Energy of the adsorption of gases and vapors on microporous adsorbents

Abstract

1. A calorimeter of the Tian-Calvet type was constructed. The measuring constants and technical operating characteristics of the instrument in certain respects are better than that of the well-known Calvet precision instrument. 2. The new method was used to measure endothermic processes (heats of desorption) by compensating for them with an exothermic Peltier effect. The heats of desorption are in good agreement with the heats of adsorption. 3. The adsorption isotherm of propane on NaX is strictly linear all the way up to 20% filling of the adsorption space (the Henry region). In this region, in the formal calculation the adsorption is less than or, in the limit, equal to one propane molecule on the average per large cavity of the zeolite, while the differential heats of adsorption are practically constant. When the number of adsorbed molecules increases on the average for four per cavity, a linear increase in the differential heat of adsorption is observed. The corresponding contribution of the fifth adsorbed molecule to the differential heat of adsorption is practically twice as great as for each of the preceding molecules. 4. On the whole, the calorimetric measurements indicated that final energy characteristics of systems of microporous adsorbents can be obtained with the instrument designed; these characteristics had heretofore been inaccessible either to indirect methods of calculation or to other high-class calorimeters.