Use of a catalyst layer for propane partial oxidation in solid oxide fuel cells

In most solid oxide fuel cell (SOFC) designs the Ni-based anode acts as an effective catalyst for internal reforming. However, there are some SOFCs, e.g. segmented-in-series cells or ceramic anode cells, in which the anode may be less effective for internal reforming. In order to test this case, we have studied SOFCs supported on a thick ceramic layer. While these cells worked well with hydrogen fuel, the performance with propane-air mixtures was poor. The addition of a Ru-CeO₂ catalyst layer to the support surface yielded much better performance in propane-air. The catalyst promoted propane partial oxidation at temperatures ≥500°C without carbon formation. Gas diffusion limitations for the reformed fuel limited the performance at high temperature, e.g., ≈0.5 W/cm² at 750°C. The results are discussed based on calculated gas diffusion rates for different possible reaction pathways.