Temperature Dependence of the Isosteric Heat of Adsorption

Abstract

Direct calorimetric measurements of the isosteric heats of adsorption of (a) pure CO₂ on a strongly heterogeneous adsorbent (silicalite with an alumina binder) and (b) pure N₂ on a mildly heterogeneous adsorbent (5A zeolite) at different temperatures and adsorbate loadings demonstrated the validity of the conventional assumption that isosteric heats are very weak functions of temperature. A simple thermodynamic model for the adsorption of a pure gas on an adsorbent containing two different energetic sites also validated the same assumption in the Henry's law region.