Patent ID: 7211536

Claim:
A supported metallocene catalyst comprising: silica particles having an average particle size within the range of 20–40 microns, an average effective pore size within the range of 50–200 angstroms, and a differential pore size distribution of a pore volume of at least 0.01 cm 3 /g within the range of no more than 300 angstroms; and a stereospecific metallocene supported on said particulate support wherein the metallocene ligand structure having two sterically dissimilar cyclopentadienyl ring structures coordinated with a central transition metal atom; at least one of said cyclopentadienyl ring structures being a substituted cyclopentadienyl group which provides an orientation with respect to said transition metal atom which is sterically different from the orientation of the other cyclopentadienyl group with respect to said transition metal atom, both of said cyclopentadienyl groups being in a relationship with each other providing a stereorigid relationship relative to said coordinating transition metal atom to prevent rotation of said ring structures; and said metallocene ligand structure having a kinetic diameter which is less than the average pore size of said silica and being carried within the interior pore volume of said silica particles to provide at least 50% of the polymerization sites provided on said transition metal atom being within the interior pore volume of said support, wherein said metallocene is aged in tributylaluminum at a temperature of 25° C. for a period of 12 hours and has a retention factor on said support of at least 90% after aging.