Abstract:
A qualitative survey of available data has enabled pure oxides to be divided into five groups according to their catalytic activity. Zeolites are less active than oxides corresponding to their cationic forms. The activity of an oxide catalyst either increases continuously or passes through a maximum with increase in its temperature of ignition. This type of dependence is explained by the surface dehydroxylation model on the assumption that the activity is determined by the presence of electron-donating and electron-accepting sites situated side by side on the surface. The hydrogenation of alkenes involves stages of activation of the alkene and of hydrogen, with on most oxides appearance of a semi-hydrogenated form. A list of 91 references is included.