Gas Sorption in Ionic Liquid-Carbon Nanotube Composite Materials

Molecular dynamics and Monte Carlo simulations were used to study the ionic liquid 1-n-Hexyl-3-methylimidazolium bis(Trifluoromethylsulfonyl)amide ([hmim][Tf2N]) confined into the (20,20) and (9,9) carbon nanotubes and gases (CO2, H2) absorption into the composite material consisting of the ionic liquid and the carbon nanotube. Structures of the ionic liquid confined in the carbon nanotubes will be presented. The self-diffusivity of the gases and the ionic liquid in the carbon nanotube have been calculated. For gas sorption, the highest amounts of adsorbed CO2 and H2 are observed in carbon nanotube, followed by the composite material, and the ionic liquid exhibits the least amounts of absorption. The CO2/H2 sorption selectivity exhibits the highest value in the composite material, followed by the ionic liquid, and the carbon nanotube exhibits the least selectivity. When the temperature is increased, the CO2 sorption decreases in all three types of materials. In contrast, the H2 sorption increases in [hmim][Tf2N], decreases in the carbon nanotube, and almost does not change in the composite material. Novel absorption behavior for CO2/IL/carbon nanotube and differences from those of CO2/IL will be shown.