Thermodynamic Insights for Electrochemical Hydrogen Compression with Proton-Conducting Membranes

Kee, Benjamin L.; Curran, David J.; Zhu, Huayang; Braun, Robert J.; DeCaluwe, Steven C.; Kee, Robert J.; Ricote, Sandrine

doi:10.3390/membranes9070077

Cited by 19 publications

(20 citation statements)

References 42 publications

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“… 1 A Nafion membrane usually operates in a temperature range below 100 °C. 10 , 11 A Nafion monomer has an electrochemically neutral semicrystalline polymer backbone and a side chain with a pendant sulfonic group (HSO 3 ). 1 , 11 As a PFSA, a Nafion membrane has a hydrophobic polytetrafluoroethylene (PFTE) backbone.…”

Section: Introductionmentioning

confidence: 99%

Electro-osmotic Drag and Thermodynamic Properties of Water in Hydrated Nafion Membranes from Molecular Dynamics

et al. 2022

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One of the important parameters in water management of proton exchange membranes is the electro-osmotic drag (EOD) coefficient of water. The value of the EOD coefficient is difficult to justify, and available literature data on this for Nafion membranes show scattering from in experiments and simulations. Here, we use a classical all-atom model to compute the EOD coefficient and thermodynamic properties of water from molecular dynamics simulations for temperatures between 330 and 420 K, and for different water contents between λ = 5 and λ = 20. λ is the ratio between the moles of water molecules to the moles of sulfonic acid sites. This classical model does not capture the Grotthuss mechanism; however, it is shown that it can predict the EOD coefficient within the range of experimental values for λ = 5 where the vehicular mechanism dominates proton transfer. For λ > 5, the Grotthuss mechanism becomes dominant. To obtain the EOD coefficient, average velocities of water and ions are computed by imposing different electric fields to the system. Our results show that the velocities of water and hydronium scale linearly with the electric field, resulting in a constant ratio of ca. 0.4 within the error bars. We find that the EOD coefficient of water linearly increases from 2 at λ = 5 to 8 at λ = 20 and the results are not sensitive to temperature. The EOD coefficient at λ = 5 is within the range of experimental values, confirming that the model can capture the vehicular transport of protons well. At λ = 20, due to the absence of proton hopping in the model, the EOD coefficient is overestimated by a factor of 3 compared to experimental values. To analyze the interactions between water and Nafion, the partial molar enthalpies and partial molar volumes of water are computed from molecular dynamics simulations. At different water uptakes, multiple linear regression is used on raw simulation data within a narrow composition range of water inside the Nafion membrane. The partial molar volumes and partial molar excess enthalpies of water asymptotically approach the molar volumes and molar excess enthalpies of pure water for water uptakes above 5. This confirms the model can capture the bulklike behavior of water in the Nafion at high water uptakes.

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Section: Introductionmentioning

confidence: 99%

Electro-osmotic Drag and Thermodynamic Properties of Water in Hydrated Nafion Membranes from Molecular Dynamics

et al. 2022

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“…6,13−15 To date, most of the required hydrogen in refineries is produced from steam methane reforming (SMR) with CO 2 as a byproduct. 2,4,8,12,16 About 50% of the produced hydrogen worldwide is used in ammonia synthesis plants. Hydrogen is also used as a hydrocarbon upgrader or feedstock in refineries, e.g., reducing nitrogen oxides, sulfur oxides, and other particles causing smog.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, EHCs have become cost-competitive alternatives to their mechanical counterparts. 16,30,31 Due to the advantages over mechanical compression, EHCs are on the way to be commercialized on a large scale. EHCs can generate a high output pressure (up to 1000 bar), which is suitable for refueling hydrogen vehicles.…”

Section: Introductionmentioning

confidence: 99%

“…30,33 The highest differential pressure reported in the literature for a single compression cell is 168 bar. 20 Two types of proton conducting membranes are typically used for electrochemical compression: 1616 (1) proton electrolyte membranes such as Nafion-type membranes, 16,28,34 which are suitable for lowtemperature applications; and (2) protonic-ceramic electrolyte membranes, which are suitable for high-temperature applications (e.g., 600 °C). 16 These membranes are highly selective to permeation of protons as impurities cannot pass the membrane.…”

Section: Introductionmentioning

confidence: 99%

“…To produce hydrogen as a free gas, energy is required. , Hydrogen can be a carbon-free renewable energy source depending on the production pathway, e.g ., green hydrogen can be produced from water electrolysis in which the required energy is supplied from renewable sources. The high energy density of hydrogen per unit of mass (higher heating value of 141.8 MJ/kg at 298 K) makes it a flexible off-peak energy carrier, especially for storing intermittent renewable energy at peak times, or as a fuel for transportation. ,− To date, most of the required hydrogen in refineries is produced from steam methane reforming (SMR) with CO 2 as a byproduct. ,,,, About 50% of the produced hydrogen worldwide is used in ammonia synthesis plants. Hydrogen is also used as a hydrocarbon upgrader or feedstock in refineries, e.g ., reducing nitrogen oxides, sulfur oxides, and other particles causing smog. , …”

Section: Introductionmentioning

confidence: 99%

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Effect of Water Content on Thermodynamic Properties of Compressed Hydrogen

Rahbari

Garcia-Navarro²,

Ramdin

et al. 2021

J. Chem. Eng. Data

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Force field-based molecular simulations were used to calculate thermal expansivities, heat capacities, and Joule− Thomson coefficients of binary (standard) hydrogen−water mixtures for temperatures between 366.15 and 423.15 K and pressures between 50 and 1000 bar. The mole fraction of water in saturated hydrogen−water mixtures in the gas phase ranges from 0.004 to 0.138. The same properties were calculated for pure hydrogen at 323.15 K and pressures between 100 and 1000 bar. Simulations were performed using the TIP3P and a modified TIP4P force field for water and the Marx, Vrabec, Cracknell, Buch, and Hirschfelder force fields for hydrogen. The vapor−liquid equilibria of hydrogen−water mixtures were calculated along the melting line of ice Ih, corresponding to temperatures between 264.21 and 272.4 K, using the TIP3P force field for water and the Marx force field for hydrogen. In this temperature range, the solubilities and the chemical potentials of hydrogen and water were obtained. Based on the computed solubility data of hydrogen in water, the freezing-point depression of water was computed ranging from 264.21 to 272.4 K. The modified TIP4P and Marx force fields were used to improve the solubility calculations of hydrogen− water mixtures reported in our previous study et al. J. Chem. Eng. Data 2019, 64, 4103−4115] for temperatures between 323 and 423 K and pressures ranging from 100 to 1000 bar. The chemical potentials of ice Ih were calculated as a function of pressure between 100 and 1000 bar, along the melting line for temperatures between 264.21 and 272.4 K, using the IAPWS equation of state for ice Ih. We show that at low pressures, the presence of water has a large effect on the thermodynamic properties of compressed hydrogen. Our conclusions may have consequences for the energetics of a hydrogen refueling station using electrochemical hydrogen compressors.

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Technologische Pfade für die Herstellung von komprimiertem und hochreinem Wasserstoff mit Hilfe von Sonnenenergie

et al. 2023

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Übersetzung wird gemeinsam mit der endgültigen englischen Fassung erscheinen. Die endgültige englische Fassung (Version of Record) wird ehestmöglich nach dem Redigieren und einem Korrekturgang als Early-View-Beitrag erscheinen und kann sich naturgemäß von der AA-Fassung unterscheiden. Leser sollten daher die endgültige Fassung, sobald sie veröffentlicht ist, verwenden. Für die AA-Fassung trägt der Autor die alleinige Verantwortung.

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Thermodynamic Insights for Electrochemical Hydrogen Compression with Proton-Conducting Membranes

Cited by 19 publications

References 42 publications

Electro-osmotic Drag and Thermodynamic Properties of Water in Hydrated Nafion Membranes from Molecular Dynamics

Electro-osmotic Drag and Thermodynamic Properties of Water in Hydrated Nafion Membranes from Molecular Dynamics

Effect of Water Content on Thermodynamic Properties of Compressed Hydrogen

Technologische Pfade für die Herstellung von komprimiertem und hochreinem Wasserstoff mit Hilfe von Sonnenenergie

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