Sorption kinetics of eight gases on a carbon molecular sieve at elevated pressure

The sorption kinetics of eight different molecules (O-2, N-2, Ar, CO, CO2, SO2, CH4 and H-2) on a carbon molecular sieve was studied over a wide range of pressures up to 15 atm by using a volumetric method. The acentric factor was suggested as a potential factor to estimate the relative sorption rate. Since the apparent time constants of all the components showed much stronger dependence of pressure than those expected by the traditional Darken relation and the structural diffusion model, new models with the diffusion relation at the supercritical condition was proposed to predict the kinetic behaviors in the micropores. The proposed model successfully predicted the apparent time constant up to high pressure. In addition, the semi-empirical model that combined acentric factor with the proposed model was able to predict the strong pressure dependence accurately. However, since the strong adsorbates, CO2 and SO2, showed two-stage kinetic behavior with pressure, which was different from that of the other adsorbates. The kinetic behaviors of these molecules could be predicted by using two different sorption models. (C) 2004 Elsevier Ltd. All rights reserved.