Durability of solid oxide fuel cells using sulfur containing fuels

Hagen, Anke; Rasmussen, Jens Foldager Bregnballe; Thydén, Karl Tor Sune

doi:10.1016/j.jpowsour.2011.02.053

Cited by 116 publications

(138 citation statements)

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“…a fuel utilization of 51%. 5 The addition of H 2 S to the fuel inlet gas will affect the reformate gas equilibrium as reported by Rasmussen and Hagen and upon addition of 2 ppm H 2 S the CH 4 conversion degree will be decreased and a fuel utilization of approximately 70% can be expected at the chosen test conditions. 23 OCV was checked before starting the test under current load.…”

Section: /H 2 O/h 2 Fuel Mixtures At 850mentioning

confidence: 83%

“…-Table I lists test acronyms, cell and test specifications, along with a summary of the test results in form of cell voltage changes Overview of cell and test specifications is given in Table I. al., 5 and are included here for comparison. In the article by Hagen et al these tests were denoted "Ni,YSZ,LSM" and "Ni,ScYSZ,LSM", respectively.…”

Section: Resultsmentioning

confidence: 99%

“…4,7-9 Fewer results are reported on the long-term, and often irreversible, loss of performance due to sulfur poisoning, 5,8,10 even though this will inevitably be of high importance for SOFC as an emerging energy conversion technology. In order to establish the acceptable limits for sulfur impurities in carbon containing fuels in order to avoid longterm, irreversible degradation, 5,11 it is necessary to understand how the sulfur impurity tolerance correlate to operating parameters such as gas mixtures, temperature and current density, and indirectly to the cell overpotential.It has been suggested that Ni-zirconia based SOFC anodes containing Sc are more tolerant toward H 2 S poisoning than Ni/YSZ based anodes 5,7 and in this work both short and long term tests were performed to investigate this hypothesis. Tests were mainly carried out at the same set of test conditions (e.g.…”

mentioning

confidence: 99%

“…A well-known drawback for the use of carbon containing fuels is the fact that they contain varying amounts of sulfur, which poisons Ni-based SOFC anodes. [1][2][3][4][5][6][7][8] Therefore, it is important to investigate the SOFC tolerance toward sulfur poisoning and how it is affected by operating parameters.…”

mentioning

confidence: 99%

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Sulfur Poisoning of SOFC Anodes: Effect of Overpotential on Long-Term Degradation

Hauch

Hagen

Hjelm

et al. 2014

J. Electrochem. Soc.

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Sulfur impurities in carbon containing fuels for solid oxide fuel cells (SOFC), e.g. natural gas and biogas, typically lead to significant losses in performance due to the sulfur sensitivity of Ni/yttria-stabilized-zirconia (YSZ) anodes for SOFC. Full cells having Ni/YSZ anodes have been characterized during long-term galvanostatic operation in internal reforming gas mixture (CH 4 /H 2 O/H 2 :30/60/10), with 2 ppm H 2 S exposure to the anode for 500 hours at 850 • C, at different current densities. This work focus on the long-term effect of H 2 S exposure over a few hundreds of hours; and describes and correlates the observed evolution of anode performance, over hundreds of hours, with sulfur exposure at low cell overpotential (low current density) and at high overpotential (high current density) with and without H 2 S exposure. For tests at low overpotential with H 2 S exposure only a reversible loss in performance was observed and post-mortem SEM analysis showed an intact Ni/YSZ anode microstructure. For tests at high cell overpotential the H 2 S exposure caused both a reversible loss in performance and an irreversible long-term degradation. Post-mortem SEM analysis of the Ni/YSZ anode from this tests showed increased porosity and lack of percolating Ni in the few microns of the anode closest to the anode/electrolyte interface. Fuel flexibility is an attractive characteristic of solid oxide fuel cells (SOFC). They can for instance be fuelled with carbon containing fuels such as natural gas or fuels derived from biomass. A well-known drawback for the use of carbon containing fuels is the fact that they contain varying amounts of sulfur, which poisons Ni-based SOFC anodes.1-8 Therefore, it is important to investigate the SOFC tolerance toward sulfur poisoning and how it is affected by operating parameters.There are many studies concerning the initial, and mainly reversible, loss in performance occurring at SOFC anodes upon sulfur poisoning as a function of different operating conditions. 4,7-9 Fewer results are reported on the long-term, and often irreversible, loss of performance due to sulfur poisoning, 5,8,10 even though this will inevitably be of high importance for SOFC as an emerging energy conversion technology. In order to establish the acceptable limits for sulfur impurities in carbon containing fuels in order to avoid longterm, irreversible degradation, 5,11 it is necessary to understand how the sulfur impurity tolerance correlate to operating parameters such as gas mixtures, temperature and current density, and indirectly to the cell overpotential.It has been suggested that Ni-zirconia based SOFC anodes containing Sc are more tolerant toward H 2 S poisoning than Ni/YSZ based anodes 5,7 and in this work both short and long term tests were performed to investigate this hypothesis. Tests were mainly carried out at the same set of test conditions (e.g. temperature, current density, fuel) in order to compare Sc-Y co-doped (ScYSZ) and Y doped zirconia (YSZ) Ni cermet SOFC anodes. There are several studies s...

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Section: /H 2 O/h 2 Fuel Mixtures At 850mentioning

confidence: 83%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Sulfur Poisoning of SOFC Anodes: Effect of Overpotential on Long-Term Degradation

Hauch

Hagen

Hjelm

et al. 2014

J. Electrochem. Soc.

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“…2,5,8 On the other hand it is well known that natural gas and biogas can have substantially higher sulfur concentrations and that catalytic steam reforming of methane can be carried out on Ni even with 100 ppm H 2 S without losing all catalytic activity 9,10 e.g., a methane conversion (in model biogas) of ∼35% can be maintained using a supported Ni catalyst with 100 ppm H 2 S at 800…”

mentioning

confidence: 99%

Sulfur Poisoning of SOFCs: A Model Based Explanation of Polarization Dependent Extent of Poisoning

Janardhanan

Monder

2014

J. Electrochem. Soc.

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Several experimental studies have shown that, 1) the extent of the poisoning effect due to trace amounts of sulfur compounds in the fuel is lower if a SOFC is operated at a higher current density, and 2) the performance drop due to sulfur poisoning is much lower for Ni-GDC or Ni-ScSZ anodes when compared to Ni-YSZ anodes. This work presents a first principles numerical model that simulates experimental studies of sulfur poisoning on SOFC button cells. The exchange current densities for the electrodes are determined using sulfur-free polarization data for cells fueled by humidified mixtures of H 2 and N 2 . A detailed surface reaction model that predicts the fractional coverage of all adsorbed species at the three phase interface is coupled to the SOFC model and the sulfur coverage is used to alter the anode exchange current density. The resulting model predictions match experimental observations during both galvanostatic and potentiostatic operation. Our analysis shows that the observed lower performance drop at higher current density is due to the non-linear nature of the electrochemical rate equations, and that the lower impact of sulfur poisoning on Ni-GDC and Ni-ScSZ anodes (compared to Ni-YSZ anodes) is due to their higher electrochemical activity. Solid oxide fuel cell (SOFC) systems operating on natural gas or gasified coal can be significantly more energy efficient than today's combustion systems and can thus reduce CO 2 emissions. However, a major problem associated with the use of hydrocarbon fuels is the presence of sulfur containing compounds that are converted to H 2 S under SOFC operating conditions.1 The H 2 S present in the feed gas can readily deactivate conventional Ni cermet anodes. One can certainly have a desulfurization unit before the fuel cell stack to deal with the sulfur poisoning. However, this leads to increased system complexity and decrease in overall efficiency. Nevertheless, it is important to understand and quantify the sulfur tolerance of SOFC anodes in the event of sulfur breakthrough from the desulfurizer. Sulfur poisoning of Ni-YSZ anodes in SOFC is well studied experimentally for model fuel compositions consisting of ppm levels of H 2 S in mixtures of H 2 , H 2 O and an inert 2-4 as well as H 2 S in gas mixtures representative of natural gas or reformed natural gas.5-8 Most of the experimental literature deals with H 2 S concentrations well below 10 ppm and work that treats H 2 S concentrations higher than 20 ppm is rather limited. 2,5,8 On the other hand it is well known that natural gas and biogas can have substantially higher sulfur concentrations and that catalytic steam reforming of methane can be carried out on Ni even with 100 ppm H 2 S without losing all catalytic activity 9,10 e.g., a methane conversion (in model biogas) of ∼35% can be maintained using a supported Ni catalyst with 100 ppm H 2 S at 800• C. 10For an electrolyte supported cell Zha et al., 2 studied the cell performance for a wide range of H 2 S concentrations using DC polarization and electrochemical i...

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Solid Oxide Fuel Cell ( SOFC )

Desideri

Barelli

2015

Handbook of Clean Energy Systems

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The reduction of CO2 emissions, considering its greenhouse effect, and primary energy saving are ones of the most important challenges for the worldwide scientific community. The study of power plants with reduced CO2 emission factor (EF), through the achievement of higher conversion efficiency and switching to less carbon intense fuels, can significantly contribute to the these targets.\ud In this scenario, fuel cells (FCs) technology can represent an alternative to traditional power generation systems; it offers the potential for higher electrical efficiencies and lower emissions. In particular, high temperature solid oxide fuel cells (SOFCs), thanks to their favorable characteristics as high efficiency, reaction kinetics, power density, and usable heat, beyond that fuel flexibility, are considered to be one of themost promising technologies for future power generation. Main advantages of high temperature FCs, respect to low temperature FCs, are represented by the possibility to use the produced heat (at operating temperatures typically over 600◦C) in both fuel-processing and heat-generation systems.\ud They are, therefore, highlighted, respect to low temperature FCs:\ud • potential to be independent from a pure hydrogen infrastructure and, therefore, fuel flexibility and application in transitional fuels such as natural gas, syngas, and biogas;\ud • unsurpassed efficiencies, approaching 90% total efficiency (electrical and thermal), in cogenerative applications

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Durability of solid oxide fuel cells using sulfur containing fuels

Cited by 116 publications

References 20 publications

Sulfur Poisoning of SOFC Anodes: Effect of Overpotential on Long-Term Degradation

Sulfur Poisoning of SOFC Anodes: Effect of Overpotential on Long-Term Degradation

Sulfur Poisoning of SOFCs: A Model Based Explanation of Polarization Dependent Extent of Poisoning

Solid Oxide Fuel Cell ( SOFC )

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