Titre :

Caveat on the actual robustness of heteronuclear nmr methods for probing the surface of gamma-alumina and related catalysts

Auteur(s) :

Szeto, Kai C. [Auteur]
Merle, Nicolas [Auteur]
Unité de Catalyse et Chimie du Solide (UCCS) - UMR 8181
Trebosc, Julien [Auteur]
Unité de Catalyse et Chimie du Solide (UCCS) - UMR 8181
Taoufik, Mostafa [Auteur]
Gauvin, Regis [Auteur]
Unité de Catalyse et de Chimie du Solide (UCCS) - UMR 8181
Pourpoint, Frederique [Auteur]
Unité de Catalyse et Chimie du Solide (UCCS) - UMR 8181
Delevoye, Laurent [Auteur]
Unité de Catalyse et Chimie du Solide (UCCS) - UMR 8181

Titre de la revue :

The journal of physical chemistry. C, Nanomaterials and interfaces

Nom court de la revue :

J. Phys. Chem. C

Numéro :

123

Pagination :

12919-12927

Date de publication :

2019-05-23

ISSN :

1932-7447

Discipline(s) HAL :

Chimie/Catalyse
Chimie/Chimie inorganique

Résumé en anglais : [en]

Transitional aluminas are a very important class of materials in catalysis. The detailed understanding of their surface chemistry has attracted much attention with input from spectroscopic and theoretical studies. In this ...
Lire la suite >Transitional aluminas are a very important class of materials in catalysis. The detailed understanding of their surface chemistry has attracted much attention with input from spectroscopic and theoretical studies. In this context, NMR is a key technique, which, thanks to recent methodological developments, provides insights into local structures and relative arrangements. In the present paper, we first assess two 1 H− 27 Al heteronuclear correlation NMR methods for studying the surface of γ-Al 2 O 3 dehydroxylated at 500°C. The commonly used cross-polarization (CP) transfer method is compared to the dipolar heteronuclear multiple quantum coherence (D-HMQC) experiment, revealing that the latter is significantly more robust and efficient with less signal distortion that hampers the recording of meaningful signals. Furthermore, a new MQ-D-HMQC pulse sequence is proposed to confirm the presence of sites, with a large quadrupolar coupling constant at the surface of alumina. The robustness of D-HMQC is further probed by two additional alumina-based catalysts, namely, aluminum hydrides supported on γ-Al 2 O 3 , which are active in olefin hydrogenation and polymerization, and ZrCp 2 Me 2 grafted onto γ-Al 2 O 3 , a single-site olefin polymerization catalyst. In both cases, this provides information on the configuration of surface aluminum species in the vicinity of catalytically active sites and on the residual hydroxyl networks. The present study combines advanced NMR methods and complex catalytic materials for which a critical, yet fruitful, spectroscopic approach is required for deeper understanding.Lire moins >

Langue :

Anglais

Audience :

Internationale

Vulgarisation :

Non

Établissement(s) :

CNRS
Centrale Lille
ENSCL
Univ. Artois
Université de Lille

Collections :

• Unité de Catalyse et Chimie du Solide (UCCS) - UMR 8181

Équipe(s) de recherche :

Catalyse et synthèse éco-compatible (CASECO)
RMN et matériaux inorganiques (RM2I)

Date de dépôt :

2022-03-02T07:13:23Z
2023-12-15T19:26:20Z