Active Sites for the Reaction of Ethanol to Acetaldehyde on Co/YSZ(100) Model Steam Reforming Catalysts

Structure-activity relationships for the reaction of ethanol on model Co/YSZ(100) (YSZ = yttria-stabilized ZrO(2)) steam reforming catalysts were investigated using temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy and compared with those obtained previously for the reaction of ethanol on Co/ZnO(0001) and Co foils. Oxygen-free, metallic Co sites were found to be active for ethanol decarbonylation to form CO, H(2), and adsorbed CH(3) groups, whereas oxygen adatoms on metallic Co promoted ethoxide dehydrogenation to produce acetaldehyde at 330 K during TPD. In contrast, oxidized Co surfaces containing only Co(2+) sites were found to be less reactive for ethanol dehydrogenation producing acetaldehyde at 480 K. These results, along with comparisons with those from Co/ZnO(0001) and Co foils, provide new insights into the active site for ethanol steam reforming on Co-based catalysts and the influence of the support on both catalyst reactivity and stability.