Hiroyuki ISHIGA
Electrochemical Cell Performance of a Sr(Zr0.95Y0.05)O3-¦Ò Added Ni-Co-YSZ Anode for the Oxidation of Methane
Kazunori SATO
Carbon deposition due to the methane decomposition and disproportionate reaction of carbon monoxide causes loss of cell performance and poor long-term stability of solid oxide fuel cells. In order to reduce the effect of carbon deposition on the degradation of cell performance, effects of the SrZr0.95Y0.05O3-¦Ä (SZY) incorporation into the Ni(Co)-YSZ (yttria-stabilized zirconia) cermet on the anodic oxidation of methane have been investigated. A cycle deterioration test, which was composed of repetitive cycles of the methane supply under the open circuit condition with a combination of the discharge state each at a fixed time at, was carried out at 800 degrees Celsius for the cell samples using the Ni-YSZ-5~30mass¡óSZY cermet anode. The cell using Ni-YSZ-10 mass%SZY (Ni-YSZ-SZY10) cermet anode showed the highest cell performance for the direct supply of methane. The anodic polarization measurement, exhaust gas analysis by gas choromatography, and microstructural characterization by X-ray diffraction and
electron microprobe analysis have revealed that the incorporation of SZY particles in the cermet anode reatard the carbon deposition. This effect is probably caused by the property of SZY, which can supply water molecules with proton to the methane-adsorbed surface. Reforming reaction for the adsorbed methane or water gas shift reaction for the adsorbed CO produced by the partial oxidation of methane seems to be effective for the activity of the direct oxidation of methane by oxide ions supplied through the YSZ electrolyte
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