Energetic Performances of Channel and Cage-Type Zeosils

Abstract

Energetic performances of nine channel or cage-type zeosils (AFI, FER, MFI, MEL, TON, MTW, DDR, STT, and CHA-type pure silica zeolites) are obtained using water intrusion−extrusion isotherms. The water intrusion is obtained by applying a high hydraulic pressure corresponding to the intrusion step. When the pressure is released, these nine "zeosil−water" systems behave like a molecular spring, water being spontaneously expelled out of the cavities of the zeosils (extrusion step). The first part of this study details the energetic characteristics of MEL-type zeosil (Silicalite-2), which displays a molecular spring behavior reproducible over several water intrusion−extrusion cycles. However, solid-state NMR spectroscopy revealed the presence of structure defects (>5%), which are responsible for the low value of the stored energy (6.5 J/g of zeosil). In a second part, the energetic properties of the nine channel or cage-type zeosils are compared. For these samples, structural modifications can be observed by solid-state NMR spectroscopy. An overall view of the characteristics derived from the water intrusion− extrusion isotherms of these nine zeosils is discussed. The relation between the structure type, in particular, the porous system (cages or channels) and the intrusion pressure, is studied to better understand the mechanism of water intrusion and to predict the zeolite behavior (intrusion pressure values) for a given structure type. The Laplace−Washburn relationship seems to be not appropriate for microporous materials. A correlation was found between the intrusion pressure and the pore diameter for channel systems and the largest cage size for cage systems.

Synergetic effect of temperature and pressure on energetic and structural characteristics of {ZIF-8 + water} molecular spring

“…As far as we know there are no data for thermal effects of intrusion/extrusion in HLS at high temperatures available in the literature for comparison. The mechanical energy capacity of the investigated system may be considered close to the average value of that of a wide range of available HLSs [14][15][16][17]22,26,27,31,33,34] , but it should be noted that in most of these cases higher values of the stored mechanical energy is reached through an increase of the operational (intrusion) pressure, which is not always suitable for practical applications. The low temperature sensitivity of the mechanical performances (Table1S and Figure1S) of the investigated system is another advantage.…”

Nonlinear Frequency Response Analysis and Jump Avoidance Design of Molecular Spring Isolator

“…Considering that the expressions of Φ and Ψ change when a crosses critical displacement, we substitute Eq. (13), (14), (16), (17), (19) and (20) into Eq. (6) and (7) to get piecewise differential equations of a and θ respectively.…”

“…For water and hydrophobic silica gels, the confined liquid would remain in the nano-environment, resulting in a significant hysteresis of sorption isotherm [6][7][8][9]. On the contrary, for water and some kinds of hydrophobic zeo lites, water molecules extrude from the nano-pores as soon as the pressure drops, resulting in coincidence sorption isotherm [10][11][12][13][14]. For the former, the mechanical energy is absorbed so the mixture of water and hydrophobic silica gels is used as colloidal damper.…”

“…Suciu [6,7] and Qiao [8][9] tried to use colloidal damper for energy absorption. Eroshenko and Patarin [10][11][12][13][14] start to investigate molecular spring material at the beginning of this century. They have affirmed that several kinds of zeolites such as Silicalite-1, SSZ-24, ZSM-22, ZSM-12, DD3R and Si-CHA can be used as the nano-porous material for molecular spring.…”

Current Status and Perspectives of the Thermomolecular Engine Developing

“…Therefore, it is necessary to use more advanced techniques of synthesis of HWB matrices, their further thermal and (or) hydrothermal treatment, that leads to improvement of HWB operational characteristics [17,44].…”