Simple mechanisms of CH4 reforming with CO2 and H2O on a supported Ni/ZrO2 catalyst.

To understand the metal-support interaction of oxide supported transition metal catalysts, we computed the reaction mechanisms of dry and steam reforming of methane on tetragonal ZrO2(101) supported Ni catalyst. Based on the limited number of active sites on the surface, an irregular and non-idea Ni13 cluster on ZrO2(101) is identified as catalyst. A simple reaction mechanism is proposed and the first direct dissociation step of CO2, CH4 and H2O is most difficult based on the computed Gibbs free energies and no surface CHXO and CHXOH intermediates are involved, different from that on the flat Ni(111) surface. Analysis into other supported nickel catalysts shows that not only support but also size and shape of metal clusters play an important role in reaction mechanisms and kinetics.