Study of Titanium/Vanadium Ziegler-Natta hybrid catalysts performance in slurry-phase ethylene polymerization for producing polyethylene with broad/bimodal molecular weight distribution

In this work, titanium/vanadium (Ti/V) Ziegler-Natta hybrid catalyst was synthesized by loading TiCl4 and VOCl3 on MgCl2 support formed by the Grignard reagent method. The effects of vanadium content on the catalyst activity, and introducing different types of alkyl aluminums (triethylaluminum (TEA) and trioctylaluminium (TnOA)) as cocatalyst on the efficiency of the Ti/V Ziegler-Natta hybrid catalyst in the polymerization process were investigated. The polymerization data demonstrated that hybrid catalyst has good activity with both TEA and TnOA cocatalysts. The activity and productivity of Ti/V Ziegler-Natta hybrid catalyst was higher than single titanium-based catalyst. GPC and DSC data indicated that polyethylene (PE) produced with hybrid catalyst has some good characteristics, a broader/bimodal molecular weight distribution (MWD), high melting point and high degree of crystallization. With increasing of V content in hybrid catalyst and using TnOA cocatalyst, MWD is broadened with no steady increase in molecular weight (MW). Although the tensile strength of the obtained PE product increases with the increase of the vanadium content of Ti/V Ziegler-Natta hybrid catalyst, but the optimal amount of vanadium is 0.3 molar ratio of V/Ti.

Automated summary

A titanium/vanadium (Ti/V) Ziegler-Natta hybrid catalyst was synthesized by loading TiCl4 and VOCl3 on MgCl2 support. The effects of vanadium content and different types of alkyl aluminums as cocatalyst on the efficiency of the hybrid catalyst were investigated. The results showed that the hybrid catalyst with both TEA and TnOA cocatalysts exhibited good activity and productivity, and the produced polyethylene had desirable characteristics.