Zeolites are aluminum-silicate minerals with sub-nanometer pores, widely used as support for heterogeneous catalysis and as gas traps. Their capability of trapping water makes these porous minerals appealing also as desiccants in food drying technology. Understanding the processes of water adsorption and desorption at the molecular scale would be essential to design desiccants with specific temperature range, higher efficiency and stability. Here we investigate the process of water adsorption and desorption in Faujasite - a natural zeolite - as a function of the aluminum content, by combining molecular modeling techniques at different scales, including first-principle total energy calculations, classical and <i>ab initio</i> molecular dynamics and grand canonical Montecarlo (GCMC) simulations. GCMC simulations are predictive as for  the thermodynamics and kinetics of water adsorption, providing an estimate of the water uptake at various thermodynamic conditions. First principles calculations shed light on the preferred adsorption sites, which are characterized by computing NMR shifts. Equilibrium and non equilibrium MD simulations unravel the mechanisms of water dynamics and desorption.

Water adsorption in zeolites: Insight from multiscale modeling

2019 Fall National Meeting

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