Carbon deposition and sulfur poisoning during CO2 electrolysis in nickel-based solid oxide cell electrodes

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Abstract

Reduction of CO2 to CO and O2 in the solid oxide electrolysis cell (SOEC) has the potential to play a crucial role in closing the CO2 loop. Carbon deposition in nickel-based cells is however fatal and must be considered during CO2 electrolysis. Here, the effect of operating parameters is investigated systematically using simple current-potential experiments. Due to variations of local conditions, it is shown that higher current density and lower fuel electrode porosity will cause local carbon formation at the electrochemical reaction sites despite operating with a CO outlet concentration outside the thermodynamic carbon formation region. Attempts at mitigating the issue by coating the composite nickel/yttria-stabilized zirconia electrode with carbon-inhibiting nanoparticles and by sulfur passivation proved unsuccessful. Increasing the fuel electrode porosity is shown to mitigate the problem, but only to a certain extent. This work shows that a typical SOEC stack converting CO2 to CO and O2 is limited to as little as 15–45% conversion due to risk of carbon formation. Furthermore, cells operated in CO2-electrolysis mode are poisoned by reactant gases containing ppb-levels of sulfur, in contrast to ppm-levels for operation in fuel cell mode.
Original languageEnglish
JournalJournal of Power Sources
Volume373
Pages (from-to)54-60
ISSN0378-7753
DOIs
Publication statusPublished - 2017

Keywords

  • High temperature electrolysis
  • CO2 reduction
  • Carbon formation
  • Sulfur poisoning
  • Electrode gradients
  • Mitigation

Cite this

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title = "Carbon deposition and sulfur poisoning during CO2 electrolysis in nickel-based solid oxide cell electrodes",
abstract = "Reduction of CO2 to CO and O2 in the solid oxide electrolysis cell (SOEC) has the potential to play a crucial role in closing the CO2 loop. Carbon deposition in nickel-based cells is however fatal and must be considered during CO2 electrolysis. Here, the effect of operating parameters is investigated systematically using simple current-potential experiments. Due to variations of local conditions, it is shown that higher current density and lower fuel electrode porosity will cause local carbon formation at the electrochemical reaction sites despite operating with a CO outlet concentration outside the thermodynamic carbon formation region. Attempts at mitigating the issue by coating the composite nickel/yttria-stabilized zirconia electrode with carbon-inhibiting nanoparticles and by sulfur passivation proved unsuccessful. Increasing the fuel electrode porosity is shown to mitigate the problem, but only to a certain extent. This work shows that a typical SOEC stack converting CO2 to CO and O2 is limited to as little as 15–45{\%} conversion due to risk of carbon formation. Furthermore, cells operated in CO2-electrolysis mode are poisoned by reactant gases containing ppb-levels of sulfur, in contrast to ppm-levels for operation in fuel cell mode.",
keywords = "High temperature electrolysis, CO2 reduction, Carbon formation, Sulfur poisoning, Electrode gradients, Mitigation",
author = "Skafte, {Theis L{\o}ye} and Peter Blennow and Johan Hjelm and Graves, {Christopher R.}",
year = "2017",
doi = "10.1016/j.jpowsour.2017.10.097",
language = "English",
volume = "373",
pages = "54--60",
journal = "Journal of Power Sources",
issn = "0378-7753",
publisher = "Elsevier",

}

Carbon deposition and sulfur poisoning during CO2 electrolysis in nickel-based solid oxide cell electrodes. / Skafte, Theis Løye; Blennow, Peter; Hjelm, Johan; Graves, Christopher R.

In: Journal of Power Sources, Vol. 373, 2017, p. 54-60.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Carbon deposition and sulfur poisoning during CO2 electrolysis in nickel-based solid oxide cell electrodes

AU - Skafte, Theis Løye

AU - Blennow, Peter

AU - Hjelm, Johan

AU - Graves, Christopher R.

PY - 2017

Y1 - 2017

N2 - Reduction of CO2 to CO and O2 in the solid oxide electrolysis cell (SOEC) has the potential to play a crucial role in closing the CO2 loop. Carbon deposition in nickel-based cells is however fatal and must be considered during CO2 electrolysis. Here, the effect of operating parameters is investigated systematically using simple current-potential experiments. Due to variations of local conditions, it is shown that higher current density and lower fuel electrode porosity will cause local carbon formation at the electrochemical reaction sites despite operating with a CO outlet concentration outside the thermodynamic carbon formation region. Attempts at mitigating the issue by coating the composite nickel/yttria-stabilized zirconia electrode with carbon-inhibiting nanoparticles and by sulfur passivation proved unsuccessful. Increasing the fuel electrode porosity is shown to mitigate the problem, but only to a certain extent. This work shows that a typical SOEC stack converting CO2 to CO and O2 is limited to as little as 15–45% conversion due to risk of carbon formation. Furthermore, cells operated in CO2-electrolysis mode are poisoned by reactant gases containing ppb-levels of sulfur, in contrast to ppm-levels for operation in fuel cell mode.

AB - Reduction of CO2 to CO and O2 in the solid oxide electrolysis cell (SOEC) has the potential to play a crucial role in closing the CO2 loop. Carbon deposition in nickel-based cells is however fatal and must be considered during CO2 electrolysis. Here, the effect of operating parameters is investigated systematically using simple current-potential experiments. Due to variations of local conditions, it is shown that higher current density and lower fuel electrode porosity will cause local carbon formation at the electrochemical reaction sites despite operating with a CO outlet concentration outside the thermodynamic carbon formation region. Attempts at mitigating the issue by coating the composite nickel/yttria-stabilized zirconia electrode with carbon-inhibiting nanoparticles and by sulfur passivation proved unsuccessful. Increasing the fuel electrode porosity is shown to mitigate the problem, but only to a certain extent. This work shows that a typical SOEC stack converting CO2 to CO and O2 is limited to as little as 15–45% conversion due to risk of carbon formation. Furthermore, cells operated in CO2-electrolysis mode are poisoned by reactant gases containing ppb-levels of sulfur, in contrast to ppm-levels for operation in fuel cell mode.

KW - High temperature electrolysis

KW - CO2 reduction

KW - Carbon formation

KW - Sulfur poisoning

KW - Electrode gradients

KW - Mitigation

U2 - 10.1016/j.jpowsour.2017.10.097

DO - 10.1016/j.jpowsour.2017.10.097

M3 - Journal article

VL - 373

SP - 54

EP - 60

JO - Journal of Power Sources

JF - Journal of Power Sources

SN - 0378-7753

ER -