TY - JOUR
T1 - Catalytic properties of the perovskite oxide La0.75Sr0.25Cr0.5Fe0.5O3-d in relation to its potential as an SOFC anode material
AU - Tao, Shanwen
AU - Irvine, John Thomas Sirr
PY - 2004/10/19
Y1 - 2004/10/19
N2 - Natural gas is an extremely attractive fuel for use in fuel cells. Steam-reforming and oxidation of methane are particularly important for the direct methane fuel cell. A perovskite-related material, La0.75Sr0.25Cr0.5Fe0.5O3-delta (LSCrF), has been synthesized, and its catalytic properties as a potential anode material for solid oxide fuel cells (SOFCs) have been examined. The material exhibits an overall orthorhombic structure with a = 5.4926(5) Angstrom, b = 5.5339(4) Angstrom, c = 7.7646(8) Angstrom, and V = 236.01(5) Angstrom(3) according to the X-ray data. It is at its limit of stability under reducing SOFC anode conditions. An 11% conversion for methane steam-reforming was observed at 900 degreesC when the steam-to-methane ratio was 1/1. A conversion of 68% for methane oxidation with a CO2 selectivity of 99% was achieved at 900 degreesC when an equimolar mixture of CH4 and O-2 was introduced into the reactor. The partial or complete oxidation depends on both temperature and the pO(2)/pCH(4) ratio. Therefore, LSCrF is a good catalyst for methane-reforming and oxidation. LSCrF is a methane complete oxidation catalyst when close to oxygen stoichiometric and a methane partial oxidation catalyst when the oxygen vacancy content increases. The anode polarization resistances in wet 5% H-2/Ar and wet H-2 are about 1.79 and 1.15 Omega cm(2), respectively, at 850 degreesC. This was improved to 0.98 Omega cm(2) in wet H-2 when the operation temperature was increased to 900 degreesC, but this is still too high for a viable SOFC electrode system.
AB - Natural gas is an extremely attractive fuel for use in fuel cells. Steam-reforming and oxidation of methane are particularly important for the direct methane fuel cell. A perovskite-related material, La0.75Sr0.25Cr0.5Fe0.5O3-delta (LSCrF), has been synthesized, and its catalytic properties as a potential anode material for solid oxide fuel cells (SOFCs) have been examined. The material exhibits an overall orthorhombic structure with a = 5.4926(5) Angstrom, b = 5.5339(4) Angstrom, c = 7.7646(8) Angstrom, and V = 236.01(5) Angstrom(3) according to the X-ray data. It is at its limit of stability under reducing SOFC anode conditions. An 11% conversion for methane steam-reforming was observed at 900 degreesC when the steam-to-methane ratio was 1/1. A conversion of 68% for methane oxidation with a CO2 selectivity of 99% was achieved at 900 degreesC when an equimolar mixture of CH4 and O-2 was introduced into the reactor. The partial or complete oxidation depends on both temperature and the pO(2)/pCH(4) ratio. Therefore, LSCrF is a good catalyst for methane-reforming and oxidation. LSCrF is a methane complete oxidation catalyst when close to oxygen stoichiometric and a methane partial oxidation catalyst when the oxygen vacancy content increases. The anode polarization resistances in wet 5% H-2/Ar and wet H-2 are about 1.79 and 1.15 Omega cm(2), respectively, at 850 degreesC. This was improved to 0.98 Omega cm(2) in wet H-2 when the operation temperature was increased to 900 degreesC, but this is still too high for a viable SOFC electrode system.
KW - SOFC ANODE
KW - METHANE
KW - OXIDATION
KW - TEMPERATURE
KW - STABILITY
UR - http://www.scopus.com/inward/record.url?scp=6344263497&partnerID=8YFLogxK
UR - http://pubs.acs.org/cgi-bin/article.cgi/cmatex/2004/16/i21/pdf/cm049341s.pdf
U2 - 10.1021/cm049341s
DO - 10.1021/cm049341s
M3 - Article
SN - 0897-4756
VL - 16
SP - 4116
EP - 4121
JO - Chemistry of Materials
JF - Chemistry of Materials
ER -