(112h) Effect of ZnO Morphology on Methanol Steam Reforming Activity of Pd/ZnO Catalysts
Pd/ZnO/Al2O3 catalysts have been shown to be highly active for methanol steam reforming and selective towards production of CO2 and H2. Previous work has shown that Pd/ZnO catalysts prepared from an acidic precursor can etch the support, thus destroying the faceted morphology of the ZnO and leading to a decrease in activity. However, it has also been shown that preserving the ZnO facets leads to improved catalytic activity. It is not clear whether ZnO participates in this reaction through a bifunctional pathway. This work examines the role of ZnO by systematically investigating the catalytic activity of Pd/Zn-based samples prepared from faceted ZnO of different exposed facets (nanorods and flat plates), etched ZnO, and ZnAl2O4. Pd deposition on each support was carried out using incipient wetness technique with a PdAc precursor. The supports were characterized using BET, and the catalysts were characterized via XRD and SEM. Catalytic performance of each catalyst was then examined via methanol steam reforming (after forming PdZn particles in-situ). These results show that the ZnO surface morphology does play a role in affecting the reactivity of Pd based steam reforming catalysts.