Drastic change of the intrusion-extrusion behavior of electrolyte solutions in pure silica *BEA-type zeolite.

Abstract

High pressure water and electrolyte solutions intrusion-extrusion experiments in pure-silica *BEA-type zeolite (zeosil β) were performed in order to study the performances of these systems in energy absorption and storage. The "zeosil β-water" system displays a bumper behavior with an intrusion pressure of 53 MPa and an absorbed energy of 8.3 J g(-1). For the "zeosil β-LiCl aqueous solutions" systems the intrusion pressure increases with the LiCl concentration to 95, 111 and 115 MPa for 10, 15 and 20 M solution, respectively. However, for concentrations above 10 M, a transformation of the system behavior from bumper to shock-absorber is observed. The zeolite samples were characterized by several structural and physicochemical methods (XRD, TGA, solid-state NMR, N2 physisorption, ICP-OES) before and after intrusion-extrusion experiments in order to understand the influence of the LiCl concentration on the intrusion-extrusion behavior. It is shown that the intrusion of water and LiCl solutions with low concentration leads to the formation of Si-(OSi)3OH groups, whereas no defects are observed under intrusion of concentrated LiCl solutions. A possible mechanism of LiCl solution intrusion based on separate intrusion of H2O molecules and Li(H2O)x(+) ions is proposed.