Preparation of the Ziegler-Natta/metallocene hybrid catalysts on SiO2/MgCl2 bisupport and ethylene polymerization

Ziegler-Natta and metallocene hybrid catalysts were impregnated on a bisupport prepared by the polymerization of colloidal phase of SiO2 using MgCl2 solution as an initiator. The prepared bisupport was modified by treatment with aikyl aluminum compounds. In terms of the treatment of the prepared bisupport, trimethylaluminum (TMA) was superior to methylaluminoxane (MAO) with respect to the stability of the metallocene catalyst. The prepared hybrid catalysts exhibited characteristics of both Ziegler-Natta and metallocene catalysts. The polyethylene produced on the hybrid catalysts showed a bimodal molecular weight distribution in GPC profile and two different melting points in differential scanning calorimetry (DSC) thermogram. (C) 1999 Elsevier Science B.V. All rights reserved.