Investigations on catalytic systems containing nickel supported on silica gel and bonded with organic ligands and complexed by lewis acids. II

Abstract

The catalytic activity in the oligomerization of propylene, of compounds formed by reaction of (C 3H 5) 2Ni with the hydroxide groups of silica gel and complexation with different Lewis acids, Lewis bases, or both, have been studied. TiCl 4, AlCl 3, AlBr 3 and R n AlCl 3− n (R = Me, Et; n = 1, 1.5, 2, 3) were used as Lewis acids and PPh 3 as a Lewis base. Systems complexed by Lewis acids showed differing activity. The greatest degree of conversion was obtained with catalysts containing alkylaluminium dichloride compounds. Systems complexed only by a Lewis base were inactive, and those complexed by a Lewis base and Lewis acid showed a decreasing activity with increasing content of Lewis base in the catalyst. The order of acidity of Lewis acids as regards their activating influence on the catalysts studied was determined. The temperature at which the reaction proceeded was found to have an essential influence on the degree of conversion of the substrate.