IR SPECTROSCOPIC STUDY OF BUTANE AND PROPENE ADSORPTION ON PT/CEO2-AL2O3 CATALYSTS

IR spectra have been measured following adsorption of butane and propene on reduced Pt/CeO2-Al2O3 catalysts containing 0-20% CeO2 and also on catalysts exposed to O-2 at ambient temperature. Adsorption of butane on oxidised catalysts containing CeO2 produced surface formate and hydrogencarbonate species on Al2O3 after it was heated to 350 degrees C, although these species were not formed in the absence of CeO2. By contrast, adsorption of butane on reduced catalysts yielded either surface CO alone (1-5% CeO2) or CO and carbonate (greater than or equal to 10% CeO2), after heating to 350 degrees C. CO adsorption experiments provided evidence for Pt site deactivation after adsorption of butane. Adsorption of propene on reduced catalysts yielded adsorbed CO and either surface acrylate (Pt/Al2O3) or carbonate (Pt/CeO2-Al2O3) on heating to 350 degrees C. Subsequent exposure to O-2 at ambient temperature, followed by heating to 450 degrees C, resulted in the desorption of all surface species. These observations are interpreted in terms of the electronic theory of catalysis and a strong Pt-CeO2 interaction.