AN INVESTIGATION OF ANODES FOR DIRECT-OXIDATION OF CARBON IN SOLID OXIDE FUEL-CELLS

Several transition metal carbides were examined as anodes for the internal direct-oxidation of carbon in solid oxide fuel cells. Observed values of open-circuit voltage of carbide anode cells were found to be in the same order as the oxygen potentials calculated for the respective metal carbide/metal oxide equilibrium. All the carbide anodes investigated showed higher performance in polarization curves than graphite. The chemical stability of anodes under a polarized condition was estimated by thermochemical calculations. Based on this calculation and outlet gas analysis from the cells, a VC anode was able to activate carbon, while ZrC and TiC anodes were not able to activate carbon due to the oxidation of carbides. The redox reaction of anodes plays an important role for activating carbon in carbide anode cells.