Multilayer Graphene Sheet with Conical Nanopores as a Membrane for High-Permeance Molecular Separation

Sun, Chengzhen; Zhou, Runfeng; Bai, Bofeng; Lin, Yuzhen; Li, Bangming

doi:10.1021/acs.jpcc.0c10717

Cited by 13 publications

(11 citation statements)

References 41 publications

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“…On the theory and simulation sides, the mechanism of gas permeation through nanometer-scale pores in NATMs has been investigated in depth. Novel design ideas of NATM pores that enhance gas separation have been proposed based on simulations, including edge functionalization, [196] asymmetrical pores, [104,107] and continuously tunable pore size by strain or by the overlapping of two pores. [101,119,133] Pore nucleation and pore expansion processes have also been gaining increasing attention.…”

Section: Discussionmentioning

confidence: 99%

“…[88,136] Multilayer membranes with overlapping pores in different layers can also be analyzed using the same framework as that used in the case of singlelayer NATMs. [122] For example, conical pores, [107] asymmetric pores, [104] and pores with tunable sizes [101,103] have all been simulated for gas separations.…”

Section: Simulationsmentioning

confidence: 99%

“…As discussed above, MD simulations cannot effectively predict the gas permeance through a high-energy-barrier NATM pore by simply counting the number of permeation events. The typical time scale of an MD simulation is ≈10 ns, [67,107] but it would take ≈10 4 ns for one permeation event to occur, if E a = 0.3 eV, given Δp = 20 bar.…”

Section: Simulationsmentioning

confidence: 99%

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Gas Separations using Nanoporous Atomically Thin Membranes: Recent Theoretical, Simulation, and Experimental Advances

Yuan

et al. 2022

Advanced Materials

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The separation of gaseous mixtures is essential in the chemical industry, including hydrogen separation in ammonia or petrochemical plants, nitrogen separation from air, CO 2 separation in natural gas processing, [7] olefin/ paraffin separation, [1] and H 2 S separation from sour gas. [8] Similar to separation processes in general, thermal-based gasseparation methods, such as cryogenic distillation, amine adsorption, and vapor condensation, consume a high amount of energy, which can be significantly reduced using gas-separation membrane units. [5,8] A membrane that can separate gases allows certain components in a mixture to permeate at higher rates than others. The economic competitiveness of a gas-separation membrane highly depends on its gas permeance K and its selectivity S. The permeance K i of gas species i (in SI units of mol m −2 s −1 Pa −1 ) is defined as K i = F i /Δp i , where F i (in SI units of mol m −2 s −1 ) is the flux of gas i through the membrane, and Δp i is the partial pressure difference (the driving force) of gas i between the feed side and the permeate side. For relatively thick conventional membranes, whose crossmembrane transport resistance is dominated by the bulk interior, the permeance K i is inversely proportional to the membrane thickness d. Correspondingly, the permeability P i of gas i (in SI units of mol m −1 s −1 Pa −1 ) is defined aswhich is an intrinsic property of a material. The selectivity S ij between gases i and j is defined as S ij = K i /K j = P i /P j .Polymers have been the most widely used materials for gasseparation membranes for decades because of their relatively low cost and low manufacturing difficulty. [8,9] However, membrane separations using state-of-the-art polymeric membranes cannot outcompete the thermal-based separation methods economically. [7] One of the limitations of the polymeric membranes is the trade-off between permeability and selectivity, originally investigated by Robeson. [10,11] The best combination of permeability and selectivity for a binary gas pair is referred to as the polymer upper bound. This trade-off originates from the interplay between the free volume spacing in the polymer matrices and the size of the gas molecules. [12] Smaller polymeric spacing increases the selectivity but sacrifices the permeability due to the lower gas Porous graphene and other atomically thin 2D materials are regarded as highly promising membrane materials for high-performance gas separations due to their atomic thickness, large-scale synthesizability, excellent mechanical strength, and chemical stability. When these atomically thin materials contain a high areal density of gas-sieving nanoscale pores, they can exhibit both high gas permeances and high selectivities, which is beneficial for reducing the cost of gas-separation processes. Here, recent modeling and experimental advances in nanoporous atomically thin membranes for gas separations is discussed. The major challenges involved, including controlling pore size distributions, scaling up the membrane ar...

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Section: Discussionmentioning

confidence: 99%

Section: Simulationsmentioning

confidence: 99%

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Gas Separations using Nanoporous Atomically Thin Membranes: Recent Theoretical, Simulation, and Experimental Advances

Yuan

et al. 2022

Advanced Materials

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“…The interaction between the oil phase and the gas molecule varies with their separation distance, so does the value of PMF. This method was widely used in our previous works , to calculate the PMF curves.…”

Section: Results and Discussionmentioning

confidence: 99%

Miscibility Process of Hydrocarbon Mixture Gas and Crude Oil: Insights from Molecular Dynamics

Zhu

Yan

et al. 2021

Ind. Eng. Chem. Res.

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Using molecular dynamics simulations, we investigate the miscibility process of hydrocarbon mixture gas and crude oil in Tarim Oilfield, which was not well understood from the microscopic points of view. The results show that the increase of the pressure of hydrocarbon mixture gas is favorable for the gas−oil miscibility until the interfaces vanish under a minimum miscible pressure (MMP). The identified MMP (37.3 MPa) is well consistent with the experimental value. With increasing gas pressure, the parallel diffusion coefficients of gas molecules in the gas− oil interfaces decrease, while the perpendicular ones increase. We also analyze the profiles of potential of mean force between different gas and various oil components, identifying the components which dominate the process of gas−oil miscibility from the perspective of molecular forces. In addition, the introduction of gravity in gas flooding slightly increases the MMP. These results can guide the optimization and design of the enhanced oil recovery technology with hydrocarbon mixture gas flooding.

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“…Currently, the industrial-scale NPG membranes have been successfully synthesized with a high molecular permeance as the theoretically expected (Boutilier et al, 2017;Wang et al, 2017;Zhao et al, 2019). Meanwhile, the molecular permeation mechanisms through NPG membranes were also well revealed (Drahushuk and Strano, 2012;Sun et al, 2014;Yuan et al, 2017;Sun et al, 2019a;Sun et al, 2021a;Sun et al, 2021b). In short, the NPG membranes for molecular separation has become a reality, especially for the application of gas separation.…”

Section: Introductionmentioning

confidence: 93%

Quasi-Unidirectional Transport Bilayer Two-Dimensional Nanopores for Highly-Efficient Molecular Sieving

et al. 2021

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Two-dimensional nanopores are very promising for high-permeance molecular sieving, but the molecular backflow from permeate-side to feed-side is not beneficial for improving molecular permeance. We study the quasi-unidirectional molecular transport through a graphene-hexagonal boron nitride bilayer nanopore, aiming to realize a high-permeance molecular sieving. Molecular dynamics simulations of CO2/CH4 separations show that the bilayer pore presents 3.7 times higher selectivity comparing to the single-layer graphene nanopore with the same size. The quasi-unidirectional molecular transport is attributed to the distinctive adsorption abilities of gas molecules on the two sides of bilayer nanopores and the inhibited molecular backflow from permeate-side to feed-side. This work provides a promising way to realize the ultra-permeable porous membranes with molecular permeance even higher than the single-layer atomic-thickness membranes.

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Multilayer Graphene Sheet with Conical Nanopores as a Membrane for High-Permeance Molecular Separation

Cited by 13 publications

References 41 publications

Gas Separations using Nanoporous Atomically Thin Membranes: Recent Theoretical, Simulation, and Experimental Advances

Gas Separations using Nanoporous Atomically Thin Membranes: Recent Theoretical, Simulation, and Experimental Advances

Miscibility Process of Hydrocarbon Mixture Gas and Crude Oil: Insights from Molecular Dynamics

Quasi-Unidirectional Transport Bilayer Two-Dimensional Nanopores for Highly-Efficient Molecular Sieving

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