关键词: Ziegler-Natta catalyst, polyethylene, slurry polymerization process, structure and properties

Abstract: A novel high performance MgCl₂/TiCl₄ catalyst with tetrabutyloxsilicane as electron donor was prepared for ethylene slurry polymerization process. The properties of the catalyst such as particle size distribution, catalytic activity, hydrogen responsibility and copolymerization performance were investigated and compared with commercial catalyst (imported catalyst). Copolymerization of ethylene and 1-butylene using the catalyst was studied in a pilot plant. The composition, structure and property of the copolymer were characterized by ¹³C nuclear magnetic resonance (¹³C NMR) and gel permeation chromatography-Infrared (GPC-IR), and compared with those of the copolymer obtained from a commercial catalyst. In comparison with the commercial catalyst, the novel catalyst had a higher activity (up to 34.6 kg·g^-1) and a better particle size distribution (PSD), and produced polymers having higher bulk density (up to 0.37 g·cm^-3) with less fine resin. Meanwhile, the novel catalyst showed a higher hydrogen responsibility and better copolymerization performance. The results indicated that the copolymer obtained from the novel catalyst has a higher branch in the high molecular weight fraction and lower branch in the low molecular weight fraction.

Key words: Ziegler-Natta catalyst, polyethylene, slurry polymerization process, structure and properties