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

Rare-earth element is efficient to enhance the surface adsorbed oxygen species. CH4 and CO2 reactivity are accelerated by the surface adsorbed oxygen species. Carbon deposition is mainly formed at the initial stage and subsequently inert. Rate gap between carbon deposition and removal is strongly affected by temperature. During dry reforming of methane, oxygen species over the catalyst surface play an important role in CH 4 /CO 2 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 CO 2 activation and CH 4 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 CH 4 dissociation than CO 2 activation. The gap between carbon deposition and removal was potential to be ameliorated through the accelerated activation to CO 2 at high temperature. [ABSTRACT FROM AUTHOR]