Preparation of silica-supported late transition metal catalyst and ethylene polymerization

The late transition metal catalyst 2,6-bis[1-(2,6-diisopropylphenylimino)ethyllpyridine iron(II) chloride was supported on silica. Fourier transform infrared spectroscopy, scanning electronic micrograph and X-ray photoelectron spectroscopy measurements were utilized to examine the process of supporting catalyst on silica and investigate the possible mechanism of support. Furthermore, ethylene polymerizations with the supported catalysts were carried out in various conditions such as different reaction temperatures and Al/Fe molar ratios. The results showed that MAO first reacted with the hydroxyl of silica forming Si-O-Al bonds and then the catalyst was bridged through MAO on the surface of silica. Compared with homogeneous catalysts, the supported catalysts show some decrease in catalyst activity. However, they can show good activity at a lower Al/Fe molar ratio with MAO as co-catalyst and give rise to higher molecular weight and melting temperature of the polymer. Better morphology of polyethylene was obtained by a supported catalyst than by its corresponding homogeneous catalyst. (C), 2002 Society of Chemical Industry.