(560a) An Investigation of the Interaction Between Catalyst and Support in Pd/ZnO and Co/ZnO Catalyzed Alcohol Decomposition

Zinc oxide has been demonstrated as an effective support for catalytic alcohol steam reforming, a potential means to produce hydrogen from biorenewable sources. For Pd catalyzed methanol steam reforming, the presence of ZnO alters the reaction pathway such that CO2 is the primary carbonaceous product rather than CO, which needs to be removed from the hydrogen stream. Likewise, ZnO enhances selectivity of Co catalyzed ethanol steam reforming. While there is some understanding of how ZnO influences these reactions, further examination of the interaction between the catalyst and ZnO support is necessary to develop a comprehensive picture.

To investigate the interaction, we performed experiments on model Pd/ZnO and Co/ZnO catalysts. The metals were vapor deposited on ZnO(0001) and ZnO(10-10) single crystals in ultrahigh vacuum chambers. X-ray photoelectron spectroscopy (XPS) and CO temperature programmed desorption (TPD) spectroscopy were used to characterize the structural and electronic properties of the catalysts. Methanol and ethanol TPD were used to characterize the catalytic alcohol decomposition activity.

In this talk, we present findings of this investigation identifying a dependence on the ZnO crystal plane on the catalyst properties. Additionally, we reveal the complex behavior of Co on ZnO, in particular the tendency to disperse when oxidized and replace Zn in the oxide lattice. Finally, we will make connections between our investigation using model catalysts and those using ?real world? catalysts.