High-Pressure Intrusion–Extrusion of Water and Electrolyte Solutions in Pure-Silica LTA Zeolite

Abstract

The energy performances of pure-silica LTA-type zeosil were studied by intrusion–extrusion of water and concentrated aqueous solutions of LiCl. The LTA structure is characterized by a highly symmetrical three-dimensional pore system that consists of large cages separated by eight-membered-ring openings. The LTA-type zeosil–water system exhibits a bumper behavior with an intrusion pressure of 20 MPa and an absorption energy of 3.4 J g–1. Despite the small pore openings (0.41 × 0.41 nm2), the value of the intrusion pressure is one of the lowest obtained among all zeosils studied to date. The bumper behavior of the LTA-type zeosil–water system is explained by the formation of silanol groups arising from the breaking of siloxane bridges under water intrusion as confirmed by 29Si NMR spectroscopy, Rietveld refinement, and TG data. The change of the intruded liquid from water to aqueous LiCl solutions changes the system behavior dramatically: from bumper to a combination of shock-absorber and bumper behavior. U...