单层多孔石墨烯膜结构对C_(2)烃气体分离性能影响的分子动力学研究

Influence of Single-Layer Porous Graphene Membrane Structure on C_(2) Hydrocarbons Separation Performance:A Molecular Dynamics Study

利用分子动力学模拟研究了孔径、孔形状、官能团修饰对纳米多孔石墨烯膜分离C_(2)烃气体的效率和选择性的影响。结果表明:孔径为0.444~0.484 nm的石墨烯膜对乙烷的截留性能较好,乙烯的通过率较高;圆形孔石墨烯膜具有较高的气体通过效率,扁平孔石墨烯膜具有较高的气体分离的选择性;孔短径为0.510 nm、孔长径为1.164 nm的石墨烯膜对乙烷的截留性能较好,其乙烯通量较大;孔径为0.596 nm且孔口周围带有两个羧基的石墨烯膜对乙烯的截留性能较好,乙炔的通过率较高。所得模拟结果为设计高效、高选择性分离C_(2)烃气体的单层多孔石墨烯膜提供理论依据。

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.However,this process is very energyconsuming.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 their outstanding separation performance;however,relevant studies are scarce.Herein,molecular dynamics simulations are 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 0.444—0.484 nm facilitate ethane retention with high ethylene passability.High gas passability and selectivity are determined for circular and oval pores,respectively.Oval pores with a short diameter of 0.510 nm and a long diameter of 1.164 nm are able to effectively pass ethylene molecules while retaining ethane molecules.A pore size of 0.596 nm with the pore being modified with two carboxyl groups can retain ethylene and pass acetylene.Our simulation results provide theoretical insights into the design of single-layer porous graphene membranes to separate C_(2) hydrocarbons gases efficiently and selectively.