Effect of the steam-methane ratio on reactions occurring on Ni/yttria-stabilized zirconia cermet anodes used in solid-oxide fuel cells

Journal Article · Thu Jul 01 04:00:00 EDT 1999 · Journal of the Electrochemical Society

DOI:https://doi.org/10.1149/1.1391959· OSTI ID:680048

Ihara, Manabu; Yokoyama, Chiaki ^[1]; Abudula, Abulet; Kato, Ryuzaburo; Komiyama, Hiroshi; Yamada, Koichi ^[2]

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1. Tohoku Univ., Sendai (Japan). Inst. for Chemical Reaction Science
2. Univ. of Tokyo (Japan). Dept. of Chemical System Engineering

Power-generation experiments of solid-oxide fuel cells with Ni/yttria-stabilized zirconia cermet anodes were carried out by changing the water-to-methane ratio in the fuel. To separate the electrochemical reactions occurring on the three-phase boundary of the anode from the steam-reforming reactions, premixed gases corresponding to the composition at thermal equilibrium were used as the fuel. The reactions on the anode were quantitatively clarified at different steam-to-methane ratios by making a mass balance of the elements and electrons and by determining the anode exit gas composition. For dry (i.e., no water) methane fuel, the carbon deposited on the three-phase boundary from the methane mainly reacted with oxide ions (O{sup 2}{sup {minus}}). With increasing steam-carbon (S/C) ratio from S/C = 0.5 to 1, hydrogen became the dominant reactant. The anode potential vs. current density for S/C = 1 agreed with that for hydrogen diluted with argon. At S/C ratios higher than 1.5, CO in the inlet gas reacted with oxide ions.

• OSTI ID: 680048
• Journal Information: Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 7 Vol. 146; ISSN JESOAN; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
08 HYDROGEN
30 DIRECT ENERGY CONVERSION
ANODES
NATURAL GAS FUEL CELLS
NICKEL
SOLID ELECTROLYTE FUEL CELLS
STEAM REFORMER PROCESSES
YTTRIUM OXIDES
ZIRCONIUM OXIDES