Synthesis of supported titanocene amide complex and its use as a catalyst in ethylene polymerization

Heterogeneous ethylene polymerization catalysts were prepared by supporting tetrakis(dimethylamino)titanium, Ti[N(CH3)(2)](4), on chemically modified silica surface. The modification of silica was made using a silane coupling agent, Cp(CH2)(3)Si(OCH2CH3)(3) and atomic layer chemical vapor deposition (ALCVD). Titanium amide was also immobilized straight on the silica and on a methyllithium-treated modified silica. The aim of methyllithium treatmen t was to alkylate the unreacted ethoxy groups of the silane coupling agent on the silica. Methyllithium methylates, besides ethoxy groups, also silica surface and surface cyclopentadienyl groups. A model compound for these he terogeneous catalysts was prepared using a reaction of Ti[N(CH3)(2)](3) wit h trimethylsilylcyclopentadienyl yielding a monocyclopentadienyl titanium c ompound, Me3SiCpTi[N(CH3)(2)](3). The preliminary results of ethylene polym erization using the prepared heterogeneous and homogeneous titanocene amide complexes and the effect of amount of MAO are presented. (C) 1999 Elsevier Science B.V. All rights reserved.