The effect of O₂ addition on the carbon dioxide reforming of methane over Pt/ZrO₂ catalysts

Pt/ZrO₂, Pt/Al₂O₃ and Ni/Al₂O₃ catalysts were found to be active in the temperature range 550-800°C under the conditions for both CO₂ reforming and partial oxidation of methane; of those, the Pt/ZrO₂ material was found to be least prone to deactivation. Combined CO₂ reforming and partial oxidation of methane was used to produce synthesis gas over the Pt/ZrO₂ catalyst. Higher yields of synthesis gas were obtained at lower temperatures than would be obtained with CO₂ reforming of methane alone. Combining the endothermic carbon dioxide reforming reaction with the exothermic partial oxidation reaction, hot spots in the catalyst bed were reduced significantly. Furthermore, the loss of activity of the catalyst with time on stream decreased with the amount of O₂ added to the feed stream; a small amount of carbon deposition occurred in parts of the catalyst bed which were not exposed to oxygen. The reaction pathway for the partial oxidation and the combined partial oxidation and reforming reactions appeared to be methane combustion followed by reforming of the remainder of the methane by the resultant CO₂ and steam.