Energetic Performances of Pure-Silica DDR Zeolite by High-Pressure Intrusion–Extrusion of Electrolyte Aqueous Solutions: A Shock-Absorber with Huge Absorbed Energy
Аннотация:Pure-silica DDR-type zeolite (zeosil) displays a porosity composed of two kinds of small cages (pore opening of 4–6 MR) and of a large nonadecahedron cage with pore windows of 8 MR. In order to study the energetic performances of this hydrophobic material by high-pressure intrusion–extrusion experiments, water and 10 and 20 M LiCl aqueous solutions were chosen as nonwetting liquids. The intrusion pressure increases from 60 to 357 MPa when using water and 20 M LiCl aqueous solution, respectively. The latter pressure is the highest ever found for a zeosil-based system. It is associated with a large intruded volume of 0.26 mL/g, which is close to the total theoretical porosity of the DDR structure. The corresponding "DDR-20 M LiCl aqueous solution" system demonstrates mainly shock-absorber behavior, and both features (high intrusion pressure and large intruded volume) lead to the highest amount of absorbed mechanical energy for such systems: 93 and 61 J/g for the first and the following intrusion cycles, respectively. After intrusion–extrusion of LiCl aqueous solutions and depending on the concentration of the solution or the number of the intrusion–extrusion cycles, slight distortions of the DDR unit cell are clearly evidenced by XRD and 29Si MAS NMR analyses. Two possible explanations are advanced to explain such distortions.
