Comparison of the group V and VI transition metal carbides for methane dryreforming and thermodynamic prediction of their relative stabilities

The group V and VI transition metal carbides have been prepared by CH4 TPR, and tested for the dry reforming of methane with carbon dioxide, at elevat ed pressure. Mo2C and WC were the most stable catalysts, while the group V metal carbides showed the stability order: vanadium > niobium > tantalum. C atalyst deactivation was due to carbide oxidation with CO2, while stability was associated with the reaction of metal oxide (from deactivation) with C H4, giving the metal carbide. Calculation of the Gibbs free energy for this reaction resulted in a predicted catalyst stability trend similar to that obtained experimentally.