Investigation of the Energetic Performance of Pure Silica ITQ-4 (IFR) Zeolite under High Pressure Water Intrusion

Zhang

et al. 2016

Carbon

Carbon nanotube (CNT) buckypaper, a randomly non-woven fibrous film structure, has enjoyed its popularity in the sensor, actuator, filtration, and distillation devices owing to its exceptional mechanical and electrical properties. However, there is no report aimed at unraveling the fundamental mechanism of its energy-absorption capability under high-velocity impact despite its extraordinary frequency-and temperature-invariant viscoelastic properties. To bridge this gap, here coarse-grained molecular dynamics simulations are implemented to investigate effects of the external impact energy, the density of the buckypaper, and the length of individual CNTs on energy dissipation capability and dynamic response of the buckypaper under high-velocity impacts. Simulation results indicate that within its deformation limit the buckypaper possesses extremely high kinetic energy dissipation efficiency. The critical impact energy related to the deformation limit of the buckypaper tightly depends on the impact velocity since the same impact energy with a larger impact velocity yields less compression. The energy dissipation capability and impact response of the buckypaper are demonstrated to be independent of the length of individual SWCNTs. Overall, owing to the remarkable energy dissipation capability and flexibility of the buckypaper, it can be regarded as a promising candidate for energy dissipation.

Section: Discussionmentioning

confidence: 99%

Energy dissipation capability and impact response of carbon nanotube buckypaper: A coarse-grained molecular dynamics study

Zhang

et al. 2016

Carbon

Phys. Chem. Chem. Phys.

“…An irreversible behavior, with water molecules trapped in the micropores upon pressure release, is reported for ITQ-4, which behaves as a bumper. 23 In contrast few studies are available in the literature on the HP-intrusion and self-organization of organic molecules in zeolite pores. Among these, the possibility of HP-induced polymerization has recently been demonstrated for acetylene and ethylene inserted into the MFI framework.…”

Section: Introductionmentioning

confidence: 99%

Pressure-induced penetration of guest molecules in high-silica zeolites: the case of mordenite

Arletti

Leardini

Vezzalini

et al. 2015

A synthetic high-silica mordenite (HS-MOR) has been compressed in both non-penetrating (silicone oil, s.o.) and penetrating [methanol : ethanol : water (16 : 3 : 1) (m.e.w.), water : ethanol (3 : 1) (w.e.), and ethylene glycol (e.gl.)] pressure transmitting media (PTM). In situ high-pressure (HP) synchrotron X-ray powder diffraction (XRPD) experiments allowed the unit cell parameters to be followed up to 1.6, 1.8, 8.4, and 6.7 GPa in s.o., w.e., m.e.w., and e.gl., respectively. Moreover, e.gl. was also used as a PTM in in situ HP Raman and ex situ IR experiments. The structural refinement of HS-MOR compressed in e.gl.at 0.1 GPa -the lowest investigated pressure -revealed the presence of 3.5 ethylene glycol molecules per unit cell. The infrared spectrum of the recovered sample, after compression to 1 GPa, is consistent with the insertion of ethylene glycol molecules in the pores. XRPD and Raman spectroscopy experiments performed under pressure indicated the insertion of a small number of guest molecules. Ethylene glycol is partially retained inside mordenite upon pressure release. A symmetry lowering was observed in s.o. above 0.8 GPa, while above 1.6 GPa the patterns indicated a rapid loss of long range order. From ambient pressure (P amb ) to 1.6 GPa, a high cell volume contraction (DV = À9.5%) was determined. The patterns collected with penetrating PTM suggested the penetration of guest molecules into the porous host matrix, starting from a very low P regime. The entrapment of PTM molecules inside micropores contributes to the stiffening of the structure and, as a consequence, to the decrease of the compressibility with respect to that measured in s.o. From the structural point of view, HS-MOR reacts to compression and to the penetration of different guest species with appropriate framework deformations. Interestingly, ethylene glycol is partially retained inside mordenite upon pressure release, which is of importance for potential application of this composite material.

“…Pure silica zeolites (zeosils), particularly the ones obtained in fluoride medium, are known to have highly hydrophobic character and thus are of high interest for the use in heterogeneous lyophobic systems. Many zeosils pertaining to different framework types were studied in high-pressure water intrusion-extrusion experiments [28][29][30][31][32][33][34][35][36][37][38][39][40]. Due to the sub-nanometer pore diameter of these materials, extremely high values of water intrusion pressure, up to 210 MPa, and, consequently, of stored energy, up to 15 J/g [28,29], are achieved.…”

Section: Heterogeneous Lyophobic Systems Based On Hydrophobic Zeolitesmentioning

confidence: 99%

“…For all the frameworks considered, the average pore diameter values calculated from corresponding CIF (Crystallographic Information File) files and maximal diameter of the sphere which can be included in the microporosity are presented in Table 1 [56]. The studies of water intrusion-extrusion were performed for many zeosils with different framework types [26,[28][29][30][31][32][33][34][35][36][37][38][39][40]. The results obtained for some of these zeosils (lines for the concentration of 0 M) are summarized in Table 2 along with the results obtained for intrusion of LiCl aqueous solutions.…”

Section: Water Intrusion In Zeosilsmentioning

confidence: 99%

Energetic Performance of Pure Silica Zeolites under High-Pressure Intrusion of LiCl Aqueous Solutions: An Overview

et al. 2020

An overview of all the studies on high-pressure intrusion—extrusion of LiCl aqueous solutions in hydrophobic pure silica zeolites (zeosils) for absorption and storage of mechanical energy is presented. Operational principles of heterogeneous lyophobic systems and their possible applications in the domains of mechanical energy storage, absorption, and generation are described. The intrusion of LiCl aqueous solutions instead of water allows to considerably increase energetic performance of zeosil-based systems by a strong rise of intrusion pressure. The intrusion pressure increases with the salt concentration and depends considerably on zeosil framework. In the case of channel-type zeosils, it rises with the decrease of pore opening diameter, whereas for cage-type ones, no clear trend is observed. A relative increase of intrusion pressure in comparison with water is particularly strong for the zeosils with narrow pore openings. The use of highly concentrated LiCl aqueous solutions instead of water can lead to a change of system behavior. This effect seems to be related to a lower formation of silanol defects under intrusion of solvated ions and a weaker interaction of the ions with silanol groups of zeosil framework. The influence of zeosil nanostructure on LiCl aqueous solutions intrusion–extrusion is also discussed.