茂金属单活性中心复合催化剂制备双峰聚乙烯

将茂金属催化剂四甲基环戊二烯二氯二茂锆(TMCP)和Schiff碱单活性中心催化剂双N-环己基-(3-叔丁基水杨醛亚胺基)]二氯化锆(FI)同时负载到硅胶上得到TMCP-FI复合催化剂。当n(TMCP)∶n(FI)=3.05～4.00时,可得到具有不同高、低相对分子质量聚乙烯含量的双峰聚乙烯,从而实现双峰可调。气相凝胶色谱分析结果表明,使用该复合催化剂可制备具有高相对分子质量组分高支化度、低相对分子质量组分低支化度特征的双峰聚乙烯。使用TMCP-FI复合催化剂,较佳的聚合条件为:聚合温度70～85℃、聚合时间0.5～3.0h、压力1.00MPa、三乙基铝用量2mmol、共聚单体1-己烯用量5～10mL。

Preparation of Bimodal Polyethylene with Metallocene Single Site Compounded Catalyst

By co-supporting of metallocene catalyst—bis(tetramethylcyclopendaienyl)zirconium dichloride(TMCP)and Schiff base catalyst—bisN-cyclohexyl-(3-t-butylsalicylidene imine)zirconium dichloride(FI)on silica gel,TMCP-FI compounded catalyst was prepared.Behavior of TMCP-FI compounded catalyst system in ethylene polymerization was investigated.When n(TMCP)∶n(FI)3.05-4.00 in TMCP-FI catalyst system,bimodal polyethylene with different polymer contents of high and low relative molecular mass can be produced.Relative molecular mass distribution of bimodal polyethylene can possibly be modulated.By two alternative catalyst preparation methods,either TMCP catalyst is deposited prior to FI catalyst or two catalysts are co-deposited onto the support at same time,both can produce feasible compounded catalyst.The bimodal polyethylene can be produced by using the compounded catalyst within a broad polymerization condition range.Preferred conditions are:polymerization temperature 70-85 ℃,time 0.5-3.0 h,pressure 1.00 MPa,Al(Et)_3 dosage 2 mmol,co-monomer hexene dosage 5-10 mL.