Study of some parameters on the zirconocene immobilization over silica

Abstract

This work presents a 23-1 factorial planning designed to evaluate the effect of some parameters of the metallocene immobilization route in the ethylene polymerization. The highest ethylene polymerization activity was observed for the catalyst synthesized using TMA as modifier agent, in the inverse addition order, and impregnation temperature of 60 ◦C. These results indicated that the immobilization route played an important role on the catalysts performance. UV-Vis DRS results suggested the formation of MAO-like species on the silica surface. These species may be formed from the reaction of TMA either with water adsorbed on the support or OH groups of the silica surface. DSC analyses indicated that the crystallinity of these polymers varied as a function of the catalytic activity, the more active catalysts producing polymers with higher crystallinity. The obtained polymers presented melting point around 133 ◦C, typical of commercial polyethylene.