Date of Award

2004

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

Dr. Brian Murphy

Second Advisor

Dr. Maryam AI-Yousef

Third Advisor

Prof. Mike Hursthouse

Abstract

This thesis presents several fundamental studies of structure-reactivity relationships between pure iron oxides, supported and composite oxides specifically in relation to the decomposition of carbon tetrachloride, CCI4. A series of iron oxides were synthesized and characterized using infrared (FT-IR) spectroscopy to establish their composition spectroscopically, using BET surface area measurements to determine their surface areas and X-ray diffraction powder (XRD) experiments to measure their structural parameters.

A new method was then developed to decompose CCl4 at a lower temperature than previously found, choosing the optimum catalyst. The effects of varying the temperature on the CCl4 decomposition was then studied in this work. Some suggested possible structural inferences were explored based on the empirical results obtained via surface area measurements and FT-IR methods of characterization. The optimum catalyst was found to be Fe2O3/ Al2O3 with a high surface area. Small amount of CCl4 decomposed at 100°C which then increased as the temperature increased progressively with a concomitant decrease in the amount of COCl2. In this work, binary systems generally showed higher reactivity, especially the Fe2O3/ Al2O3 system than pure iron oxides. Among the pure iron oxides, magnetite showed the highest reactivity and an ability to adsorb water which could be the main reason behind its reactivity. Tentative reaction mechanisms were suggested, based on the new empirical results, outlining what may be taking place structurally on the surface.

In the final part of this work, some of the characteristics of metal oxides in general, including both main-group and transition metal oxides were firstly considered. Recently reported structural models (2002) from the literature were then examined, specifically in relation to iron oxides and the role of carbon tetrachloride on the surface, which has been the example chosen for this work. Specifically in the case of magnetite (Fe3O4), the products were found to be significantly different. The major observed products were CO2, COCl2, C2Cl4 and small traces of CO and HCI. This different behavior may indicate a different reaction mechanism due to different structures. However, further continued work using advanced structural techniques (not available at UAEU) need to be carried out to ascertain these observations.

This work may pave the way for the future development of a newer and simpler technique for the treatment of carbon tetrachloride, which has huge implications environmentally, if fully exploited and developed at a later stage.

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