EQUILIBRIUM AND TRANSPORT PROPERTIES OF SMALL ALKANES AND ALKENES CONFINED IN SINGLE-WALLED CARBON NANOTUBES.

In recent years it has been suggested that carbon nanotubes (CNTs) could be used as active separating agents both in carbon adsorbents and in membranes [1-3]. To efficiently use CNTs in such separation devices, it becomes essential not only to study their selectivity/equilibrium properties but also to understand the confined fluid dynamics. This work presents molecular simulation results of both the adsorption and diffusion of low molecular weight saturated (alkanes) and unsaturated (alkenes) hydrocarbons inside single-walled carbon nanotubes (SWCNTs) of different topologies. Classical Molecular Dynamics simulations were employed to study both the adsorption and the flow dynamics. Large-scale simulations were set up where several open-ended SWCNTs were exposed to a bulk fluid in an overall canonical ensemble. The endohedral physical adsorption and non-equilibrium diffusion into the pore was monitored until steady state conditions were attained [4]. We present adsorption isotherms for both components at 300K for pressures up to 30 bar. We have seen that the adsorption is insensitive to the chirality of the nanotubes. Additionally, our results show that for the binary mixtures there is only a modest selectivity of the adsorption towards ethane. During the transient period of filling u