Abstract:

In this article，catalysts treated with various Al-alkyl groups in the catalytic system TiCl_x/MgCl₂/THF were prepared and their chemical structures were characterized by XPS and EPR. The influences of Al-alkyl on catalyst chemical structure，especially on titanium valence were discussed. The analytical results indicated that Al-alkyl affected Ti structure of the catalysts. In addition，chemical structures of catalysts were found to changed obviously by the pre-treatment process. These structure changes were found to be related to the performance of ethylene homo-polymerization. The results of evaluation experiments showed that catalytic activity was improved from 4890 gPE/gcat to 9300 g PE/gcat after Al-alkyl pre-treatment on a lab scale and from 8400 gPE/gcat to 11000 g PE/gcat on a pilot plant scale.

摘要：

研究了一系列不同烷基铝处理的TiCl_x/MgCl₂/THF体系Ziegler-Natta催化剂，并采用XPS、EPR对其化学结构进行表征，初步探讨了烷基铝变化对催化剂化学结构的影响，特别是对Ti价态的影响。研究结果表明，由于烷基铝的作用，催化剂中活性组分Ti的结构发生了明显的改变，而其中烷基铝预还原过程对催化剂的结构影响较大。借助催化剂的这些结构上的变化引起其催化性能的显著提高，对比评价结果表明，小试催化剂的乙烯均聚活性从预还原前的4890 gPE/gcat提高到9300 g PE/gcat，工业生产催化剂从8400 g PE/gcat提高到11000 g PE/gcat。