Performance evaluation of WNi-CeO2 as anode in a solid oxide fuel cell fed by simulated biogas mixtures

In this work, tungsten and nickel formulation combined with CeO2 (CNWO) has been synthesized by inverse microemulsion and investigated as anode material for solid oxide fuel cell (SOFC) fed by biogas. Initially, the catalytic properties of the anode towards methane partial oxidation and combined reforming were examined by gas chromatography as a function of temperature. On the other hand, a single cell (CNWO/LDC/LSGM/LSCF) has been fabricated and tested with three simulated biogas mixtures (CH4/CO2/H2 70/25/5, 60/35/5 and 50/45/5) at the anode and static air at the cathode at 750, 800 and 850 °C. In addition, the effect of H2S (10 ppm (v)) incorporation in the biogas on the cell performance has been examined at 850 °C. The electrochemical behaviour of the cell has been evaluated using IV curves, impedance spectroscopy and load demands. The results revealed that the compound exhibits an optimum activity for both methane partial oxidation and combined reforming reactions. In cell, the best performance was obtained with the methane-rich biogas at higher temperature probably due to better catalytic activity of CNWO in this operation condition. Furthermore, the presence of H2S in biogas causes an important decrease on the cell performance owing to the sulphuration reactions of anodic material and the effect of biogas quality diminishes. However, the stability tests under load demands during 1 h revealed that the cell does not suffer degradation under any studied operation conditions (biogas composition, temperature and H2S in the fuel). This suggests that CNWO could be a suitable anode material for direct-biogas SOFC.