TITLE:
Influence of Dry Methane Reactions on the Cell Output Characteristics of Solid Oxide Fuel Cells
AUTHORS:
Hongxin You, Bin Qu, Guoqing Guan, Abudula Abuliti
KEYWORDS:
Solid Oxide Fuel Cell, Reaction, Methane, Output Performance
JOURNAL NAME:
American Journal of Analytical Chemistry,
Vol.6 No.4,
February
28,
2015
ABSTRACT: In order to study the influence
of dry methane concentration on outputs in solid oxide fuel cells (SOFCs), the output
performance was obtained for dry methane of different concentrations on a Ni-ScSZ
anode in solid oxide fuel cells, and the anode exhaust gas was measured by online
chromatography. The underlying causes of the output performance change were analyzed
from the anode reactions by summarizing the anode exhaust gas regular pattern for
different reactions, and analyzing the electrochemical reaction kinetics of methane
with oxygen ion. As the oxygen ion concentration at the anode three-phase boundary
proportionally increased with current density, the following reactions occurred
for different dry methane concentrations in sequence CH4 + O2﹣ → CO + 2H2 +
2e﹣, CH4 + 2O2﹣ → CO + H2O +
H2 + 4e﹣, CH4 + 3O2﹣ → CO + 2H2O
+ 6e﹣, CH4 + 4O2﹣ → CO2 + 2H2O
+ 8e﹣. With various concentrations
of methane at a low current, the outlet methane continuously reduced with the increase
of the current density. Meanwhile, CO and H2 exhaust gas increased with
increasing current density for low concentration of methane. With methane concentrations
at 3.85% and 5.66%, the cell output voltage dropped rapidly. For concentrations
of 29.7% and 3.85%, the anode exhaust residual methane changed irregularly with
current density and this phenomenon was associated with the dry methane that reacted
on anode of the cell. The transformation of reactions, the water produced in the
electrochemical reactions and the polarization in response to the change of reactions
maybe induced the output voltage and power density reducing as low concentrations
of dry methane were used.