Oxygen abstraction together with CO adsorption and oxidation over palladium/platinum-doped cerium (IV) oxide and gold catalyst supported on iron (III) oxide were studied employing density functional theory with the inclusion of on-site Coulomb interaction (DFT+U). Hybrid functionals employing DFT method are able to re-produce structural properties for CeO2 that agrees well with experimental data. The localisation of two excess electrons upon the removal of an oxygen atom from the CeO2 lattice is well described by DFT+U and is found to be most favourable on two next nearest neighbour cerium sites from the vacancy site. This defective bulk structure gave an oxygen vacancy formation energy (Evac) of 2.45 eV using PW91+U (2.43 eV using PBE+U). The surface defect formation energies are calculated to be lower than that of the bulk structure. Other structures with different pair of Ce3+ sites at higher Evac are also present. At higher temperature, it is predicted that the energy gained from thermal heating will allow the defect structure to end up at one of the higher energy defective structures obtained. Both the CeO2 and α-Fe2O3 support are reduced more easily in the presence of transition metal atoms or clusters. Supported gold nanoparticle is found to affect the Evac on the α-Fe2O3(0001) surface only to a certain limited influential area around the nanoparticle. The Evac is reduced further when the Au atoms at the periphery sites are oxidised to give Au10O6 cluster. CO has weak interaction with the CeO2(111) surface. However, by doping the surface with Pd2+ and Pt2+ ions, CO is found to adsorb strongly at the three coordinated metal dopant that has a vacancy coordination site exposed on the surface. Weak adsorptions are also observed at the perimeter sites of Au10O6/α-Fe2O3(0001). Overall, it is predicted that CO oxidation, which follows the Mars-van Krevelen type mechanism can be enhanced by the presence of transition metal dopants or clusters. The continuous effort of researchers to reduce CO emission and the curiosity on where the excess electrons from the removed oxygen localised in the CeO2 system have been the motivation of this project. This work will provide insight on catalyst design and the understanding of the electronic structure of the systems studied.

The research presented in this thesis describes the direct synthesis of hydrogen peroxide from H2 and O2 using supported palladium based catalysts. The direct synthesis of hydrogen peroxide offers a more straightforward and sustainable alternative to the current industrial anthraquinone autoxidation (AO) process. Au-Pd bimetallic catalysts have been proved to be highly active for the direct synthesis process. The work presented in this thesis attempted to produce less expensive catalysts through adding cheap secondary metal to Pd as an effective substitute to Au or using an effective preparation for a low metal loading of Au-Pd nanoparticles. In addition, a comprehension of the actual active sites over bimetallic and Pd monometallic particles for H2O2 direct synthesis was also attempted. The first part of this work aims to explain an interesting phenomenon – an increase of activity for H2O2 direct synthesis and a decrease of hydrogenation of H2O2 over carbon supported Ni-Pd bimetallic and Pd only catalysts after both hydrogen peroxide synthesis and storage under ambient conditions. Based on the results of XPS, XRD and CO-chemisorption integrated with previous publications, it was concluded that (i) both the reaction of hydrogen peroxide direct synthesis and catalyst storage led to an decrease of particle dispersion; (ii) relative to the active sites on high energy surfaces/small particles of Pd (0), those on low energy surfaces/large particles are more selective for H2O2 synthesis, as the latter demonstrates lower activity of dissociative adsorption of O2 and H2O2. The role of secondary metal-Ni added to Pd was also investigated for H2O2 direct synthesis in the thesis. For carbon supported Ni/Pd catalysts (including Ni monometallic, Pd monometallic and Ni-Pd bimetallic catalysts), the addition of Ni to Pd enhanced catalytic activity and selectivity for H2O2 synthesis. The results of MP-AES, XPS, XRD and TPR implied that metallic Pd may sit on the top of Ni oxides with a dissolution of metallic Ni in Pd to some degree. Electron transfer from Ni to Pd probably also occurred which was inferred by XPS analysis. The role of Ni in Pd for H2O2 direct synthesis was Preface III also investigated over TiO2 supported catalysts which led to an enhancement of H2O2 productivity, H2 conversion rate and H2O2 selectivity relative to Pd only catalyst. Based on the results of XPS, TPR and STEM, it was concluded that inactive Ni species diluted Pd sites as individual Pd atoms which are the selective active sites for H2O2 direct formation. The next part of the study addressed a modified impregnation method (MIm) for the preparation of Au-Pd nanoparticles. These nanoparticles have been proved previously by STEM which are well dispersed homogeneous particles because of excess amount of Cl- ions in the preparation. As a consequence, the resulted catalyst demonstrated a superior activity than conventional impregnation method (CIm) analogues even the latter loaded with a quintuple metal loading. Through tuning Pd metal loading in 1 wt% Au-Pd and Pd only catalysts for H2O2 direct synthesis, two typical phenomena were observed in general: (i) an enhanced synergistic effect of Au and Pd by MIm than CIm and (ii) a rise of H2O2 productivity based on the mass of Pd loading with the addition of Au in 1 wt% Au-Pd MIm catalysts. As the possible formation of homogeneous Au-Pd alloy, an increase of H2O2 productivity based on Pd with the increase of Au content is probably out of the ensemble effect from the secondary metal.

This thesis targets the selective oxidation of polynuclear aromatic compounds, which is considered as a preliminary step of upgrading of heavy oils, resids and bitumens to higher value materials in the liquid phase using different catalytic systems. Oxidation studies concentrated on simple model polyaromatic compounds and their alkylated derivatives. Ruthenium ion catalyzed oxidation chemistry has the potential to selectively oxidize PAHs and this system was studied in great detail with particular attention made to the reaction solvent system. Through careful studies it was found that the use of a monophasic solvent system led to the selective oxidative opening of an aromatic ring to produce the dialdehyde derivative. It was demonstrated that under standard conditions the rate of oxidation increased with the size of the fused ring system. 1H NMR methodology was developed to quantify the percentage of alkyl chain hydrogens preserved after reaction. It was found that the ruthenium based system demonstrated a high affinity for the oxidation of aromatic carbon with a low tendency to oxidise aliphatic carbon. These studies formed the basis of a detailed investigation into the mechanism of ruthenium ion catalyzed oxidation of PAHs. Investigation into another catalytic system which uses a homogeneous tungsten catalyst with hydrogen peroxide as the oxidant was also performed. Early studies showed that the H2WO4/H2O2 catalytic system exhibits high solvent dependant selectivity towards preferential oxidation of aromatic carbon. What is more, studies using alkylated aromatics with a alkyl chain greater than C8 showed that even in a non polar solvent the selectivity of oxidation is directed towards the aromatic carbon. A range of catalytic systems containing tungsten, ruthenium, heteropolyacids and their heterogenised equivalents were also applied to the oxidation of PAHs. Au-Pd supported catalysts in combination with molecular oxygen and H2WO4 were also used for the oxidation of PAHs and the results obtained opened a new path in the research of PAHs. Studies on the oxidative desulfurization, denitrogenation of heteroaromatics and the demetallation of nickel and vanadium porphyrines was also performed and are reported in this thesis.

While total exhaust emissions from individual road vehicles continue to be reduced, it is becoming increasingly important to identify and quantify the residual chemical compounds in tail-pipe emissions that are potential hazards to the environment and to human health. Diesel particulate matter (DPM) is known to consist mostly of carbonaceous soot together with minor components, such as volatile organic fractions (from unburned fuel), lubricating oil, and inorganic compounds that include ash and sulphur compounds. Polycyclic aromatic hydrocarbons (PAHs) are invoked as the key intermediates in diesel soot formation. These are mutagenic air pollutants formed as by-products of combustion. PAH-precursors identified in soot include single ring structures such as benzene and toluene. Soot nucleation and growth gradually leads to the formation of five to six membered ring structures, such as benzopyrene, dibenzopyrene and coronene. Several methods have been devised to reduce the emissions of DPM, which include the use of a diesel particulate filter, or a technology which combines selective catalytic reduction of NOx with a regenerating particulate trap in a single unit. These oxidise the combustible content of the particulate matter collected on the filter through a non-catalytic reaction with NO2. As an alternative, the more difficult catalysed oxidation of soot by direct reaction with O2 has been gaining a lot of attention. Several studies have shown that the oxidation of soot requires a redox catalyst, such as CeO2, CeO2-ZrO2 and CeO2-ZrO2-Al2O3, or other reducible metal oxides including perovskites and spinels. In the past, proposed mechanisms have assumed that exhaust soot is simply graphitic carbon, and so have not taken into account the other organic components. In this work, we have carried out a speciation of soot that has been sourced from a diesel particulate trap. The soluble components have been identified by GC-MS, following extraction by Soxhlet and ultrasonication techniques. The speciation has been repeated as a function of temperature during the non-catalysed and catalysed combustion of the soot, allowing the conversion of individual components to be tracked. The results provide important catalyst design information, which should allow the formulation of materials that will be catalytically active in the combustion both of graphitic carbon and the complete range of retained organic species.

The work presented in this thesis represents the study of the polymorphism exhibited by several molecular, organic solid-state systems. In-situ techniques are used to explore aspects of the polymorphism and crystallization behaviour displayed by these systems. The crystal structures of new polymorphs and other solid phases are determined directly from powder X-ray diffraction data. Chapter 1 provides background information on the phenomenon of polymorphism and the importance of its study. In addition, the range of in-situ techniques that have been used to study crystallization and solid-state systems is described. Chapter 2 gives details on the experimental techniques used in the work presented in this thesis. These include powder X-ray diffraction (including the methodology behind structure determination from powder X-ray diffraction data), solid-state nuclear magnetic resonance (NMR) spectroscopy, X-ray photoelectron spectroscopy, thermal analysis techniques and dynamic vapour sorption. Chapter 3 explores the polymorphism of m-aminobenzoic acid, resulting in the discovery and characterization of three new polymorphs. The crystallization of m-aminobenzoic acid from solution is studied via in-situ solid-state NMR spectroscopy and this in-situ technique is expanded to allow the evolution of both the solid and liquid phases during the crystallization process to be studied. Chapter 4 investigates the crystallization behaviour of triphenylphosphine oxide and methyldiphenylphosphine oxide from solution using in-situ solid-state NMR spectroscopy. Evidence is found for transient, unknown solid phases formed during the crystallization process. Chapter 5 reports new insights into the crystallization behaviour of polymorph II of the drug rac-ibuprofen. Differential scanning calorimetry and in-situ powder X-ray diffraction experiments demonstrate that previous assumptions about the crystallization behaviour of this polymorph were incorrect. Finally, Chapter 6 explores the crystalline phases of the amino acid L-phenylalanine. A new polymorph and two hydrate phases are discovered and their hydration/dehydration behaviour.

This thesis describes the searching, preparation, characterization and catalytic evaluation of active catalysts for the terminal selectivity of long chain linear alkanes. The focus of the thesis is the study of shape selective materials, including the organic material cyclodextrins, and the inorganic material, zeolite and zeolitic membranes. Prepared catalysts were performed with n-decane or n-hexane as models to produce the terminal oxidation products 1-decanol, 1-hexanol, decanoic acid and hexanoic acid. Studies with the Andrews glass reactor showed a stable terminal selectivity of 5%-9% in the autoxidation of n-hexane in short time reactions. A comparison between the Andrews glass reactor and Parr stainless steel reactor showed that the autoxidation reactions can get higher conversion but lower terminal selectivity in the stainless steel reactor than the glass reactor. Most of the metal/support catalysts showed very low conversion and very poor terminal selectivity. Increasing the temperature leads to higher conversion but results in more cracked products and less selectivity for oxygenated C10 products. The most active catalyst was 5 w.t.% Au/TiO2. However, these catalysts did not show good terminal alcohol selectivity (<3%); whereas the cracked acid selectivity was high (32.0%). Cyclodextrin covered Au/SiO2 catalysts showed limited changes in terminal selectivities (1-2%). Zeolite 4A, silicalite-1, ZSM-5, zeolite X/Y coated catalysts were successfully synthesized with alumina and silica sphere supports. The most attractive oxidation results were performed by zeolite X/Y and zeolite 4A coated silica catalysts in n-hexane liquid phase oxidation, iv especially for with short reaction time. With zeolite X/Y membrane, in a 30 min reaction, the terminal selectivity was 16%, while the terminal selectivity for the blank reactions was 0-9%. With longer reaction time, the terminal selectivity decreased to 6-7%. Zeolite 4A membrane can produce a terminal selectivity of 13% in 4 h reactions.

ENDOR spectroscopy and DFT calculations were used for the first time to thoroughly investigate the ligand hyperfine couplings for [Cu(acac)2] in frozen solution. Anisotropic hyperfine couplings to the methine protons (HAi = 1.35, -1.62, -2.12 MHz; aiso = -0.80 MHz) and smaller couplings to the fully averaged methyl group protons (HAi = -0.65, 1.66, -0.90 MHz; aiso = 0.04 MHz) were identified by simulation of the angular selective CW Q-band ENDOR spectra and confirmed by DFT. Variable temperature X-band Mims ENDOR revealed an additional set of hyperfine couplings which showed a pronounced temperature dependency. These additional couplings were characterised by HAi = 3.45, 2.90, 2.62 MHz, aiso = 2.99 MHz and assigned to a sub-set of methyl groups undergoing hindered rotation in frozen solution. From DFT calculations the hindered rotation is proposed to occur in 120° jumps via proton tunnelling. Changes in the spin Hamiltonian parameters (g/CuA) of [Cu(acac)2] upon addition of nitrogen bases evidenced the formation of adducts. Pyridine bases were found to form square pyramidal, mono-axial adducts, labelled [Cu(acac)2(X)], even in a large molar excess of base, whilst both mono-axial [Cu(acac)2Im] and bis-equatorial [Cu(acac)2Im2] adducts were formed by imidazole coordination depending on the molar equivalents of imidazole present in solution. Angular selective 1H ENDOR studies confirmed that the acetylacetonato ligand protons were largely unaltered upon adduct formation. The proton hyperfine tensors for the coordinated substrates were found to be informative on the mode of coordination, confirming the axial coordination of the pyridine bases. Furthermore, discrimination between endocyclic and exocyclic coordination of the 2-aminomethylpyridine bases was achieved. A cis-mixed plane geometry of the [Cu(acac)2Im2] adduct was observed in the 10K ENDOR spectrum and supported by DFT calculations. This was in contrast to the bis-equatorial configuration evident in the 140K EPR, implying a temperature dependant isomerisation. Finally, a series of square planar Casiopeina copper complexes of general formula [Cu(acac)(N-N)], consisting of an acetylacetonato ligand and a diimine ligand (N-N) of varying size, were prepared and characterised by EPR and ENDOR spectroscopy. Angular selective 1H ENDOR spectra revealed the magnitude of the largest imine hyperfine component, observed at g, to be sensitive to size of the diimine ligand. This is thought to be related to the extent of spin delocalisation in the diimine ligand.

Light-Oxygen-Voltage (LOV) domains are flavoproteins that are part of photoreceptors found in plants, prokaryotes and algae. LOV domains act as biological switches in response sensors to oxygen, redox potential or light, making them ideal for use as an optogenetics tool. The protein-switch is activated by formation of a covalent adduct between the flavin cofactor and an internal cysteine residue, causing changes in the hydrogen bonding network in the core of the protein. This results in a conformational change in the LOV domain leading to undocking of an amphiphilic helix that is generally coupled to a catalytic or transcriptional activation domain. In this investigation the LOV2 domain of phototropin 1 from Avena sativa has been modified to control protein-protein interactions in apoptosis by incorporating the Bcl homology region 3 (BH3) of a key pro-apoptotic protein (Bid) to the mobile helix of AsLOV2 (J). The design, cloning, production and structure of these hybrid proteins (AsLOV-Bid1-4) are discussed and their photo-switching characteristics are examined using UV/Vis and CD spectroscopy. Half-lives of the proteins varied between 13 min and 7.5 min, with small deviation between UV/Vis and CD half-life measurements for each protein. A further investigation on the binding of AsLOV2-Bid proteins to Bcl-xL, the natural binding partner of Bid, has been conducted in the dark and light states using fluorescence anisotropy measurements. The results verified that AsLOV-Bid1-4 bound to Bcl-xL effectively in the light state with KD values at less than 300 nM. However, AsLOV-Bid2 also bound in the dark state with KD at 1 mM. A second LOV domain, YtvA from Bacillus subtilis is characterised using UV/Vis and CD spectroscopy. YtvA is a homodimeric photo-switch, with a longer relaxation half-life than Avena sativa LOV2, making it more suitable for use as an optogenetics tool. Here, investigations on amino acid residues key for the dimerisation of this protein were performed, before any hybrid proteins could be engineered. Residues V27 and I113, were replaced with aspartate residues by site-directed mutagenesis to explore the effects on the protein quaternary structure using size-exclusion chromatography. Comparing against standards mutant I113D is considered as monomeric, however further experiments need to be conducted to verify this.

Concerns over dwindling fossil fuel reserves, and the impact of CO2 emissions on climate change, is driving the quest for alternative feedstocks to reduce dependence on non-renewable sources of fuels and chemicals. Biomass offers the only renewable source of organic molecules for the manufacture of bulk, fine and speciality chemicals necessary to secure the future needs of society. In this regard, conversion of biomass derived C6 sugars to 5-hydroxymethylfurfural (HMF), the latter a potential, bio-derived platform chemical, is of significant current interest. However, commercial implementation of HMF as a chemical intermediate is impeded by high production costs. A heterogeneously catalysed route to directly convert glucose into HMF in aqueous media thus remains highly sought after. In this thesis, the telescopic conversion of glucose to fructose and then HMF has been explored over a family of bifunctional sulfated zirconia catalysts possessing tuneable acid–base properties. Characterisation by acid–base titration, XPS, XRD and Raman reveal that sub-monolayer SO4 coverages offer the ideal balance of basic and Lewis– Brønsted acid sites required to respectively isomerise glucose to fructose, and subsequently dehydrate fructose to HMF. Here we demonstrate that systematic control over the Lewis–Brønsted acid and base properties of SZ enables one-pot conversion of glucose to HMF in aqueous media, employing a single bi-functional heterogeneous catalyst. Further improvements in catalytic performance have been achieved through the synthesis of monolayer grafted ZrO2/SBA-15 catalysts in which conformal layers of ZrO2 are grown from Zr propoxide. Analysis reveals 1-3ML can be achieved; subsequent sulfation yields a catalyst with 1.25 to 2 times the activity of bulk SZ. These catalysts also exhibit remarkable water tolerance with retention of pore structure upon hydrothermal treatment at 170 °C for 6 h. All catalysts find application in esterification,with optimum activity for samples treated with 0.1 M H2SO4.

Density functional theory has been used to model the selective catalytic oxidation of model polynuclear aromatic hydrocarbons, in particular pyrene. Two transition metal catalysts have been employed, ruthenium tetroxide and a peroxy tungsten complex. The B3LYP method was used in all calculations. The LANL2DZ effective core potential was used for ruthenium and tungsten atoms. The 6-31G(d,p) basis set was used for all other atoms. Selectivity studies show that catalyst-substrate adducts will form at the carbon-carbon bond of the polynuclear aromatic hydrocarbon that will give the least reduction in aromaticity. The strain induced in planar polynuclear aromatic hydrocarbon structures did not have a bearing on catalyst selectivity. Interior carbon-carbon bonds of polynuclear aromatic hydrocarbons will not be attacked, meaning that oxidative fragmentation of these compounds starts at the exposed carbon-carbon bonds. For the ruthenium catalysed oxidation system, multiple catalyst attacks at similar sites on polynuclear aromatic hydrocarbons is possible but unlikely due to the catalytic amounts used. It is indicated that the presence of aliphatic functional groups at the adduct formation sites for the ruthenium catalyst will not hinder adduct formation. Water is necessary for the success of both catalysts. The pathway found for ruthenium catalysed oxidation shows a stable dione intermediate, this intermediate has been confirmed by experimental findings and the literature. For the ruthenium catalyst water is required as it is involved in the reaction mechanism, facilitating the abstraction of hydrogen atoms adjacent to the catalyst adduct formation site. Water is not as directly involved in the tungsten catalyst mechanism, taking the role of a stabilising agent for transition state structures. The reaction pathways found for both catalysts show that the final reaction intermediate before breaking the carbon-carbon bond is an organic anhydride. Each reaction type shows a different route to this structure. Both reaction mechanisms show an energetically favourable trend from reactants to products. Transition state energy barriers are not prohibitive.