The effect of a ceria coating on the H2S tolerance of a molten carbonate fuel cell

Devianto, Hary; Yoon, Sung Pil; Nam, Suk Woo; Han, Jonghee; Lim, Tae Hoon

doi:10.1016/j.jpowsour.2005.11.092

Cited by 63 publications

(38 citation statements)

References 4 publications

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“…(iii) The phase-predominance calculations are made for stoichiometric CeO 2 and do not include gadolinia doped ceria (GDC) or partially reduced GDC phases, but non-stoichiometric phases have very different oxygen chemical potentials in crystal lattice [54] and higher reactivity as well as adsorption activity compared with nondoped and non-reduced CeO 2 [32]. Another important detail is that there was no thermodynamic equilibrium in the studied system at working conditions, and only steady state conditions (flowing gas feeds and flow of oxide ions through the fuel cell membrane) have been established.…”

Section: Agreement Of Spectroscopic Results With Thermodynamic Predicmentioning

confidence: 99%

“…Slow decline in performance might also be caused by adsorption of sulphur on nickel surface grains which are more difficult to access, such as pores with bottlenecks [14], or, because of surface reconstruction or recrystallization of nickel grains from catalytically more active into catalytically less active crystallographic form [14], or, because of bulk phase diffusion of sulphur penetrating into Ni grains [14]. One possible reason of slow degradation could be the formation of Ce 2 O 2 S as well as Ce(SO 4 ) 2 at relatively low H 2 S concentrations in reaction with nonstoichiometric CeO n (n < 2), because reduced or doped ceria exhibits significantly larger affinity for H 2 S compared to CeO 2 used in theoretical calculations [20,32]. Thus, while there is some information about changes in electrical performance and degradation of electrode structure caused by sulphur at different conditions, there is no comprehensive explanation of the physico-chemical mechanisms which ultimately constitute sulphur poisoning.…”

Section: Introductionmentioning

confidence: 99%

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Redox dynamics of sulphur with Ni/GDC anode during SOFC operation at mid- and low-range temperatures: An operando S K-edge XANES study

Nurk

Huthwelker

Braun

et al. 2013

Journal of Power Sources

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h i g h l i g h t s g r a p h i c a l a b s t r a c tAn operando SOFC anode S-poisoning XAS experiment at 550 C to 250 C was performed. S K-edge XANES spectral information at Ni/GDC outer surface was collected.Intermediates with different sulphur oxidation states (6þ, 4þ, 0, 2À) were observed. Proportion of oxidation states changed as a function of temperature. Differences between TD calculations and XAS information were observed and discussed. a r t i c l e i n f o a b s t r a c t Sulphur poisoning of nickelebased solid oxide fuel cell (SOFC) anode catalysts is a well-documented shortcoming, but not yet fully understood. Here, a novel experiment is demonstrated to obtain spectroscopic information at operando conditions, in particular the molecular structure of sulphur species in the sulphur K-shell X-ray absorption near edge structure (XANES) region for a SOFC anode under realistic operando conditions, thus, with the flux of O 2À from cathode to anode. Cooling from T ¼ 550 C stepwise down to 250 C, 5 ppm H 2 S/H 2 reacting with Ni-gadolinium doped ceria (GDC) anode resulted in several sulphur species in different oxidation states (6þ, 4þ, 0, À2) and in amounts being at a minimum at high temperature. According to sulphur speciation analysis, the species could either relate to eSO 4 2À or SO 3 (g), eSO 3 2À or SO 2 (g), S 2 (g) or surface-adsorbed S atoms, and, Ni or Ce sulphides, respectively. The coexistence of different sulphur oxidation states as a function of temperature was analysed in the context of thermodynamic equilibrium calculations. Deviations between experimental results and calculations are most likely due to limitations in the speed of some intermediate oxidation steps as well as due to differences between stoichiometric CeO 2 used in calculations and partially reduced Ce 0.9 Gd 0.1 O 2Àd .

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Section: Agreement Of Spectroscopic Results With Thermodynamic Predicmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Redox dynamics of sulphur with Ni/GDC anode during SOFC operation at mid- and low-range temperatures: An operando S K-edge XANES study

Nurk

Huthwelker

Braun

et al. 2013

Journal of Power Sources

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“…CeO 2 is a widely used promoter with Ni to reduce sintering, enhance oxygen storage capacity (OSC), and increase sulfur tolerance since Ce-based oxides have excellent sulfidation thermodynamics in realistic reformate gas compositions, such as the ones produced by steam reforming, or coal gasification [15,[18][19][20][21][22]. The use of zirconia in A c c e p t e d M a n u s c r i p t 5 conjunction with ceria increases OSC, which is extremely important to the stability, redox property, activity and selectivity of the catalyst [12,[23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Molecular-size selective H-β zeolite-encapsulated Ce-Zr/Ni-Mg catalysts for steam reforming

Cimenler

Joseph

Kuhn

2015

Applied Catalysis A: General

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“…Furthermore, it is used in Molten Carbonate Fuel Cell (MCFC) as well. Coated on the anode, it can enhance its sulphur tolerance [6]. For both high temperature fuel cells applications, ceria coating could prevent or reduce the corrosion of the stainless steel bipolar plates [7].…”

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confidence: 99%

Synthesis and characterization of cerium oxide by electrochemical methods

Lair

Ringuedé

Vermaut

et al. 2008

Phys. Status Solidi (c)

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Ceria‐based materials have been synthesized by electrochemical process. Electrodeposition is an interesting cheap method which can be performed at ambient pressure and rather low temperature (less than 100 °C). Moreover, it is easy to control in situ the film thickness. Ceria coatings were obtained by an indirect electrodeposition method. A potentiostatic technique (–0.7 V/SCE) was used to first reduce a hydroxide precursor (O2 or NO3–) before leading to the formation of cerium oxide after 2h of deposition time. This work focused on the characterization of ceria films deposited onto stainless steel in view of high temperature fuel cell applications. The chosen deposition conditions lead to quite adherent, homogenous and covering films. The microstructure and the crystallinity of the ceria thin layers were characterized by SEM, TEM and XRD measurements. Electrochemical microscopy (SECM) was also used to locally study the conductive properties of ceria layers and the homogeneity of the deposited films. Finally, electrochemical characterizations such as impedance spectroscopy were performed under air atmosphere. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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The effect of a ceria coating on the H2S tolerance of a molten carbonate fuel cell

Cited by 63 publications

References 4 publications

Redox dynamics of sulphur with Ni/GDC anode during SOFC operation at mid- and low-range temperatures: An operando S K-edge XANES study

Redox dynamics of sulphur with Ni/GDC anode during SOFC operation at mid- and low-range temperatures: An operando S K-edge XANES study

Molecular-size selective H-β zeolite-encapsulated Ce-Zr/Ni-Mg catalysts for steam reforming

Synthesis and characterization of cerium oxide by electrochemical methods

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