Realistic surface science models of supported catalysts: The chromium oxide ethylene polymerization catalyst

Depositing catalytically active particles onto flat, thin oxide films which have electric conductivity forms an attractive way to make supported catal ysts suitable for surface science investigations. Here we describe the deve lopment of a model system for the chromium oxide on silica catalyst used in industry for the polymerization of ethylene, the so-called Phillips cataly st. The model system, consisting of molecularly dispersed chromium ions, de posited by wet chemical impregnation on a thin silica film and anchored to it by treating it in oxygen, displays a representative activity for polyeth ylene formation.