Microcalorimetric investigation of the acidity and basicity of metal oxides

The acidity and basicity of about twenty simple oxides mainly used in catalysis and ceramic materials were investigated by adsorption microcalorimetry of basic and acidic gas probe molecules such as ammonia and carbon dioxide. The determination of the number, strength and site energy distribution of both acidic and basic sites in all the samples led to an improved description of the surfaces. The results allowed us to classify our samples in three main groups in relation to their acidic, basic or amphoteric character. Their acid-base behaviour was tentatively correlated to more general electronic and redox data given in the literature such as the electronegativity.