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

We present the results of extensive nonequilibrium molecular dynamics simul ations of transport and separation characteristics of binary and ternary ga s mixtures consisting of CO2, CH4, and H-2 through a carbon nanopore, in th e presence of an external chemical potential gradient. The gas molecules ar e 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 i n detail. The simulations' predictions are compared with experimental data obtained with a carbon molecular-sieve membrane. In some cases, there is go od agreement between the predictions and the experimental data, while in ot her cases the simulations' results and the data do not agree. Possible caus es for the (dis)agreement are discussed, including the crucial interplay be tween two main factors in gas separation in a pore space, namely, adsorptio n on the pores' walls versus the morphology (the pores' interconnectivity a nd size distribution) of the porous material. Improved models are thus sugg ested. (C) 2000 American Institute of Physics. [S0021-9606(00)50602-3].