Performance of (La, Sr)(Cr, Mn)O₃ anode for direct oxidation of methane in solid oxide fuel cell

The pervoskite material, La_0.75Sr_0.25Cr _0.5Mn_0.5O₃ (LSCM), was synthesized through solid-state reactions and successfully applied as anode in solid oxide fuel cell for direct oxidation of methane. Optimum sintering temperature of 1200°C was found for the LSCM/YSZ composite anode (50 wt% LSCM/50 wt% YSZ). Although the performance of the composite anode is lower than a Ni/YSZ anode, it exhibits high stability in methane. No carbon deposition and performance deterioration were observed for the LSCM/YSZ composite anode even if the dry methane was fed into the anode as the fuel. The observed OCV in 3% H₂O-97% CH ₄/Air for LSCM/YSZ/Pt system is much lower than the theoretical value calculated from the equilibrium concentration of the mixture gases, CH ₄, CO, CO₂, H₂O and H₂, implying the slow steam reforming processes of Cut at LSCM surface. The voltage difference between the experimental and simulation results decreases with the increase of the operating temperature (0.34 V at 750°C and 0.21 V at 950°C) suggesting that the high operating temperature favors the steam reforming processes of CU₄ at LSCM surface.