Title:
Development of SOFC anodes resistant to sulfur poisoning and carbon deposition

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dc.contributor.advisor Liu, Meilin
dc.contributor.author Choi, Song Ho en_US
dc.contributor.committeeMember Gokhale, Arun M.
dc.contributor.committeeMember Christoper Summers
dc.contributor.committeeMember Preet Singh
dc.contributor.committeeMember Tom Fuller
dc.contributor.department Materials Science and Engineering en_US
dc.date.accessioned 2009-01-22T15:49:23Z
dc.date.available 2009-01-22T15:49:23Z
dc.date.issued 2007-11-14 en_US
dc.description.abstract The surface of a dense Ni-YSZ anode was modified with a thin-film coating of niobium oxide (Nb2O5) in order to understand the mechanism of sulfur tolerance and the behavior of carbon deposition. Results suggest that the niobium oxide was reduced to NbO2 under operating conditions, which has high electrical conductivity. The NbOx coated dense Ni-YSZ showed sulfur tolerance when exposed to 50 ppm H2S at 700°C over 12 h. Raman spectroscopy and XRD analysis suggest that different phases of NbSx formed on the surface. Further, the DOS (density of state) analysis of NbO2, NbS, and NbS2 indicates that niobium sulfides can be considered as active surface phases in the H2S containing fuels. It was demonstrated that carbon formation was also suppressed with niobium oxide coating on dense Ni-YSZ in humidified CH4 (3% H2O) at 850ºC. In particular, under active operating conditions, there was no observable surface carbon as revealed using Raman spectroscopy due probably to electrochemical oxidation of carbon. Stable performances of functional cells consisting of Pt/YSZ/Nb2O5 coated dense Ni-YSZ in the fuel were achieved; there was no observable degradation in performance due to carbon formation. The results suggest that a niobium oxide coating has prevented carbon from formation on the surface probably by electrochemically oxidation of carbon on niobium oxide coated Ni-YSZ. On the other hand, computational results suggest that, among the metals studied, Mo seems to be a good candidate for Ni surface modification. Ni-based anodes were modified with Mo using wet-impregnation techniques, and tested in 50 ppm H2S-contaminated fuels. It was found that the Ni-Mo/CeO2 anodes have better sulfur tolerance than Ni, showing a current transient with slow recovery rather than slow degradation in 50 ppm H2S balanced with H2 at 700°C. en_US
dc.description.degree Ph.D. en_US
dc.identifier.uri http://hdl.handle.net/1853/26601
dc.publisher Georgia Institute of Technology en_US
dc.subject Coking en_US
dc.subject Carbon deposition en_US
dc.subject Solid oxide fuel cell en_US
dc.subject Sulfur poisoning en_US
dc.subject.lcsh Solid oxide fuel cells
dc.subject.lcsh Anodes
dc.subject.lcsh Carbon
dc.subject.lcsh Niobium oxide
dc.subject.lcsh Nickel alloys
dc.subject.lcsh Molybdenum
dc.subject.lcsh Sulfur
dc.title Development of SOFC anodes resistant to sulfur poisoning and carbon deposition en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Liu, Meilin
local.contributor.corporatename School of Materials Science and Engineering
local.contributor.corporatename College of Engineering
relation.isAdvisorOfPublication 30dd1bbc-edf1-406a-9183-d985863cbab3
relation.isOrgUnitOfPublication 21b5a45b-0b8a-4b69-a36b-6556f8426a35
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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