Thermodynamics of High-Pressure Tian-Calvet Adsorption Calorimetry and the Heats of Adsorption of Xe on Na-X Zeolite over the Temperature Range 299-467 K

Abstract

The development of Tian-Calvet adsorption calorimetry for studies of a bulk fluid at elevated pressures is demonstrated by a calorimetric investigation of Xe adsorption on Na-X zeolite. A thermodynamic analysis of the system examined and a discussion of the relationship between isosteric and calorimetric differential heats of adsorption are given. The strong dependence of differential calorimetric heats of adsorption on temperature at sufficiently high surface loadings is interpreted in terms of adsorbate-adsorbate interactions and the adsorption deformation of the adsorbent Overcertain regions of comparatively low pressure and temperature, differential calorimetric heats and isosteric heats of adsorption, determined on the basis that the adsorbent is inert, are in good agreement with each other, thus confirming the validity of the above assumptions. Outside such regions, however, interaction of the adsorbent is considerable.