KINETICS OF ADSORPTION AND DIFFUSIONAL CHARACTERISTICS OF CARBON MOLECULAR-SIEVES

Commercially available carbon molecular sieve (CMS) materials, from a variety of sources, and molecular sieving carbons produced from the ca rbonization of coal have been studied. These materials have been asses sed in terms of their kinetics of adsorption of oxygen and nitrogen. T he diffusion kinetics of gases into the carbons have been analysed usi ng Fickian and phenomenological models. The Arrhenius activation energ ies and pre-exponential factors for gas adsorption in the two types of material have been compared. The adsorption kinetic results are discu ssed in relation to structural models for carbon molecular sieves wher e the kinetic selectivity for gases has been introduced by carbon depo sition in the case of commercial CMS and by the variation of carboniza tion conditions in the case of the coal-based carbons produced in the laboratory.