Sr(Ti0.3Fe0.7Ru0.07)O3-δ for applications in solid oxide fuel cells supplied with ethanol steam reforming mixtures

Direct utilization of alcohols in Solid Oxide Fuel Cells (SOFCs) can improve the conversion efficiency by using excess heat for internal reforming and simplify the system balance of plant. Thanks to their scarce carbon-formation tendency, perovskite oxide anodes are promising alternatives to Ni-based cermets. Here we show that Sr(Ti0.3Fe0.7Ru0.07)O3-δ (STF-Ru) exsolution anodes provide both catalytic reforming activity and electrochemical activity with steam/ethanol (S/E) mixtures at 3:1 and 2:1 M ratio between 700 and 800 °C. Electrolyte-supported scandia stabilized zirconia SOFCs with STF-Ru anodes and Sr0.95Ti0.3Fe0.7O3-δ (STF) cathodes are reasonably stable in the 3:1 S/E mixture over 20 h at 800 °C, with maximum power density of 195 mW/cm2 and 140 mW/cm2 at 0.7 V. Deactivation instead occurs with the 2:1 S/E mixture. Comparatively, cells with Ni-YSZ anodes rapidly coke and fail under the same conditions. Ethanol steam reforming experiments in a fixed bed powder reactor reveal that, above 650 °C, gas phase reactions convert ethanol to CO, hydrogen, acetaldehyde and ethylene, while STF-Ru catalyzes steam reforming. Thermogravimetric and Raman characterizations show that a moderate amount of carbon is deposited on the STF-Ru surface, which is more amorphous than the disruptive carbon which degrades Ni-YSZ.