Insights into CO2/N2 separation through nanoporous graphene from molecular dynamics.

We show from molecular dynamics simulations that porous graphene of a certain pore size can efficiently separate carbon dioxide from nitrogen with high permeance, in agreement with the recent experimental finding (Koenig et al., Nat. Nanotechnol., 2012, 7, 728-732). The high selectivity is reflected in the much higher number of CO2 passing-through events than that of N2 from the trajectories. The simulated CO2 permeance is on the order of magnitude of 10(5) GPU (gas permeation unit). The selective trend is further corroborated by the free energy barriers of permeation. The predicted CO2/N2 selectivity is around 300. Overall, the combination of high CO2 flux and high CO2/N2 selectivity makes nanoporous graphene a promising membrane for post-combustion CO2 separation.