Probing ge distribution in zeolite frameworks by post-synthesis introduction of fluoride in as-made materials

Handle URI:
http://hdl.handle.net/10754/562274
Title:
Probing ge distribution in zeolite frameworks by post-synthesis introduction of fluoride in as-made materials
Authors:
Liu, Xiaolong; Ravon, Ugo; Bosselet, Françoise; Bergeret, Gérard; Tuel, Alain
Abstract:
A new method has been developed to introduce fluoride in the structure of as-made germanium-containing zeolites prepared under pure alkaline media. Incorporation of fluoride species occurs without modification of the framework composition (Si/Ge ratio) and of the crystallinity, as evidenced by X-ray diffraction and electron microscopy. After incorporation, 19F solid-state NMR has been used to probe the location and distribution of Ge atoms in the framework. In the case of ITQ-13 and ITQ-17, which can be prepared from both hydroxide and fluoride routes, incorporated F anions are located in the same structural units as those occupied when zeolites are prepared in the presence of fluoride. In the case of ITQ-22 and ITQ-24, fluoride goes mainly in D4R units, which appear to be in the most energetically favorable positions for these zeolites. All experiments clearly show that zeolites prepared in the absence of fluoride in the synthesis medium are enriched in germanium, compared to the same materials obtained from F-containing gels. Moreover, Ge plays a strong structure-directing role by replacing Si atoms preferentially in D4R, leading to zeolites with mainly [4Si, 4Ge] units in the framework. In the particular case of ITQ-22, a new line observed around -2 ppm in 19F NMR spectra has been tentatively assigned to [3Si, 5Ge] D4R units, which corroborates the structural data obtained via X-ray diffraction. © 2012 American Chemical Society.
KAUST Department:
KAUST Catalysis Center (KCC)
Publisher:
American Chemical Society
Journal:
Chemistry of Materials
Issue Date:
14-Aug-2012
DOI:
10.1021/cm301511y
Type:
Article
ISSN:
08974756
Sponsors:
This publication is based on the work supported by Award No. UK-C0017, made by King Abdullah University of Science and Technology (KAUST). The authors would like to thank Dr. Aude Demessence for SEM pictures.
Appears in Collections:
Articles; KAUST Catalysis Center (KCC)

Full metadata record

DC FieldValue Language
dc.contributor.authorLiu, Xiaolongen
dc.contributor.authorRavon, Ugoen
dc.contributor.authorBosselet, Françoiseen
dc.contributor.authorBergeret, Gérarden
dc.contributor.authorTuel, Alainen
dc.date.accessioned2015-08-03T09:59:00Zen
dc.date.available2015-08-03T09:59:00Zen
dc.date.issued2012-08-14en
dc.identifier.issn08974756en
dc.identifier.doi10.1021/cm301511yen
dc.identifier.urihttp://hdl.handle.net/10754/562274en
dc.description.abstractA new method has been developed to introduce fluoride in the structure of as-made germanium-containing zeolites prepared under pure alkaline media. Incorporation of fluoride species occurs without modification of the framework composition (Si/Ge ratio) and of the crystallinity, as evidenced by X-ray diffraction and electron microscopy. After incorporation, 19F solid-state NMR has been used to probe the location and distribution of Ge atoms in the framework. In the case of ITQ-13 and ITQ-17, which can be prepared from both hydroxide and fluoride routes, incorporated F anions are located in the same structural units as those occupied when zeolites are prepared in the presence of fluoride. In the case of ITQ-22 and ITQ-24, fluoride goes mainly in D4R units, which appear to be in the most energetically favorable positions for these zeolites. All experiments clearly show that zeolites prepared in the absence of fluoride in the synthesis medium are enriched in germanium, compared to the same materials obtained from F-containing gels. Moreover, Ge plays a strong structure-directing role by replacing Si atoms preferentially in D4R, leading to zeolites with mainly [4Si, 4Ge] units in the framework. In the particular case of ITQ-22, a new line observed around -2 ppm in 19F NMR spectra has been tentatively assigned to [3Si, 5Ge] D4R units, which corroborates the structural data obtained via X-ray diffraction. © 2012 American Chemical Society.en
dc.description.sponsorshipThis publication is based on the work supported by Award No. UK-C0017, made by King Abdullah University of Science and Technology (KAUST). The authors would like to thank Dr. Aude Demessence for SEM pictures.en
dc.publisherAmerican Chemical Societyen
dc.subjectfluorideen
dc.subjectgermaniumen
dc.subjectnuclear magnetic resonanceen
dc.subjectpost-synthesis modificationsen
dc.subjectzeoliteen
dc.titleProbing ge distribution in zeolite frameworks by post-synthesis introduction of fluoride in as-made materialsen
dc.typeArticleen
dc.contributor.departmentKAUST Catalysis Center (KCC)en
dc.identifier.journalChemistry of Materialsen
dc.contributor.institutionIRCELYON, UMR 5256, CNRS-Université Lyon 1, 2 Avenue A, Einstein 69626 Villeurbanne Cedex, Franceen
kaust.authorRavon, Ugoen
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