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.