The Effect of H<sub>2</sub>S on the Performance of SOFCs using Methane Containing Fuel

Rasmussen, Jens Foldager Bregnballe; Hagen, Anke

doi:10.1002/fuce.201000012

Cited by 50 publications

(90 citation statements)

References 22 publications

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“…Oxidized species (such as O*) obtained during CO 2 activation (dissociation) play a significant role during biogas reforming or methane dry reforming; oxidizing CH x species [Eq. (16)] to CH x O* species. Subsequent decomposition of CH x O* species produces synthesis gas [Eq.…”

Section: Transient Reaction Studies: Co 2 Dissociationmentioning

confidence: 99%

“…(1)- (8)]. This approach has been employed by researchers to gain useful understanding of mechanistic details and catalytic interactions of CH 4 with Ni/YSZ (nickel/yttria-stabilized zirconia) and similar anodes [16][17][18][19][20]. For example, Triantafyllopoulos and Neophytides [17,21] studied catalytic dissociation of CH 4 on Ni/YSZ at various temperatures, monitoring carbonaceous species deposited as well as their reactivity with H 2 and O 2 .…”

Section: Introductionmentioning

confidence: 99%

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Biogas Catalytic Reforming Studies on Nickel‐Based Solid Oxide Fuel Cell Anodes

et al. 2016

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Heterogeneous catalysis studies were conducted on two crushed solid oxide fuel cell (SOFC) anodes in fixed-bed reactors. The baseline anode was Ni/ScYSZ (Ni/scandia and yttria stabilized zirconia), the other was Ni/ScYSZ modified with Pd/doped ceria (Ni/ScYSZ/Pd-CGO). Three main types of experiments were performed to study catalytic activity and effect of sulfur poisoning: (i) CH 4 and CO 2 dissociation; (ii) biogas (60% CH 4 and 40% CO 2 ) temperature-programmed reactions (TPRxn); and (iii) steady-state biogas reforming reactions followed by postmortem catalyst characterization by temperature-programmed oxidation and timeof-flight secondary ion mass spectrometry. Results showed that Ni/ScYSZ/Pd-CGO was more active for catalytic dissociation of CH 4 at 750°C and subsequent reactivity of deposited carbonaceous species. Sulfur deactivated most catalytic reactions except CO 2 dissociation at 750°C. The presence of Pd-CGO helped to mitigate sulfur deactivation effect; e.g. lowering the onset temperature (up to 190°C) for CH 4 conversion during temperature-programmed reactions. Both Ni/ScYSZ and Ni/ScYSZ/Pd-CGO anode catalysts were more active for dry reforming of biogas than they were for steam reforming. Deactivation of reforming activity by sulfur was much more severe under steam reforming conditions than dry reforming; a result of greater sulfur retention on the catalyst surface during steam reforming.

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Section: Transient Reaction Studies: Co 2 Dissociationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Biogas Catalytic Reforming Studies on Nickel‐Based Solid Oxide Fuel Cell Anodes

et al. 2016

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“…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. It was observed that complete internal reforming was obtained, since OCV values of ∼988-992 mV correspond to the reformed equilibrium gas mixture of H 2 /CO/H 2 O/CO 2 :65.6/15.5/15.6/3.2 (OCV theo.…”

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

confidence: 99%

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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“…As pointed out in the work by RostrupNielsen et al [19], it is still not fully clear how sulfur interacts with Ni active sites in terms of heterogeneous catalytic and electro-catalytic processes respectively. Anyway, sulfur certainly reduces the catalytic activity of Ni in an SOFC cermet anode [20,21]. In [21], authors showed how sulfur strongly reduces Ni reforming activity toward methane more than the electrochemical reactions.…”

Section: Introductionmentioning

confidence: 97%

“…Anyway, sulfur certainly reduces the catalytic activity of Ni in an SOFC cermet anode [20,21]. In [21], authors showed how sulfur strongly reduces Ni reforming activity toward methane more than the electrochemical reactions. For this reason, in a direct internal reforming SOFC configuration, as we are interested in, sulfur should be removed to satisfactory levels that guarantee a proper catalytic activity of the Ni.…”

Section: Introductionmentioning

confidence: 97%

Experimental Investigations and Modeling of Direct Internal Reforming of Biogases in Tubular Solid Oxide Fuel Cells

et al. 2011

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Biogas‐fed Solid Oxide Fuel Cell (SOFC) systems can be considered as interesting integrated systems in the framework of distributed power generation. In particular, bio‐methane and bio‐hydrogen produced from anaerobic digestion of organic wastes represent renewable carbon‐neutral fuels for high efficiency electrochemical generators.With such non‐conventional mixtures fed to the anode of the SOFC, the interest lies in understanding the multi‐physics phenomena there occurring and optimizing the geometric and operation parameters of the SOFC, while avoiding operating and fuel conditions that can lead to or accelerate degradation processes.In this study, an anode‐supported (Ni‐YSZ) tubular SOFC was considered; the tubular geometry enables a relatively easy separation of the air and fuel reactants and it allows one to evaluate the temperature field of the fuel gas inside the tube, which is strictly related to the electrochemical and heterogeneous chemical reactions occurring within the anode volume.The experiments have been designed to analyze the behavior of the cell under different load and fuel utilization (FU) conditions, providing efficiency maps for both fuels.The experimental results were used to validate a multi‐physics model of the tubular cell. The model showed to be in good agreement with the experimental data, and was used to study the sensitive of some selected geometrical parameters modification over the cell performances.

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The Effect of H₂S on the Performance of SOFCs using Methane Containing Fuel

Cited by 50 publications

References 22 publications

Biogas Catalytic Reforming Studies on Nickel‐Based Solid Oxide Fuel Cell Anodes

Biogas Catalytic Reforming Studies on Nickel‐Based Solid Oxide Fuel Cell Anodes

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

Experimental Investigations and Modeling of Direct Internal Reforming of Biogases in Tubular Solid Oxide Fuel Cells

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The Effect of H2S on the Performance of SOFCs using Methane Containing Fuel

Cited by 50 publications

References 22 publications

Biogas Catalytic Reforming Studies on Nickel‐Based Solid Oxide Fuel Cell Anodes

Biogas Catalytic Reforming Studies on Nickel‐Based Solid Oxide Fuel Cell Anodes

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

Experimental Investigations and Modeling of Direct Internal Reforming of Biogases in Tubular Solid Oxide Fuel Cells

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The Effect of H₂S on the Performance of SOFCs using Methane Containing Fuel