Mechanistic studies of hydrogen production from methanol on palladium zinc catalysts

The rising energy demands of today\u27s economy require the development of a renewable energy supply system. Hydrogen has been proposed as an alternative to fossil fuels but issues about production and storage still remain. Methanol and ethanol have the potential of being bio-renewable sources of hydrogen but require the production of stable reforming catalysts that have high activity at low temperatures. Pd/ZnO is one potential catalyst for this reaction since it exhibits an unusually high selectivity (\u3e95%) for the production of CO2 and H2 from methanol. This catalyst also exhibits high selectivity to CO2 for the steam reforming of ethanol. Recent results have identified the alloying of Pd and Zn as a significant step in the activation of the Pd/ZnO catalyst but the reason for this is not understood. Therefore, in an effort to understand how Zn alters the reactivity of Pd, this thesis describes the use of surface science techniques, such as TPD and HREELS, to study of the kinetics and mechanisms of alcohol decomposition on PdZn. Overall the results show that through an ensemble and considerably long-rang electronic effect, Zn dramatically suppresses the catalytic behavior of Pd. This involves destabilizing the Pd-CO bond, dramatically reducing the dehydrogenation of adsorbed alcohols and aldehydes to CO, stabilizing the aldehyde intermediate produced from alcohol decomposition and altering the formate decomposition pathway to favor dehydrogenation over dehydration