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

Abstract

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 10⁵ 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.