H-passivated nanoporous graphene membranes for CO2/N2 separation: A reactive molecular dynamic simulation

Abstract

We used a reactive force-field (ReaxFF) to investigate the capability of H-passivated nanoporous graphene as a membrane for the separation of carbon dioxide from nitrogen. Unlike traditional atomistic force-fields, the reactive force field considers chemical bond-forming/braking and estimates the polarisation effect more accurately. We examined the effect of pore size and pore shape in several gas mixtures with different mole ratios. We assessed the selectivity of six H-passivated pores by counting the number of transmitted molecules from them. The simulation shows that the H-modified porous graphene membrane with pore diameter (short side) of about 2.4 Å only allow N2 molecules to permeate through and have the best separation selectivity. The CO2 molecules can pass through pores greater than 4.2 Å diameters. However, they tend to accumulate near the graphene membranes due to non-bonded interactions and do not diffuse in the vacuum until they saturate the graphene walls.