Behavior of Carbon Deposition on Fuel Electrode and Subsequent Deterioration of Cell Performance During Internal Reforming Operation of SOFCs

Abstract

Several cermet anodes were investigated for direct internal reforming operation of solid oxide fuel cells. The effects of steam and discharge conditions were examined for internal reforming operation with propane as a hydrocarbon fuel. Even at high steam-to-carbon (S/C) ratio, power generation characteristics with Ni-YSZ were deteriorated during internal reforming operation with propane at 1000åC, due to carbon formation at low current densities, whereas stable generation was observed for the cells with Ni-ScSZ or Ni-SDC anode by feeding propane at low S/C = 0.8. Carbon deposition rate was measured for several cermets by feeding dry or humidified methane by the gravimetric technique. The carbon deposition rate over Ni-ScSZ was lower than Ni-YSZ, leading to better generation performance with propane at low S/C. Ni-SDC showed the highest carbon deposition rate among the cermets investigated, even for humidified methane. This implies that carbon formed over Ni-SDC could be effectively removed upon power generation.