峰聚乙烯的可能性。将甲基铝氧烷（MAO）/（nBuCp）_2ZrCl_2催化体系固定在以SiO_2、SiO_2-Al_2O_3、磷酸铝和介孔SBA-15为载体的活性铬催化剂上。反应结果表明，载体的物理化学性质对茂金属和铬中心的相对贡献以及对聚合物分子量分布有明显的影响。将茂金属催化剂负载到直接合成的介孔铬催化剂上，制得双峰聚乙烯。
The investigation of a multicomponent catalyst in polyolefin field came up as an alternative for synthesizing bimodal polymers in only one step process under constant reaction conditions. In the present work, new bifunctional catalysts were prepared by combining chromium and metallocene species on the same solid and tested in ethylene polymerization in order to evaluate the possibility of producing bimodal polyethylene. The catalytic system methylaluminoxane (MAO)/(nBuCp)2ZrCl2was immobilized on activated chromium catalysts supported onto several inorganic carriers (silica, silica–alumina, aluminophosphate and mesostructured SBA-15-type materials). The reaction results showed a clear influence of the physicochemical properties of the support on the relative contribution of metallocene and chromium centers as well as on polymers molecular weight distribution. A bimodal polyethylene was obtained by supporting the MAO/metallocene system on a mesostructured chromium catalyst prepared by direct synthesis.