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In situ K-edge X-ray absorption spectroscopy of the ligand environment of single-site Au/C catalysts during acetylene hydrochlorination

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posted on 03.08.2020 by Grazia Malta, Simon Kondrat, Simon J. Freakley, David J. Morgan, Emma K. Gibson, Peter P. Wells, Matteo Aramini, Diego Gianolio, Paul B. J. Thompson, Peter Johnston, Graham J. Hutchings
The replacement of HgCl2/C with Au/C as a catalyst for acetylene hydrochlorination represents a significant reduction in the environmental impact of this industrial process. Under reaction conditions atomically dispersed cationic Au species are the catalytic active site, representing a large-scale application of heterogeneous single-site catalysts. While the metal nuclearity and oxidation state under operating conditions has been investigated in catalysts prepared from aqua regia and thiosulphate, limited studies have focused on the ligand environment surrounding the metal centre. We now report K-edge soft X-ray absorption spectroscopy of the Cl and S ligand species used to stabilise these isolated cationic Au centres in the harsh reaction conditions. We demonstrate the presence of three distinct Cl species in the materials; inorganic Cl-, Au-Cl, and C-Cl and how these species evolve during reaction. Direct evidence of Au-S interactions is confirmed in catalysts prepared using thiosulfate precursors which show high stability towards reduction to inactive metal nanoparticles. This stability was clear during gas switching experiments, where exposure to C2H2 alone did not dramatically alter the Au electronic structure and consequently did not deactivate the thiosulfate catalyst.

History

School

  • Science

Department

  • Chemistry

Published in

Chemical Science

Volume

11

Issue

27

Pages

7040 - 7052

Publisher

The Royal Society of Chemistry

Version

VoR (Version of Record)

Rights holder

© The Royal Society of Chemistry

Publisher statement

This is an open access article. It is published by the Royal Society of Chemistry under the Creative Commons Attribution 3.0 Unported Licence (CC BY 3.0). Full details of this licence are available at: https://creativecommons.org/licenses/by/3.0/

Acceptance date

23/06/2020

Publication date

2020-06-24

Copyright date

2020

ISSN

2041-6520

eISSN

2041-6539

Language

en

Depositor

Dr Simon Kondrat. Deposit date: 3 August 2020

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