Atomically detailed simulations were used to examine the adsorption and transport diffusion of CO2 and N2 in single-walled carbon nanotubes at room temperature as a function of nanotube diameter. Linear and spherical models for CO2 were compared, showing that representing this species as spherical has only a slight impact in the computed diffusion coefficients. The results supported previous predictions that transport diffusivities of molecules inside carbon nanotubes were extremely rapid when compared with other porous materials. By examining carbon nanotubes as large as the (40,40) nanotube, it was possible to compare the transport rates predicted by these calculations with experimental measurements. The predicted transport rates were in reasonable agreement with experimental observations.

Adsorption and Diffusion of Carbon Dioxide and Nitrogen through Single-Walled Carbon Nanotube Membranes. Skoulidas, A.I., Sholl, D.S., Johnson, J.K.: Journal of Chemical Physics, 2006, 124[5], 054708