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Direct Correlation between Adsorption Energetics and Nuclear Spin Relaxation in a Liquid-saturated Catalyst Material.

Accepted version
Peer-reviewed

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Authors

Robertson, Christopher 
Gladden, Lynn F 
Jenkins, Stephen J 
D'Agostino, Carmine 

Abstract

The ratio of NMR relaxation time constants T 1 / T 2 provides a non-destructive indication of the relative surface affinities exhibited by adsorbates within liquid-saturated mesoporous catalysts. In the present work we provide supporting evidence for the existence of a quantitative relationship between such measurements and adsorption energetics. As a prototypical example with relevance to green chemical processes we examine and contrast the relaxation characteristics of primary alcohols and cyclohexane within an industrial silica catalyst support. T 1 / T 2 values obtained at intermediate magnetic field strength are in good agreement with DFT adsorption energy calculations performed on single molecules interacting with an idealised silica surface. Our results demonstrate the remarkable ability of this metric to quantify surface affinities within systems of relevance to liquid-phase heterogeneous catalysis, and highlight NMR relaxation as a powerful method for the determination of adsorption phenomena within mesoporous solids.

Description

Keywords

Adsorption, NMR relaxation, Porous media, Surface analysis, ab initio calculations

Journal Title

Chemphyschem

Conference Name

Journal ISSN

1439-4235
1439-7641

Volume Title

19

Publisher

Wiley
Sponsorship
Catalysis@Cambridge, BP plc