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Exploring heterogeneous bimetallic nanoparticle catalysts for sustainable oxidations

Exploring heterogeneous bimetallic nanoparticle catalysts for sustainable oxidations
Exploring heterogeneous bimetallic nanoparticle catalysts for sustainable oxidations

Prior work in the group has focused on developing the synthesis and activation of supported monometallic noble metal nanoparticle (Au, Pt and Pd) copper chlorophosphate frameworks (CuClPs), and exploring their potential as oxidation catalysts. Herein, bimetallic variants (AuPt/CuClP, PtPd/CuClP and AuPd/CuClP) have been synthesised, characterised and employed in catalytic reactions. Characterisation by TEM and XPS revealed the presence of small, metallic nanoparticles in the bimetallic CuClP materials, with the AuPt/CuClP sample containing the smallest and most uniform particles. The bimetallic AuPt/CuClP material was found to be highly active in the aerobic oxidation of KA-oil, with the catalyst reduced at 300 °C giving the most promising result (89 mol % conversion, > 99 % selectivity to cyclohexanone). The AuPt/CuClP catalyst reduced at 300 °C showed the most promise, achieving the highest conversion of the monometallic and bimetallic CuClP catalysts, while also showing an increased stability over a range of temperatures compared to the monometallic analogues. Through physical mixture tests, the nature of the bimetallic nanoparticles in the AuPt/CuClP catalyst reduced at 250 °C was probed and predicted to contain discrete sites, however the increased thermal stability of the AuPt/CuClP reduced at 300 °C alluded to a synergistic interaction between the Au and Pt species, suggesting the possibility of alloyed nanoparticle sites.

The catalytic potential of the CuClP materials was further explored in the oxidation of valerolactam, the hydrogenation of furfural, the Beckmann rearrangement of cyclohexanone oxime, and the Baeyer-Villiger oxidation of cyclohexanone. However, the presence of unexpected acid-catalysed products gave rise to the consideration of the inclusion of weak Lewis acid sites in the CuClP framework, although acid characterisation is required in order to confirm this.

University of Southampton
Van Aswegen, Sivan
68316820-cf51-40bf-b85d-d30ba81ea594
Van Aswegen, Sivan
68316820-cf51-40bf-b85d-d30ba81ea594
Raja, Robert
74faf442-38a6-4ac1-84f9-b3c039cb392b

Van Aswegen, Sivan (2017) Exploring heterogeneous bimetallic nanoparticle catalysts for sustainable oxidations. University of Southampton, Doctoral Thesis, 137pp.

Record type: Thesis (Doctoral)

Abstract

Prior work in the group has focused on developing the synthesis and activation of supported monometallic noble metal nanoparticle (Au, Pt and Pd) copper chlorophosphate frameworks (CuClPs), and exploring their potential as oxidation catalysts. Herein, bimetallic variants (AuPt/CuClP, PtPd/CuClP and AuPd/CuClP) have been synthesised, characterised and employed in catalytic reactions. Characterisation by TEM and XPS revealed the presence of small, metallic nanoparticles in the bimetallic CuClP materials, with the AuPt/CuClP sample containing the smallest and most uniform particles. The bimetallic AuPt/CuClP material was found to be highly active in the aerobic oxidation of KA-oil, with the catalyst reduced at 300 °C giving the most promising result (89 mol % conversion, > 99 % selectivity to cyclohexanone). The AuPt/CuClP catalyst reduced at 300 °C showed the most promise, achieving the highest conversion of the monometallic and bimetallic CuClP catalysts, while also showing an increased stability over a range of temperatures compared to the monometallic analogues. Through physical mixture tests, the nature of the bimetallic nanoparticles in the AuPt/CuClP catalyst reduced at 250 °C was probed and predicted to contain discrete sites, however the increased thermal stability of the AuPt/CuClP reduced at 300 °C alluded to a synergistic interaction between the Au and Pt species, suggesting the possibility of alloyed nanoparticle sites.

The catalytic potential of the CuClP materials was further explored in the oxidation of valerolactam, the hydrogenation of furfural, the Beckmann rearrangement of cyclohexanone oxime, and the Baeyer-Villiger oxidation of cyclohexanone. However, the presence of unexpected acid-catalysed products gave rise to the consideration of the inclusion of weak Lewis acid sites in the CuClP framework, although acid characterisation is required in order to confirm this.

Text
Van Aswegen thesis final - Version of Record
Available under License University of Southampton Thesis Licence.
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Published date: March 2017

Identifiers

Local EPrints ID: 415218
URI: http://eprints.soton.ac.uk/id/eprint/415218
PURE UUID: b2f47b37-3236-4571-a4ea-e03338691db9
ORCID for Robert Raja: ORCID iD orcid.org/0000-0002-4161-7053

Catalogue record

Date deposited: 02 Nov 2017 17:30
Last modified: 30 Sep 2020 04:01

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