In situ optical studies of methane and simulated biogas oxidation on high temperature solid oxide fuel cell anodes

Kirtley, John D.; Steinhurst, Daniel A.; Owrutsky, Jeffrey C.; Pomfret, Michael B.; Walker, Robert A.

doi:10.1039/c3cp53278j

Cited by 37 publications

(77 citation statements)

References 50 publications

(72 reference statements)

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“…However, notable advancements have provided direct insights in real time, particularly in regard to molecular and material changes on electrode surfaces. Pomfret et al were the first to collect Raman spectra from the anode surface of SOFCs operating near 715 °C [11,12] and Kirtley et al later increased the limiting temperature to over 800 °C [13]. This innovative technique has provided information about electrochemical changes (including voltage and impedance) accompanying materials changes (such as carbon growth and electrode oxidation) [14,15].…”

Section: Introductionmentioning

confidence: 99%

In situ, simultaneous thermal imaging and infrared molecular emission studies of solid oxide fuel cell electrodes

Kirtley

Qadri

Steinhurst

et al. 2016

Journal of Power Sources

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Various in situ probes of solid oxide fuel cells (SOFCs) have advanced recently to provide detailed, real time data regarding materials and chemical processes that relate to device performance and degradation. These techniques offer insights into complex fuel chemistry at the anode in particular, especially in the context of model predications. However, cell-to-cell variations can hinder mechanistic interpretations of measurements from separate, independent techniques. The present study describes an in situ technique that for the first time simultaneously measures surface temperature changes using near infrared thermal imaging and gas species using Fourier-transform infrared emission spectra at the anodes of operating SOFCs. Electrolytesupported SOFCs with Ni-based anodes are operated at 700 °C with internal, dry-reformed methane at 75% maximum current and at open circuit voltage (OCV) while electrochemical and optical measurements are collected. At OCV, more cooling is observed coincident with more CO reforming products. Under load, CO is depleted while the anode cools less, especially near the current collectors. The extent of cooling is more sensitive to polarization for electrolytesupported cells because their anodes are thinner relative to anode-supported cells. This study exemplifies how this duplex technique can be a useful probe of electrochemical processes in SOFCs.

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Section: Introductionmentioning

confidence: 99%

In situ, simultaneous thermal imaging and infrared molecular emission studies of solid oxide fuel cell electrodes

Kirtley

Qadri

Steinhurst

et al. 2016

Journal of Power Sources

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“…4 In addition, the high operating temperatures of solid oxide fuel cells (SOFCs) allow operation with many different fuels including biogas, syngas, natural gas, gasoline and even some alcohols. [5][6][7][8] However, this versatility comes at the cost of having to develop SOFC materials capable of withstanding impurities intrinsic to each fuel type. These impurities include, but are not limited to, carbon deposits, sulfur, chlorine, silicon, phosphorus, and mercury.…”

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confidence: 99%

“…CO in syngas can form carbon deposits through Boudouard chemistry and alcohols such as methanol and ethanol are capable of forming large carbon deposits in SOFC anodes as is biogas (a mixture of CH 4 and CO 2 ) at relatively low temperatures (700 • C). 5 However, the effects of contaminants on carbon accumulation with cells operating on even the simplest carbon-containing fuels are un- * Electrochemical Society Student Member. * * Electrochemical Society Active Member.…”

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confidence: 99%

In Operando Vibrational Raman Studies of Chlorine Contamination in Solid Oxide Fuel Cells

Reeping

Walker

2015

J. Electrochem. Soc.

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Vibrational Raman spectroscopy coupled with voltammetry and impedance measurements was used to explore the effects of chlorine on solid oxide fuel cell (SOFC) performance and durability. SOFC anodes were exposed to 110 ppm dry CH 3 Cl at 650 • C for up to four hours while intermittently exposing the cell to methane for ten minute intervals. In these experiments Raman spectroscopy was used to monitor carbon accumulation kinetics. Electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) measurements performed under CH 4 following 1 hour of exposure to CH 3 Cl showed marked degradation. This degradation was less apparent when the SOFC was operated with H 2 in the presence of CH 3 Cl. With methane and CH 3 Cl, peak power diminished at a rate of 14% per hour. Observable carbon accumulation during CH 3 Cl exposure became less pronounced over time. Eventually, carbon formation was suppressed completely suggesting that the primary effect of the Cl contaminant was deactivation of the Ni catalyst with respect to CH bond dissociation. SOFC performance with H 2 in the presence of CH 3 Cl remained largely unchanged. Interestingly, these effects of Cl on SOFC performance with methane proved partially reversible as electrochemical performance and carbon accumulation behavior were recovered upon removal of the CH 3 Cl from the fuel feed. Solid oxide fuel cells are electricity-generating devices capable of fuel-to-electricity conversion efficiencies of more than 80% when combined with heating applications.1-3 These efficiencies far outpace even the most modern fossil fuel fired power plants. 4 In addition, the high operating temperatures of solid oxide fuel cells (SOFCs) allow operation with many different fuels including biogas, syngas, natural gas, gasoline and even some alcohols.5-8 However, this versatility comes at the cost of having to develop SOFC materials capable of withstanding impurities intrinsic to each fuel type. These impurities include, but are not limited to, carbon deposits, sulfur, chlorine, silicon, phosphorus, and mercury. Each can cause premature degradation of SOFC materials.6,9-15 Many, if not all, of these impurities have been studied extensively using electrochemical methods. Techniques such as electrochemical impedance spectroscopy (EIS) and voltammetry consistently show how exposure to these individual contaminants lead to performance degradation with differing levels of severity and reversibility. However, while the electrochemical results quantify overall cell degradation, direct, in-situ evidence of the mechanisms responsible for diminished performance remain speculative. Coupling electrochemical methods with in-situ optical spectroscopy, such as Raman spectroscopy or XPS, advances understanding of the reactions that occur on the SOFC electrode surfaces as well as how those reactions affect performance. Raman spectroscopy has already shown to be a promising technique for high temperature in-situ characterization of molecules on the surface of an SOFC operating on hydrocarbon ...

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“…The use of hydrocarbon fuels on the surface temperature of operational SOFCs was investigated by Kirtley et al who combined thermal imaging with Raman spectroscopy and Fourier-transform infrared emission spectroscopy to give a holistic view of the processes occurring at the anode. Effects induced by methane were investigated and compared to those observed using biogas [79] The combination of these techniques enabled the reforming process to be examined in substantially more detail than was previously possible, with the study observing that both gaseous carbon emissions and solid phase carbon deposits were reduced when operating in biogas. As carbon deposition has widely been reported to significantly impair and degrade the performance of SOFCs, this finding highlights the potential use of SOFCs in a more sustainable manner.…”

Section: Correlative Metrology Employing Thermal Imagingmentioning

confidence: 99%

Thermal Imaging of Electrochemical Power Systems: A Review

2016

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The performance and durability of electrochemical power systems are determined by a complex interdependency of many complex and interrelated factors, temperature and heat transfer being particularly important. This has led to an increasing interest in the use of thermal imaging to understand both the fundamental phenomena and effects of operation on the temperature distribution and dynamics in these systems. This review describes the application thermal imaging and related techniques to the study of electrochemical power systems with the primary focus on fuel cells and batteries. Potential opportunities and directions for future research are also highlighted, indicating the wide scope for further insights to be gleaned using infrared thermal imaging techniques.

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In situ optical studies of methane and simulated biogas oxidation on high temperature solid oxide fuel cell anodes

Cited by 37 publications

References 50 publications

In situ, simultaneous thermal imaging and infrared molecular emission studies of solid oxide fuel cell electrodes

In situ, simultaneous thermal imaging and infrared molecular emission studies of solid oxide fuel cell electrodes

In Operando Vibrational Raman Studies of Chlorine Contamination in Solid Oxide Fuel Cells

Thermal Imaging of Electrochemical Power Systems: A Review

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