Surface processes on oxides and their significance for heterogeneous catalysis

Abstract

The initial processes whereby reactants are chemically activated for catalysis at the surfaces of ionic oxides are described. It is shown how charge transfer behaviour can be exploited and investigated for the alkaline earth oxides using ultraviolet-visible diffuse reflectance spectroscopy. Heterolytic dissociative adsorption of hydrogen-containing molecules is discussed, and the activation of carbon monoxide to form anionic coupled species on MgO and CaO is taken as a detailed example to which both UV-vis and IR spectroscopy have been applied. Reference is also made to solid solutions of alkaline earth oxides with transition metal oxides and their significance for catalysis, and finally the role of basic oxides as chemically-relevant supports for metals is indicated.