溶解析出体系催化剂性能的影响因素探究

Factors influencing performances of dissolution-precipitation system catalyst

以MgCl_(2)、正丁醇、异丙醇和TiCl_(4)为原料,钛酸四乙酯为给电子体,通过溶解析出的方式制备了一种聚乙烯催化剂,并将其用于乙烯聚合。利用SEM、粒径分布、熔体流动速率(MFR)测试等方法研究了影响溶解析出体系催化剂性能的因素。实验结果表明,调节溶解析出体系中的镁钛摩尔比、含镁溶液含量和给电子体用量可有效调控催化剂颗粒中的结块、细粉含量、催化活性、氢调敏感性和聚合物的堆密度(BD)及颗粒形态。综合各影响因素开发的一种溶解析出体系高性能聚乙烯催化剂的聚合活性为32.23 kg/g,所得聚合物的BD为0.304 g/cm^(3),MFR(10 min)为0.49 g,综合性能优于参比工业催化剂。

Polyethylene catalyst for ethylene polymerization was prepared by dissolutionprecipitation method with MgCl_(2),n-butyl alcohol,isopropanol,and TiCl_(4) as raw materials and tetraethyl titanate as the electron donor.Factors influencing dissolution-precipitation catalyst performances were analyzed by SEM,particle size distribution,and melt flow rate(MFR)test.Experimental results show that agglomeration,fine powder content,catalytic activity,hydrogen response,as well as polymer’s bulk density(BD)and particle morphology can be effectively controlled by adjusting the magnesium-titanium mole ratio,magnesium solution content and the amount of electron donor added in the dissolution-precipitation system.In consideration of every influencing factor,a highperformance dissolution-precipitation polyethylene catalyst is developed with polymerization activity of 32.23 kg/g,polymer BD of 0.304 g/cm^(3),and polymer MFR(10 min)of 0.49 g.The general performance of the catalyst is better than that of the reference industrial catalyst.