FINITE SUPERCLUSTER MODEL OF VANADIUM-OXIDE CATALYSTS .2. ADSORBATE ADSORBATE INTERACTIONS

The recently proposed supercluster model is applied to study the interaction between two molecules (atoms) adsorbed at the surface of a vanadium oxide catalyst. The results suggest that the interaction between adsorbed molecules via the catalyst may be particularly important for weakly chemisorbed species. For a pair of identical, weakly adsorbed molecules this interaction may (for some relative orientations) affect to some extent the conclusions obtained for a single admolecule, which may be of some relevance at high coverages. The interaction between unlike admolecules is normally expected to result in complete electron transfer to the molecule which is more strongly chemisorbed, but for some relative orientations of the two molecules substantial back donation may take place. This fact may have some consequences for the dependence of the reaction yield on reactant concentration.