Propylene/propane separation by porous graphene membrane: Molecular dynamic simulation and first-principle calculation

Abstract

Molecular dynamic (MD) simulation and first-principle density functional theory (DFT) calculation are applied to study the C3H6/C3H8 separation performance of porous graphene membrane. It was found that porous graphene membrane with appropriate pore size and shape can be employed to separate propylene and propane. Among the ten kinds of pores investigated, the graphene membrane with NH modified pores exhibit extremely superior selectivity for propylene while maintaining high permeance. According to the study on adsorption mechanism, porous graphene (PG) membranes show preferential adsorption towards propylene mainly attributed to van der Waals interaction, which gives C3H6 molecules more chances to approach the pores. On the other hand, interaction energy and electron density by DFT demonstrate that the attractive potential energy well and the less pronounced overlap of PG membrane towards propylene molecules do facilitate their penetration through the pores. On the contrary, the case is totally different with propane. We anticipate that our work will accelerate the application of porous PG membrane in the C3H6/C3H8 separation.