Molecular simulation of adsorption: Gibbs dividing surface and comparison with experiment

At low temperature near the normal boiling point, computer simulations of a dsorption of gases can be compared directly with experiment. However, for a dsorptive gas separations in which the gas is adsorbed near or above its cr itical temperature, absolute simulation variables must be converted to exce ss variables for comparison with experiment. The conversion of absolute to excess variables requires the helium pore volume of the adsorbent. Lennard- Jones potential parameters for helium gas molecules interacting with the ox ygen atoms of silicalite are epsilon /k = 28.0 K and sigma = 2.952 Angstrom The helium pore volume of silicalite is 0.175 cm(3)/g. Lennard-Jones poten tial parameters derived for Ar-O interactions in silicalite are epsilon /k = 93.0 K and sigma = 3.335 Angstrom. Density profiles for adsorption of arg on in silicalite at 300 K show that the local density is highest in the mid dle of the channels where the gas-solid potentials overlap.