| abstract |
The present invention provides a new type of supported metallocene catalyst system. In one aspect of the invention, an inorganic oxide support, such as silica, is impregnated with a Group XIII element such as B, Al or GA. The support is then contacted with a liquid catalyst system prepared by combining in a liquid an organo aluminoxane and a metallocene having two cyclopetadienyl-type ligands selected from substituted or unsubstituted cyclopentadienyl, indenyl, benzoindenyl, tetrahdroindenyl, benzofluorenyl, octahydrofluorenyl, and fluorenyl ligands to form a supported metallocene catalyst system. In preferred embodiments the process further includes conducting prepolymerization of at least one olefin in the presence of the supported metallocene catalyst system to produce a prepolymerized metallocene catalyst system. The prepolymerized metallocene catalyst system prepared in this manner yields substantially increased activity for the polymerization of olefins. In another aspect, the present invention also provides a method for polymerization of olefins using the inventive supported metallocene catalyst system. |