Spectroscopic Signatures of Internal Hydrogen Bonds of Brønsted-Acid Sites in the Zeolite H-MFI.
Angew Chem Int Ed Engl
; 62(25): e202303204, 2023 Jun 19.
Article
en En
| MEDLINE
| ID: mdl-37159109
ABSTRACT
The location of Brønsted-acid sites (bridging OH groups, b-OH) at different crystallographic positions of zeolite catalysts influences their reactivity due to varying confinement. Selecting the most stable b-OH conformers at each of the 12 T-sites (T=Si/Al) of H-MFI, a representative set of 26 conformers is obtained which includes free b-OH groups pointing into the empty pore space and b-OH groups forming H-bonds across five- or six-membered rings of TO4 tetrahedra. Chemically accurate coupled-cluster-quality calculations for periodic models show that the strength of internal H-bonds and, hence, the OH bond length vary substantially with the framework position. For 11 of the 19 H-bonded b-OH groups examined, our predictions fall into the full width at half maximum range of the experimental signals at 3250±175â
cm-1 and 7.0±1.4â
ppm which supports previously debated assignments of these signals to H-bonded b-OH sites.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Zeolitas
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Angew Chem Int Ed Engl
Año:
2023
Tipo del documento:
Article
País de afiliación:
Alemania