Publication: Effect of lattice shrinking on the migration of water within zeolite LTA
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Water adsorption within zeolites of the Linde Type A (LTA) structure plays an important role in processes of water removal from solvents. For this purpose, knowing in which adsorption sites water is preferably found is of interest. In this paper, the distribution of water within LTA is investigated in several aluminum-substituted frameworks ranging from a Si:Al ratio of 1 (maximum substitution, framework is hydrophilic) to a Si:Al ratio of 191 (almost pure siliceous framework, it is hydrophobic). The counterion is sodium. In the hydrophobic framework, water is found in the large α-cages, whereas in the most hydrophilic frameworks, water is found preferably in the small β-cages. For frameworks with moderate aluminum substitution, β-cages are populated first, but at intermediate loading water favors α-cages instead. Framework composition and pressure therefore drive water molecules selectively towards α- or β-cages.
This work was supported by the Spanish Ministerio de Economía y Competitividad (MINECO) through the grant number CTQ2016-80206-P. We thank C3UPO for the HPC support. S.R.G.B. thanks Spanish Ministerio de Economía y Competitividad (MINECO) for his predoctoral and postdoctoral fellowship (BES-2014-067825 from CTQ2013-48396-P).
Microporous and Mesoporous Materials volume 293 (2020) 109808-1 109808-6