Fischer-Tropsch Synthesis (FTS) is known as the most practical way to convert natural gas to hydrocarbon products including synthetic fuel depending on the catalysts and operating conditions. Australia has 25% of world's natural gas resources hence Australia's crude oil dependency can be reduced extensively by developing catalysts that will facilitate the technique of converting natural gas to synthetic fuel. Molybdenum nitride has been employed in this study for FTS because of its superior mechanical strength, stability, exceptional resistance to carbon deposition & suifur poisoning. In particular, molybdenum nitride is endowed with similar electronic properties to those of noble metals. Other transition metal nitrides such as Co nitride and Co-Mo nitride were also investigated in this study. The physicochemical attributes of nitride catalysts were examined by BET surface area, particle dispersion, acid site strength & concentration, and surface elemental composition. Gas to solid nitridation kinetic was thermogravimetrically monitored. CO hydrogenation activity was measured in a fixed bed reactor using various syngas compositions and temperatures at atmospheric pressure. The effect of nitridation conditions on catalytic properties of nitrides was investigated via 23 factorial design. It has revealed that nitridation parameters; temperature, nitriding gas composition (H2:NH3) and nitridation reaction time were all significantly influencing catalyst properties. The optimal nitridation condition was 973 K, H2:NH3=1: 1, and 4 hours of nitriding time which gave higher alkene selectivity. 20 wt% M02N/Ah03 was found to be the better FT catalyst compare to catalysts with lower Mo loading and other inorganic oxide supports. Nitridation kinetic studied by thermogravimetric analysis showed that successful nitridation of transition metal oxide precursor was dependent of nitridation temperature and hydrogen concentration. Co-Mo nitride has several forms of nitride species, COS.47N, C03M03N, MoN, and Mo2N. It was shown that COS.47N was the most active component favouring the CO hydrogenation rate and alkene selectivity. Mechanistically-based kinetic models suggested that methanation over Co nitride occurs mainly via surface carbon while surface oxygenated intermediates were accountable for methanation over Co-Mo nitride and Mo nitride.

Glyphosate (N-(phosphonomethyl)glycine) is the phytotoxic reagent in the widely used Roundup® herbicide. Its mode of action in plants is the disruption of the Shikimate pathway, part of an important route to the biosynthesis of essential aromatic amino acids. It is well documented that glyphosate can be degraded by soil microorganisms after contact of the herbicide solution with the soil. It is also accepted that glyphosate, an excellent ligand, is readily absorbed to metal ions, such as Fe(III), that can be abundant in soils. There have been many accounts on the microbial degradation of glyphosate, and several metal-glyphosate complexes have been synthesised and characterised. Surprisingly, given the degree of adsorption to metal ions in the soil, there have not, to date, been any reports in the literature on the reactivity of metal-glyphosate complexes. The behaviour of these types of complexes under various reaction conditions may give us an insight into the mechanisms present when glyphosate degrades. In order to explore the behaviour of metal-glyphosate adducts, we have prepared several new cobalt-PMG complexes in the lab. These complexes have been characterised by NMR, mass spectrometry, elemental analysis, and in some cases X-ray crystal structure determination. We chose to synthesise complexes where the PMG ligand is bidentate or tridentate, filling the remaining four or three (respectively) coordination sites with an ancillary, nitrogen-containing ligand. We have subjected the complexes to photolytic and basic conditions, as we are interested in ascertaining how coordinated PMG might behave when irradiated with UV light, and when it is C-deprotonated. Metal-glyphosate complexes in nature may be exposed to UV light, so we are concerned with how the coordinated ligand might react under these circumstances. We have found that the prepared cobalt-PMG complexes are reactive when exposed to UV light, and that this appears to result in the degradation of the complex, and in some cases, the PMG ligand itself. The reactivity of C-deprotonated PMG is also an area of interest to us. It is possible that elevations in soil pH can lead to C-deprotonation of glyphosate, then further reactivity that may contribute to the degradation of the compound. Furthermore, when the herbicide is held in the active site of an enzyme within a microbe, it may become deprotonated, and this may aid in its microbial degradation. We have found that, under basic conditions, the reactivity of the prepared PMG complexes depends on the ancillary ligand attached - π-acidic, pyridine-containing ancillary ligands appear to increase the reactivity of coordinated PMG. It seems that amine-containing ligands hinder the reactivity of the coordinated PMG such that the complex remains intact. It is hoped that the results of the research described in this thesis will assist in the future investigations into the reactivity of the herbicide glyphosate.

This thesis reports a study of polydentate amino acid complexes of cobalt(III). The complexes prepared during this project have been characterized by a range of techniques, including ¹³C{¹H} and ¹H NMR spectroscopy, UV-visible spectroscopy, infra-red spectroscopy, elemental analysis and single crystal X-ray structure determination. A total of seven single crystal X-ray structure determinations have been performed during these studies. The imino acid polydentate complex, [Co(Aim₂trien)]₂[ZnCl₄], was reduced to the corresponding amino acid complex, [Co(A₂trien)]Cl, where as many as ten diastereoisomers could be formed due to the formation of new stereogenic centres. The crude product of these reactions was a mixture of isomers, according to ¹³C{¹H} NMR data. These isomers were separated using ion-exchange chromatography. The major isomer (I1), a minor isomer (I2a) and a half reduced complex (I4a) from the [Co(A₂trien)]Cl reduction and separation experiment were characterised. The predominant isomers produced were found to have had the proton on the α-carbon atoms positioned on the amine face of each amino acid ligand fragment. To investigate the ratio of the isomers formed by the initial borohydride reduction, an isomerisation study of the major isomer of the [Co(A₂trien)]⁺ complex (I1) was performed. This study hoped to establish the degree to which the distribution of isomers was a result of dynamic equilibrium. Experiments on a small scale showed the initial isomer distribution to be similar to that obtained from the borohydride reduction reaction. However, prolonged exposure to the carbonate buffer (≈ two weeks) resulted in isomers not previously seen. Experiments on a large scale were performed to establish whether the results were consistent. The materials from both the two hour and two week experiments were mixtures of isomers by ¹³C{¹H} NMR spectroscopy and were separated using ion-exchange chromatography. ¹H NMR data of the two hour experiment showed only epimerisation of the amine proton adjacent to the α-carbon atom. Therefore the isomers produced from the isomerisation of I1 have the same configuration of the proton on the α-carbon atoms, which is on the amine face of each amino acid chelate ring. ¹H NMR data from the two week experiment resulted in new isomers not previously seen as both the amine proton and the proton on the α-carbon atom have been epimerised. The polyamine wrapping around the central metal ion may also have changed in some cases. It would appear, from the ¹H NMR data that the methyl group signals of these isomers fall in two distinct clusters; a cluster at δ 1.50-1.65 ppm and a cluster at δ 1.40-1.49 ppm. From these results, and the results of Chapter Two, it has been calculated that there is at least 92% facial selectivity for the amine face of the molecule during the initial borohydride reduction reactions. This may be due to a di-hydrogen bonding interaction between an adjacent amine proton and a hydride of the borohydride, which directs the attack. Following on from this study, a new range of imino and amino acid complexes were synthesised using different tetraamine and pentaamine cobalt(III) complexes. X-ray quality crystals of [Co(Aim₂2,2,3-tet)][ClO₄] and [Co(Aim₂2,3,2-tet)][ClO₄] were obtained and solved with assistance from Dr. Chris Fitchett and Dr. Jennifer Burgess. Borohydride reductions were performed on the [Co(Aim₂2,2,3-tet)]⁺ and [Co(Aim₂2,3,2-tet)]⁺ systems. The products were a mixture of isomers according to 1H and ¹³C{¹H} NMR spectroscopy. The results from the ¹H NMR experiments showed similarity between the [Co(A₂2,3,2-tet)]⁺ and [Co(A₂trien)]⁺ systems, where three major stereoisomers were present in solution. Analogous results for the asymmetric [Co(A₂2,2,3-tet)]⁺ system were also observed. Preliminary attempts have been made to separate these isomers using ion-exchange chromatography.

The oxidation of 4-t-butyltoluene in glacial acetic acid by hydrogen peroxid in a process catalysed by cobalt(II) acetate tetrahydrate and sodium bromide has been studied with the aim of increasing the selectivity towards 4-t-butylbenzaldehyde.

The work described i n this thesis deals mainly with a fundamental study of two cementation reactions, i.e., Cu(II)/Zn and Co(II)/Zn, using the electrochemical techniques of linear potential sweep voltammetry, cyclic vol tammetry, chronopotentiometry (stripping), capacitance measurements,ring current measurements and impedance spectroscopy. In addition, solution analysis, x-ray diffraction and scanning electron microscopy were employed to achieve a better understanding of the kinetics and mechanisms of the two cementations. The half reactions of the two systems were also investigated as an essential part of the whole study. Of the two systems investigated, the Cu(II)/Zn system, was mainly used as a reference system on which some of the new techniques could be proved. The Cu(II)/Zn reaction has been shown to be diffusion controlled. Five methods, including solution analysis, have been used to determine the rate of reaction. The values of the rate constants thus determined were in good agreement provided allowance was made for the nonstoichiometry of this reaction due to proton displacement by zinc. The Co(II)/Zn cementation reaction, though thermodynamically highly favourable, is kinetically very sluggish. Of the factors affecting this reaction, the solution pH was found to play a substantial role. For example, while the reaction is largely under chemical control, at pH 5 the reaction rate becomes limited by the speed at which cobalt(I1) ions diffuse to the reacting metal surface. The favourable influence of a higher pH on the reduction of cobalt(II) carried out either electrochemically or chemically using zinc powder was ascribed to the increasing formation of the electrochemically active species, CoOH+ . Increasing the temperature also favours the shift from chemical control to diffusion control. Values for the rate constants of the Co(II)/Zn reaction in the absence of added zn2+ ions were determined from Evans' diagram, chronopotentiometry and impedance spectroscopy, The reasons for the differences in the values of rate thus obtained were discussed. The presence of zinc ions in the reaction solution greatly suppressed the rate of Co(II)/Zn cementation reaction. Several factors have been identified as contributing to the reduced reaction rate. These are the double layer effect, zinc ion and hydrogen atom adsorption, and precipitation of basic zinc salts which blanket the reacting metal surface. The action of compounds such as Sb(III) and As(III), which are commonly used to activate the Co(II)/Zn reaction in the presence of large amounts of zn2+, was investigated mainly by impedance spectroscopy. From the similarity of the impedance spectra for the reaction i n the presence of benzoqui none, it was inferred that one role of the activators was to suppress the formation of adsorbed hydrogen on the reacting surface and to allow a higher concentration of the active species, COOH'.

Thesis (Ph.D.)--Tufts University, 1991. / Submitted to the Dept. of Electrical Engineering (Electro-Optics Option). Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (Ph. D.)--Murdoch University, 1987. / Submitted to the ChemistryProgramme, School of Mathematical and Physical Sciences, Murdoch University.

Zugl.: Dresden, Techn. Univ., Diss., 2008

Th.--Sci.--Université de Strasbourg 1, 1985. / Bibliogr. p. 257-280.

Th. univ.--Sci. pétrolières, spécialité Chimie--Paris VI et Ecole nationale supérieure du pétrole et des moteurs, 1987. / 1988 d'après la déclaration de dépôt légal. Bibliogr. p. 181-188.