Linear-driving-force model for non-isothermal gas adsorption kinetics

Abstract

The solid-film-resistance linear-driving-force model (l.d.f.) for mass transfer provides a mathematically simple but adequate description of non-isothermal gas sorption kinetics in a differential test. Analytical equations for mass uptake and adsorbent-temperature–time profiles are derived. The model allows direct calculation of a mass-transfer coefficient from the experimental uptake data to be used in the design of adsorbers. Interactions between the equilibrium and transport properties of the adsorption system predicted by the l.d.f. model are equivalent to those given by other mathematically more complicated non-isothermal models.

Experimental uptake curves for adsorption of n-butane and n-pentane on 5 Å zeolite and i-octane on 13X zeolite were quantitatively described by the l.d.f. model. The analysis shows that a ‘surface barrier’ may be the principal resistance to mass transfer for these systems.