Isosteric Heats of Adsorption of N2O and NO on Natural Zeolites

Abstract

We studied the capacities of three natural zeolites to adsorb N2O or NO using a glass high-vacuum volumetric system that permitted characterization of the energetics of the adsorption process. Adsorption equilibrium data were analyzed using the classical Freundlich equation and the Dual–Langmuir model. We employed the Clausius–Clapeyron relationship to calculate the isosteric heats of adsorption using the equilibrium data of the isotherms measured at 273.15 K and 293.15 K. The isosteric heats of reversible adsorption of both gases were smaller than the heats of total adsorption. The interaction energy of N2O with mordenite was larger than the interaction energies of N2O with either erionite or clinoptilolite. The interaction energy of NO was found to be largest with erionite.