PHYSICOCHEMICAL AND CATALYTIC STUDIES ON THE CALCINATION PRODUCTS OF BACRO4-CRO3 MIXTURE

The phase composition, electrical behaviour, and the catalytic activity towards H2O2 decomposition were studied for the products of the solid state reaction of BaCrO4-CrO3 mixture (1:1 molar ratio) in the temperature range 300-1000-degrees-C. Experimental evidence from acid-soluble chromate estimation and X-ray analysis revealed that the presence of the low melting point component CrO3 enhances the chromite spinel formation. On the basis of these experimental data together with those obtained from electrical conductivity measurements, a mechanism of chromite formation was suggested. The decisive role of surface Cr6+ ions in the catalytic decomposition reaction of H2O2 indicated the existence of these surface active centers in different energy states depending on the calcination temperature. This was also verified from the electrical conductivity measurements.