Probing the acid sites of zeolites with pyridine: quantitative AGIR measurements of the molar absorption coefficients - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Catalysis Année : 2020

Probing the acid sites of zeolites with pyridine: quantitative AGIR measurements of the molar absorption coefficients

Résumé

This study presents a detailed methodology, which combines high-precision thermogravimetry and FTIR spectroscopy, aiming to establish the most accurate and reliable means of measuring the molar absorption coefficients of adsorbed species. As the integrated molar absorption coefficients of Py complexes with Brønsted and Lewis acid sites, ɛ(Py-B) and ɛ(Py-L), are determined and the validity of the Beer-Lambert-Bouguer law for IR characterisation of solid acids is demonstrated, this work is setting a benchmark for the quantitative acidity measurements in zeolites and related materials. The following values of ɛ(Py-B) have been obtained at 150°C (band at ~1545 cm-1): 1.09±0.08 cm µmol-1 for ZSM-5; 1.12±0.16 cm µmol-1 for BEA; 1.29±0.04 cm µmol-1 for MOR and 1.54±0.15 cm µmol-1 for FAU. The value of ɛ(Py-L) (band at ~1455 cm-1 , which refers to different cations) measured at the same temperature is 1.71±0.1 cm µmol-1. Values of ɛ(Py-B) depend on the zeolite structure, in contrast to that for ɛ(Py-L). Clear correlations are presented between the temperature of the FTIR measurements and ɛ values for Py complexes and other species, which decrease by ~10% as the temperature increases by 100oC. In addition, the effects of key experimental procedures, instrumentation design and sample preparation are established and quantified.
Fichier principal
Vignette du fichier
Zholobenko_JCAT_preprint.pdf (2.68 Mo) Télécharger le fichier
Zholobenko_JCAT_preprint_SI.pdf (7.01 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)
Loading...

Dates et versions

hal-02500425 , version 1 (05-03-2020)

Identifiants

Citer

Vladimir Zholobenko, Cátia Freitas, Martin Jendrlin, Philippe Bazin, Arnaud Travert, et al.. Probing the acid sites of zeolites with pyridine: quantitative AGIR measurements of the molar absorption coefficients. Journal of Catalysis, 2020, 385, pp.52--60. ⟨10.1016/j.jcat.2020.03.003⟩. ⟨hal-02500425⟩
156 Consultations
1311 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More