Zirconocene Aluminohydride‐Methylaluminoxane Clathrates for Ethylene Polymerization in Slurry

Abstract

The main aim of this work is to obtain heterogeneous, zirconocene aluminohydride/methylaluminoxane (MAO) polymerization catalysts, without using inorganic carriers like silica. The syntheses of zirconocenium ion‐based clathrates, formed from aluminohydride zirconocene complexes activated with MAO, are reported here. Several different approaches were examined for the synthesis of these clathrate compositions; in one approach the catalyst ( n BuCp 2 ZrH 3 AlH 2 /MAO) was first prepared in toluene solution, and the clathrate phase then generated by addition of silicone oil. An alternate approach involved reaction of silicone oil or another clathrate‐forming additive (e.g. KCl) with MAO to form a solidified clathrate, and then introducing the zirconocene aluminohydride complex ( n BuCp 2 ZrH 3 AlH 2 ). The clathrate catalysts were probed in the polymerization of ethylene in hydrocarbon slurry, without using additional co‐catalyst (MAO), or at very low concentrations of modified MAO (MMAO 7, 13 wt‐% in iso‐octane). The catalytic activities of the solid clathrate catalysts were compared as well as the morphology and properties of the polyethylene synthesized in slurry.