无机/有机复合载体负载TiCl_3/(n-BuCp)_2ZrCl_2的

Immobilizing TiCl_3/(n-BuCp)_2ZrCl_2 catalyst on organic/inorganic support for gas-phase ethylene polymerization

采用溶胶-凝胶法将苯乙烯丙烯酸共聚物(PSA)包裹在负载型Ziegler-Natta催化剂表面,随后用表面改性剂n-BuSnCl3处理有机载体表面的官能团,最后在PSA上负载(n-BuCp)2ZrCl2制得复合催化剂,研究了复合催化剂的气相聚合行为。实验首先通过BET、粒径分析、红外分析等手段考察了采用n-BuSnCl3改性前后载体的结构特征。乙烯气相聚合结果表明,改性后催化剂具有较高的活性,达2.56×107g PE.(mol Zr)-1.h-1.MPa-1。实验研究了不同聚合时间下聚乙烯产物的性质及外层PSA载体在聚合过程中的破碎行为,并与乙烯淤浆聚合结果进行对比。结果表明,溶剂对催化剂外层PSA载体的溶胀作用,对催化剂活性点均匀发挥起着至关重要的作用。

Abstract： Styrene and acrylic copolymer （PSA） modified by n-BuSnC13 was coated on commercial M-1 catalyst （SiO2/MgC12-TiC13）. Then （n-BuCp）2ZrC12 was immobilized on the modified PSA to obtain a hybrid catalyst. The catalyst performance for gas-phase ethylene polymerization was measured. The structure and morphology of the modified support was characterized by BET, SEM, FTIR and particle size analysis. It was found that n-BuSnC13 was a relative weak modifier, the change of support structure not obvious and there was interaction between n-BuSnCl3 and carboxyl group of PSA. The results of ethylene polymerization showed that the modified catalyst had high activity, 2.56 X 107 g PE ~ （tool Zr） 1 . h-＇ ~ MPa 1. The copolymerization ability and hydrogen responsibility of the catalyst were also investigated. The low density polyethylene blends with high molecular weight and the high density one with low molecular weight can be obtained by using the hybrid catalyst. The obtained polyethylene blends had broad molecular weight distribution. Furthermore, the polymer obtained at different polymerization time was studied in order to observe the fragmentation behavior of PSA support during the gas-phase polymerization. Finally,the results of gas-phase polymerization were compared with that in slurry phase polymerization.