Supported metallocene on mesoporous materials

Abstract

A series of hybrid supported catalysts was prepared by sequentially grafting Cp 2 ZrCl 2 and ( n BuCp) 2 ZrCl 2 (1:3 ratio) onto alumino-silicates (MCM-41, SBA-15, MCM-22, ITQ-2), alumina and chrysotiles (native and leached). Supports and catalysts were characterized by Rutherford backscattering spectrometry, atomic force microscopy and nitrogen adsorption. Grafted metal content laid between 0.2 and 0.8 wt.% Zr/SiO 2 and 0.9 wt.% Zr/Al 2 O 3 . All the systems were shown to be active in ethylene polymerization with methylaluminoxane as the cocatalyst. Catalyst activity and molecular weight were shown to depend on the textural characteristic of the silicas, namely grain size and pore diameter. The highest activity in ethylene polymerization (ca. 3200 kg PE mol Zr −1 h −1 ) was obtained with the supported catalyst using SBA-15 with average particle size around 0.21 μm. Resulting polymers were characterized by gel permeation chromatography and differential scanning calorimetry. A series of hybrid supported catalysts was prepared by sequentially grafting Cp 2 ZrCl 2 and ( n BuCp) 2 ZrCl 2 (1:3 ratio) onto alumino-silicates, alumina and chrysotile. The supported catalysts were characterized by Rutherford backscattering spectrometry, atomic force microscopy and nitrogen adsorption grafted metal content. Catalyst activity and polyethylene molecular weight were shown to be dependent on textural properties of the supports.