Highly Efficient CO/CH Separation by Porous Graphene via Quadrupole Gating Mechanism.

Acetylene (CH) is an important and widely used raw material in various industries (such as petrochemical). Generally, a product yield is proportional to the purity of CH; however, CH from a typical industrial gas-production process is commonly contaminated by CO. So far, the achievement of high-purity CH separated from a CO/CH mixture is still challenging due to their very close molecular dimensions and boiling temperatures. Taking advantage of their quadrupoles with opposite signs, here, we show that the graphene membrane embedded with crown ether nanopores can achieve an unprecedented separation efficiency of CO/CH. Combining the molecular dynamics simulation and the density functional theory (DFT) approaches, we discovered that the electrostatic gas-pore interaction favorably allows the fast transport of CO through crown ether nanopores while completely prohibiting CH transport, which yields a remarkable permeation selectivity. In particular, the utilized crown ether pore is capable of allowing the individual transport of CO while completely rejecting the passage of CH, independent of the applied pressures, fed gases ratios, and exerted temperatures, featuring the superiority and robustness of the crown pore in CO/CH separation. Further, DFT and PMF calculations demonstrate that the transport of CO through the crown pore is energetically more favorable than the transport of CH. Our findings reveal the potential application of graphene crown pore for CO separation with outstanding performance.