The Nature of Interfacial Catalysis over Pt/NiAl2O4 for Hydrogen Production from Methanol Reforming Reaction

Reforming of methanol is one of the most favorable chemical processes for on-board H₂ production, which alleviates the limitation of H₂  storage and transportation. The most important catalytic systems for  methanol reacting with water are interfacial catalysts including  metal/metal oxide and metal/carbide. Nevertheless, the assessment on the  reaction mechanism and active sites of these interfacial catalysts are  still controversial. In this work, by spectroscopic, kinetic, and  isotopic investigations, we established a compact cascade reaction model  (ca. the Langmuir–Hinshelwood model) to describe the methanol and water  activation over Pt/NiAl₂O₄. We show here that  reforming of methanol experiences methanol dehydrogenation followed by  water–gas shift reaction (WGS), in which two separated kinetically  relevant steps have been identified, that is, C–H bond rupture within  methoxyl adsorbed on interface sites and O–H bond rupture within O_lH (O_l:  oxygen-filled surface vacancy), respectively. In addition, these two  reactions were primarily determined by the most abundant surface  intermediates, which were methoxyl and CO species adsorbed on NiAl₂O₄  and Pt, respectively. More importantly, the excellent reaction  performance benefits from the following bidirectional spillover of  methoxyl and CO species since the interface and the vacancies on the  support were considered as the real active component in methanol  dehydrogenation and the WGS reaction, respectively. These findings  provide deep insight into the reaction process as well as the active  component during catalysis, which may guide the design of new catalytic  systems.