Investigating Alternative Green Methods for Carbon Dioxide Utilisation and Carbon Capture and Storage

Reducing carbon dioxide emissions is vital to reducing the effects of global warming. Numerous industrial methods exist, but developing alternative, greener and more energy-efficient methods is essential. Two pieces of work were investigated in this thesis towards developing alternative methods and are presented as two individual chapters, each with their own introduction, results, discussion, conclusion and future work sections. A general introduction to carbon dioxide and the vitality of decreasing carbon dioxide emissions acts as a preface to these chapters and is presented in Chapter 1. Chapter 2 examines promoting Carbon Dioxide Utilisation with new chromium(III) salophen complexes and Chapter 3 investigates a novel electrochemical carbon capture and mineralisation methodology. A range of chromium(III) salophen complexes were synthesised and were found to catalyse the synthesis of cyclic carbonates from carbon dioxide and terminal or internal epoxides at ambient conditions. The most active catalyst contained methoxy and tert-butyl groups on the salicylaldehyde and a bromide counterion, and is one of the most active catalysts in this field. Some of these catalysts were also used to catalyse the synthesis of the oxazolidinone diphenyloxazolidin-2-one from styrene oxide and phenyl isocyanate with successful results. A new electrochemical method was developed to perform carbon dioxide mineralisation, forming an amorphous aluminium hydroxycarbonate, at ambient conditions. The most energy efficient methods captured carbon with an energy requirement of 231-250 kJ mol-1 of carbon dioxide. This methodology worked with sustainable energy and materials, such as solar energy, seawater and “waste” aluminium. The carbon capture and energy efficiency of this methodology however could be improved to promote future developments and industrialisation, but nonetheless provides an interesting and alternative method to capture and mineralise carbon dioxide.