Ce0.9Sr0.1VOx (x=3, 4) as anode materials for H2S-containing CH4 fueled solid oxide fuel cells

The stability and activity in 0.5% H2S-CH4 of Ce0.9Sr0.1VO3 and Ce0.9Sr0.1VO4 anode materials for H2S-containing CH4 fueled SOFCs have been determined. XRD showed that Ce0.9Sr0.1VO4 was reduced when the fuel gas was 0.5% H2S-CH4, while Ce0.9Sr0.1VO3 remained stable over 24 h at 950 degrees C. Electrochemical tests in 0.5% H2S-CH4 showed stable performance at 950 and 800 degrees C for cells comprising Ce0.9Sr0.1VO3 vertical bar YSZ vertical bar Pt. Comparison of fuel cell performances using 0.5% H2S-CH4, 0.5% H2S-N-2 and 5% H2S-N-2 as feeds showed that Ce0.9Sr0.1VO3 was not active for oxidation of methane, but highly active for conversion of H2S. Electrochemical impedance results were consistent with the finding that the anode was activated only in an environment that contained H2S. Conductivity measurements showed there was an increase in conductivity in H2S-containing environments, and that this increase resulted from a change in composition and structure from the oxide to monoclinic Ce0.9Sr0.1V(O,S)(3), as evidenced by XPS and XRD analyses. (C) 2009 Elsevier B.V. All rights reserved.