High Efficiency of Na- and Ca-Exchanged Chabazites in D2/H2 Separation by Quantum Sieving
Résumé
Quantum sieving is a promising approach for separation of hydrogen isotopes using porous solids as sorbents at cryogenic temperatures (<77 K). In the present work, we characterized the properties of two aluminumrich chabazites: Na-CHA and Ca-CHA (Si/Al = 2.1). The single-gas D 2 and H 2 adsorption isotherms were measured, and the thermodynamic selectivities were determined through coadsorption experiments in the temperature range 38-77 K. We found that at 38 K, Na-CHA shows a selectivity of 25.8 at a loading of 10.6 mmol•g -1 . At the same temperature, Ca-CHA has slightly lower selectivity (18.3), but its uptake (12.9 mmol•g -1 ) is higher than that for Na-CHA. Comparison with the literature shows that the obtained values of selectivity are among the highest reported so far. This property combined with robustness and availability on the industrial scale of Al-rich chabazites makes them very promising materials for separation of hydrogen isotopes by quantum sieving.
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