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

IR spectra have been measured following adsorption of butane and prope ne on reduced Pt/CeO2-Al2O3 catalysts containing 0-20% CeO2 and also o n catalysts exposed to O-2 at ambient temperature. Adsorption of butan e on oxidised catalysts containing CeO2 produced surface formate and h ydrogencarbonate species on Al2O3 after it was heated to 350 degrees C , although these species were not formed in the absence of CeO2. By co ntrast, adsorption of butane on reduced catalysts yielded either surfa ce 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 p rovided evidence for Pt site deactivation after adsorption of butane. Adsorption of propene on reduced catalysts yielded adsorbed CO and eit her surface acrylate (Pt/Al2O3) or carbonate (Pt/CeO2-Al2O3) on heatin g to 350 degrees C. Subsequent exposure to O-2 at ambient temperature, followed by heating to 450 degrees C, resulted in the desorption of a ll surface species. These observations are interpreted in terms of the electronic theory of catalysis and a strong Pt-CeO2 interaction.