Carbon dioxide reforming of methane over Ni incorporated into Ce-ZrO2 catalysts

A co-precipitation/digestion method was employed in a single step to prepare Ni-Ce-ZrO2 catalysts useful for carbon dioxide reforming of methane. The loading amount of Ni and the ratio of CeO2 to ZrO2 were systematically varied to optimize the co-precipitated Ni-Ce-ZrO2 catalysts. The prepared catalysts were characterized by various physico-chemical characterization techniques such as XRD, BET surface area, hydrogen chemisorption, SEM, TPR and XPS. It was found that 15% Ni (w/w) co-precipitated with Ce0.8Zr0.2O2 having cubic phase gave synthesis gas with CH4 conversion more than 97% at 800 degreesC and such activity was maintained without significant loss during the reaction for 100 h. On the contrary, Ni-Ce-ZrO2 having tetragonal phase (Ce0.2Zr0.8O2) or mixed phase (Ce0.5Zr0.5O2) deactivated during the reaction due to carbon formation. The enhanced catalytic activity and stability of the co-precipitated Ni-Ce0.8Zr0.2O2 catalyst is attributed to a combination of the nano-crystalline nature of cubic Ce0.8Zr0.2O2 support and the finely dispersed nano-sized NiOx crystallites, resulting in the intimate contact between Ni and Ce0.8Zr0.2O2 particles. (C) 2004 Elsevier B.V. All rights reserved.