Sustainable thermochemical energy storage through eco-friendly zeolites - A characterization study

Judicious utilization of natural resources always helps protect the environment from several ill-effects. This paper was aimed at exploring the merits of natural and environment friendly zeolites towards sustainable thermochemical energy storage. Sorption behaviour of selected zeolites were investigated using a differential thermogravimetric analyser. The desorption kinetics was studied by heating the materials from room temperature to 600 °C. The materials lose their water molecules on heating and become anhydrous mostly around 300 °C. The desorption enthalpies due to heating were noted to decrease with increase of heating rate, and found low for Zeolite-Mordenite (334.5 J g-1) and high for Molecular Sieves-4A (1060 J g-1). Materials’ adsorption enthalpies were determined by subjecting them to single cycle tests comprising of heating, cooling and hydration processes in sequence. The desorption and adsorption enthalpies of a single cycle were found to vary with the material and temperature program used. To understand the desorption and adsorption kinetics better, the materials were also tested on X-ray photoelectron spectroscopy, Brunauer–Emmet–Teller, and thermal constants analysers respectively for their elemental composition, structural properties, and thermal conductivity. This paper concludes that many of the naturally available zeolites stand as potential candidates for a sustainable thermochemical energy storage and recovery.