An Interrupted Zeolite PKU-26 and Its Transformation to a Fully Four-Connected Zeolite PKU-27 upon Calcination.
Chemistry
; 25(13): 3219-3223, 2019 Mar 01.
Article
em En
| MEDLINE
| ID: mdl-30681744
ABSTRACT
The thermal stability and structural transformation mechanism are critical for the industrial applications of zeolites and the design of new framework types. Herein, a new zeolite PKU-26 has been hydrothermally synthesized under fluoride conditions using a tetraethylammonium (TEA+ ) cation as the structure-directing agent (SDA) and its framework contains partial Q3 T atoms [Q3 for T(-O-T)3 OH]. Upon calcination, PKU-26 processed a single-crystal to single-crystal transformation to another novel zeolite PKU-27 with the elimination of terminal -OH groups and enhanced thermal stability up to 650 °C, exhibiting the first Q3 âQ4 transformation [Q4 for T(-O-T)4 ] in 3D zeolite frameworks. The mechanism of the structural transformation, involving proton transfer, framework dehydration, and TO4 reconstruction, is proposed and supported by theoretical calculations.
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01-internacional
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MEDLINE
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article