A New Method of Preparation of Porous Titanium Trichloride Catalyst for Propylene Polymerization and the Elucidation of Catalyst Formation Mechanism

Hiroshi UENO*, Tadanao KOHARA, Kunihiko IMANISHI and Satoshi UEKI

Corporate Research & Development Laboratory, Tonen Corporation;
1-3-1 Nishi-tsurugaoka, Ohi-machi, Iruma-gun, Saitama 356-8505 Japan

A new method of preparation of porous titanium trichloride catalyst for propylene polymerization was developed. α-Titanium trichloride was selectively obtained by the reduction of titanium tetrachloride with concentrated alkylaluminum compound. It was then, converted to porous δ-titanium trichloride catalyst by treating with the mixture of ether and chlorinated organic compounds. The aluminum compound contained in the α-titanium trichloride solid was extracted with ether, and simultaneously the crystalline structure of titanium trichloride was transformed from α-type to δ-type with chlorinated organic compound. The porous δ-titanium trichloride catalyst showed very high activity for propylene polymerization and gave highly isotactic polypropylene. It was proposed that chlorine radical formed by the reaction of chlorinated organic compound and extracted alkylaluminum compound transformed to crystalline structure, on the basis of the results chlorinated organic compound in which the chlorine atoms have lower negative charge gave catalysts with higher propylene polymerization activity.

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