H-passivated nanoporous graphene membranes for CO2/N-2 separation: A reactive molecular dynamic simulation

Z Negaresh and M Fazli and SM Hashemianzadeh, JOURNAL OF MOLECULAR STRUCTURE, 1253, 132255 (2022).

DOI: 10.1016/j.molstruc.2021.132255

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 forcefields, 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 angstrom only allow N-2 molecules to permeate through and have the best separation selectivity. The CO2 molecules can pass through pores greater than 4.2 angstrom 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. (c) 2021 Elsevier B.V. All rights reserved.

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