Mechanistic origins of accelerated hydrogenation of mixed alkylaromatics by synchronised adsorption over Rh/SiO2

Cherkasov, N., Asano, S., Tsuji, Y., Okazawa, K., Yoshizawa, K., Miyamura, H., Hayashi, J.-i., Kunitsa, A. A. and Jackson, S. D. (2023) Mechanistic origins of accelerated hydrogenation of mixed alkylaromatics by synchronised adsorption over Rh/SiO2. Reaction Chemistry and Engineering, 8(6), pp. 1341-1348. (doi: 10.1039/D3RE00032J)

Abstract

Catalytic reactions of mixed substrates sometimes behave differently from those of individual substrates. For example, the hydrogenation of propylbenzene over Rh/SiO2 proceeds 120% faster in the presence of toluene. Such an acceleration effect does not agree with the well-accepted Langmuir–Hinshelwood reaction model. In this paper, we examined its mechanism experimentally and computationally. The hydrogenation experiment of vaporised aromatics confirmed that the acceleration was specific to the liquid phase with the isopropanol solvent. Direct adsorption measurements revealed that toluene adsorption synchronises with propylbenzene adsorption. Density functional theory calculations confirmed the associates of toluene and propylbenzene on the catalyst surface in the polar environment. The formation of associates increased the adsorption energy of toluene and decreased that of propylbenzene. Lowered adsorption energy reduces the activation barrier for catalytic reaction and intensifies the reaction rate beyond the Langmuir–Hinshelwood model prediction.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Jackson, Professor David
• Authors: Cherkasov, N., Asano, S., Tsuji, Y., Okazawa, K., Yoshizawa, K., Miyamura, H., Hayashi, J.-i., Kunitsa, A. A., and Jackson, S. D.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Reaction Chemistry and Engineering
• Publisher: Royal Society of Chemistry
• ISSN: 2058-9883
• ISSN (Online): 2058-9883
• Published Online: 14 March 2023
• Copyright Holders: Copyright © 2023 The Royal Society of Chemistry
• First Published: First published in Reaction Chemistry and Engineering 8(6): 1341-1348
• Publisher Policy: Reproduced under a Creative Commons License