STRUCTURE SENSITIVITY, SELECTIVITY, AND ADSORBED INTERMEDIATES IN THE REACTIONS OF ACETONE AND 2-PROPANOL ON THE POLAR SURFACES OF ZINC-OXIDE

The reactions of 2-propanol and acetone on the (0001)-Zn and (0001)-O polar surfaces of zinc oxide were investigated by using temperature-programmed desorption and X-ray photoelectron spectroscopy. 2-Propanol adsorbed dissociatively on the (0001)-Zn surface to form surface isopropoxide ((CH3)2HCO) species. These alkoxide intermediates underwent both dehydration and dehydrogenation reactions to produce propylene and acetone. Acetone dissociated on the (0001)-Zn surface to form enolate intermediates, fingerprinted by a broad envelope in the C(1s) spectrum. These enolates decomposed unselectively above 600 K to deposit carbon, which was oxidized to CO and CO2 at higher temperatures. Neither acetone nor 2-propanol reacted on the oxygen polar surface, and both were adsorbed molecularly and desorbed intact from this surface below 300 K.