| abstract |
Catalysts deposited on a support are described. The catalyst itself is formed by combining (i) a metallocene of a transition, lanthanide or actinide metal and (ii) a siloxy-aluminoxane composition which comprises an aluminoxane which contains hydrocarbyl-siloxane moieties which are free of Si-OH groups, wherein the molar ratio of aluminum to hydrocarbylsiloxane is from about 1:1 to 1000:1. The siloxy-aluminoxane composition used is free of Si-OH groups, and the aluminoxane of the siloxy-aluminoxane composition was formed by partial hydrolysis of trialkylaluminum. Supports for the catalysts are particulate inorganic oxides, preferably silica, alumina, silica-alumina, or a mixture thereof, or resinous polyolefin support materials. |