title: Catalytic Partial Oxidation of Cyclohexane by Bimetallic Ag/Pd Nanoparticles on Magnesium Oxide.
abstract: The liquid-phase oxidation of cyclohexane to cyclohexanol and cyclohexanone was investigated by synthesizing and testing an array of heterogeneous catalysts comprising: monometallic Ag/MgO, monometallic Pd/MgO and a set of bimetallic AgPd/MgO catalysts. Interestingly, Ag/MgO was capable of a conversion comparable to current industrial routes of approximately 5 %, and with a high selectivity (up to 60 %) to cyclohexanol, thus making Ag/MgO an attractive system for the synthesis of intermediates for the manufacture of nylon fibres. Furthermore, following the doping of Ag nanoparticles with Pd, the conversion increased up to 10 % whilst simultaneously preserving a high selectivity to the alcohol. Scanning transmission electron microscopy and energy dispersive spectroscopy of the catalysts showed a systematic particle-size-composition variation with the smaller Ag-Pd nanoparticles being statistically richer in Pd. Analysis of the reaction mixture by electron paramagnetic resonance (EPR) spectroscopy coupled with the spin-trapping technique showed the presence of large amounts of alkoxy radicals, thus providing insights for a possible reaction mechanism.
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK.|Syncat@Beijing, Synfuels China Technology Co., Ltd, Beijing, 101407, P.R. China.
authors.forename: Xi
authors.initials: X
authors.lastname: Liu
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK.|Department of Chemistry, Dainton Building, University of Sheffield, Sheffield, S3 7HF, UK.
authors.forename: Marco
authors.initials: M
authors.lastname: Conte
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK.|Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, PA, 18015-3195, USA.
authors.forename: Qian
authors.initials: Q
authors.lastname: He
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK.
authors.forename: David W
authors.initials: DW
authors.lastname: Knight
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK.
authors.forename: Damien M
authors.initials: DM
authors.lastname: Murphy
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK.
authors.forename: Stuart H
authors.initials: SH
authors.lastname: Taylor
authors.affiliation: INVISTA Textiles (UK) Limited, P.O. Box 2002, Wilton, Redcar, TS10 4XX, UK.
authors.forename: Keith
authors.initials: K
authors.lastname: Whiston
authors.affiliation: Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, PA, 18015-3195, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Kiely
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK.
authors.forename: Graham J
authors.identifier: http://orcid.org/0000-0001-8885-1560
authors.initials: GJ
authors.lastname: Hutchings
keywords: EPR spectroscopy; cyclohexane oxidation; palladium; scanning transmission electron microscopy (STEM); silver