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Organic transformations utilising in-situ hydrogen peroxide synthesis: An experimental and theoretical study

Singleton, James 2020. Organic transformations utilising in-situ hydrogen peroxide synthesis: An experimental and theoretical study. PhD Thesis, Cardiff University.
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Abstract

The research presented within this thesis focused on the utilisation of hydrogen peroxide for a subsequent oxidation reaction. Hydrogen peroxide (H2O2) is considered a ‘green’ oxidant as it can be easily degraded to form water. To complete the utilisation, the H2O2 was made via the direct synthesis route, in a one-pot synthesis reaction. Furthermore, this in-situ technique decreases the complexity of the simulated manufacturing process as only one reactor is required. The first part of this thesis focused on experimentally investigating the utilisation of H2O2 for the ammoximation reaction. Cyclohexanone was used as the target molecule for this ammoximation reaction. Cyclohexanone oxime is an important precursor to the manufacturing process of the plastic nylon-6. The tandem-catalyst system used comprised of a supported gold-palladium (AuPd) catalyst, with a low loading (0.66 wt%, 1:1), and a Titanium Silicalite-1 (TS-1) molecular sieve. The first catalyst synthesised the H2O2 needed to form hydroxylamine (NH2OH), which was synthesised using the TS-1. In a non-catalytical reaction at 353.15 K, NH2OH reacted with cyclohexanone. In the present work, a series of the H2O2 synthesis catalysts were made and investigated for both the direct H2O2 synthesis reaction, and the cyclohexanone ammoximation reaction utilising in-situ direct H2O2 synthesis. The second part of this thesis focused on computationally investigating the utilisation of H2O2 for the epoxidation reaction. The key advantage of this method of investigation is that catalytic performance can be estimated to a good degree of accuracy, which in turn can provide information on how to synthesise a highly active and selective catalyst. Propene was used as the target molecule as it was a computationally simple molecule to use, and propene oxide is an important precursor to numerous manufacturing processes, such as the production of polyurethane and propene glycol. Using Density Functional Theory, surfaces of Au and Pd were used to represent the facets of those catalysts. The surfaces were cut at Miller indices (111) and (100). The reactions studied and presented in this work were the direct H2O2 synthesis reaction and the propene epoxidation utilising in-situ direct H2O2 synthesis. Both parts of the research in this thesis could be used to inform future work on catalytic in-situ H2O2 synthesis and its subsequent utilisation.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Cardiff Catalysis Institute (CCI)
Chemistry
Subjects: Q Science > QD Chemistry
Date of First Compliant Deposit: 9 June 2021
Last Modified: 09 Jun 2021 15:08
URI: http://orca.cardiff.ac.uk/id/eprint/141823

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