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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。
The styrene-acrylic copolymer (PSA) was coated on the surface of supported Ziegler-Natta catalysts by sol-gel method, then the functional groups on the surfaces of the organic supports were treated with n-BuSnCl3 as the surface modifier and finally loaded on PSA (n-BuCp ) 2ZrCl2 composite catalyst was synthesized, the gas phase polymerization behavior of the composite catalyst was studied. First, the structure characteristics of the carrier before and after modification by n-BuSnCl3 were investigated by means of BET, particle size analysis and infrared analysis. The results of gas-phase polymerization of ethylene show that the modified catalyst has a high activity of 2.56 × 107g PE. (Mol Zr) -1.h-1.MPa-1. The properties of polyethylene product at different polymerization times and the breaking behavior of the outer PSA carrier during the polymerization were experimentally studied and compared with the results of the ethylene slurry polymerization. The results show that the solvent on the outer layer of the PSA carrier swelling of the catalyst active point play an important role.