New topology of levyne B under quasi-equilibrium conditions: A temperature-dependent in situ single crystal X-ray diffraction study

Cametti, Georgia (2018). New topology of levyne B under quasi-equilibrium conditions: A temperature-dependent in situ single crystal X-ray diffraction study. Microporous and mesoporous materials, 265, pp. 162-171. Elsevier 10.1016/j.micromeso.2018.02.002

[img] Text
MMM_Levyne2018.pdf - Published Version
Restricted to registered users only
Available under License Publisher holds Copyright.

Download (929kB) | Request a copy

The dehydration behavior of natural levyne-Ca was investigated from 25 to 400 °C by in-situ single-crystal X-ray diffraction under dry conditions. The dehydration started at 50 °C. From 125 to 250 °C the structure changed to levyne B topology, characterized by statistical breaking of T1-O-T1 bonds in the original D6R units. At 275 °C, additional rupture of T2-O-T2 bonds in 6mR units started. This second rupture associated with the release of remaining water was not reported before. At 300 °C the structure is assumed to be anhydrous. The new levyne B topology, referred to levyne B′, is characterized by 37% T1B and 15% T2B that are new tetrahedral sites arising as a consequence of the T-O-T breaking process. In contrast to the T1B site, T2B is at general position, originating a system of T2B face sharing tetrahedra, mutually exclusive. Complete migration of T sites to the new positions would lead to different LEV topologies with different kind of cages and, as a consequence, of stacking sequences depending on the position occupied by the T2B tetrahedra. The different results obtained in this study compared to previous ones, confirmed that the applied experimental set-up is fundamental in tracking the transformations upon dehydration in zeolitic materials. Understanding these differences is crucial for subsequent applications of these microporous compounds.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences > Mineralogical Crystallography (discontinued)
08 Faculty of Science > Institute of Geological Sciences > Mineralogy
08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Cametti, Georgia

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

1387-1811

Publisher:

Elsevier

Language:

English

Submitter:

Georgia Cametti

Date Deposited:

07 May 2018 14:59

Last Modified:

26 Oct 2019 12:51

Publisher DOI:

10.1016/j.micromeso.2018.02.002

BORIS DOI:

10.7892/boris.113065

URI:

https://boris.unibe.ch/id/eprint/113065

Actions (login required)

Edit item Edit item
Provide Feedback