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. Unlike water, no formation of silanol groups is observed after intrusion of concentrated LiCl aqueous solutions. A huge increase of the intrusion pressure from water to 20 M LiCl aqueous solution (from 20 to 148 MPa) occurs. This can be explained by the change of the intruded liquid to solvated (Li+, Cl–) ions and by the necessity of distortion of the water–ion complexes to penetrate into the small eight-membered-ring openings of the LTA structure. The results obtained confirm the hypothesis already proposed that cage-type zeosils show lower intrusion pressure values than channel-type structures.

Forced intrusion of water and aqueous solutions in microporous materials: from fundamental thermodynamics to energy storage devices

“…An important number of other all-silica zeolites (zeosil) was investigated by the Patarin group over the years, from 2001 until very recently. [40][41][42][43][44][45][46][47][48][49][50] They are gathered in Table 1, together with the main intrusion-extrusion properties. As already mentioned the energy storage behavior can either be depicted as a ''spring'' (S) when the intrusion-extrusion cycle is fully reversible, a ''shock absorber'' (SA) when the cycle displays an hysteresis, or a ''bumper'' (B), when the cycle is incomplete and some water is retained in the porous framework upon pressure release.…”

“…The same phenomenon was observed in the case of BEC zeosil-LiCl aqueous solution systems, 46 and to a certain extend to LTA zeosil. 48 In the case of CHA zeosil, the mixed shockabsorber-bumper behavior 40 turned into a pure shock-absorber behavior in presence of aqueous LiCl solutions. 87 Along these lines, it was also shown that weakly hydrophilic materials such as high Si/Al ratio zeolites 88 or COK-14 zeolites 89 could exhibit an intrusion transition in the presence of electrolyte aqueous solutions.…”

Intrusion-extrusion experiments of MgCl2 aqueous solution in pure silica ferrierite: Evidence of the nature of intruded liquid by in situ high pressure synchrotron X-ray powder diffraction

“…The intrusion of highly concentrated electrolyte solutions can also change the behavior of the "zeosil-aqueous solution" system. It was the case, for instance, for the LTA-and *BEA-type zeosil [27,19].…”

A Porous POSiSil Suited for Pressure‐Driven Reversible Confinement of Solutions: PSS‐2

“…Water intrusion-extrusion capacity [mm 2 g À1 ] PSS-2 1000 Pure silicaITQ-7 [46] 210 Pure silicaL TA [48] 170 Pure silicaBEA [52] 140 IFR [51] 136 MTW [50] 114 AFR [53] 390 AEI [53] 370 ZIF-8 [54,55] up to 480 MIL-100 [55] up to 820 Cr-MIL-101 [55] up to 1400 UiO-66 [55] up to 400 CPO-27 [55] up to 680 MCM-41 [56] up to 400 tively low pressures (intrusion pressure up to 5MPa with an extrusionp ressure of 0.3MPa). The material was able to take up as ubstantial amount of liquid (1000 mm 3 g À1 for water and between 1100-1200 mm 3 g À1 for LiCl solution) in the pores.…”