Proton transfer in SrCeO3-based oxide with internal reformation under supply of CH4 and H2O

Mass and charge transfer in a proton-conducting ceramic with internal reformation under the supply of CH4 + H2O was experimentally investigated for application to a fuel detritiation system of a fusion reactor. The oxide used in the present experiment was SrCe0.95Yb0.05O3−a, and the electrodes were composed of Ni–SiO2 paste and Ni wire mesh. The system was described by CH4 + H2O∣Ni∣SrCe0.95Yb0.05O3−a∣NiO∣O2 + H2O. Plots of the I–V (electric current density versus cell potential) characteristic curve were determined under the conditions of different H2O/CH4 concentration ratios and temperatures of 600–800 °C. It was found that the system could work well even without any external CH4 reformer. Mass-transfer process in/on the porous Ni electrode and in the ceramic electrolyte was experimentally clarified. The distribution of carbon depositions in the porous electrode was also determined with EDX by scanning over entire surface in the scope of SEM. The ratio of CH4 to H2 direct decomposition to its steam-reforming reaction was found to be different from location to location in the porous Ni electrode.