Patent ID: 6780809
Filing Date: 2004-08-24
Classification: C08F

Abstract:
A particulate, modified chromium oxide catalyst for the polymerisation of ethylene or ethylene with &agr;-olefins, comprising:a) a chromium-oxide catalyst comprising a chromium oxide mainly in a bivalent oxidation state combined with an inorganic support wherein the catalyst contains 0.4% to 10% by weight of Cr; 0.1% to 0.6% by weight of Zr or Hf; and 5% to 20% by weight of Al; calculated as metals based on the total weight of the catalyst, b) a transition metal compound comprising at least one cyclopentadienylic ring bonded to said transition metal, which cyclopentadienylic ring may contain hetero atoms, be unsubstituted or substituted, bonded to the transition metal through a bridge, optionally annealed to other substituted or unsubstituted ring structures, and if two cyclopentadienyl rings are present they may be bonded to each other through a bridge, and c) an aluminoxane; said transition metal compound and said aluminoxane being impregnated in said chromium oxide catalyst.