Direct utilization of ethanol on ceria-based anodes for solid oxide fuel cells

The direct utilization of ethanol was investigated ill Cu-CeO2, Cu-Zr0.35Ce0.65O2 (ZDC) and Cu/Ru-Zr0.35Ce0.65O2 anodes for solid oxide fuel cells (SOFC). The anodes were prepared by impregnation with nitrate precursors on a porous layer of yttria-stabilized zirconia (YSZ) obtained by tape casting, while (La0.8Sr0.2MnO3-delta) LSM cathodes were screen-printed. The cells were tested in both hydrogen and ethanol. The Outlet gas composition was monitored with a gas chromatograph, which showed that almost all the ethanol was decomposed, mainly to H-2, CH4, CO, H2O and C2H4. The maximum power outputs obtained in ethanol were 0.075 and 0.400 W/cm(2) on Cu CeO2|YSZ|LSM and Cu-ZDC|YSZ|LSM, respectively. All cells were more active in alcohol than in hydrogen with the peak performance occurring after approximately 4 h. That is, the power density initially increased. peaked and then decreased. This behavior was likely a consequence of carbon deposition that initially results in all improvement of the electronic conductivity in the anode but later results in the blocking of the active sites. Zirconia doping (in the ZDC anodes) resulted in better stability and, in addition, the initial activity of the ZDC anodes could be recovered after approximately 1 h Of exposure to humidified hydrogen, whereas the initial activity of the ceria anodes could not he recovered. The addition of ruthenium (<0.5 wt%) further improved the stability by delaying the onset of carbon formation. (C) 2008 Curtin University of Technology and John Wiley & Sons, Ltd.