Liquid phase oxidation of cyclohexane using bimetallic Au–Pd/MgO catalysts

•Unique catalytic performance of MgO supported Au–Pd bimetallic catalysts for cyclohexane oxidation.•Identification of reactive intermediates by EPR-spin trapping.•Evidence for differences in the mode of action of Co-naphthenate versus Au–Pd nanoparticles.•Au–Pd alloys have a higher activity for O–O...

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Bibliographic Details
Published in:Applied catalysis. A, General General, 2015-09, Vol.504, p.373-380
Main Authors: Liu, Xi, Conte, Marco, Sankar, Meenakshisundaram, He, Qian, Murphy, Damien M., Morgan, David, Jenkins, Robert L., Knight, David, Whiston, Keith, Kiely, Christopher J., Hutchings, Graham J.
Format: Article
Language:English
Subjects:
Cyclohexane oxidation
EPR
Gold catalysis
Oxidation
STEM
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Summary:•Unique catalytic performance of MgO supported Au–Pd bimetallic catalysts for cyclohexane oxidation.•Identification of reactive intermediates by EPR-spin trapping.•Evidence for differences in the mode of action of Co-naphthenate versus Au–Pd nanoparticles.•Au–Pd alloys have a higher activity for O–O catalytic dissociation. A detailed study of the selective oxidation of cyclohexane has been performed using bimetallic gold–palladium catalysts supported on magnesium oxide. Mono-metallic supported gold or palladium catalysts show limited activity for cyclohexane oxidation. However, a significantly enhanced catalytic performance is observed when supported gold–palladium alloy catalysts are used for this particular reaction. This synergy is observed for alloys spanning a wide range of gold-to-palladium molar ratios. Mechanistic studies reveal a promotion effect that occurs from alloying palladium with gold on the supported catalyst, which significantly improves the homo-cleavage of the O–O bond in cyclohexyl hydroperoxide, an important intermediate species in cyclohexane oxidation.
ISSN:0926-860X
1873-3875
DOI:10.1016/j.apcata.2015.02.034