Competitive Adsorption of Toluene and Water in MFI-type Zeolites

Fuente: arXiv
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Main Authors: Arbiv, Gavriel, Radhakrishnan, Sambhu, Morais, Alysson F., Chandran, C. Vinod, Vandenabeele, Dries, Dom, Dirk, Duerinckx, Karel, Kirschhock, Christine E. A., Breynaert, Eric
Format: Preprint
Published: 2025
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author Arbiv, Gavriel
Radhakrishnan, Sambhu
Morais, Alysson F.
Chandran, C. Vinod
Vandenabeele, Dries
Dom, Dirk
Duerinckx, Karel
Kirschhock, Christine E. A.
Breynaert, Eric
author_facet Arbiv, Gavriel
Radhakrishnan, Sambhu
Morais, Alysson F.
Chandran, C. Vinod
Vandenabeele, Dries
Dom, Dirk
Duerinckx, Karel
Kirschhock, Christine E. A.
Breynaert, Eric
contents Competitive adsorption is a major challenge in understanding catalytic activity, selectivity and reaction mechanisms in confined environments such as zeolites. This study investigated competitive adsorption in MFI-type zeolites (ZSM-5) using solid-state NMR, focusing on the interplay between toluene and water. Quantitative 1H NMR spectroscopy identified three distinct populations of adsorbed toluene evolving with increasing toluene loading. The adsorption behavior was consistent across a series of samples with Si/Al ratio ranging from 11.5 to 140. Combining 1D and 2D NMR techniques with sample engineering (e.g. pore-blocking) enabled the assignment of the populations to toluene within the zeolite channels, at the pore mouths, and adsorbed on the external crystal surface. Crucially, introducing water to toluene-loaded zeolites caused a partial displacement of toluene from the internal channels, but significant removal from the pore mouths. This dis-placement occurred even in the highly hydrophobic zeolite (Si/Al = 140), where water still preferentially adsorbed to Brønsted acid sites and silanol species. The results highlight the critical impact that competitive adsorption from solvents, products, or impurities can have on the efficiency and selectivity of zeolite-mediated transformations.
format Preprint
id arxiv_https___arxiv_org_abs_2509_10219
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Competitive Adsorption of Toluene and Water in MFI-type Zeolites
Arbiv, Gavriel
Radhakrishnan, Sambhu
Morais, Alysson F.
Chandran, C. Vinod
Vandenabeele, Dries
Dom, Dirk
Duerinckx, Karel
Kirschhock, Christine E. A.
Breynaert, Eric
Materials Science
Chemical Physics
Competitive adsorption is a major challenge in understanding catalytic activity, selectivity and reaction mechanisms in confined environments such as zeolites. This study investigated competitive adsorption in MFI-type zeolites (ZSM-5) using solid-state NMR, focusing on the interplay between toluene and water. Quantitative 1H NMR spectroscopy identified three distinct populations of adsorbed toluene evolving with increasing toluene loading. The adsorption behavior was consistent across a series of samples with Si/Al ratio ranging from 11.5 to 140. Combining 1D and 2D NMR techniques with sample engineering (e.g. pore-blocking) enabled the assignment of the populations to toluene within the zeolite channels, at the pore mouths, and adsorbed on the external crystal surface. Crucially, introducing water to toluene-loaded zeolites caused a partial displacement of toluene from the internal channels, but significant removal from the pore mouths. This dis-placement occurred even in the highly hydrophobic zeolite (Si/Al = 140), where water still preferentially adsorbed to Brønsted acid sites and silanol species. The results highlight the critical impact that competitive adsorption from solvents, products, or impurities can have on the efficiency and selectivity of zeolite-mediated transformations.
title Competitive Adsorption of Toluene and Water in MFI-type Zeolites
topic Materials Science
Chemical Physics
url https://arxiv.org/abs/2509.10219