Methanol steam reforming over Ni-CeO2 model and powder catalysts: Pathways to high stability and selectivity for H2/CO2 production

Nickel-ceria has been reported as a very good catalysts for the reforming of methane. Here, the methanol steam reforming reaction on both powder (Ni-CeO2) and model (Ni-CeO2-x(111)) catalysts was investigated. The active phase evolution and surface species transformation on powder catalysts were studied via in situ X-ray diffraction (XRD) and diffuse reflectance infrared transform spectroscopy (DRIFTS). Phase transitions of NiO → NiC → Ni and CeO2 → CeO2-x were observed during the reaction. The simultaneous production of H2/CO2 demonstrates that the active phase of the catalysts contains metallic Ni supported over partially reduced ceria. The DRIFTS experiments indicate that a methoxy to formate transition is associated with the reduction of ceria whereas the formation of carbonate species results from the presence of metallic Ni. A study of the reaction of methanol with Ni-CeO2-x(111) by X-ray photoelectron spectroscopy (XPS) points to the essential role of metal-support interactions in an oxygen transfer from ceria to Ni that contributes to the high selectivity of the catalysts.