Ethanol upgrading catalysis for advanced biofuels

Richards Gonzales, Andres 2023. Ethanol upgrading catalysis for advanced biofuels. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Bio-derived butanols (1-butanol, 2-butanol and isobutanol) are considered more attractive liquid fuels than the easily sourced bioethanol. Compared to bioethanol, butanols boast greater energy density (comparable to conventional petrol), offers a lower affinity for water and can be used neat without engine modification. In addition, butanols have a lower corrosion factor, as a consequence they can be used as a sustainable ‘drop-in’ replacement. For these reasons the conversion of bioethanol to biobutanol has gained much attention. In this thesis, I aim to build on the groundwork already established to gain new mechanistic insights with a view to design more efficient catalysts based on more earth abundant metals (period 3). This will be investigated using synthetic and computational techniques. Chapter 3 looks to benchmark various functionals and basis sets used in DFT so that the computational method is robust and reliable and can be trusted as an informative tool to explain experimental observation. Both electronic and geometric properties will be collected and compared to real systems as a measure of accuracy. Studies into the origin of selectivity for the most active Ru and Mn catalysts will also be conducted. Chapter 4 aims to take the Ruthenium diphosphino bischelates, PP, to take a closer look at critical mechanistic steps and species thought to be implicated in the reaction. In particular, the unusual mode of deprotonation at the methylene backbone and its relation to activity is explored. Catalysts with a range of electronic and steric properties and a range of bite angles are investigated to elucidate which factors affect the acidity of the aforementioned proton. The catalysts explored include different PP analogues with variations at phosphorous or the alkyl backbone, along with structures that have different ancillary ligands. Chapter 5 investigates a range of metals across period 3 bearing the same pincer PNP ligand. These catalysts perform poorly, and by breaking down the reaction into its component parts, hydrogenation, condensation and dehydrogenation, it can be ascertained which steps are problematic for which catalysts.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Date of First Compliant Deposit:	22 May 2024
Last Modified:	22 May 2024 14:26
URI:	https://orca.cardiff.ac.uk/id/eprint/169088

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