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Assessment of Sulfur Poisoning of Ni/CGO-Based SOFC Anodes

Riegraf, Matthias and Zekri, Atef and Yurkiv, Vitaliy and Costa, Rémi and Schiller, Günter and Friedrich, K. Andreas (2017) Assessment of Sulfur Poisoning of Ni/CGO-Based SOFC Anodes. 231st ECS Meeting, New Orleans, USA.

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Abstract

The presence of fuel impurities, such as hydrogen sulfide, siloxane and phosphine, in biogas, diesel and natural gas can cause Solid Oxide Fuel Cell (SOFC) degradation due to surface poisoning of Ni-containing anodes. In this regard, Ni/CGO anodes have shown higher sulfur tolerance than Ni/YSZ anodes and a comparable high performance. In order to allow for a more profound understanding of the processes underlying sulfur poisoning, this study presents an extensive experimental investigation of commercial Ni/CGO-based SOFC operating on H2/H2O fuel gases and reformate fuel mixtures with trace amounts of hydrogen sulfide (H2S). The short-term poisoning behavior of high-performance electrolyte-supported Ni/CGO10-based cells was systematically investigated by means of transient voltage stability experiments and electrochemical impedance measurements for a wide range of operating conditions. The effects of temperature (800 – 950 °C) and current density (OCV – 0.75 A·cm‒2) on the extent of sulfur poisoning (1 – 20 ppm H2S) was evaluated. The poisoning behavior was shown to be completely reversible for short exposure times in all cases. The chemical capacitance of Ni/CGO10 anodes was demonstrated to be strongly dependent upon temperature and gas phase composition reflecting a changing Ce3+/Ce4+ ratio in the CGO phase. Using a model reformate as fuel gas, it was shown that CO can still be electrochemically converted under sulfur exposure. Furthermore, long-term experiments of 1500 h were conducted at 900 °C and 0.5 A·cm‒2 with and without sulfur exposure and the degradation progress was monitored by impedance spectroscopy.

Item URL in elib:https://elib.dlr.de/115353/
Document Type:Conference or Workshop Item (Speech)
Title:Assessment of Sulfur Poisoning of Ni/CGO-Based SOFC Anodes
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Riegraf, Matthiasmatthias.riegraf (at) dlr.dehttps://orcid.org/0000-0002-0383-2545
Zekri, Atefatef.zekri (at) uni-oldenburg.deUNSPECIFIED
Yurkiv, Vitaliyvitaliy.yurkiv (at) dlr.deUNSPECIFIED
Costa, Rémiremi.costa (at) dlr.dehttps://orcid.org/0000-0002-3534-1935
Schiller, GünterGuenter.Schiller (at) dlr.dehttps://orcid.org/0000-0001-5093-7625
Friedrich, K. Andreasandreas.friedrich (at) dlr.deUNSPECIFIED
Date:2017
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:Sulfur poisoning, ceria, water gas shift
Event Title:231st ECS Meeting
Event Location:New Orleans, USA
Event Type:international Conference
HGF - Research field:Energy
HGF - Program:Storage and Cross-linked Infrastructures
HGF - Program Themes:Fuel cells
DLR - Research area:Energy
DLR - Program:E SP - Energy Storage
DLR - Research theme (Project):E - Electrochemical Processes (Fuel Cells)
Location: Stuttgart
Institutes and Institutions:Institute of Engineering Thermodynamics > Electrochemical Energy Technology
Deposited By: Riegraf, Matthias
Deposited On:01 Dec 2017 13:07
Last Modified:31 Jul 2019 20:12

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