CO2-Reforming of Methane over Transition Metals

Catalysts based on Ni, Ru, Rh, Pd, Ir, and Pt are compared for CO2-reforming of methane by studying the equilibrium for methane decomposition, the activity for reforming, and carbon formation. as well as the selectivity for carbon formation. Replacing steam by carbon dioxide has no significant impact on the reforming mechanism. All catalysts show smaller equilibrium constants for methane decomposition than that based on graphite, the effect being largest for the noble metals. Ru and Rh show high selectivity for carbon-free operation, which can be ascribed to high reforming rates combined with low carbon formation rates. Similar high selectivity can be achieved with a sulfur-passivated nickel catalyst.