(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.