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

Abstract

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.