Nonequilibrium molecular dynamics simulation of transport and separation of gases in carbon nanopores. II. Binary and ternary mixtures and comparison with the experimental data

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We present the results of extensive nonequilibrium molecular dynamics simulations of transport and separation characteristics of binary and ternary gas mixtures consisting of CO2, CH4, and H2 through a carbon nanopore, in the presence of an external chemical potential gradient. The gas molecules are represented as Lennard-Jones (LJ) hard spheres. The effect of the various factors, such as the temperature, feed composition, and the pore size, on the transport, adsorption, and separation characteristics is investigated in detail. The simulations’ predictions are compared with experimental data obtained with a carbon molecular-sieve membrane. In some cases, there is good agreement between the predictions and the experimental data, while in other cases the simulations’ results and the data do not agree. Possible causes for the (dis)agreement are discussed, including the crucial interplay between two main factors in gas separation in a pore space, namely, adsorption on the pores’ walls versus the morphology (the pores’ interconnectivity and size distribution) of the porous material. Improved models are thus suggested.