A molecular dynamics simulation was performed to probe the mechanism of molecular permeation through nanoporous graphene gas separation membranes. The investigation involves 4 different gas molecules (He

H2

N2 and CH4) permeating 9 graphene nanopores with different sizes. The results show that the permeation flux depends not only on the kinetic parameters of molecules

i.e. molecular mass and kinetic diameter

but also on the adsorption of molecules on the surface of graphene membrane. Apart from the permeation free of interactions with the graphene surface

the adsorption layer composed of molecules with high densities on the graphene surface provides an additional way for molecular permeation

increasing the permeation flux as the molecular adsorption increases. In addition

the permeation flux of H2 molecules increases linearly with the pressure for different graphene nanopores.