Accurate predictions of H2O and CO2 co-electrolysis outlet compositions in operation

Aicart, J.; Petitjean, Marie; Laurencin, Jérôme; Tallobre, L.; Dessemond, Laurent

doi:10.1016/j.ijhydene.2015.01.031

Cited by 26 publications

(20 citation statements)

References 51 publications

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“…The results shows that (i) the effect of changing T is small, (ii) changing ε / τ or d p has a large effect when the parameter has a low value, but a low effect when they are above about 0.2 and 1 µm, respectively, i.e., at about the standard values they are assigned (common values for the ε / τ fraction is 0.1 to 0.2 , , and for the pore diameter it is 0.13 µm to 1.5 µm , , ), 3) the CO mole fraction is proportional to the CO mole fraction in the channel, current density and electrode depth. Thus, in order to minimize the CO mole fraction at the electrode‐electrolyte interface, ε / τ and d p must be above a certain value while d e should be small.…”

Section: Resultsmentioning

confidence: 99%

“…One approach to model co‐electrolysis is to assume that only reaction 15 occurs at the interface and that subsequently CO 2 is converted to CO via the water‐gas shift reaction . Another approach is to assume that both reactions occur at the interface and include a parameter β , that determines the fraction of the interface surface available for H 2 O electrolysis . In this approach, the electrical current is divided between the two reactions depending on the mole fraction of CO 2 and H 2 O at the interface.…”

Section: Modelsmentioning

confidence: 94%

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Modeling of Gas Diffusion in Ni/YSZ Electrodes in CO₂ and Co‐electrolysis

Duhn¹,

Jensen²,

Wedel³

et al. 2017

Fuel Cells

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Carbon formation may occur during CO 2 and CO 2 /H 2 O electrolysis using solid oxide electrolyzer cells due to the Boudouard reaction (2CO CO 2 + C(s)). Formed carbon may disintegrate the cell structure and it is therefore of importance to be able to predict when carbon is formed, and take actions to prevent its formation. For prediction of carbon formation, the gas composition in the electrode must be known. In this work, the diffusion of gases in the electrode has been modeled with the dusty gas model in 1 and 2 dimensions, and the effect of tortuosity, porosity, temperature, electrode thickness, pore diameter, current density, pitch and rib width has been investigated. It is shown that diffusion limitations on reactant/product transport may lead to carbon formation. The parameters describing the microstructure and the dimensions of the cathode channels and interconnect ribs are found to have a large effect on the carbon formation propensity. Given a set of parameters, a simple correlation between the CO mole fraction in the channel and under the interconnect rib, and current density during CO 2 -electrolysis can be derived. This correlation makes it possible to efficiently integrate the calculation of carbon formation risk in existing electrolyzer cell models.

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Section: Resultsmentioning

confidence: 99%

Section: Modelsmentioning

confidence: 94%

Modeling of Gas Diffusion in Ni/YSZ Electrodes in CO₂ and Co‐electrolysis

Duhn¹,

Jensen²,

Wedel³

et al. 2017

Fuel Cells

View full text Add to dashboard Cite

show abstract

“…The typical electrochemical reaction does not significantly affect the flow rate of the electrode. However, it will affect the overall reaction according to the flow given that the cathode reaction as the rate limiting step and considering that the key reaction occurs in the cathode of the RWGS reaction for the H 2 OeCO 2 coelectrolysis process [8,28]. A kinetic analysis for RWGS is necessary in this case, and further experiments accordingly are planned.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical performance of H2O–CO2 coelectrolysis with a tubular solid oxide coelectrolysis (SOC) cell

Lee

et al. 2016

International Journal of Hydrogen Energy

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“…Similarly, when doubling the current density to 300 mA/cm 2 , a small ratio of H 2 :CO = 0.67 is observed (with production rates of 0.73 ml/min. Some authors suggest that a maximum of 10% of CO is produced by RWSR at 800ºC [35] while others conclude that only at high limiting current densities the CO 2 contributes to the electrochemical performance and the main production of CO is due to the thermo-chemical path [36] . cm 2 of CO).…”

Section: Faraday Discussion Accepted Manuscriptmentioning

confidence: 99%

Co-electrolysis of steam and CO₂ in full-ceramic symmetrical SOECs: a strategy for avoiding the use of hydrogen as a safe gas

et al. 2015

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The use of cermets as fuel electrodes for solid oxide electrolysis cells requires permanent circulation of reducing gas, e.g. H2 or CO, so called safe gas, in order to avoid oxidation of the metallic phase. Replacing metallic based electrodes by pure oxides is therefore proposed as an advantage for the industrial application of solid oxide electrolyzers. In this work, full-ceramic symmetrical solid oxide electrolysis cells have been investigated for steam/CO2 co-electrolysis. Electrolyte supported cells with La(0.75)Sr(0.25)Cr(0.5)Mn(0.5)O3-δ reversible electrodes have been fabricated and tested in co-electrolysis mode using different fuel compositions, from pure H2O to pure CO2, at temperatures between 850-900 °C. Electrochemical impedance spectroscopy and galvanostatic measurements have been carried out for the mechanistic understanding of the symmetrical cell performance. The content of H2 and CO in the product gas has been measured by in-line gas micro-chromatography. The effect of employing H2 as a safe gas has also been investigated. Maximum density currents of 750 mA cm(-2) and 620 mA cm(-2) have been applied at 1.7 V for pure H2O and for H2O : CO2 ratios of 1 : 1, respectively. Remarkable results were obtained for hydrogen-free fuel compositions, which confirmed the interest of using ceramic oxides as a fuel electrode candidate to reduce or completely avoid the use of safe gas in operation minimizing the contribution of the reverse water shift reaction (RWSR) in the process. H2 : CO ratios close to two were obtained for hydrogen-free tests fulfilling the basic requirements for synthetic fuel production. An important increase in the operation voltage was detected under continuous operation leading to a dramatic failure by delaminating of the oxygen electrode.

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Accurate predictions of H2O and CO2 co-electrolysis outlet compositions in operation

Cited by 26 publications

References 51 publications

Modeling of Gas Diffusion in Ni/YSZ Electrodes in CO₂ and Co‐electrolysis

Modeling of Gas Diffusion in Ni/YSZ Electrodes in CO₂ and Co‐electrolysis

Electrochemical performance of H2O–CO2 coelectrolysis with a tubular solid oxide coelectrolysis (SOC) cell

Co-electrolysis of steam and CO₂ in full-ceramic symmetrical SOECs: a strategy for avoiding the use of hydrogen as a safe gas

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Accurate predictions of H2O and CO2 co-electrolysis outlet compositions in operation

Cited by 26 publications

References 51 publications

Modeling of Gas Diffusion in Ni/YSZ Electrodes in CO2 and Co‐electrolysis

Modeling of Gas Diffusion in Ni/YSZ Electrodes in CO2 and Co‐electrolysis

Electrochemical performance of H2O–CO2 coelectrolysis with a tubular solid oxide coelectrolysis (SOC) cell

Co-electrolysis of steam and CO2 in full-ceramic symmetrical SOECs: a strategy for avoiding the use of hydrogen as a safe gas

Contact Info

Product

Resources

About

Modeling of Gas Diffusion in Ni/YSZ Electrodes in CO₂ and Co‐electrolysis

Modeling of Gas Diffusion in Ni/YSZ Electrodes in CO₂ and Co‐electrolysis

Co-electrolysis of steam and CO₂ in full-ceramic symmetrical SOECs: a strategy for avoiding the use of hydrogen as a safe gas