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

Manabu Ihara, Chiaki Yokoyama, Abulet Abudula, Ryuzaburo Kato, Hiroshi Komiyama, Koichi Yamada

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

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 (O2-). 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.

Original languageEnglish
Pages (from-to)2481-2487
Number of pages7
JournalJournal of the Electrochemical Society
Volume146
Issue number7
DOIs
Publication statusPublished - 1999 Jul

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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