Abstract:
C
2 hydrocarbons are important intermediates in petrochemical industry. Cryogenic rectification is broadly used to separate mixed C
2 hydrocarbon gas to obtain pure C
2 products, while this process consumes a lot of energy. Employing membrane separation technology to separate mixed gases can effectively reduce costs and energy consumption. Single-layer porous graphene membranes have great potential for mixed C
2 hydrocarbons gas separation because of superior separation performance, however, related studies are scarce. Herein, molecular dynamics simulations were applied to study the effect on the efficiency and selectivity of C
2 hydrocarbons gas separation by single-layer porous graphene membranes with different pore sizes, pore shapes, and modified functional groups. The results show that the single-layer porous graphene membranes with pore sizes of 0.439-0.484 nm exhibit great ethane retention and high ethylene passability. Circular pores show high gases passability and oval pores display high gases selectivity. Oval pores with short diameter of 0.510 nm and a long diameter of 1.164 nm are able to effectively pass ethylene molecules and retain ethane molecules. A pore size of 0.596 nm with two carboxyl groups can retain ethylene and pass acetylene. The simulation results provide theoretical insights on design of the single-layer porous graphene membranes to separate C
2 hydrocarbons gases efficiently and selectively.