Intrinsic flexibility of the EMT zeolite framework under pressure
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
The roles of organic additives in the assembly and crystallisation of zeolites are still not fully understood. This is important when attempting to prepare novel frameworks to produce new zeolites. We consider 18-crown-6 ether (18C6) as an additive, which has previously been shown to differentiate between the zeolite EMC-2 (EMT) and faujasite (FAU) frameworks. However, it is unclear whether this distinction is dictated by influences on the metastable free-energy landscape or geometric templating. Using high-pressure synchrotron X-ray diffraction, we have observed that the presence of 18C6 does not impact the EMT framework flexibility—agreeing with our previous geometric simulations and suggesting that 18C6 does not behave as a geometric template. This was further studied by computational modelling using solid-state density-functional theory and lattice dynamics calculations. It is shown that the lattice energy of FAU is lower than EMT, but is strongly impacted by the presence of solvent/guest molecules in the framework. Furthermore, the EMT topology possesses a greater vibrational entropy and is stabilised by free energy at a finite temperature. Overall, these findings demonstrate that the role of the 18C6 additive is to influence the free energy of crystallisation to assemble the EMT framework as opposed to FAU.
Date Issued
2019-02-12
Date Acceptance
2019-02-04
Citation
Materials, 2019, 24 (3)
ISSN
1420-3049
Publisher
MDPI
Journal / Book Title
Materials
Volume
24
Issue
3
Copyright Statement
© 2019 The Author(s). This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0 - https://creativecommons.org/licenses/by/4.0/).
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000458934000265&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Life Sciences & Biomedicine
Physical Sciences
Biochemistry & Molecular Biology
Chemistry, Multidisciplinary
Chemistry
zeolite
framework materials
EMC-2
crystallization
high pressure
X-ray diffraction
flexibility window
compressibility
lattice dynamics
RAY-POWDER DIFFRACTION
TEMPLATE
18-CROWN-6
CRYSTALLIZATION
SOFTWARE
DYNAMICS
LOCATION
PROGRAM
WINDOW
FAU
Publication Status
Published
Article Number
641
Date Publish Online
2019-02-12