N-doped porous graphene for carbon dioxide separation: a molecular dynamics study

Using molecular dynamics simulations, it is shown that N-doped porous graphene membrane can efficiently separate CO₂ from the CO₂/CH₄ mixture. The effects of pore rim modifications, N-doping sites, initial gas pressure, and feed gas compositions on CO₂ separation performance of N-doped porous graphene membrane are also examined. It is found that gas permeability increases with increasing initial gas pressure or the feed gas percentages. Pore rim modifications with nitrogen atoms (pyridinic N) can significantly improve the selectivity of CO₂ over CH₄ owing to the enhanced electrostatic interactions compared to the unmodified one, and the all-N-modified pore-16 shows the highest CO₂ selectivity over CH₄ (~29). Doping N atoms on the graphene sheets (quaternary N) has little effect on the CO₂ selectivity. Our study demonstrates that the N-doped porous graphene is an excellent candidate for CO₂ separation, which may be beneficial for the realization of a low carbon society.