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DOI: 10.1039/A606366G (Paper) Reference Section for: J. Chem. Soc., Faraday Trans., 1997, 93, 1205-1210

FTIR study of chromium carbonyl complexes on silica–alumina: Active ethene polymerisation catalysts

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Geoffrey Hunter, Colin H. Rochester, Anthony G. Wilkinson and John Paton

Abstract

IR spectra are reported of [Cr(CO)3(η-C6H6)] and Cr(CO)6 adsorbed on silica–alumina. The molecules were physically adsorbed, O-ligated to two types of Lewis-acidic Al3+ site or underwent ligand loss to give sub-carbonyl species which were active as ethene polymerisation catalysts. Ligand loss was promoted by evacuation at 25°C, thermal ageing at 30–80°C, or exposure to ethene and involved retention of incompletely coordinated Cr on the surface. Contact with ethene gave highly linear polyethene chains. The efficiency of silica–alumina as a support for active catalysts is attributed to the high population of strongly Lewis-acidic surface sites.

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