Investigating catalytic enhancements in Au oxidation catalysts arising from Pd as a second metal or TiOx encapsulation

Zhao, Liang 2023. Investigating catalytic enhancements in Au oxidation catalysts arising from Pd as a second metal or TiOx encapsulation. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Catalytic oxidation reactions are of paramount importance in academia and industry for the production of key chemicals and intermediates. Supported Au catalysts have been demonstrated to be highly efficient in selective oxidation reactions. In this thesis, various types of Au catalysts have been prepared and evaluated in the oxidation of 5- Hydroxymethylfurfural, benzyl alcohol and carbon monoxide. In Chapter 3, following the recent discovery of the cooperative redox enhancement (CORE) effect in aqueous-phase oxidation of alcohols, the investigations to assess whether the CORE effect can be extended to other Au/Pd molar ratios were conducted. It has been demonstrated that the CORE effect exhibited by the separated Au and Pd sites is present in a wide range of Au/Pd molar ratios. Furthermore, the roles of Au and Pd were shown to be interchangeable, which can be influenced by the relative reaction rates of HMF dehydrogenation and the oxygen reduction reaction processes, and the ease of electron transfer from one active site to the other. In Chapter 4, to further investigate the CORE generality, solvent-free benzyl alcohol oxidation catalytic system was adopted to assess the carbon supported Au and Pd catalysts. Surprisingly, the similar CORE effect to the aqueous-phase alcohol oxidation system exhibited by the physical mixtures of Au/C and Pd/C was also observed. In Chapter 5, a core-shell Au@TiOx composite has been prepared for CO oxidation in a mild and reproducible way. The fabricated Au-TiOx interface has been proven to be the active site responsible for the enhanced catalytic activity and stability. Optimal activity can be achieved at the balance between improved Au-TiOx interfacial perimeter and exposed Au sites for CO adsorption.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Date of First Compliant Deposit:	23 April 2024
Last Modified:	24 Apr 2024 09:42
URI:	https://orca.cardiff.ac.uk/id/eprint/168255

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