Chromium supported onto swelled Al-MCM-41 materials: a promising catalysts family for ethylene polymerization

Abstract

Swelled MCM-41 and Al-MCM-41 materials with large pore size and pore volume were synthesized and used as supports to prepare novel chromium catalysts for ethylene polymerization. Aluminium incorporation favoured chromium anchorage onto MCM-41 surface. Attachment of Cr species resulted from H-bonding of cuasi ¿-electron system of the acetylacetonate ligands with hydroxyls groups or with electron acceptor centres like Al3+. Chromium supported onto swelled Al-MCM-41 showed higher ethylene polymerization activity than conventional Cr/SiO2 catalysts tested in the same conditions. Properties of both obtained polymers were similar, indicating the formation of linear high density polyethylene.