Influence of palladium precursors on oxidation of alumina-supported palladium

The oxidation phenomena of alumina-supported palladium prepared from various precursors has been investigated by a simultaneous thermogravimetric analysis–differential scanning calorimetric (TGA–DSC) technique over a wide temperature range between 250 and 900 K. Three different temperature ranges were found in oxidation on Pd(C)/Al2O3: chemisorption of dioxygen at 250–300 K; penetration of adsorbed oxide ions into sublayers at temperature over 300 K; and formation of a stable bulk oxide at 800 K. However, four different temperature ranges were found on Pd(N)/Al2O3: chemisorption of dioxygen at 250–300 K and further formation of unstable PdsO2 at 300–320 K; decomposition of PdsO2 into PdxsO at 320–420 K; penetration of adsorbed oxide ions into sublayers at temperature over 420 K; and formation of a stable bulk oxide at 800 K.