ADSORPTION ISOTHERM OF AMMONIA ON SYNTHETIC СаА (MSS-622) ZEOLITE

Abstract

This article presents the experimentally obtained values of the adsorption isotherm of ammonia molecules on synthetic zeolite СаА (MSS-622) at a temperature of 303 K. The isotherm values were measured using a microcalorimeter connected to a universal high-vacuum device. The differential values of free energy were calculated based on equilibrium pressure values. A regular relationship between the adsorption amount and the energetic properties of ammonia molecules on СаА (MSS-622) zeolite was identified. Additionally, the sorption mechanism and the law of ammonia molecules filling the zeolite volume were determined, ranging from the initial adsorption region to the condensation heat region of ammonia. Under experimental conditions, the adsorption capacity of this zeolite for ammonia was found to be 10.2 mmol/g per gram of zeolite. It was established that 44% of total adsorption occurs at an equilibrium pressure of 0.33 mmHg, 53% at 1.4 mmHg, 71% at 25 mmHg, 80% at 200 mmHg, 98% at 476 mmHg, and 100% at 614 mmHg. The adsorption isotherm was reinterpreted using the volumetric micropore filling theory (VMOT) with a three-term equation, and it was demonstrated that the theoretically calculated values fully correspond to the experimental data.