乙烯聚合用钛改性铬系催化剂的进展

Progress in titanium modified chromium catalyst for ethylene polymerization

综述了钛改性铬系催化剂的国内外研发现状、制备方法、性能以及对乙烯聚合性能的影响。与用表面浸渍法制备的钛改性铬系催化剂相比,用共凝胶法制备的钛改性铬系催化剂可以缩短诱导期,提高聚乙烯(PE)的熔体流动速率。钛改性铬系催化剂中的钛可阻止α-烯烃在PE的低相对分子质量部分插入,有效降低了含支链低相对分子质量PE的含量。随着钛的加入,低相对分子质量部分的共聚支链减少,从而可改变PE的支链分布。钛改性铬系催化剂的聚合性能明显改善,制备的聚乙烯性能优异。

The research status at home and abroad,preparation method,performances of Ti modified chro-mium catalyst,and the effects of the catalyst on ethylene polymerization were summarized. Compared with the ti-tanium modified chromium catalyst prepared by surface-impregnated method,the catalyst prepared by congelled method could shorten the induced time and improve the melt flow rate of the polyethylene（PE）. The presence of titanium in the titanium modified chromium catalyst could inhibit the incorporation of alpha olefin into the low relative molecular mass part of PE and decrease the content of low relative molecular mass PE with branch. The copolymerized branch in low relative molecular part reduced with the addition of titanium,so the branch distri-bution of PE could be modified. The polymerization performances of the titanium modified chromium catalysts were improved remarkably,and the performances of the resultant PE were excellent.