Reactions on Ni-YSZ cermet anode of solid oxide fuel cells during internal steam reforming of n-octane

Abstract

Direct n-octane combustion is demonstrated with a solid oxide fuel cell (SOFC) with a porous nickel and yttria-stabilized zirconia (Ni-YSZ) cermet anode. We systematically investigate the influences of the steam/carbon ratio (S/C) and the cell temperature on the internal steam reforming reaction and the electrochemical reaction on the anode by evaluating short-term power generation. The n-octane is fully reformed to H2, CO, C, CO2, CH4, and/or C2H6 by internal steam reforming, and is considered a suitable fuel for obtaining high yields of H2 and CO, which are important for achieving high power generation efficiency. However, very little deposited carbon is consumed, and the carbon deposition is not suppressed even under the maximum power generation conditions at 950 °C and an S/C ratio of 1.0. At an S/C ratio of more than 1.0, the open-circuit voltage and power generation are unstable. In addition, the concentration overpotential is remarkably large, resulting in a decrease in the power density.