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Indexed by:Journal Papers
Date of Publication:2016-04-21
Journal:DALTON TRANSACTIONS
Included Journals:SCIE、EI、PubMed
Volume:45
Issue:15
Page Number:6634-6640
ISSN No.:1477-9226
Abstract:Polymorph A-enriched beta zeolites were synthesized by employing high HF concentrations in the synthesis medium. The polymorphic compositions of the synthesized beta zeolites were determined by the complementary characterization methods F-19 NMR analysis and PXRD simulation. With a variety of SDAs, a high HF concentration (HF/SDA > 1.0) in the synthesis medium results in the A-rich feature (55-65% A) of beta zeolites, while a moderate HF concentration only results in typical beta zeolites. A systematic study on the synthesis conditions reveals the existence of a buffered system of H+ and F- formed in the highly HF-concentrated medium. This buffer results in a small but continuous supply of F- during zeolite crystallization, in contrast to the conventional fluoride route where all F-are discharged all-at-once at the initial stage.
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