Selectivity trend of gas separation through nanoporous graphene

• Classical MD simulations show the flux trend of H2>CO2≫N2>Ar>CH4 for their permeation through a porous graphene.
• Free energy calculations yield permeation barriers for those gases.
• Selectivities for several gas pairs are estimated from the free-energy barriers and the kinetic theory of gases.
• The selectivity trend is in excellent agreement with a recent experiment.

By means of molecular dynamics (MD) simulations, we demonstrate that porous graphene can efficiently separate gases according to their molecular sizes. The flux sequence from the classical MD simulation is H2>CO2≫N2>Ar>CH4, which generally follows the trend in the kinetic diameters. This trend is also confirmed from the fluxes based on the computed free energy barriers for gas permeation using the umbrella sampling method and kinetic theory of gases. Both brute-force MD simulations and free-energy calcualtions lead to the flux trend consistent with experiments. Case studies of two compositions of CO2/N2 mixtures further demonstrate the separation capability of nanoporous graphene.

Classical molecular dynamics simulations show the flux trend of H2>CO2≫N2>Ar>CH4 for their permeation through a porous graphene, in excellent agreement with a recent experiment.Figure optionsDownload as PowerPoint slide