Theoretical Design of Highly Efficient CO2/N2 Separation Membranes Based on Electric Quadrupole Distinction

Membrane separation of CO2/N-2 in fossil fuel gas is promising for the control of greenhouse gas emission, but challenging due to close kinetic diameters. Here, we propose a generalized model for the design of efficient CO2/N-2 separation membranes by taking advantage of the large difference between the electric quadrupole moments of the two molecules. The interaction between the molecular electric quadrupole moment and the built-in electric field of the membrane leads to high CO2/N-2 selectivity. We validate this model in five nitrogen-rich membranes, g-C3N4, g-C3N3, C2N-h2D, g-C12N8, and p-BN, and demonstrate via molecular dynamics simulations that highly efficient CO2/N-2 separation can be achieved in the theoretically predicted g-C12N8 membrane with a permeance of 2.8 x 10(5) GPU. This work offers a guidance to improve the separation efficiency of molecules With distinct electric quadrupole moments.