Nanoscale Study of CO2/CH4 Separation through Two-stage Nanoporous Graphene Membranes*

During the last decade, various designs have been introduced to separate CH$_{\mathrm{4\thinspace }}$from other components in gas mixtures. The development of effective membranes with high selectivity and permeability is one of the most challenging subjects in carbon capturing and storage. In this context, we investigated the transport and separation of CO$_{\mathrm{2}}$/CH$_{\mathrm{4}}$ binary mixture through a two-stage bilayer nanoporous graphene design. The molecular dynamics technique is applied to investigate the transport properties. Benchmarked forcefields are adopted for modeling the interactions between different molecules. Three boxes are considered as feeding, transferring, and capturing reservoirs. Three configurations of nanoporous graphene membranes are examined, namely, in-line, offset of 10 angstroms, and offset of 20 angstroms. The simulation results indicate that increasing the offset distance leads to a considerable decrease in the number of CH$_{\mathrm{4}}$ molecules in the CO$_{\mathrm{2}}$ capturing reservoir. This study suggests one of the practical designs for the separation of CH$_{\mathrm{4\thinspace }}$with the application in the CO$_{\mathrm{2}}$ abatement industry.