Methane Electrochemical Oxidation Pathway over a Ni/YSZ and La 0.3 Sr 0.7 TiO 3 Bi-Layer SOFC Anode

Abstract

The electrochemical conversion of dry CH 4 was studied over a NiYSZ and La 0.3 Sr 0.7 TiO 3 bi-layer anode at 1023 K. In order to understand the electrochemical pathway, a fuel mixture composed of H 2 , CH 4 , CO, and CO 2 was fed to the SOFC anode while the gas products were analyzed at different current densities. In this fuel mixture, the Nernst potential and material balance, calculated from the H 2 electrochemical oxidation reaction, were consistent with the experimental OCV and the gas product analysis. In dry CH 4 fuel, the electrochemical oxidation pathway is more complex. The conversion of dry CH 4 strongly depends on the anode polarization. CO formed at low current densities (i < 0.1 Acm 2 ) from the electrochemical oxidation of carbon deposits, whereas H 2 O and CO 2 formed above this current density from the electrochemical oxidation of H 2 and CO. © 2012 The Electrochemical Society.