Polymer, Vol.37, No.8, 1399-1403, 1996
Studies on Magnesium Dichloride-2,2-Dimethoxypropane-Titanium Tetrachloride Catalyst System for Propylene Polymerization
Magnesium dichloride supported titanium catalysts were prepared by solubilizing anhydrous magnesium dichloride in 2-ethyl-1-hexanol followed by treatment with titanium tetrachloride. 2,2-Dimethoxypropane was used as an internal Lewis base. Solid products were characterized by compositional analysis, and specific surface area. Titanium magnesium catalysts (Ti-Mg) in conjunction with triethylaluminium showed high activity (5110 g PP/g Ti) and high stereospecificity (I.I = 92) for propylene polymerization. The variation in the amount of 2,2-dimethoxypropane during catalyst synthesis governs the productivity of the catalyst. Furthermore, the increase in the chain length of the alkyl group from ethyl to hexyl of trialkylaluminum cocatalyst retards the activity of the catalyst system, with minor variation in the isotactic index of polypropylene. The addition of diphenyldimethoxysilane into triethylaluminum further improves the stereospecificity of the catalyst system.
Keywords:ZIEGLER-NATTA CATALYSTS;HIGH-YIELD CATALYSTS;EXTERNAL LEWIS BASE;OLEFIN POLYMERIZATION;SUPPORTED CATALYSTS;STEREOSPECIFIC POLYMERIZATION;PROPENE POLYMERIZATION;OXIDATION-STATES;TICL4 CATALYST;ALPHA-OLEFINS