Effect of the zeolite HY-support on the monoalkene polymerization by groupIV metallocenes

Various metallocene complexes of the IV group transition metals supported o n HY zeolites were investigated in the polymerization of ethylene and propy lene. A comparative study with the-same catalysts operating in solution was also performed. Generally, a decrease in the catalytic activity after supp ort was, observed, whose extent depends on the preliminary treatment of the support with aluminum alkyl. In general, better stability with the time an d higher molecular weight of the polymers were obtained, The high isotactic stereospecificity of-chiral metallocene catalysts for propylene polymeriza tion was maintained after support. In the case of the aspecific bis(indenyl ) complex, a modest but significant effect on the stereospecific control wa s observed due to the steric influence of the support. (C) 2000 Elsevier Sc ience B.V. All rights reserved.