Oxidation Activity and Acid-base Properties of Mixed Oxide Catalysts Containing Titania. II. The TiO2–V2O5–P2O5 System

Abstract

Abstract The acidity and basicity of a series of TiO2–V2O5–P2O5(atomic ratio Ti : V : P=9 : 1 : x) catalysts with different P2O5 contents (x=0–18), were measured by studying the adsorption of the basic and acidic molecules in the gas phase, using both the static and pulse methods. TiO2–V2O5(V/Ti=1/9) is rather basic, but this catalyst can be modified from basic to acidic by the introduction of P2O5. The vapor-phase oxidation of butadiene and 1-butene, which were chosen as electron-donor-type reactants, and that of acetic acid, as an acidic reactant, were carried out in the presence of an excess of air, and then the relationship between the catalytic behavior and the acid-base properties was investigated. The results support an earlier proposal that the activity and selectivity in mild oxidation can be interpreted in terms of the acid-base properties of the catalyst and the reactant.