IDENTIFICATION OF ACTIVE SPECIES AND THEORETICAL CLASSIFICATION OF SIMPLE CATALYST OXIDES USING SURFACE REDOX COUPLES

The concept of surface redox couples is used with a view to explaining quantitatively the activity of a number of simple oxides and, by using thermodynamical and structural parameters, to build a theoretical classification compatible with experimental ones. This approach makes it possible to identify the active surface redox couples and the corresponding active sites in oxidation reactions of probe molecules reported in the literature, including oxidation on de-activated catalysts. A near-linear correlation between experimental activities and oxygen adsorption-desorption enthalpies is observed and discussed, as well as the importance of some classification criteria.