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

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 CH4. The mesoporous membrane model clearly follows a Knudsen diffusion mechanism, while the microporous model, having a hard-sphere cut-off pore diameter of similar to 3.4 Angstrom, demonstrates molecular sieving of CH4 (sigma=3.8 Angstrom), but anomalous behavior for Ar (sigma=3.4 Angstrom). (C) 1999 Elsevier Science B.V. All rights reserved.