Prealkylation of a supported catalyst system comprising a transition metal
or inner transition metal complex precatalyst and a bulky,
non-coordinating anion on an inorganic support by treatment with a
solution of metal alkyl in a ratio of metal of metal alkyl to transition
metal or inner transition metal of precatalyst less than 20:1, and in an
amount of solution insufficient to form a paste or dispersion provides
supported catalysts of high olefin polymerization activity which promote
production of polyolefins of low polydispersity and improved morphology.
