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Title: | Multinuclear solid-state NMR characterization of the Bronsted/Lewis acid properties in the BP HAMS-1B (H-[B]-ZSM-5) borosilicate molecular sieve using adsorbed TMPO and TBPO probe molecules |
Author: | Wiper, Paul V. Amelse, Jeffrey Mafra, Luis |
Keywords: | BORON-SUBSTITUTED ZSM-5 ISOMORPHOUS SUBSTITUTION P-31 NMR TRIMETHYLPHOSPHINE OXIDE THEORETICAL CALCULATION DEHYDRATED ZEOLITE CHEMICAL-SHIFT SITES SPECTROSCOPY BORALITES |
Issue Date: | 2014 |
Publisher: | ACADEMIC PRESS INC ELSEVIER SCIENCE |
Abstract: | The acid properties of a dehydrated borosilicate, HAMS-1B (H-[B]-ZSM-5), including the acid types, strengths, location, and quantities are investigated by means of trialkylphosphine oxides through multinuclear ID/2D MAS NMR experiments. B-11 DQF-STMAS combined with H-1 MAS NMR studies revealed B-OH and distinct Si-OH protons associated with trigonal boron. P-31 NMR spectra of TMPO-treated HAMS-1B reveal three Bronsted and three Lewis acid sites. We have found a number of limitations applying the TMPO/TBPO method to identify internal/external acidity. Therefore, we propose a new approach to unambiguously discriminate external/internal acid sites by treating a pore-free and pore-blocked HAMS-1B zeolite. This method provided unique structural insight regarding the identification of boron species/coordinations associated with Bronsted/Lewis acid sites. Additionally, ICP analysis in tandem with solid-state NMR enabled full assignment of the detected internal/external acid species and the study of their acid strength. Moreover, we identify the nature of TMPO complexes arising from Bronsted/Lewis interactions. (C) 2014 Elsevier Inc. All rights reserved. |
Peer review: | yes |
URI: | http://hdl.handle.net/10773/19608 |
DOI: | 10.1016/j.jcat.2014.05.017 |
ISSN: | 0021-9517 |
Publisher Version: | 10.1016/j.jcat.2014.05.017 |
Appears in Collections: | CICECO - Artigos |
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