| Titre : | Crystal structure of tubular Na-LTA zeolite membrane used for a vapor permeation process : unusual distribution of adsorbed water molecules (2010) |
| Auteurs : | Tomohiro Kyotani, Auteur ; Takuji Ikeda, Auteur ; Junji Saito, Auteur |
| Type de document : | Article : texte imprimé |
| Dans : | Industrial & engineering chemistry research (Vol. 48 N° 24, Décembre 2009) |
| Article en page(s) : | pp. 10870–10876 |
| Note générale : | Chemical engineering |
| Langues : | Anglais |
| Tags : | Tubular zeolite Na− ; LTA membranes Bioethanol Vapor permeation processes |
| Résumé : | The crystal structure of two tubular zeolite Na−LTA membranes—one as-prepared membrane and a membrane used in vapor permeation (VP) processes of bioethanol—was analyzed using Rietveld refinement with parallel-beam powder X-ray diffraction data. The crystal structure of the as-prepared membrane was consistent with that of typical Na−LTA powder. After the VP process, an unusual relative peak intensity ratio between 200 and 220 reflections was observed in the membrane. The number of adsorbed water molecules in the β-cage was reduced to half. Furthermore, detachment of sodium cations at the six-membered rings was confirmed. The electron density distributions of these Na−LTA zeolite membranes were analyzed by combining the Rietveld method and the maximum entropy method (MEM). MEM electron density images revealed that the adsorbed water molecules and Na+ cations were bonded, forming a hydrated cluster, and that the guest atoms or molecules were highly disordered. |
| En ligne : | http://pubs.acs.org/doi/abs/10.1021/ie900967e |
