Olefin Polymerization with Novel Type of Ziegler Catalysts

A series of dichlorobis(β-diketonato)titanium complexes were synthesized and the corresponding MgCl₂ -supported catalysts were prepared by impregnation method. Those complexes combined with MAO or alkylaluminums hardly showed the activity for propene polymerization. Whereas, the MgCl₂-supported catalysts displayed high activity even using alkylaluminums as cocatalyst. The catalyst isospecificity was drastically increased by adding a suitable Lewis base as an external donor. Isotactic polypropene (PP) with Tm over 169 °C could be thus obtained under appropriate polymerization conditionsOn the other hand, copolymerization of ethene and propene over them gave poly(ethene-co-propene) with a fairly high molecular weight and a narrow chemical composition in high yieldThis paper summarizes the characteristics of the MgCl₂-supported catalysts for propene polymerization and ethene–propene copolymerization.