Liquid phase catalytic hydrogenation of carbon dioxide

Mitchell, Claire E. 2020. Liquid phase catalytic hydrogenation of carbon dioxide. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Concerns of global warming and climate change have dominantly been the consequence of rising anthropogenic carbon dioxide (CO2) atmospheric concentration. One method of reducing CO2 emissions is unlocking the potential of CO2 as a chemical C-1 feedstock, converting this current waste compound into high value chemicals and fuels. The research presented in this thesis addresses the utilisation of CO2 using catalysis to form formate. This work can be divided into three catalytic materials, hence, 3 results chapters. First, a series of Pd/Mo2C catalysts were synthesised, optimised and evaluated for CO2 hydrogenation, achieving TON of 109. The role of base and the pH of the reaction medium is importantly identified, having an impact on the intermediates essential for the reaction process. A key message conveyed is the crucial role of adding Ru to Pd in enhancing catalytic stability. The two next chapters of research were inspired by the origin of life theory. First investigated is the iron sulphide pyrrhotite, (Fe1-xS), and its ability as a catalyst towards the hydrogenation of CO2. Controlled oxidation of the material was found to increase the surface oxygen content, creating new oxygen containing Fe and S species, having a positive effect on the catalytic activity increasing formate productivity from 0.3 μmol to 1.0 μmol. The material was characterised, and catalyst preparation optimised for catalytic activity. In the next chapter, iron nickel sulphide was then investigated under the same study. Violarite (Fe,Ni)3S4 was synthesised, characterised, and the synthesis procedure was optimised. Again, calcination is required for the optimal catalytic activity, creating vital oxygen containing species. Violarite achieved a superior catalytic performance than pyrrhotite, producing 4.9 μmol of formate. Overall, this work was intended to investigate novel materials for the catalytic hydrogenation of CO2. Catalyst characterisation has been crucial for understanding the catalytic properties of such materials, and this work hopes to convey their importance within this globally significant reaction process.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Date of First Compliant Deposit:	16 July 2020
Last Modified:	16 Jul 2021 01:30
URI:	https://orca.cardiff.ac.uk/id/eprint/133537

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