Rate and equilibrium sorption parameters for nitrogen and methane on carbon molecular sieve

Sorption parameters for nitrogen and methane on carbon molecular sieve (CMS) have been obtained using chromatographic, volumetric and gravimetric techniques. The equilibrium parameters-Henry constants, heats of adsorption and Langmuir constants-are consistent with reported literature values. Measurements of adsorption rates using a volumetric apparatus give results inconsistent with the diffusion hypothesis. The phenomena can be explained by the presence of a barrier resistance along with a diffusion mechanism. Analysis of results shows that the resistance measured by the chromatographic method is consistent with the resistance of the combined barrier resistance-diffusion model. The latter two resistances can only be obtained from the volumetric results. The general equation for additivity of resistances of Haynes and Sarma (AIChE J (1973) 19 1043) for breakthrough curves on a chromatogram is modified to account for the barrier resistance.