Zeolite 4A: heat capacity and thermodynamic properties

The heat capacity of zeolite 4A (also known as LTA, Linde Type A and sodium zeolite A), in the temperature range from 37 to 311 K, is reported. The he at capacity shows no anomalies in this temperature range. Thermodynamic par ameters, H, S and G, relative to their values at T = 0 K were derived. From these data, we fmd that zeolite 4A is stabilized by strong enthalpic inter actions. Furthermore, its thermodynamic stability results from the strong S i-O and Al-O bonds in the primary building units, with bond strengths very close to those in other similar materials. (C) 2000 Editions scientifiques et medicales Elsevier SAS. All rights reserved.