Interaction of hydrogen sulfide with Zr0.92Y0.08O2−δ/40% Ni cermet

Siriwardane, Ranjani; Poston, James A.; Fisher, Edward P.

doi:10.1016/j.apsusc.2004.07.070

Cited by 6 publications

(2 citation statements)

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“…There is some consensus about the first step of poisoning, but there are several significantly different if not controversial views about the second, slower step. Some authors are supporting the idea that slow degradation is caused by the formation of volatile Ni x S y phase, which causes restructuring and degradation of electrode structure [14,15,27]. Sasaki et al proposed that blocking of hydrogen diffusion to the TPB caused by sulphur adsorption leads to the oxidation of Ni at TPB interface, causing depletion of active sites [9].…”

Section: Introductionmentioning

confidence: 99%

“…But, up to now, spectroscopic measurements with X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), or, Raman microspectroscopy either obtain information from SOFC anode surface in the presence of H 2 S, H 2 , and, possibly even heat, or ex-situ and under postmortem conditions [14,15,22,33]. The molecular structure of sulphur compounds has been studied with sulphur K-shell edge Xray absorption spectroscopy in various fields of application, particularly in relation to fossil fuels, such as sulphur in coal [34], sulphur in residual oil fly ash [35] and heterogeneous catalysis [36].…”

Section: Motivation and Goalmentioning

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: Introductionmentioning

confidence: 99%