Analysis of the performance of the electrodes in a natural gas assisted steam electrolysis cell

Wang, Wensheng; Gorte, Raymond J.; Vohs, John M.

doi:10.1016/j.ces.2007.10.026

Cited by 41 publications

(24 citation statements)

References 18 publications

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“…A practical steam electrolyzer is operated at 90 pct steam content, which would make the open-circuit potential significantly negative. [5][6][7] Any applied external potential will continue to increase the rate of hydrogen production.…”

Section: Open-circuit Potentialmentioning

confidence: 99%

“…In previous studies, researchers have proposed using CO and natural gas to decrease the anodic oxygen chemical potential in a SOSE. [5][6][7] However, the conventional SOSE anode cannot handle solid waste as a reductant feed, because the solid anode in the SOSE does not provide sites to perform charge transfer simultaneously while oxidizing the reductant feed. In this article, a solid oxide membrane (SOM) electrolyzer with liquid-metal anode is proposed in which any hydrocarbon waste and fossil fuel such as coal, methane, and natural gas can be used as the reductant in the anode, and pure hydrogen can be produced from steam at the cathode.…”

Section: Introductionmentioning

confidence: 99%

“…The cermet serves as the cathode, and the liquid metal serves as the anode. Ni/Cu-Co-CeO 2 [7] or Ni-YSZ [9] can be used as the cathode, and silver, [8,10] tin, [11][12][13] or copper [14] can be used as the liquid-metal anode. The SOM electrolyzer is operated between 850°C and 1000°C by providing a steam-rich gas feed to the cathode and carbon/hydrocarbon/or other reductant feed into the liquid-metal anode.…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical Characterization of a Solid Oxide Membrane Electrolyzer for Production of High-Purity Hydrogen

Pati

Yoon

Gopalan

et al. 2009

Metall Mater Trans B

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A laboratory-scale solid oxide membrane (SOM) steam electrolyzer that can potentially use energy value in waste or any source of carbon or hydrocarbon to produce high-purity hydrogen has been fabricated and evaluated. The SOM electrolyzer comprises an oxygen-ion-conducting yttria-stabilized zirconia (YSZ) electrolyte with a Ni-YSZ cermet cathode coated on one side and liquid-metal anode on the other side. The SOM electrolyzer is operated at 1000°C by providing a steam-rich gas feed to the Ni-YSZ cermet cathode and feeding a reductant source into the liquid-metal anode. The steam is reduced over the cathode, and oxygen ions are transported through the YSZ electrolyte and are oxidized at the molten metal electrode by the reductant feed. The advantage of SOM electrolyzer over the state-of-the-art solid oxide electrolyzer is its ability to use solid, liquid, and gaseous reductant feed in the liquid-metal anode to reduce the oxygen chemical potential and drive the reaction for hydrogen production. In this study, an electrochemical process model for a SOM electrolyzer was developed. The condition of the liquid-metal anode with reductant was simulated by bubbling humidified hydrogen (3 pct H 2 O) in the liquid metal, and the electrochemical performance of the SOM electrolyzer was modeled. The experimental data were curve-fitted into the model to identify the various polarization losses. It showed that the performance of the SOM electrolyzer was dominated by the ohmic resistance of the YSZ membrane. Based on the results of this study, future work is needed toward increasing the performance efficiency of the SOM electrolyzer.

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Section: Open-circuit Potentialmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electrochemical Characterization of a Solid Oxide Membrane Electrolyzer for Production of High-Purity Hydrogen

Pati

Yoon

Gopalan

et al. 2009

Metall Mater Trans B

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“…[5] And direct oxidation of methane dominates and resulting in a higher ASR at low CH4 conversions. [6] At system level, analysis of Martinez-Frias et al…”

Section: Introductionmentioning

confidence: 99%

Elementary reaction modeling and experimental characterization of solid oxide fuel-assisted steam electrolysis cells

Luo

Shi

et al. 2014

International Journal of Hydrogen Energy

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“…Several studies have demonstrated the use of methane and carbon monoxide at the anode of a SOE to assist in decomposing water into hydrogen and oxygen. [18][19][20][21] A solid oxide fuel cell containing carbon in contact with a molten silver anode has also been described. 22 A similar approach for low temperature electrolysis using high surface area carbon was also recently reported.…”

mentioning

confidence: 99%

Steam-Carbon Fuel Cell Concept for Cogeneration of Hydrogen and Electrical Power

Alexander¹,

Mitchell²,

Gür

2011

J. Electrochem. Soc.

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This study describes and presents the results of a new electrochemical approach to co-production of hydrogen and electric power using a steam-carbon fuel cell, within which carbon-containing species are kept physically separate from the hydrogen stream by a solid oxide electrolyte membrane. The fuel cell used for this purpose consists of H 2 , H 2 O (g) /Pt/YSZ/Pt/C (s) ,CO,CO 2 and measurements are taken between 600 and 900 C. Peak electrical power generated at 900 C is 8 mW/cm 2 at a current density of 40.5 mA/ cm 2 corresponding to simultaneous production of carbon-free hydrogen at a rate of 354 g H 2 /m 2 day. Electrochemical behavior and cell loss mechanisms are studied using impedance spectroscopy in different cell arrangements operating in steam-carbon and air-carbon modes. Exchange current densities extracted from these measurements indicated activation energies of 80.3 6 7.9 kJ/ mol for oxygen reduction, 132 6 12 kJ/mol for CO oxidation, and 189 6 35 kJ/mol for steam reduction. These results indicate that steam reduction is the dominant loss mechanism with significant contribution from CO oxidation kinetics. Modeling results for the carbon bed indicate that a bed height of 7 mm is capable of supporting cell current densities of 700 mA/cm 2 at 85% effective char utilization, allowing for high performing steam-carbon fuel cells for the simultaneous production of hydrogen and electrical work. Hydrogen is a desirable fuel because it is both an effective energy carrier as well as a clean burning fuel with minimal impact on the environment. Unfortunately, hydrogen does not occur naturally, and must be generated from other sources. If widespread use of hydrogen is to be achieved, an efficient method for distributed hydrogen production is desired due to the cost and technical challenges posed by hydrogen transportation and storage.Currently, the majority of hydrogen production is performed centrally using steam reforming of methane, and to a lesser extent, coal. The fuel is reformed with steam and then undergoes the water-gas shift reaction to produce hydrogen. Unfortunately, this process produces a hydrogen stream that is contaminated by various carbonaceous species, and therefore requires expensive separation techniques to clean the gas. Carbon monoxide remnants in the hydrogen gas are of particular concern, as even trace amounts of CO in the hydrogen stream render the hydrogen product undesirable for catalytic processes due to CO poisoning. This is a critical problem especially for low temperature fuel cells. In addition, the reforming process is only economically feasible at large scales, requiring expensive storage and distribution of the hydrogen product to its point of use.A variety of alternative hydrogen production schemes that attempt to solve or avoid the limitations of reforming have been proposed. Thermal decomposition of steam into hydrogen and oxygen is one such option, but this reaction is thermodynamically uphill and energetically expensive. Another approach is the electrolysis of water in an e...

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Analysis of the performance of the electrodes in a natural gas assisted steam electrolysis cell

Cited by 41 publications

References 18 publications

Electrochemical Characterization of a Solid Oxide Membrane Electrolyzer for Production of High-Purity Hydrogen

Electrochemical Characterization of a Solid Oxide Membrane Electrolyzer for Production of High-Purity Hydrogen

Elementary reaction modeling and experimental characterization of solid oxide fuel-assisted steam electrolysis cells

Steam-Carbon Fuel Cell Concept for Cogeneration of Hydrogen and Electrical Power

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