CARBON-DIOXIDE REFORMING OF METHANE TO SYNTHESIS GAS OVER SUPPORTED NI CATALYSTS

Carbon dioxide reforming of methane to synthesis gas has been investigated over supported Ni catalysts in the temperature range of 500-850 degrees C. Addition of CaO (10 mol%) promoter to the Ni/gamma-Al2O3 resulted in an increase of reaction rate and an improvement of catalyst stability, which may be related to enhanced reducibility of the promoted catalyst. The kinetic studies show that the overall reaction can be described by a Langmuir-Hinshelwood mechanistic scheme, assuming that methane dissociation is the rate determining step. In addition to adsorbed CO and formate species, three types of carbonaceous species, C-alpha, C-beta and C-gamma were found to exist on the Ni catalyst. While the active C-alpha species is suggested to be responsible for CO formation, the less active C-beta and C-gamma species are attributed to causing catalyst deactivation.