Pathways of Methanol Steam Reforming on PdZn and Comparison with Cu

PdZn alloy has been shown to catalyze methanol steam reforming (MSR), producing hydrogen gas and carbon dioxide with high selectivity. Despite many studies, the mechanism for MSR on this catalyst is still not completely understood. In this work, several possible pathways of MSR are explored using a plane-wave density functional theory. The focus is placed on the reaction network starting from a facile reaction between adsorbed formaldehyde and hydroxyl species, produced from the decomposition of methanol and water, respectively. These pathways were found to have barriers lower than the rate-limiting step, namely, the dehydrogenation of methoxyl, and they involve species that have been detected in various experiments. Interestingly, the reaction pathways share many similarities with the MSR process on copper, which is the traditional catalyst for MSR.