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Title: Trimerisation and polymerisation of olefins catalysed by triazacyclohexane complexes of chromium
Author: Hawkins, Christopher
Awarding Body: University of Bath
Current Institution: University of Bath
Date of Award: 2012
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Six new R3 TACCrCl3 complexes, displaying branching on the second or third carbon of the ligand R group, were prepared for catalytic studies for ethylene oligomerisation and polymerisation. Five of the complexes made were activated with MAO and their reactivity towards ethylene, at ambient pressure and in a pressurised autoclave tested under various conditions. A number of the complexes were found to give good activities and selectivity for ethylene oligomerisation under optimum conditions. Chapter 2 discusses the design and synthesis of new R3 TACCrCl3 complexes displaying branching on the second or third carbon of the ligand R group. The complexes synthesised were characterised by paramagnetic NMR, magnetic moments, mass spectrometry, X-ray crystallography and elemental analysis. Chapter 3 explores the catalysis of an active selective ethylene oligomerisation R3TACCrCb complex which at optimal conditions shows higher activity for oligomerisation (trimerisation to l-hexene and higher oligomers) than the best system of its type from literature (tested in tandem). Experiments were carried out at various conditions discovering raised pressure and lowered temperature increased the selectivity for the competing polymerisation processes. The selectivity for oligomerisation was found to improve when the solvent was changed from toluene to heptane. Effort was made to identify some of the higher oligomers produced. Chapter 4 investigates the effect of new R3 TACCrCb complexes containing halogenation of the ligand on the ethylene trimerisation reaction, giving evidence that chlorination and bromination of the ligand have a positive effect on the selectivity for ethylene trimerisation. The catalysis of the most active system, bearing chlorination of the ligand, was explored at various conditions. Chapter 5 discusses a new R3TACCrCh system branched at the third carbon of the ligand R group which shows good activity for ethylene polymerisation. The catalytic reaction was explored at different catalyst Joadings and temperatures, finding lower temperature and an optimum catalyst loading gave high activity.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available