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Instruments / Technical Area	Publication Details	Published	Actions
B18-Core EXAFS E01-JEM ARM 200CF	Facile synthesis of precious-metal single-site catalysts using organic solvents Xi Sun , Simon R. Dawson , Tanja E. Parmentier , Grazia Malta , Thomas E. Davies , Qian He , Li Lu , David J. Morgan , Nicholas Carthey , Peter Johnston , Simon A. Kondrat , Simon J. Freakley , Christopher J. Kiely , Graham J. Hutchings Nature Chemistry 46 DOI: 10.1038/s41557-020-0446-z Diamond Proposal Number(s): [22766, 20643, 19580] Show Abstract ▼ Abstract: Single-site catalysts can demonstrate high activity and selectivity in many catalytic reactions. The synthesis of these materials by impregnation from strongly oxidizing aqueous solutions or pH-controlled deposition often leads to low metal loadings or a range of metal species. Here, we demonstrate that simple impregnation of the metal precursors onto activated carbon from a low-boiling-point, low-polarity solvent, such as acetone, results in catalysts with an atomic dispersion of cationic metal species. We show the generality of this method by producing single-site Au, Pd, Ru and Pt catalysts supported on carbon in a facile manner. Single-site Au/C catalysts have previously been validated commercially to produce vinyl chloride, and here we show that this facile synthesis method can produce effective catalysts for acetylene hydrochlorination in the absence of the highly oxidizing acidic solvents previously used.	Apr 2020
B18-Core EXAFS	Homocoupling of Phenylboronic Acid using Atomically Dispersed Gold on Carbon Catalysts: Catalyst Evolution Before Reaction Tanja E. Parmentier , Simon R. Dawson , Grazia Malta , Li Lu , Thomas E. Davies , Simon A. Kondrat , Simon J. Freakley , Christopher J. Kiely , Graham J. Hutchings Chemcatchem DOI: 10.1002/cctc.201701840 Diamond Proposal Number(s): [15151] Show Abstract ▼ Abstract: Coupling reactions to form new C-C bonds are extensively used in industrial synthetic processes. Gold has been shown to be an active catalyst for such reactions however, conflicting reports exist as to whether cationic Au or metallic Au is acting as the active species. We prepared a heterogeneous catalyst consisting of atomically dispersed Au-Clx supported on carbon and showed this to be active in the homocoupling of phenylboronic acid to biphenyl. However; characterisation of the catalyst materials, even after just a short exposure time to the reactants, revealed rapid reduction and sintering of the Au species into larger metallic nanoparticles which we propose to be the true active species in this instance. This study suggests that if cationic Au is an active catalyst, it must be stabilised against reduction and agglomeration by either forming complexes which are more stable than common chlorides or by strongly anchoring them firmly onto alternative support materials; as in this case the carbon supported Au-Cl species were easily reduced.	Dec 2017

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