Cruz Fernando J A L, Esteves Isabel A A C, Mota José P B, Agnihotri Sandeep, Müller Erich A
Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.
J Nanosci Nanotechnol. 2010 Apr;10(4):2537-46. doi: 10.1166/jnn.2010.1395.
We have carried out configurational-bias Grand Canonical Monte Carlo simulations of propane and propylene adsorption onto homogeneous bundles of single-walled carbon nanotubes, at ambient temperature (T = 298.15 K) and over a pressure range of 0.1 bar < or = p < 10.4 bar. The distinct contributions from external sites (grooves and external surface) and endohedral volume (inter- and intra-tubular) are individually addressed for bundles with nanotube diameters (D) within the range 11.0 A < D < or = 18.1 A. The different contributions from the various adsorption sites are interpreted from a molecular perspective, which takes into account both the skeletal geometry of the bundle and individual tube diameter. The resulting microscopic picture is then related to a macroscopic measurable isotherm by modeling the nanotube bundles, as a function of a characteristic hydraulic diameter (Dh) over the range 100 A < or = Dh < or = 310 A. A previously unobserved anisotropic behavior of the adsorption isotherm for the peripheral surface of the bundles as a function of hydraulic diameter is reported.
