Adsorption and Separation of CO2 and CH4 Gas Mixture in a Graphene Layer and a Graphite Surface*

The goal of this work is to predict the selective adsorption of CO2 from a mixture with CH4 on a graphene/graphite substrate. The substrate consists on a layer of graphene with slits suspended on top of graphite at a distance of 10 Å. Molecular dynamics was used to simulate this adsorption. In this system, methane is modeled as a single, spherical atom with one Lennard-Jones site.Carbon dioxide is modeled as a linear rigid body with three Lennard-Jones sites and three partial charges. The slits in graphene are made by deleting carbon atoms from the lattice within a region of specified width. Graphite is modeled as a 10-4-3 wall. We run the simulations at 300K and compare the selectivity of CO2/CH4on the substrate to test the capability of the graphene/graphite to separate CO2 from CH4.The result shows that the selectivity is higher for narrow slits.