Revealing the Promoting Effect of CeO₂ on the Cu/ZnO Catalyst for Methanol Steam Reforming

Cu-based catalysts have been extensively used in methanol steam reforming (MSR) reactions because of their low cost and high efficiency. ZnO is often used in commercial Cu-based catalysts as both a structural and an electronic promoter to stabilize metal Cu nanoparticles and modify metal–support interfaces. Still, the further addition of chemical promoters is essential to further enhance the MSR reaction performance of the Cu/ZnO catalyst. In this work, CeO₂-doped Cu/ZnO catalysts were prepared using the coprecipitation method, and the effects of CeO₂ on Cu-based catalysts were systematically investigated. Doping with appropriate CeO₂ amounts could stabilize small Cu nanoparticles through a strong interaction between CeO₂ and Cu, leading to the formation of more Cu⁺–ZnO_x interfacial sites. However, higher CeO₂ contents resulted in the formation of larger Cu nanoparticles and an excess of Cu⁺–CeO_x interfacial sites. Consequently, the Cu/5CeO₂/ZnO catalyst with maximal Cu–ZnO interfaces exhibited the highest H₂ production rate of \({94}{\text{.6}}\;{\text{mmol}}_{{{\text{H}}_{{2}} }} {\text{/(g}}_{{{\text{cat}}}} \cdot {\text{h)}}\) $94\text{.6}{\text{mmol}}_{{\text{H}}_2}{\text{/(g}}_{\text{cat}}·\text{h)}$ , which was 1.5 and 10.2 times higher than those of Cu/ZnO and Cu/CeO₂, respectively.