Highly Efficient CO₂/C₂H₂ Separation by Porous Graphene via Quadrupole Gating Mechanism

Acetylene(C2H2) is an important and widelyused raw material in various industries (such as petrochemical). Generally,a product yield is proportional to the purity of C2H2; however, C2H2 from a typical industrialgas-production process is commonly contaminated by CO2.So far, the achievement of high-purity C2H2 separatedfrom a CO2/C2H2 mixture is stillchallenging due to their very close molecular dimensions and boilingtemperatures. Taking advantage of their quadrupoles with oppositesigns, here, we show that the graphene membrane embedded with crownether nanopores can achieve an unprecedented separation efficiencyof CO2/C2H2. Combining the moleculardynamics simulation and the density functional theory (DFT) approaches,we discovered that the electrostatic gas-pore interaction favorablyallows the fast transport of CO2 through crown ether nanoporeswhile completely prohibiting C2H2 transport,which yields a remarkable permeation selectivity. In particular, theutilized crown ether pore is capable of allowing the individual transportof CO2 while completely rejecting the passage of C2H2, independent of the applied pressures, fed gasesratios, and exerted temperatures, featuring the superiority and robustnessof the crown pore in CO2/C2H2 separation.Further, DFT and PMF calculations demonstrate that the transport ofCO(2) through the crown pore is energetically more favorablethan the transport of C2H2. Our findings revealthe potential application of graphene crown pore for CO2 separation with outstanding performance.