Evidence of Facilitated Transport in Crowded Nanopores

Phan, Anh; Striolo, Alberto

doi:10.1021/acs.jpclett.9b03751

Cited by 15 publications

(31 citation statements)

References 45 publications

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“…The CO 2 separation is significantly enhanced in the micropores with respect to the mesopores, where the CO 2 separation factors may reach values of up to 6. Self‐diffusivities,

D_{{CH}_{4}}

and

D_{{CO}_{2}}

, along the mixture adsorption isotherms, in general anti‐correlate with the mixture adsorption behavior, that is,

D_{{CO}_{2}}

is lower than

D_{{CH}_{4}}

, depending on pressure, by a factor of 2–4. In contrast to recent work on facilitated transport in crowded nanopores, 70 there was no indication that strongly adsorbing CO 2 can promote CH 4 diffusion by generating preferential transport pathways within the pores. Both

D_{{CH}_{4}}

and

D_{{CO}_{2}}

decrease with increasing pressure, and increase with increasing temperature.…”

Section: Discussioncontrasting

confidence: 94%

Methane and carbon dioxide in dual‐porosity organic matter: Molecular simulations of adsorption and diffusion

2020

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Shale gas, which predominantly consists of methane, is an important unconventional energy resource that has had a potential game-changing effect on natural gas supplies worldwide in recent years. Shale is comprised of two distinct components: organic material and clay minerals, the former providing storage for hydrocarbons and the latter minimizing hydrocarbon transport. The injection of carbon dioxide in the exchange of methane within shale formations improves the shale gas recovery, and simultaneously sequesters carbon dioxide to reduce greenhouse gas emissions. Understanding the properties of fluids such as methane and methane/carbon dioxide mixtures in narrow pores found within shale formations is critical for identifying ways to deploy shale gas technology with reduced environmental impact. In this work, we apply molecularlevel simulations to explore adsorption and diffusion behavior of methane, as a proxy of shale gas, and methane/carbon dioxide mixtures in realistic models of organic materials. We first use molecular dynamics simulations to generate the porous structures of mature and overmature type-II organic matter with both micro-and mesoporosity, and systematically characterize the resulting dual-porosity organic-matter structures. We then employ the grand canonical Monte Carlo technique to study the adsorption of methane and the competing adsorption of methane/carbon dioxide mixtures in the organic-matter porous structures. We complement the adsorption studies by simulating the diffusion of adsorbed methane, and adsorbed methane/carbon dioxide mixtures in the organic-matter structures using molecular dynamics.

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“…The CO 2 separation is significantly enhanced in the micropores with respect to the mesopores, where the CO 2 separation factors may reach values of up to 6. Self‐diffusivities,

D_{{CH}_{4}}

and

D_{{CO}_{2}}

, along the mixture adsorption isotherms, in general anti‐correlate with the mixture adsorption behavior, that is,

D_{{CO}_{2}}

is lower than

D_{{CH}_{4}}

D_{{CH}_{4}}

and

D_{{CO}_{2}}

decrease with increasing pressure, and increase with increasing temperature.…”

Section: Discussioncontrasting

confidence: 94%

Methane and carbon dioxide in dual‐porosity organic matter: Molecular simulations of adsorption and diffusion

2020

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“…The adsorption energies (Δ E ads ) of CO 2 in calcite pores of widths 2.0, 2.5, 2.8, and 3.0 nm are presented in Figure . For comparison, we also ran simulations for water confined in silica pores of width 3 nm, following the algorithms described elsewhere …”

Section: Resultsmentioning

confidence: 99%

CO₂ Solubility in Aqueous Electrolyte Solutions Confined in Calcite Nanopores

2021

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Geological carbon dioxide sequestration in deep saline aquifers can play a key role in the successful mitigation of greenhouse gas emissions. Several conditions have been identified that affect the solubility of CO 2 in water, including temperature, pressure, pH, and salinity. At similar conditions, the solubility in bulk fluids differs from the solubility in confined porous media. We conducted equilibrium molecular dynamics (MD) simulations to investigate the solubility of CO 2 in water confined in slit-shaped calcite pores. We studied the effects of brine (NaCl and MgCl 2 ). Compared to bulk water/brine, the solubility of CO 2 is lower in calcite pores and decreases as the pores narrow. Adsorption energy calculations were performed to compare our results to CO 2 solubility in water-filled silica pores. These results indicate that narrower calcite pores are less attractive for the adsorption of CO 2 . In addition, the simulation results suggest that the difference in the positions where the ions adsorb also affects whether salts increase or decrease the solubility of CO 2 in confined water. Confinement and ions also reduce the mobility of CO 2 in water. These observations contribute to the design of long-term CO 2 sequestration strategies as they provide boundary constraints for the amount of CO 2 that can dissolve in hydrated pores, as well as the timing of CO 2 transport in such systems.

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“…This tool has been extensively used in literature for pure components 37 , 53 − 57 and mixtures. 58 , 59 …”

Section: Introductionmentioning

confidence: 99%

Use of Boundary-Driven Nonequilibrium Molecular Dynamics for Determining Transport Diffusivities of Multicomponent Mixtures in Nanoporous Materials

Fayaz-Torshizi

Vella

et al. 2022

J. Phys. Chem. B

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The boundary-driven molecular modeling strategy to evaluate mass transport coefficients of fluids in nanoconfined media is revisited and expanded to multicomponent mixtures. The method requires setting up a simulation with bulk fluid reservoirs upstream and downstream of a porous media. A fluid flow is induced by applying an external force at the periodic boundary between the upstream and downstream reservoirs. The relationship between the resulting flow and the density gradient of the adsorbed fluid at the entrance/exit of the porous media provides for a direct path for the calculation of the transport diffusivities. It is shown how the transport diffusivities found this way relate to the collective, Onsager, and self-diffusion coefficients, typically used in other contexts to describe fluid transport in porous media. Examples are provided by calculating the diffusion coefficients of a Lennard-Jones (LJ) fluid and mixtures of differently sized LJ particles in slit pores, a realistic model of methane in carbon-based slit pores, and binary mixtures of methane with hypothetical counterparts having different attractions to the solid. The method is seen to be robust and particularly suited for the study of study of transport of dense fluids and liquids in nanoconfined media.

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Evidence of Facilitated Transport in Crowded Nanopores

Cited by 15 publications

References 45 publications

Methane and carbon dioxide in dual‐porosity organic matter: Molecular simulations of adsorption and diffusion

Methane and carbon dioxide in dual‐porosity organic matter: Molecular simulations of adsorption and diffusion

CO₂ Solubility in Aqueous Electrolyte Solutions Confined in Calcite Nanopores

Use of Boundary-Driven Nonequilibrium Molecular Dynamics for Determining Transport Diffusivities of Multicomponent Mixtures in Nanoporous Materials

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Evidence of Facilitated Transport in Crowded Nanopores

Cited by 15 publications

References 45 publications

Methane and carbon dioxide in dual‐porosity organic matter: Molecular simulations of adsorption and diffusion

Methane and carbon dioxide in dual‐porosity organic matter: Molecular simulations of adsorption and diffusion

CO2 Solubility in Aqueous Electrolyte Solutions Confined in Calcite Nanopores

Use of Boundary-Driven Nonequilibrium Molecular Dynamics for Determining Transport Diffusivities of Multicomponent Mixtures in Nanoporous Materials

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Product

Resources

About

CO₂ Solubility in Aqueous Electrolyte Solutions Confined in Calcite Nanopores