Simulation of Pore Width and Pore Charge Effects on Selectivities of CO2 vs. H2 from a Syngas-like Mixture in Carbon Mesopores

Trinh, Thuat T.; Vlugt, Thijs J. H.; Hägg, May‐Britt; Bedeaux, Dick; Kjelstrup, Signe

doi:10.1016/j.egypro.2015.01.018

Cited by 11 publications

(11 citation statements)

References 34 publications

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“…In our earlier work we adapted a similar strategy to demonstrate exclusively the N doping effect on CO 2 uptake, and additionally such assumptions also successfully predicted the experimentally observed isosteric heat values and the theoretical limit of N doped carbons . Such approach was also earlier used by other researchers to estimate the H 2 uptake in oxygenated carbon surfaces, single and binary adsorption of CO 2 and CH 4 and their mixtures in oxygenated carbons, and water adsorption in oxygenated surfaces, and to obtain the kinetic and thermodynamic selectivity of CO 2 /CH 4 of carbon materials. − …”

Section: Simulation Detailsmentioning

confidence: 80%

Understanding the Hydrophilicity and Water Adsorption Behavior of Nanoporous Nitrogen-Doped Carbons

et al. 2016

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Through molecular simulation we exposed the anomalous water adsorption behavior in slit-shaped and disordered nitrogen doped carbons. Instead of Langmuirian, water adsorption proceeds via mechanisms analogous to crystal nucleation: birth and spread of (poly) nucleation sites in one, two, and three dimensions forming water nanowires/pillars and water clusters before complete pore filling via capillary condensation. The adsorption of water and the adsorption hysteresis in N-doped carbons are strongly influenced by the poresize. The smaller the pore-size, the smaller is the pressure at which the abovementioned process tends to occur in N-doped carbons. The nucleation analogues are clearly visible in a pore that has a homogeneous pore structure, whereas in disordered pore structures, the complex and distributed pore-sizes disturb these nucleation analogue patterns especially at lower relative pressures. The effect of the adsorbed water molecules on the connectivity of the available pore volume is discussed. Adsorption at zero loading confirmed water molecules preferentially adsorb over specific zones, which corresponds to regions with a high local density of N atoms rather than specific sites or type of N (such as graphitic or pyridinic). Simulated adsorption isotherms showed the hydrophilicity introduced to the carbon pore via N doping is sensitive to impurities such as water, such that it can affect the ability of the carbon framework to host another guest molecule such as CO 2 , a prime fluid involved in flue gas.

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Section: Simulation Detailsmentioning

confidence: 80%

Understanding the Hydrophilicity and Water Adsorption Behavior of Nanoporous Nitrogen-Doped Carbons

et al. 2016

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“…A similar strategy was successfully applied earlier to study the hydrogen adsorption properties of oxygen functionalized carbon materials, 31 CO 2 and CH 4 single component and their binary mixture adsorption in different carbon nanopore models, 4 and water adsorption in oxygen functionalized carbons 32 and to estimate the equilibrium and dynamic selectivity of CO 2 /H 2 of carbon structures. 33 All CO 2 −CO 2 and N 2 −N 2 interactions were modeled using the TraPPE potential. 34 This model treats CO 2 as a linear triatomic molecule with charges placed at the center of the each LJ atom.…”

Section: Simulation Methodsmentioning

confidence: 99%

“…Even for periodic crystalline materials, methods to assign the point of charges to the atoms and their influence on the uptake of quadrupolar fluids is still unclear. , The limitations and the practical difficulties associated with assigning point charges while studying the adsorption of quadrupolar fluids are detailed in some of the recent works, albeit with the other class of porous materials (metal organic frameworks). , The objectives of this work are limited to exclusively portray the influence of the N doping effect on the CO 2 uptake; to do this, we kept the system electroneutral by assuming (i) the local redistribution of the charges around the C atoms which are connected to N atoms is 0.3133 and (ii) the local electronic redistribution to the next neighboring carbon atoms is negligible. A similar strategy was successfully applied earlier to study the hydrogen adsorption properties of oxygen functionalized carbon materials, CO 2 and CH 4 single component and their binary mixture adsorption in different carbon nanopore models, and water adsorption in oxygen functionalized carbons and to estimate the equilibrium and dynamic selectivity of CO 2 /H 2 of carbon structures …”

Section: Simulation Methodsmentioning

confidence: 99%

Effect of Nitrogen Doping on the CO₂ Adsorption Behavior in Nanoporous Carbon Structures: A Molecular Simulation Study

et al. 2015

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Nitrogen (N) doping is considered an effective design strategy to improve CO 2 adsorption in carbon materials. However, experimental quantification of such an effect is riddled with difficulties, due to the practical complexity involved in experiments to control more than one parameter, especially at the nanoscale level. Here, we use molecular simulations to clarify the role of N doping on the CO 2 uptake and the CO 2 /N 2 selectivity in representative carbon pore architectures (slit and disordered carbon structures) at 298 K. Our results indicate that N doping shows a marginal improvement on the CO 2 uptake, although it can improve the CO 2 /N 2 selectivity. CO 2 uptake and CO 2 /N 2 selectivity are predominantly controlled by the pore architecture as well as ultra-micropores; the tendency of linear CO 2 molecules to lie flat on the carbon surface favors the CO 2 uptake in slit pore architectures rather than disordered carbon pore structures. We also demonstrated through molecular simulations that the N doping effect may be difficult to exemplify experimentally if the material has a disordered pore architecture and complex surface chemistry (such as the presence of other functional groups).

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“…Extensive research has been conducted by studying fluid behavior in confinements to investigate reactions on membranes, 1 clay swelling, 4 drug delivery, 2,5 fluid transport, 6,7 and adsorption. 8,9 To elucidate different problems, various confining materials such as carbon compounds, 8,10−12 minerals, 3,9 and membranes 1 have been employed in experiments and simulations.…”

Section: Introductionmentioning

confidence: 99%

Quantifying Magnetic Resonance Effects Due to Solid–Fluid Interactions on Confined Water within Quartz-Lined Nanopores via Molecular Dynamics Simulations

2023

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Nuclear magnetic resonance (NMR) relaxation time provides valuable information about properties of fluid and solid surfaces within rocks; however, the complexity of rock samples makes it difficult to quantify the effect of solid–fluid interactions on NMR measurements. Additionally, the ability of 2 MHz NMR equipment to probe nanopores is limited, while detailed analyses of fluid NMR properties in nanopores are possible through molecular dynamics (MD) simulations. We performed atomistic MD simulations to quantify the effect of solid–fluid interactions on confined water within hydroxylated slit and cylindrical quartz-lined rock pores (slit width and cylinder radius from 1 to 9 nm). NMR properties along with density profiles and mean-squared displacements (MSD) were calculated to quantify the effect of solids on relaxation times. MD results indicate that the surface chemistry of slit and cylindrical pores causes differences in density profiles and NMR properties of water confined in silica nanopores. Structural features present in density profiles are important to interpret both MSD and NMR relaxation properties. Intramolecular correlation times are shorter than intermolecular correlation times except when water is confined inside a 1 nm slit pore. These results highlight the importance of pore size on the solid–fluid interactions at the nanoscale. Layer analysis of confined water shows that NMR relaxation times of central layers in small nanopores are not the same as bulk relaxation time. This difference originates an overestimation of pore-size distributions of tight rocks from NMR measurements via Brownstein–Tarr’s equation. Furthermore, relaxation times of water layers indicate that the effect of solid surfaces on NMR relaxation times in a 3 nm slit pore is 15.32% of those in a 9 nm slit pore.

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Simulation of Pore Width and Pore Charge Effects on Selectivities of CO2 vs. H2 from a Syngas-like Mixture in Carbon Mesopores

Cited by 11 publications

References 34 publications

Understanding the Hydrophilicity and Water Adsorption Behavior of Nanoporous Nitrogen-Doped Carbons

Understanding the Hydrophilicity and Water Adsorption Behavior of Nanoporous Nitrogen-Doped Carbons

Effect of Nitrogen Doping on the CO₂ Adsorption Behavior in Nanoporous Carbon Structures: A Molecular Simulation Study

Quantifying Magnetic Resonance Effects Due to Solid–Fluid Interactions on Confined Water within Quartz-Lined Nanopores via Molecular Dynamics Simulations

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Simulation of Pore Width and Pore Charge Effects on Selectivities of CO2 vs. H2 from a Syngas-like Mixture in Carbon Mesopores

Cited by 11 publications

References 34 publications

Understanding the Hydrophilicity and Water Adsorption Behavior of Nanoporous Nitrogen-Doped Carbons

Understanding the Hydrophilicity and Water Adsorption Behavior of Nanoporous Nitrogen-Doped Carbons

Effect of Nitrogen Doping on the CO2 Adsorption Behavior in Nanoporous Carbon Structures: A Molecular Simulation Study

Quantifying Magnetic Resonance Effects Due to Solid–Fluid Interactions on Confined Water within Quartz-Lined Nanopores via Molecular Dynamics Simulations

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Effect of Nitrogen Doping on the CO₂ Adsorption Behavior in Nanoporous Carbon Structures: A Molecular Simulation Study