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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Molecular Simulation of Water Sorption and Diffusion Characterizaton in Cation-Exchanged ZSM-5

Get access (open in a dialog) DOI: 10.1615/IHTC15.tpp.009505
pages 8879-8889

Abstract

Water sorption and diffusion characterization in nanoporous materials were investigated by a molecular simulation study on water sorption and diffusion on M-ZSM-5 (M: Li+, Na+, Ca2+). GCMC and MD simulations were performed using COMPASS force field and parameters were validated by comparison with experimental results. Isosteric heat distribution of different Si/Al ratios with rising RH revealed the sorption progress with the change of isosteric heat distribution. Water molecules adsorbed and form cluster around favorable sites at low loading which correspond to high isosteric heat. When the RH rises and the sorption amount increases, water cluster formation mechanism has to change for the limitation of favorable sites and free volume, therefore the isosteric heat distribution has to change. Self-diffusion coefficients of different Si/Al and different cations under 20% RH were calculated to study the relationship of sorption capacity and dynamics properties. Interactions between cations, substituted Al and water molecules decrease the self-diffusion coefficient. Otherwise when the loading is high, limited pore volume of micropore constrains the water diffusion properties.