非均相乙烯聚合有机铬系催化剂研究进展

非均相有机铬系催化剂是工业上常用的聚乙烯催化剂,20世纪60年代被广泛应用于气相法高密度聚乙烯的生产。生产的高密度聚乙烯产品分子量分布宽,长支链含量高,在加工生产高强膜和耐压聚乙烯管材等高附加值产品时具有独特的优势,近年来成为研究热点。按其负载后活性组分的不同,有机铬系催化剂可分为二茂铬和铬酸酯类。综述有机铬系催化剂的发展历程、催化剂及其前驱体的制备和催化剂结构及聚合产品特性,指出可应用于冷凝态操作的高效高活性有机铬系催化剂是今后的研发方向。由于非均相铬系催化剂结构和反应机理复杂,研究其微观机理仍面临很多瓶颈。

Research development in organochromium catalysts for ethylene heterogeneous polymerization

Heterogeneous organochromium catalysts are commonly used for polymerization of ethylene in industry,and were used widely for gas phase reactions to synthesize polyethylene with high density in 1960s.Polyethylene had unique advantages in producing the products with high additional value such as large part blowing molding pipe,and film due to its high molecular weight,wide molecular weight distribution and high contents of long chain branches,which became the research hotspots in recent years.Based on loading different active components,organochromium catalysts were divided into two kinds:chromocene and organosilyl chromate.In this paper,the development of organochromium catalysts,the preparation methods of the catalysts and their supports,catalyst structures and polymeric product characteristics were reviewed.It is pointed out that the organochromium based catalysts with high efficiency and activity is the research direction in future.The micromechanism researches on organochromium catalysts face many bottlenecks because of their highly complex structures and reaction mechanisms.