Catalysts based on supported metallocenes for α-olefin polymerization

The central purpose of this work is to develop an to attach the metallocene to a support without diminishing its catalytic activity. This article describes several methods to prepare supported EtInd2ZrCl2 (EBI) on MAO/SiO2, varying the washing step durations and washing step temperatures. The best method is the one that supports 0.7% Zr on MAO/SiO2 with a final content of Al near 5.8%. It seems that this method combines high efficiency in MAO usage at the preparation step and high activity in propylene polymerization. The activity of the supported catalysts EBI/MAO/ SiO2 decreases to the third of the soluble catalysts EBI/ MAO with the same Al/Zr molar ratio. Zr con tents higher than 0.7% produce catalysts with lower productivities. Probably, a MAO coverage in SiO2 that is higher than a monolayer is not useful in order to stabilize the zirconocene on the MASO/SiO2 support. This paper reports the kinetics of the supported catalysts and a discussion about the shape of the curves and the stability of the catalysts is appended. The molecular weight of the poly(propylene) obtained with supported catalyst increases, especially for the best preparation, comparing it with material obtained with the soluble one. The regioregularity of poly(propylene) increases when a Lewis Base (ethyl benzoate-E.B.) is added as external additive to the system EBI/MAO/ SiO2 and the activity of the supported catalyst is improved.