Ce_(0.9)Sr_(0.1)VO_x (x = 3,4) as anode materials for H_2S-containing CH_4 fueled solid oxide fuel cells

摘要

The stability and activity in 0.5% H_2S-CH_4 of Ce_(0.9)Sr_(0.1)VO_3 and Ce_(0.9)Sr_(0.1)VO_4 anode materials for H_2S-containing CH_4 fueled SOFCs have been determined. XRD showed that Ce_(0.9)Sr_(0.1)VO_4 was reduced when the fuel gas was 0.5% H_2S-CH_4, while Ce_(0.9)Sr_(0.3) VO_3 remained stable over 24 h at 950℃. Electrochemical tests in 0.5% H_2S_CH_4 showed stable performance at 950 and 800 C for cells comprising Ce_(0.9)Sr_(0.1)VO_3|YSZ|Pt. Comparison of fuel cell performances using 0.5% H_2S_CH_4,0.5% H_2S-N_2 and 5%H-2S-N-2 as feeds showed that Ce_(0.9)Sr_(0.1) VO_3 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 H-2S. Conductivity measurements showed there was an increase in conductivity in H_2S-containing environments, and that this increase resulted from a change in composition and structure from the oxide to monoclinic Ce_(0.9)Sr_(0.1)V(0,S)_3, as evidenced by XPS and XRD analyses.