Kinetic study of a ceria-promoted Mo2C/γ-Al2O3Mo2C/γ-Al2O3 catalyst in dry-methane reforming

The kinetics of dry-methane reforming has been studied over a ceria-promoted Mo2C/γ-Al2O3Mo2C/γ-Al2O3 (3 wt% Ce, 30 wt% Mo) catalyst at temperatures between 800 and 900∘C, and at CH4CH4 and CO2CO2 partial pressures up to 0.31 bar. Oxidation of the Mo2CMo2C catalyst, which has plagued earlier kinetic studies, was avoided by co-feeding CO to produce a CO:CO2CO:CO2 ratio of 3. The activation energy obtained from the data fit to a power law rate expression of 45.5 kcal/mol was found to be similar to that of bulk Mo2CMo2C. However, the activity of the ceria-promoted catalyst, on a per unit mass of Mo2CMo2C, was significantly higher than that of the bulk and is attributed to the higher metal dispersion of the former. A reaction mechanism, involving CH4CH4 activation on Mo2CMo2C particles and CO2CO2 activation on both ceria and Mo2CMo2C particles, with carbidic carbon extraction by oxygen on ceria as the rate-determining step, is consistent with the derived kinetic model and the high activation energy.