Effects of the surface adsorbed oxygen species tuned by rare-earth metal doping on dry reforming of methane over Ni/ZrO₂ catalyst

During dry reforming of methane, oxygen species over the catalyst surface play an important role in CH₄/CO₂ reactivity, catalytic performance and carbon deposition. Herein, the effects of the surface adsorbed oxygen species tuned by doping with different rare-metal metals (such as Ce, La, Sm and Y) on the catalytic behavior were elaborated systematically. It was found that Y-doped catalyst exhibited the most amount of surface adsorbed oxygen species, followed by Sm, La, Ce and non-doped catalysts. The results confirmed that the surface adsorbed oxygen species were remarkably beneficial to enhance both CO₂ activation and CH₄ dissociation. Nevertheless, carbon formation and removal did not keep pace at low temperature due to more promotional effects of the surface adsorbed oxygen species on CH₄ dissociation than CO₂ activation. The gap between carbon deposition and removal was potential to be ameliorated through the accelerated activation to CO₂ at high temperature.