摘要
通过对传统铬系催化剂进行改性,用碱式乙酸铬、四水合钼酸铵、对甲苯异氰酸酯合成了一系列新型的亚胺修饰硅胶负载型铬钼催化剂。采用计算模拟的方法研究了亚胺修饰的机理,采用氮气物理吸附、X射线光电子能谱等对新型催化剂进行了表征。考察了该催化剂催化乙烯均聚合、乙烯与1-己烯共聚合以及聚乙烯产品的性能。结果表明:亚胺配体主要和表面铬组分相互作用,降低了铬的缺电子性,从而降低了反应活性,但制得的聚乙烯具有相对分子质量高、相对分子质量分布宽、共聚物短支链多等优点。
CrO_x/Silica catalyst is one of the most important industrial catalysts to produce high density polyethylene. In this paper, a series of imido-modified Cr/Mo bimetallic catalysts were synthesized with chromium actate hydroxide,（NH_4）_6 Mo_7O_2·4H_2O and p-toluene isocyanate. The imido-modification mechanism was studied by DFT method. The catalysts were characterized by N_2 adsorption and XPS methods. The performances of ethylene homopolymerization, ethylene/1-hexene copolymerization over the catalysts were investigated. The results show that imido ligand is more favorably reacted with the Cr species, whose electrondeficiency is decreased leading to lower activity. However, the polyethylene product presents high molecular weight, ultra-broad molecular weight distribution, and more short branched chains incorporated in copolymer.
出处
《合成树脂及塑料》
CAS
北大核心
2016年第1期16-20,共5页
China Synthetic Resin and Plastics
