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Ultrastabilization of Zeolite Y Transforms Brønsted–Brønsted Acid Pairs into Brønsted–Lewis Acid Pairs
Author(s) -
Schroeder Christian,
Hansen Michael Ryan,
Koller Hubert
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201808395
Subject(s) - brønsted–lowry acid–base theory , zeolite , sodalite , chemistry , lewis acids and bases , catalysis , pairing , nuclear magnetic resonance spectroscopy , stereochemistry , organic chemistry , physics , superconductivity , quantum mechanics
Two pairs of Brønsted acid sites have been identified in H,Na‐Y zeolite, located in the supercage and in the sodalite cage, which upon ultrastabilization (dealumination) are transformed into pairs of Brønsted and Lewis acid sites. This mild postsynthetic modification step is an important process for converting this material into an active catalyst for large‐scale commercial reactions. Pairing structures and their transformations have been investigated using 1 H double‐quantum NMR spectroscopy experiments for dehydrated zeolite, H,Na‐Y, and its ultrastabilized form, H,Na‐USY. This approach enables the detection of pairs of Brønsted and Lewis acid sites with unprecedented 1 H resolution and distinguishing them from isolated acid sites. The dealumination is also detected by static 27 Al solid‐state NMR experiments.