Supported catalysts for manufacture of polymers

A supported, heterogeneous catalyst composition for use in polymerization of addition polymerizable monomers, comprising:

• 1) a substrate comprising the reaction product of a solid, particulated, high surface area, metal oxide, metalloid oxide, or a mixture thereof having a surface area as determined by the B.E.T. method of from 10 m2/g to 1000 m2/g and an organoaluminum compound,
• 2) a hafnium complex of a polyvalent, Lewis base ligand;
• and optionally,
• 3) an activating cocatalyst for the hafnium complex
• wherein the hafnium complex corresponds to the formula:
• X is an anionic, neutral or dianionic ligand group;
• Rb independently each occurrence is hydrogen, halogen, C1-20 alkyl, or C6-20 aryl, or two adjacent Rb groups are joined together thereby forming a ring, and b is 1-5;
• and
• RC independently each occurrence is hydrogen, halogen, C1-20 alkyl, or C6-20 aryl, or two adjacent RC groups are joined together thereby forming a ring, and c is 1-5.