Characterization of ZrO_2-promoted Cu/ZnOano-Al_2O_3 methanol steam reforming catalysts

摘要

Three Cu/ZnO/ZrO_2/Al_2O_3 methanol reforming catalysts were investigated using X-ray photoelectron spectroscopy (XPS). The catalysts which contained ZrO_2 from a monoclinic nanoparticle ZrO_2 precursor exhibit both a higher activity toward the methanol steam reforming reaction and a lower CO production rate compared to catalysts composed of an XRD-amorphous ZrO_2 produced by impregnation using a Zr(NO_3)_2 precursor. The presence of a monoclinic phase appears to result in an increased charge transfer between the Zr and Cu species, as evidenced by a relatively electron-rich ZrO_2 phase and a partially oxidized Cu species on reduced catalysts. This electron deficient Cu species is more reactive toward the methanol reforming reaction and partially suppresses CO formation through the reverse water gas shift or methanol decomposition reactions.