Massively parallel molecular dynamics simulation of gas permeation across porous silica membranes

Abstract

In this work, we simulate the pressure-driven gas permeation of gases in porous silica models using a dual control volume grand canonical molecular dynamics (DCV-GCMD) technique. This technique allows spatial variation of chemical potential and hence an accurate simulation of this steady-state process. The molecular sieving nature of microporous zeolites and amorphous silica made by sol–gel methods are discussed and compared. One mesoporous and one microporous membrane model are tested with Lennard-Jones gases corresponding to He, H 2, Ar, and CH 4. The mesoporous membrane model clearly follows a Knudsen diffusion mechanism, while the microporous model, having a hard-sphere cut-off pore diameter of ∼3.4 Å, demonstrates molecular sieving of CH 4 ( σ=3.8 Å), but anomalous behavior for Ar ( σ=3.4 Å).