(732a) Zn Modification of the Reactivity of Pd(111) and Co(0001) towards Ethanol and Acetaldehyde

Methanol and ethanol have been proposed as potential bio-renewable sources of hydrogen. The use of alcohols, however, as a source of H₂ or for H₂ storage requires stable reforming catalysts that have high activity at low temperatures. Pd on ZnO is one potential catalyst for this reaction since it exhibits an unusually high selectivity (>95%) for the production of CO₂ and H₂ from methanol, in spite of the fact that bulk Pd exhibits nearly 100 % selectivity for the dehydrogenation of CH₃OH to CO and H₂ under typical SRM conditions. Pd/ZnO and Co/ZnO also exhibit high selectivity to CO₂ for the steam reforming of ethanol. Recent results from our group have illustrated how alloying the Pd with Zn affects the dehydrogenation of CH₃OH and CH₂O on Pd/ZnO catalysts. In this talk we will give an overview of this work and also describe our more recent TPD and HREELS studies of the adsorption of C₂H₅OH and CH₃CHO on model catalysts consisting of sub-monolayer amounts of Zn on Pd(111). Results for the adsorption of these molecules on Co(0001) and Zn/Co(0001) model catalysts will also be presented. Overall, these studies provide new fundamental insight into how Zn alters the reactivity of Pd and Co for the dehydrogenation of C₂H₅OH and is useful in elucidating the mechanism of the steam reforming of ethanol on these catalysts.