Catalysts and processes for the polymerization of olefins

Abstract

Catalysts for the polymerization of olefins are disclosed, which comprise the product obtained by contacting: (A) a bridged and/or substituted cyclopentadienyl compound of titanium, zirconium or hafnium; (B) an organometallic aluminium compound of the formula: Al(CH —CR R —CR R R ) R H wherein R is a C -C alkyl, alkenyl, or arylalkyl group; R is hydrogen or a C -C alkyl, alkenyl, or arylalkyl group; R and R are C -C alkyl, alkenyl, aryl, arylalkyl or alkylaryl groups; R is hydrogen or a C -C alkyl, alkenyl, aryl, arylalkyl or alkylaryl group; R is a C -C alkyl, alkenyl, or arylalkyl group, a carbon atom in the compound of formula (II) being optionally replaced by a Si or Ge atom; w is 1-3, z is 0 or 1, q=3−w−z, and (C) water; the molar ratio (B)/(C) being comprised between 1:1 and 100:1. These catalysts show an improved activity with respect to known catalysts, wherein different aluminium compounds are used.