Water adsorption in hydrophilic zeolites: experiment and simulation

Abstract

We have measured experimental adsorption isotherms of water in zeolite LTA4A, and studied the regeneration process by performing subsequent adsorption cycles after degassing at different temperatures. We observed incomplete desorption at low temperatures, and cation rearrangement at successive adsorption cycles. We also developed a new molecular simulation force field able to reproduce experimental adsorption isotherms in the range of temperatures between 273 K and 374 K. Small deviations observed at high pressures are attributed to the change of the water dipole moment at high loadings. The force field correctly describes the preferential adsorption siting of water at different pressures. We tested the influence of the zeolite structure, framework flexibility, and cation mobility when considering adsorption and diffusion of water. Finally, we performed checks on force field transferability between different hydrophilic zeolite types, concluding that classical, non-polarizable water force fields are not transferable. 2

Effect of lattice shrinking on the migration of water within zeolite LTA

“…This is a valid approach because in test calculations we have found the effect of hydration on volume change to be negligible. A similar observation had been done previously for LTA 4A [10], using a different force field from ours. The size of the unit cell, and especially the size of the openings in the sodalite cages is an important factor for the capacity of the zeolite for separating multicomponent mixtures.…”

Effect of truncating electrostatic interactions on predicting thermodynamic properties of water–methanol systems

“…To date, our understanding of intermolecular and intramolecular interactions of water is far from complete [4,5]. To reproduce different thermophysical properties of water, numerous theoretical and computational models for water were developed and published [3,6,[11][12][13]. In the last decades, due to exponential increase in computational power, molecular simulations are used to compute many properties of water [4][5][6] in biomolecular [14,15], chemical and industrial applications [12,13,16].…”

“…To reproduce different thermophysical properties of water, numerous theoretical and computational models for water were developed and published [3,6,[11][12][13]. In the last decades, due to exponential increase in computational power, molecular simulations are used to compute many properties of water [4][5][6] in biomolecular [14,15], chemical and industrial applications [12,13,16]. The performance of different water models used to describe the intermolecular interactions are reported extensively in literature [4,17], and is central for predicting properties of water and reproducing experimental data.…”

Manufacturing and Assessment of Electrospun PVP/TEOS Microfibres for Adsorptive Heat Transformers

“…The results demonstrated that TEOS concentrations in the range of 5-13 wt.% produced microfibre coatings of non-woven textile structure with both good water affinity and good thermal stability. SEM images of coatings showed that the deposited microfibre layers have both a high surface area and a high permeability representing a significant advantage in adsorption systems.Coatings 2019, 9, 443 2 of 12 and silica tetrahedra that form a crystalline nanoporous structure with hydrophilic behavior [14,15]. Although zeolites are the ideal adsorbing solid for the elevated thermal stability, their use in adsorption systems is limited by the high regeneration temperatures.…”

“…Coatings 2019, 9, 443 2 of 12 and silica tetrahedra that form a crystalline nanoporous structure with hydrophilic behavior [14,15]. Although zeolites are the ideal adsorbing solid for the elevated thermal stability, their use in adsorption systems is limited by the high regeneration temperatures.…”