Direct synthesis of hydrogen peroxide from hydrogen and oxygen over catalysts containing gold

Edwards, Jennifer Kelly. ORCID: https://orcid.org/0000-0003-4089-2827 2006. Direct synthesis of hydrogen peroxide from hydrogen and oxygen over catalysts containing gold. PhD Thesis, Cardiff University.

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Abstract

The direct synthesis of hydrogen peroxide from hydrogen and oxygen over supported gold, palladium and gold palladium catalysts was studied in a high-pressure stirred autoclave containing a stabiliser-free solvent system. The rate of H2O2 synthesis for supported Au catalysts was found to be lower than that of the Pd only catalysts. However, carbon, titania, iron oxide and alumina supported Au-Pd catalysts are significantly more active and selective for H2O2 synthesis than the monometallic catalysts. For silica supported gold-palladium catalysts, the activity was found to scale directly with palladium content and no synergy was observed with gold-palladium catalysts. Gold-palladium catalysts prepared on iron oxide, alumina and titania were all found to form core-shell structures on calcination consisting of a gold core surrounded by a palladium shell. However, on silica and activated carbon the bimetallic catalysts formed homogenous alloys. The activity and selectivity of the catalyst was found to be highly dependant on the reaction conditions employed factors such as catalyst mass, solvent composition, catalyst composition and reaction length had significant effects on the catalyst activity. Modification of the support with a dilute acid prior to metal deposition led to gold-palladium catalysts with >98% selectivity to H2O2 when compared to catalysts prepared on the unmodified support. This increase in catalytic performance corresponded to an increase in metal particle size - indicating that smaller gold-palladium catalysts are highly active and selective for the direct synthesis of hydrogen peroxide. Acid pre-treatment of silica prior to metal deposition led to bimetallic catalysts where the activity did not scale with the palladium content.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Chemistry
Subjects:	Q Science > QD Chemistry
ISBN:	9781303208751
Date of First Compliant Deposit:	30 March 2016
Last Modified:	18 Jul 2024 09:02
URI:	https://orca.cardiff.ac.uk/id/eprint/56194

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