Comparative study on partial oxidation of methane over Ni/ZrO2, Ni/CeO2 and Ni/Ce-ZrO2 catalysts

The partial oxidation of methane has been studied by sequential pulse experiments with CH4 --> O-2 --> CH4 and simultaneous pulse reaction of CH4/O-2 (2/1) over Ni/CeO2, Ni/ZrO2 and Ni/Ce-ZrO2 catalysts. Over Ni/CeO2, CH4 dissociates on Ni and the resultant carbon species quickly migrate to the interface of Ni-CeO2, and then react with lattice oxygen of CeO2 to form CO. A synergistic effect between Ni and CeO2 support contributes to CH4 conversion. Over Ni/ZrO2, CH4 and O-2 are activated on the surface of metallic Ni, and then adsorbed carbon reacts with adsorbed oxygen to produce CO, which is composed of the main path for the partial oxidation of methane. The addition of ceria to zirconia enhances CH4 dissociation and improves the carbon storage capacity. Moreover, it increases the storage capacity and mobility of oxygen in the catalyst, thus promoting carbon elimination.