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Non-covalent catalysis with coordination capsules continues to be an ever-expanding subfield of supramolecular chemistry. With this expansion comes increasingly refined studies of reaction mechanism, revealing how non-covalent catalysts reshape the potential energy landscape around the reactants, offering faster reactions, more favourable selectivities, and milder conditions. However, a key methodology that remains underutilised in contemporary mechanistic studies is modelling the kinetics of reaction networks. This thesis describes the effects of a Pd₂L₄ capsule catalyst on the solution phase chemistry of a variety of guests. This is facilitated by monitoring temporal concentrations of multiple species over the duration of catalytic reactions using NMR and UV-visible spectroscopy, and conducting system-level modelling of reaction kinetics to produce new mechanistic insights. Chapter one presents a brief introduction to coordination capsules in general, some examples of their use as non-covalent catalysts, and selected examples of mechanistic study in this subfield. This chapter also introduces various classes of techniques used in mechanistic study, and gives a brief introduction to kinetic modelling methods for catalytic reaction systems. Chapter two concerns the investigation of a catalytic condensation reaction utilising a co-catalyst system of Pd₂L₄ and haloquinone p-fluoranil. Through UV-vis and 1H NMR investigations, the reactivity is proposed to originate from "hidden" Brønsted acid catalysis, initiated by capsule-activated substitution and ionisation chemistry in dichloromethane. Chapter three concerns the investigation of base-catalysed conjugate addition reactions mediated by catalytic Pd₂L₄. Through direct detection of reactive intermediates by ¹H NMR spectroscopy, the kinetics are studied in detail. An origin for the significant degree of rate enhancement is proposed, and the capsule's ability to efficiently redirect the reaction mechanism is explored. Chapter four concerns a theoretical investigation into the kinetics of product inhibition in bimolecular coupling reactions, catalysed by a generalised coordination capsule. Dual encapsulation mechanisms are shown to be kinetically viable in cases where the binding affinity of the two co-substrates is strongly "biased". The results presented strongly challenge the conventional belief that non-covalent capsule catalysts are inherently unsuited to promoting net coupling reactions. Chapter five concerns an investigation into the host-guest dynamics of Pd₂L₄-quinone complexes through direct observation of their kinetics using stopped-flow UV-visible spectroscopy. Analysis of the kinetics of binding and exchange processes leads to a more detailed understanding of the chemistry underpinning all catalytic processes using these complexes.

The intention of this doctoral work, first and foremost, has been the identification of a novel catalytic system for the production of Polycaprolactone (PCL) with added functionality through chemical tailoring of the synthetic process. Evaluation of the performance of these materials was conducted on three separate aspects; polymerisation kinetics, formulation into electrospun fibres and spin coated films and rheological responses. PCL was successfully produced via the use of a Triisobutyl Aluminium (TiBAl) catalytic precursor initiated with each one of three different alcohols 1-Adamantanemethanol (A), Isopropanol (I) and 1H,1H,2H,2H-Perfluoro-1-octanol (F). The catalytic species were further modified via the use of 2,2'-Methylenebis(6-tert-butyl-4-ethylphenol) (MDBP). Kinetic studies on these reactions concluded that each alcohol initiator affects the velocity of molecular weight increase differently, showing variant activity of three available catalytic sites with polymers of different molecular weights obtained. Introduction of MDBP to hinder two of the three sites caused linear incorporation of the monomer with time on the only available site while slowing down reaction velocity. Molecular weights obtained from these systems were comparable for all alcohol initiators. A high degree of fibre porosity was achieved via electrospinning of these materials. Electrospun fibres showed no significant morphological differences between samples resulting from different initiators. F-initiated samples presented with improved water contact angles for both electrospun fibre mats and spin coated films. Moreover, F-initiated PCL fibre mats showed superior liquid loading capabilities across the board. These results confirmed the possibility of adding functionality via chemical tailoring of the synthesis. Finally, rheological studies showcased different performance of in-house PCL compared to commercial counterparts, with higher crystallinities and increased time to achieve maximum storage modulus values under shear. Such observations, in similar fashion to ones for UHMWPE, hint at a disentangled character having been achieved due to processing conditions. It was theorised that synthetic and processing procedures lead to this result.

Liquid transport in porous media is an important phenomenon in many scientific and engineering fields. Investigating the liquid transport process is crucial for gaining a better understanding of various important industrial processes, such as the disintegration of pharmaceutical tablets as well as the impregnation of catalyst supports and heterogenous catalysis. In this thesis, the terahertz methods, i.e. terahertz time-domain spectroscopy (THz-TDS) and terahertz pulsed imaging (TPI), were used as promising techniques to quantify the impact of the microstructure characteristics and formulation on the liquid transport process in two types of porous media, i.e. pharmaceutical and catalytic powder compacts. The terahertz methods were first used to investigate the liquid uptake and swelling in fast disintegrating tablets (FDTs) that were prepared from powder mixtures of either theophylline or paracetamol as a drug and either functionalised calcium carbonate (FCC) or microcrystalline cellulose (MCC) as a filler at different porosities. The terahertz results demonstrate the clear impact of porosity and formulation on the water transport and swelling kinetics of FDTs. The methodology was then extended to study the transport of water and 1-octanol in α-alumina powder compacts that were prepared at a range of different compaction forces, i.e. 7, 23, 40 and 58 kN, and heat treatment conditions, i.e. unfired and fired. The terahertz results reveal that both the microstructure characteristics and surface properties have an impact on the liquid transport in the alumina compacts. The results show the great potential of the terahertz methods to study the liquid transport characteristics of polymeric and ceramic porous media. Quantifying the individual disintegration mechanisms, i.e. liquid ingress and swelling, is crucial for improving the design of pharmaceutical tablets through understanding the effect of raw materials and processing on the disintegration process. The information on the liquid transport in catalytic materials is also important for developing the design of catalysts and enhancing their performance upon contact with the liquid.

The excessive atmospheric CO2 emission is one of the main contributions to the global climate change. However, with the growth of global economics, more fossil fuels will be consumed to feed the global activity, especially in developing countries. Thus, carbon capture storage and utilization draws intensive attentions in recent years. This thesis not only presents a fundamental study on the mechanisms of fast stage during CaO carbonation and sequentially proposed a unique three-dimensional supported structure for the improvement of carbon capture capacity and cyclic stability, but also converts the captured CO2 into value added products or uses the carbonation of CaO to provide energy for low-temperature biomass gasification. Firstly, we study the formation of a CaCO3 product layer on the outside surface of CaO grains during the fast reaction stage for carbon capture using two types of CaO adsorbents. The carbonation at 400 ̊C filled the small pores in the commercial CaO grains and no distinct product layer of CaCO3 was observed. However, a distinct layer of CaCO3 with a thickness around 90 nm was observed on the outside surface of the commercial CaO grains after the carbonation at 600 ̊C because the internal pores in the CaO grain had been filled and a layer of CaCO3 product was deposited on the outside surface of the CaO grain. For sol-gel CaO, the carbonation reaction is limited by the availability of useful porosity for the growth of CaCO3 product (confinement effect), instead of by the diffusion of ions in the critical layer of the CaCO3 product. No surface product layer was observed. Sequentially, we focus on enhancing the capture capacity and cyclic stability of CaO, using KIT-6 as an inert support structure. At the low CaO loading, the three-dimensional mesoporous structure was filled with CaO species. The further increase of CaO loading resulted in the CaO aggregation on the external surface of the support material, as identified by the electron microscopy. These adsorbents show excellent high-temperature CO2 carbonation/calcination stability over multiple cycles. This enhancement is attributed to the interaction between CaO and the silica skeleton of KIT-6 through the formation of interfacial CaSiO3 and Ca2SiO4 which enhance the CaO sintering resistance. Thirdly, we propose and demonstrate a one-pot method synthesized dual functional materials (DFMs), which contain a CaO sorbent coupled with a Ni-based catalyst component, allowing the sorbent regeneration and CO2 conversion to CO are performed simultaneously in a single reactor without any additional thermal energy. In addition, CeO2 is incorporated into the DFMs to largely enhance the stability of the materials for the process, and the influence of different Ce loadings on the performance of integrated CO2 capture and utilization (ICCU) process is studied. It is found that the DFMs with a Ca/Ni/Ce molar ratio of 1:0.1:0.033 displays almost 100% CO selectivity and 51.8% CO2 conversion in the reverse water-gas shift (RWGS) reaction and a remarkable cyclic stability after 20 cycles of ICCU process. Therefore, the incorporation of Ce into DFMs has two profits, for one thing, the oxygen vacancies generated by CeO2 directly reduces the dissociated CO2 regenerated from the DFMs, demonstrating the high CO yield; for another, the well-dispersed CeO2, which could act as a physical barrier, effectively prevents the growth and agglomeration of CaO crystallite and NiO species. In addition, we also propose and demonstrate the intermediate temperature DFMs, which are the physical mixture of an inexpensive high-capacity MgO adsorbent and CO2 methanation catalyst (Ru supported on the CeO2 nanorods) by the mass ratio of 2:1. The synthesized DFMs allow the sorbent regeneration and CO2 conversion to perform simultaneously in a single reactor at the same temperature (300 ̊C). It is found that compared to other DFMs, the 5Ru/CeO2-MgO exhibits a better stability and the CH4 yield and CO2 conversion are 3.36 mmol g-1 and 79% after 10 cycles of ICCU, which are much higher than that of 2.5Ru/CeO2-MgO (1.14 mmol g-1 and 39%) and 10Ru/CeO2-MgO (2.31 mmol g-1 and 69%). It is mainly attributed to that more oxygen vacancies are remained in 5Ru/CeO2-MgO resulted from the metal-support interaction. At the end, we propose a novel auto-thermal CaO looping biomass gasification (Auto-CaL-Gas) technology, in which CaO-based materials react with flue gas with a high concentration of CO2 (>30 vol.%) to produce heat inside the gasifier, simultaneously providing energy for low-temperature biomass gasification using CO2 as the gasification agent. The syngas production exhibits a significant increase from 0.21kg/h to 0.90 kg/h in the Aspen simulation results and more than threefold improvement in the experimental results. We believe this thesis will provide a fundamental and systematic understanding of ICCU process.

Phosphorus-based ligands play a key role in a plethora of transition-metal catalyzed transformations. To date, only a few privileged ligand motifs have been developed for high performance application in a wide range of reactions. Despite the advances in rational design of highly selective phosphorus-based ligands in (asymmetric) homogeneous catalysis, synthetic approaches through trial-and-error remain the most common methodologies for the discovery of new powerful catalysts. High throughput experimentation has been embraced by both academia and industry to accelerate catalyst optimization requiring accesses to large and diverse ligand libraries. There is, however, still a lack of efficient combinatorial techniques enabling the synthesis and screening of vast phosphorus-based ligand libraries. Solid-phase synthesis (SPS) offers an useful tool towards the parallel synthesis of large multidentate ligand libraries. While being covalently bound to an insoluble polymeric support, a stepwise preparation of modular ligands can be realized via systematic variation of various building blocks. Moreover, purification procedures can be greatly simplified when employing this SPS approach, often requiring only easy filtration steps. Another advantage offered by immobilization of homogeneous catalysts on insoluble supports is the facilitated catalyst recovery and recycling as catalyst separation remains one of the major problems in applied homogenous catalysis. Consequently, resin-bound catalysts represent promising candidates for application in continuously operated processes. This thesis presents the efficient preparation of multidentate phosphorus ligand libraries using as solid-phase synthesis approach. Chapter 2 describes the modular access to a large and highly diverse supported phosphine-phosphite ligand library for application in asymmetric hydrogenation of enamides. The synthesis of a supported PNP pincer ligand library for application in ester reduction underlines the versatility of this SPS approach (chapter 3). Furthermore, the combinatorial ligand synthesis on a solid support has been successfully transferred to chiral PNP-type ligands (chapter 4). In chapter 5, a series of supported tripodal phosphorus ligand-based ruthenium complexes has been employed in nitrile hydrogenation providing tunable product selectivity by a simple change in the catalyst structure. Ultimately, the recovery and reusability of these heterogenized homogeneous catalysts has been investigated under batch and continuous flow conditions.

This thesis describes applications of advanced multinuclear solid-state nuclear magnetic resonance (NMR) experiments to the characterisation of industrially-relevant catalyst materials. Experiments on γ-Al₂O₃ introduce the use of solid-state NMR spectroscopy for the investigation of disordered solids. The existence of Al(V) sites on the surface of this material is demonstrated, showing that removal of adsorbed H₂O may facilitate a rearrangement effect in γ-Al₂O₃ that promotes the formation of these Al environments. A range of aluminium oxide-based supported metal catalysts has been investigated. Studies of these systems by ¹H and ²⁷Al solid-state NMR spectroscopy indicate that a metal-support interaction (MSI) exists between surface cobalt oxide crystallites and the γ-Al₂O₃ support, and is strongest for materials containing small, well dispersed Co oxide crystallites. It is shown that the hygroscopic nature of γ-Al₂O₃ allows the extent of the MSI to be visualised by ¹H MAS NMR, by observing the extent of the proton-metal oxide interaction resulting from the presence of adventitious adsorbed H₂O. The surface/bulk chemistry of Co spinel aluminate materials is also investigated. ¹H, ²⁹Si, ²⁷Al and ¹⁷O solid-state NMR techniques are used to gain insight into the structural nature of silicated alumina catalysts. The combination of isotopic enrichment and dynamic nuclear polarisation (DNP) surface-enhanced NMR spectroscopy can provide a definitive and fully quantitative description of the surface structure of Si-γ-Al₂O₃ (1.5 wt% Si), and the role of adventitious surface water is highlighted. Analysis of silicated aluminas prepared by “sequential grafting” and “single shot” approaches shows that silica growth on γ-Al₂O₃ follows two distinct morphologies. ¹⁷O gas exchange enrichment is also shown to be successful in facilitating ¹⁷O solid-state NMR studies of these materials. It is demonstrated that double (²⁹Si and ¹⁷O) enrichment of Si-γ-Al₂O₃ (1.5 wt% Si) can facilitate access to ²⁹Si-¹⁷O 2D correlation experiments, even at low silica loading. An exploratory investigation of Ti-alumina model catalysts has also been carried out using ¹H, ²⁷Al and ¹⁷O solid-state NMR spectroscopy. These studies indicate that Ti-γ-Al₂O₃ and Ti-Al M50 may be structurally distinct materials.

This PhD thesis is focused on the development of novel low-oxidation state main group catalysis for organic synthesis. More specifically, the major objective has been to explore and design non-toxic and effective catalysts based on the following isoelectronic species: nitreones [nitrogen(I)], carbones [carbon(0)], and silylones [silicon(0)]; the corresponding central nonmetal atom in these molecules is in the formal low-oxidation state ‘+I’ and ‘0’, respectively. These species have been calculated to be strong Lewis and Brønsted bases. In addition, compared with established base catalysts such as N-heterocyclic carbenes (NHCs), nitreones, carbones, and silylones formally possess an additional lone pair of electrons at the central atom. In turn, these species may be used in base catalysis or as ligands in metal catalysis, and in the context of frustrated Lewis pair (FLP) or dual catalysis. The Lewis basicity of these N(I), C(0), and Si(0) compounds has been assessed with 11B NMR analysis using a variety of boron Lewis acids. These boron binding data have been compared with results obtained using NHCs as a Lewis base. Nitreones –more specifically cyclopropen-imines– have been explored in base catalysis. These N(I) Lewis bases have been uncovered to catalytically activate a variety of silicon-based pro-nucleophiles for subsequent bond formation with carbonyl and imine derivatives as well as aziridines. Successfully used pro-nucleophiles include TMS–CN, TMS– CF3, TMS–N3, and TMS–Cl. The characteristic features of this unprecedented cyclopropenimine Lewis base catalysis include low catalyst loading, mild reaction conditions, and broad substrate scopes. Various “normal” imines have proved to be catalytically inactive under the same conditions. In a similar context, carbones and silylones have been used to develop novel catalytic umpolung reactions, which turned out to be too challenging at this stage. Importantly though, silylones have been shown to activate the B–H bond of suitable pro-nucleophiles. Finally, several carbone–metal complexes have been synthesized and characterized. These novel species may be used in Lewis acid or dual catalysis after appropriate activation of the corresponding metal site.

Oxygen Transport Membranes (OTMs) can drastically reduce the energy and cost demands of processes that require pure oxygen, as they offer the possibility to combine a separation unit with a chemical reactor. One of the most commercially viable applications of OTMs is the partial oxidation of hydrocarbons for syngas production. A typical OTM configuration is a sequential arrangement of layers, i.e. an inactive support, a fuel oxidation layer, a dense layer and an oxygen reduction layer. However, one of the limitations of the OTM system is the low catalytic activity and stability of the materials currently used for the fuel oxidation layer. Moreover, the traditional deposition techniques that are used for the catalysts preparation are difficult to perform, as the fuel oxidation layer is buried deeply in the structure of the OTM. To simplify the OTM fabrication and improve the catalysts activity and stability, this thesis explores the exsolution of Ni nanoparticles from two different host lattice compositions, as potential materials for the fuel oxidation layer of OTMs. The (La₀.₇₅Sr₀.₂₅)(Cr₀.₅Mn₀.₄₅Ni₀.₅)O₃ (LSCMNi5) perovskite was selected, as the first candidate material for the OTMs. During reduction, the exsolution of Ni nanoparticles from the perovskite lattice took place and enhanced significantly the catalytic activity of the material regarding methane conversion. However, these nanoparticles were oxidised during the first hours of the testing and slowly reincorporated into the perovskite structure, leading to drop in the performance. Thereafter, the (La₀.₇₅Sr₀.₂₅)(Cr₀.₅Mn₀.₄₅Ni₀.₅)O₃ (LSCMNi5) perovskite was selected as an alternative composition. When the oxide lattice was sufficiently reduced, the exsolution of Fe-Ni alloy nanoparticles occurred. The catalytic testing suggested that the Fe-Ni alloy nanoparticles on LSCFNi5 presented lower activity for methane conversion comparing to the Ni nanoparticles on LSCMNi5, but higher stability in oxidising conditions. By increasing the Ni doping on the B-site of LSCF to 15 mol%, the catalytic activity of the material regarding methane conversion was increased and exceeded that of LSCMNi5. A CH₄ conversion of 70% was achieved, which was 20 times higher than that of the initial LSCF perovskite. Therefore, by tailoring the perovskite composition and the exsolution of the Fe-Ni alloy nanoparticles, it was possible to synthesize a material for the fuel oxidation layer of OTMs, which combined the high catalytic activity of Ni and the good redox stability of Fe.

Optimised SBA-15 mesoporous silica with high surface area (794 m2/g) and very thick pore wall (~ 5.0 nm), which maintained its structural and hydrothermal stability in steam, up to 800 °C was successfully synthesised and used as support material for synthesis of Au/SBA-15 catalysts. Gold nano-particles of different sizes were anchored on SBA-15 using cationic gold precursor (Au(en2)Cl3), post or one pot functionalisation of SBA-15 with MPTMS, APTMS or phosphine ligand before gold loading via HAuCl4 gold precursor. Characterisation of the catalysts were done using the following techniques: Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX), Transmission Electron Microscopy (TEM), X-Ray Diffraction spectroscopy (XRD), Fourier – Transform Infrared Spectroscopy (FT-IR), Nitrogen Physisorption and Hiden Analytical CATLAB system. Characterisation results confirmed that gold particle size, dispersion of gold on SBA-15 and the oxidation state of gold had significant influence on the catalytic activity of Au/SBA-15 catalysts. The most active and stable Au/SBA-15 catalyst (Au-0.6Mdp/SBA-15), prepared by one pot synthesis of SBA-15 with MPTMS before gold loading, had high surface area of 726 m2/g, with the smallest gold particle size of 1.3 nm, well dispersed on SBA-15 support. Hydrogen reduced Au/SBA-15 catalysts were more active than their as-synthesised forms in complete oxidation of non-chlorinated VOCs, with the most active Au/SBA-15 catalyst (Au-0.6Mdp/SBA-15) attaining 100 % acetone conversion at 250 °C and 11% propane conversion at and 300 °C. The as-synthesised form of Au-0.6Mdp/SBA-15 catalyst attained 100 % acetone conversion at 280 °C and 1.8 % propane conversion at 300 °C. The reduced Au-0.6Mdp/SBA-15 catalyst was also more active than the as-synthesised form in complete oxidation of aromatic and olefin VOC mixture (BTEXB of 820 ppm). For chlorinated VOCs using dichloromethane (DCM) as model compound, only the as-synthesised form of Au/SBA-15 catalyst was active, attaining 100 % DCM conversion at 305 °C. The reduced form of Au/SBA-15 catalyst was inactive, probably ii due to instant poisoning from strong attachment of chlorides with metallic gold. A novel coating technique (fine spray of catalyst, colloidal silica and methyl cellulose slurry on heated reactor at 150°C), which drastically reduced the amount of catalyst required for VOC oxidation was developed to introduce only 2.5 mg of Au-0.6Mdp/SBA-15 catalyst in the channels of a micro-reactor. Higher conversion of propane (VOC model compound) was achieved with the catalytic micro-reactor. The use of the micro-reactor has the potential to reduce the amount of expensive catalyst used and attain higher VOC conversions at lower temperatures, which could boost the commercial viability of this noble catalytic device for elimination of indoor VOCs.

Hydrogen fuel cells have held out the promise of clean, sustainable power generation for decades, but have failed to deliver on that potential. Inefficiencies in research and development work can be overcome to increase the rate of new knowledge acquisition in this field. A number of medical and engineering disciplines utilise a wide variety of statistical tools in their research to achieve this same end, but there has been little adoption of such statistical approaches within the fuel cell research community. This research undertakes a design of experiments (DoE) approach to the analysis of multiply-covarying (M-ANOVAR) factors by using historic data, and direct experimental work, on a wide variety of polymer electrolyte membrane fuel cells (PEMFCs) cathode gas diffusion media (GDM) and dual layered catalyst structures. This research developed a gradient of polarisation regions' approach; a method for making robust numerical comparisons between large numbers of samples based on polarisation curves, while still measuring the more usual peak power of the PEMFC. The assessment of polarisation gradients was completed in a statistically robust fashion that enabled the creation of regression models of GDMs for multiple input and multiple output data sets. Having established the multivariate method; a set of possibly co-varying factors, a DoE approach was used to assess GDM selection, dual layered catalyst structures and degradation of membrane electrode assembly (MEA) performance over time. Degradation studies monopolise resources to be monopolised for protracted periods. M-ANOVAR allows the addition of other factors in the study, and the total efficiency of the degradation experiment is increased. A 20% reduction in the number of samples to be tested was achieved in the case study presented in this thesis (compared to the usual one factor at a time (OFAT) approach). This research highlights the flexibility and efficiency of DoE approaches to PEMFC degradation experimentation. This research is unique in that it creates catalyst ink formulations where the variation in catalyst loading in each sub-layer of the catalyst layer (CL) was achieved by having a different concentration of the catalyst material on the carbon supports. The final M-ANOVAR analysis indicates a simple average of the individual responses was appropriate for the experiments undertaken. It was shown that low concentration dual layer catalysts on paper GDMs have improved performance compared to paper GDMs with uniform, single layer catalysts: Demonstrating reduced platinum concentrations to achieve equivalent open cell performance. The time to peak power during testing (how long after starting the test it takes to achieve the maximum performance in the cell) was strongly impacted by GDM selection. Furthermore, there was a strong suggestion that previously published results crediting a change in performance due to a single layer, or multi-layered catalyst structures may, in fact, have been due to the selection of GDM used in the experiment instead.

Flow-through catalytic membrane reactors offer the potential for improved conversions at reduced operating temperature due to product separation and catalyst activity. An experimental work dealing with a forced flow-through membrane reactor is the subject of this thesis. The focus is on the performance and transport characteristics of selective thin-supported silica membranes and flow-through catalytic membrane systems. The improvement of VOC-selective, H2-selective and CO2-selective membrane properties by the use of systematic dip-coating techniques and the application of the technique in a bi-layer membrane repair concept for gas separation membranes has been studied. In addition, several methods were used to characterize the membranes, including scanning electron microscopy, energy diffraction X-ray, nitrogen adsorption and gas permeation. In the first part of this work, CO2 permeance (3.39 x 10-8 mol m-2 s-1 Pa-1 at 25 0C for γ-Al2O3 membrane after exposing boehmite to the support) was mainly attributed to the Knudsen diffusion mechanism. CO2/CH4 selectivity of 24.07 was obtained from the silica membrane at 25 0C and 0.7 bar. Such a selectivity value could be useful in small-scale carbon dioxide removal units for natural gas treatment processes. In addition, H2/N2 selectivity of 1.36 and 2.72 at 1 bar were obtained from macro and meso porous membranes at 25 0C. The selectivity of propylene (C3H6) over N2 was also obtained. Higher selectivity of 1.79 at 0.05 bar was obtained. This selectivity increased by a factor of 2 compared to the ideal Knudsen selectivity (0.82). Remarkable propane conversion of 95.47% was achieved at a temperature of 378 0C on a 3.52 wt% platinum (Pt) catalyst at different total flow rates, ranging from 166 to 270ml/min. The temperature at which the catalytic combustion takes place for the VOC corroborates with (or is lower than) the one obtained from the literature for the same VOC on 5 wt% Pt/γ-Al2O3 catalysts.

Background: Sintered, metallic fibre networks have been used in the design of a range of technical devices in the past years (e.g. heat exchangers or catalysts). One potential application in the field of therapeutic, biomedical engineering is the magnetic-mechanical stimulation of bone growth around prosthetic implants after joint replacement surgery. The loosening of prosthetic implants in the human bone is one of the current research topics of prosthesis design. Objectives and motivation: The present study aims at improving the understanding of the architecture of sintered fibre networks and their behaviour under mechanical, or magnetic actuation. The strain field imposed on a bone matrix in the void network phase is the final focus of the study. Materials and methods: To achieve the described objectives, 3D scans of sintered, cube-shaped fibre network samples made from AISI 316L or 444 stainless steel were acquired by means of computed tomography. Based on the finite element method and beam theory, the extracted network geometries were run as simulation models locally or on the Cambridge High Performance Computing Cluster Darwin. Results and conclusions: The obtained results show that the properties of material architecture or material mechanics are not constants. Instead, they rather have to be treated as functions of parameters such as the manufactured fibre volume fraction, of the available sample size, or of the applied boundary conditions. The results from the linear, elastic simulation under mechanical actuation were validated by experimental data. The obtained results identified the material as being transversely isotropic, the influence of the fibre segment tortuosity on the material’s Young’s modulus, or fibre deflection (instead of fibre elongation) as the dominating deformation mechanism within the fibre network samples. The size of the representative volume element could be determined, which showed a particular dependency on the applied boundary conditions. Under magnetic actuation, regions of tension, shear, and compression were obtained for the investigated samples, with strain peaks located in the free corners of the sample cubes. The obtained deformation of an inserted bone matrix confirmed that values, sufficiently large for the intended bone growth stimulation, are achievable under realistic conditions, with matrix strain peaks in the immediate proximity to the fibre structure.

Platinum-based catalysts for hydrogen fuel-cell applications have progressed greatly with the addition of a second element in either a mixed-alloy or core-shell structure. Not only do they contain a reduced amount of the more expensive platinum metal but they have been shown to demonstrate a significant improvement in catalytic activity. Further improvement of these systems can only be made by careful investigation of such catalyst panoparticles on an atomic scale. These nanoparticles provide a significant characterisation challenge due to their minute size and beam sensitivity. A new method of quantifying the annular dark-field (ADF) scanning transmission electron microscope (STEM) signal on an absolute scale has been developed to address this problem. Experimental images are scaled to a fraction of the incident beam intensity from a detector map. The integrated intensity of each individual atomic column is multiplied by the pixel area to yield a more robust imaging parameter: a scattering cross section, σ. Using this cross section approach and simulated reference data, I show it is possible to count the number of atoms in individual columns. With some prior knowledge of the sample, this makes it possible to reconstruct the 3-dimensional structures of pure platinum nanoparticles. Such an approach has subsequently been extended to bimetallic particles here the elements are close in atomic number, using the platinum-iridium system as an example. In the same way that the cross section can be calculated from ADF image intensity, it is possible to calculate an energy dispersive x-ray (EDX) partial scattering cross section, beneficial especially because of the simplicity of its implementation. In sufficiently thin samples such that the number of x-ray counts is linearly proportional to sample thickness, we can determine element-specific atom counts. Finally, it is possible to combine EDX and ADF cross sections to provide us with quantitative structural and compositional information.

This thesis describes expansion of the ability of isothioureas to act as organocatalysts in formal [2+2]-, [3+2]- and [4+2]-cycloadditions between carboxylic acids and various acceptors via Type I ammonium enolate intermediates. Chapter 2 describes the optimisation and investigation of [2+2]-cycloadditions from ammonium enolates and N-sulfonylimines as the two components. The development of this methodology allows successful access to highly stereodefined β-lactams and, following in situ ring-opening, β-aminoesters. The products are obtained from either preformed homoanhydrides or directly from carboxylic acids, using open flask conditions, from simple, bench-stable starting materials and is scalable. A variety of anti-β-lactams (21 examples, 46-68% yield, up to >95:5 dr, 21->99% ee) and β-aminoesters (9 examples, 44-74% yield, up to >95:5 dr, 68-92% ee) were accessed in moderate yield, excellent diastereo- and good enantioselectivity. This represents an improved route to anti-β-lactams over previously described ketene and N-triflyl imine based methods. Chapter 3 subsequently describes studies focussed on the use of ester surrogates in the formal [4+2]-cycloaddition reactions of isothiourea generated Type I ammonium enolates. Iso-propylphosphonate 163 proved highly effective as the four-component in this process, which following the in situ ring-opening of the initial dihydropyranone product allowed isolation of a range of novel diester products which were previously unobtainable using this methodology. The products were accessed in moderate to excellent yields, excellent diastereo- and enantiocontrol (9 examples, 12-63% yield, up to >95:5 dr, 67-99% ee) with this process also amenable to a large scale. Furthermore, selective reduction and acid-catalysed cyclisation allowed access to δ-lactone products in good yield with retention of stereocontrol. Finally, Chapter 4 describes work on isothiourea-catalysed formal [3+2]-cycloadditions of oxaziridines and acetic anhydrides gave access to stereodefined five-membered oxazolidin-4-one heterocycles. In this case, the use of preformed homoanhydrides and an inorganic base was imperitive to avoid reduction of the oxaziridine starting material. The oxazolidin-4-one products could be accessed in excellent yield and ee however poor dr (13 examples, 63-96% yield, up to 59:41 dr anti:syn, up to >99% ee for both diastereoisomers). Following isolation, reduction of these heterocycles allowed access to enantioenriched diols with little loss in stereocontrol. Mechanistic analysis has shown that an improvement in diasterocontrol can be obtained by the use of an enantioenriched oxaziridine, demonstrating the stereospecificity of this process.

This thesis investigates the preparation and characterisation of Co/Mo bimetallic carbides and their stability and catalytic activity as bulk catalysts for the Dry Methane Reforming (DMR) reaction and as supported catalysts on alumina. The DMR reaction was chosen due to its importance in producing syngas, as a precursor for liquid fuels, from CO2 and CH4, two greenhouse gases. Bulk and supported bimetallic carbides were prepared by reductive carburization of the oxides with various hydrocarbons. The resultant carbides were characterized by X-Ray diffraction. Reactivity studies were undertaken by investigating the variable temperature reactivity of the catalysts on the DMR reaction. Characterization studies indicate that the oxides were transformed to the carbides successfully and these carbides had significant catalytic activity and were stable under the conditions used in the investigations.

Ce[subscript(x)]Zr[subscript(1-x)]O₂ mixed oxides of varying compositions were prepared by a sol-gel citrate complexion technique. In order to improve the catalytic activity of the oxides they were impregnated with copper using two different impregnation techniques. The bare oxides and copper impregnated samples were investigated using a range of Temperature Programmed (TP) techniques, in an attempt to establish their effectiveness as anode materials for solid oxide fuel cells (SOFCs) run on hydrocarbon fuels. In order to conduct the TP experiments a novel system was designed and constructed. The high Ce containing mixed oxides were shown to be reduced at lower temperature than high Zr content samples. TPRx experiments were employed to investigate which of the oxides was most prone to carbon deposition when reacted in methane, with the high ceria sample displaying the lowest level of carbon deposition. Lightoff experiments were undertaken to establish which oxide composition was the most active for methane oxidation. The activity of the oxides increased with ceria content up to 75 mole% (ZCe75), before decreasing for ZCe90. All the mixed oxides were shown to be more active for methane oxidation than CeO₂.

Development of chiral ligands capable of achieving high selectivity for various asymmetric catalytic reactions has been an important aim of both academia and industry. Nature is capable to selectively catalyze chemical reactions by using enzymes. An ideal catalyst would combine the selectivity of nature and the reactivity of man-made catalysts based on transition metal complexes. The two biomolecules chosen to achieve this are DNA and PNA. DNA is a chiral molecule with high binding selectivity towards small molecules and has been used as ligand for asymmetric catalysis. PNA is an achiral structural analogue of DNA that can form duplexes with DNA. To produce DNA based catalysts it is necessary to introduce a ligand such as a phosphine that will strongly coordinate to transition metals. To achieve this, functionalized linkers need to be introduced into a DNA strand, to covalently couple the phosphine moiety at a specific location of the DNA strand. Amine linkers and several modified nucleosides have been prepared containing thiol and amine functionalities and some of them were successfully introduced into DNA strands to function as linkers for the introduction of phosphine functionalities. Those strands were purified and an adequate procedure was developed for their analysis by MALDI-TOF. Diphenylphosphino carboxylic acids have been coupled to amine modified deoxyuridines by amide bond formation. The same coupling method has been used for oligonucleotides. DNA strands containing phosphine moieties were characterized by MALDI-TOF and ³¹P NMR spectrometry. ³¹P NMR spectroscopy was also used to confirm coordination of a phosphine modified 15-mer to [PdCl(η³-allyl)]₂. The phosphine modified nucleobases were also tested as ligands for palladium catalyzed allylic alkylation and allylic amination with diphenylallyl acetate as substrate although no enantioselectivity was observed. A PNA monomer was also modified with a bidentate sulfur protected phosphine and successfully introduced into a short PNA strand using manual solid phase synthesis. This strand was analyzed by MALDI-TOF. Moreover, preliminary studies were performed to test the use of aptamers as scaffolds for targets containing a ligand functionality.

Several heterogeneously catalysed reactions have been studied at pressures above and below the critical pressure of carbon dioxide in both carbon dioxide and nitrogen. The purpose of this study was to ascertain if carbon dioxide above its critical pressure and temperature would have a beneficial effect on the active life time of the catalysts When the Beckmann rearrangement of cyclohexanone oxime was studied it was discovered that using carbon dioxide above its critical pressure and temperature was beneficial to catalyst lifetime at both 250°C and 300°C, however the beneficial effect was also observed in nitrogen under the same conditions. It is proposed that the benefits at higher pressures are due to an increased residence time in the reactor or increased competition for active sites. When the process was performed at 380°C, a previously unreported impurity was observed in the collected samples. This was shown to be N-ethyl caprolactam, it is proposed that this is formed by a Ritter style reaction with 5-cyanopent-1-ene known to be formed during the reaction When the Fries rearrangement of phenyl acetate was studied it was discovered that increasing reactor pressure appeared to have little or no effect on the catalyst; it is thought this is because the reaction temperature of 150°C is below the boiling point of phenyl acetate, and that the reaction being observed occurs purely in the liquid phase. When the Diels-Alder addition of isoprene to methyl acrylate was studied, it was discovered that using carbon dioxide above its critical pressure had the effect of improving catalyst lifetime and conversion to desired product, with the greatest effect being at 50 bar. It was discovered that using nitrogen under the same conditions led to a greater improvement in conversion and catalyst lifetime. It is thought that the reactions in carbon dioxide are in a near critical state at 50 bar leading to the maximum effect at this pressure, and at higher pressures the reactions are bi- or multi-phasic, leading to the decrease in the effect. In the process of studying the above reactions an effective rig for the study of high pressure heterogeneously catalysed reactions was built.

Hydroxymethylation catalysis provides a valuable strategy for the high volume production of alcohols from α-alkenes. Generally this involves a hydroformylation-hydrogenation sequence, but the capacity to optimise selectivity for each transformation is limited. Condensation reactions between aldehyde products and alcohol products frustrate process economics. By an alternative scheme, all relevant bond-forming reactions occur in a single mechanism. This thesis describes several approaches to catalyst development and the application of derived systems for the hydroxymethylation of allyl alcohol. A review of auto-tandem hydroxymethylation and domino hydroxymethylation is presented in Chapter 1. In Chapter 2 the synthesis of bis-(diethylphosphine) ligands based on a modular series of chiral alicyclic scaffolds is described. High pressure NMR studies have shown that the catalytically active complex [RhH(CO)₂(L-L)] adopts preferentially ea geometry, with [Rh(CO)(L-L)(μ-CO)]₂ as the primary competing species. Catalyst performance can be correlated with the flexibility of the chelating ring; this favoured a high monomer/dimer ratio which enhances activity, but could not rigidify the configuration of the diethylphosphine groups which inhibits linear selectivity. Deuterium labelling studies were suggestive of a domino hydroxymethylation scheme. From the rhodium-hydroxyalkyl-hydride-carbonyl cation, a reductive elimination furnishes the diol derivatives and a β-hydride abstraction furnishes the hydroxyaldehyde derivatives. Up to 53 mol% selectivity to 1, 4-butanediol was attained. The catalysts could be recycled via biphasic separation, however poisoning by methacrolein caused a decline of activity upon reuse of the solution. An investigation of enhanced specific activity via the meta-effect is the subject of Chapter 3. The effect of systematic meta-substitution in triphenylphosphine upon physicochemical properties was investigated by IR spectroscopy and electrochemistry, both of which showed no significant structural impact on the uncoordinated triarylphosphine. Variable temperature ¹H NMR studies however revealed a change in the solution dynamics of the corresponding Vaska complex. The activation barrier to phosphorus-(ipso)carbon rotation increases as a function of meta-substitution, with rotation of substituted aryl rings past each other being more strained. This should create a well-defined coordination sphere around rhodium, and is proposed to account for the high linear selectivity observed in the hydroformylation of allylic alcohols with [RhH(CO){(3, 5-Me₂Ph)P}₃]. Linear-selectivity reached 96 mol%. Catalyst recycling was executed via biphasic separation, retaining on over twelve cycles an average of ~ 94 % efficiency. The kinetics of allyl alcohol hydroformylation with [RhH(CO){(3, 5-Me₂Ph)P}₃] was found to be well represented by Equation 11 (Section 3.6) A detailed analysis of how substrate-specific the influence of the meta-effect remains to be performed. In Chapter 4 domino hydroxymethylation by multi-component L-L/PEt3/Rh systems is described. The regioselective performance of a diphosphine rhodium catalyst in hydroformylation was translated for hydroxymethylation upon introduction of triethylphosphine at a L-L/PEt3 molar ratio ≥ 1. The highest observed selectivity to 1, 4-butanediol was 66 mol%. Competitive activity of triethylphosphine-modified rhodium species presumably accounts for the reduced linear selectivity observed when L-L/PEt3 molar ratio < 1. Despite aggravated catalyst decomposition at higher triethylphosphine concentrations, heterogeneous hydrogenation does not appear to take place. Deuterium labelling studies also discount a sequential homogeneous hydrogenation. There is evidence for the activation of a tris-phosphine-modified rhodium-acyl-carbonyl complex, but such a species could not be isolated from complexation reactions with a variety of precursors. It would be of interest to determine alternative promotors and to establish whether it is preferential to employ a high concentration of mildly acidic species or a low concentration of highly acidic species. The self-assembly of DNA base pair analogues 2-N-pivaloylaminopyridyl phosphine and isoquinolyl phosphine, each modified with diphenylphosphine, diethylphosphine, dicyclohexylphosphine and bis(3, 5-dimethylphenyl)phosphine, is described in Chapter 5. In the presence of a rhodium precursor, exclusive formation of the heteroleptic complex was observed. Although the intramolecular hydrogen-bonding network is sensitive to temperature and free hydroxyl functionalities, highly regioselective catalysts were generally afforded under the appropriate operating conditions. Only the catalyst based on the bis(dicyclohexylphosphine)-heterodimer performed poorly, presumably due to the formation of mono-phosphine complexes. High chemoselectivity was correlated with the heterodimer acidity constant, however this is rendered non-linear by a trans influence when electronic distinction between the platforms is high. Overall, complexes based on the assembly of a dicyclohexylphosphine platform and a bis(3, 5-dimethylphenyl)phosphine platform were found to be optimal; up to 73 mol% selectivity to 1, 4-butanediol was reached. It has been demonstrated in this thesis that in order to effect linear-selective domino hydroxymethylation of allyl alcohol, two distinct transition state structures must be optimised. High regioselectivity demands an asymmetric rhodium-hydride-dicarbonyl complex, which can be generated by an asymmetric chelate or by rigidifying the configuration of the substituents on phosphorus. Interestingly, chelation geometry in this transition state has little impact on this parameter. It has been shown that domino hydroxymethylation is activated by an electron-rich rhodium-acyl-dicarbonyl. The state of electron density on rhodium can be controlled by the substitution pattern on the phosphorus donors, but can also be changed by the inclusion of a suitable promoter. The chelation geometry in this transition state is more significant; placing the acyl functionality trans to a phosphorus donor concentrates the electronic effect in the rhodium-alkyldiol-hydride-carbonyl cation to such an extent as to impede hydride migration and reductive elimination of the diol, favouring β-hydride abstraction and reductive elimination of the hydroxyaldehyde.

Heterogeneous enantioselective catalysis strives to create new successful catalysts. One of the most researched examples is the hydrogenation β-ketoesters using nickel-based catalysts. A hindrance in the industrial scale-up of this enantioselective hydrogenation reaction is the lack of exact details of how chirality is bestowed onto this achiral metal surface. While a number of mechanisms have been proposed to explain the enantioselective behaviour of this system, these are predominantly based on catalytic studies. An alternative approach is through surface science studies examining the morphology, structure and composition of this catalytic system. A range of ultrahigh vacuum based model studies investigating the structure and composition of ultrathin Ni films and Ni/Au surface alloys on Au{111} using the techniques of Scanning Tunnelling Microscopy (STM) and Medium Energy Ion Scattering (MEIS) are presented in this thesis. In addition, the adsorption of the chiral modifier (S)-glutamic acid has been studied on these surfaces using vibrational spectroscopy (Reflection Absorption Infrared Spectroscopy (RAIRS)) and Temperature Programmed Desorption (TPD). Furthermore, MEIS has been used to investigate the influence of (S)-glutamic acid on the surface composition of Au/Ni model catalysts detecting effects such as adsorbate induced segregation and de-alloying behaviour. In addition, colloidal preparative routes have been used to synthesise bimetallic Au/Ni nanoparticles supported on mesoporous silica. The catalysts are then modified by the adsorption of the chiral ligand, (R,R)-tartaric acid. Finally, the catalysts are tested for their activity and enantioselectivity with respect to methylacetoacetate hydrogenation. At each stage the catalysts are characterised by a combination of Extended X-ray Absorption Fine Structure (EXAFS); Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectrometry (EDS) and Atomic Absorption Spectroscopy (AAS).

The hydroformylation of oct-1-ene is investigated under fluorous biphasic conditions, utilising the facile catalyst recovery that is provided by the temperature dependent miscibility of the perfluorinated solvent with normal organic solvents. High conversions and selectivities have been obtained in the batch process and the system is now described under continuous-flow conditions in a custom built reactor. The continuous-flow reactor was successfully run for 46 hours, with conversions to nonanal of 60% and l:b ratios of approximately 10. To understand the mechanism of this reaction more fully, a spectroscopic study of the catalyst formation and hydroformylation reaction was undertaken, using high-pressure infrared (HPIR) and nuclear magnetic resonance (HPNMR) techniques. The results of this study showed that although there is some effect of the strongly electron withdrawing nature of the perfluorinated ligand, the species formed under reaction conditions are very similar to those formed under the analogous triphenylphosphine system. It was found that under reaction conditions the perfluorinated ligand formed both the bis- and tris- phosphine complexes, compared to triphenylphosphine, which only formed the bis-phosphine complexes. The equatorial-equatorial and equatorial-axial isomers of [RhH(CO)₂(P(C₆H₄C₆F₁₃)₃)₂] were identified by means of a deuterium study in the HPIR spectrometer. The low levels of phosphorus and rhodium leaching to the organic phase were attributed to the predominant formation of [RhH(CO)(P(C₆H₄C₆F₁₃)₃)₃] under ambient pressure and temperature (separator conditions) indicated by a well defined quartet in the metal hydride region of the ¹H NMR spectrum.

Palladium complexes of bis(di-tert-butylphosphinomethyl)benzene (DTBPMB) show remarkably high activity as alkene methoxycarbonylation catalysts, in addition to numerous other catalytic conversions, and are currently being commercialised by Lucite in ethene methoxycarbonylation to methyl propanoate. Any large-scale exploitation of this catalyst system for heavier products, however, is likely to be hindered by catalyst-product separation problems common to homogeneous catalysts; hence modification of this catalyst system to allow facile product separation was investigated. Tethering of DTBPMB residues onto polystyrene via Suzuki-type coupling of suitable precursors onto bromopolystyrene and boronic acid functionalised polystyrene resins was investigated and the phosphine was successfully immobilised. Phosphination of the resins was not complete however and as such there is concern that other phosphine residues may be present which do not exhibit a bidentate binding motif. The synthesis of a potassium sulfonate derivative of DTBPMB (KBPMBS) was successful and immobilisation of this onto ion exchange resins was also investigated. Some preliminary results from studies into 1-octene methoxycarbonylation using palladium complexes of these resins were obtained. Supporting of this diphosphine onto silica via a sol-gel co-condensation methodology was also investigated; the synthesis of a suitably functionalised precursor containing a sulfonamide linkage was successful via protection of the diphosphine using borane. Although formation of the silica support was successful, attempts to deprotect the phosphine-borane resulted in cleavage of the ligand from the support. An alternative route to this supported ligand was attempted and others discussed. Synthesis of a suitable sol-gel precursor via alkene hydrosilation was also attempted and is discussed. Supporting of the sulfonated phosphine, KBPMBS onto silica functionalised with imidazolium tethered residues was also investigated, although complete leaching of the phosphine from the support by methanol washing was observed. Immobilisation of the synthesised KBPMBS ligand in an ionic liquid (IL) phase was investigated. Complex formation and catalytic activity were demonstrated and a positive effect on conversion was observed upon addition of carbon dioxide to the system; possibly due to the increased CO solubility within the IL phase. Efficient product separation from the IL-immobilised catalyst system was demonstrated, both by organic extraction and using supercritical carbon dioxide flow. However, poor catalyst stability under these conditions appears to present a barrier to recycling this system, with loss of conversion observed on catalyst recycling. Other attempts to immobilise the DTBPMB ligand are discussed and reduction of the sulfide derivative of DTBPMB was demonstrated using hexachlorodisilane, which could be used as a general synthetic strategy for protecting highly electron rich phosphines. It is possible that increasing the bulk of the DTBPMB ligand may increase catalyst stability and result in catalyst systems with higher turnover numbers. Therefore syntheses of bulky ligands based on the DTBPMB backbone were investigated. 1,2,4,5-tetrakis(di(tert-butyl)phosphinomethyl)benzene was successfully synthesised although palladium complexes of this showed no activity in catalytic methoxycarbonylation. Attempts to synthesise a related biphenyl-based tetraphosphine is also discussed, although isolation of this in a pure form was not achieved. Routes toward tetraphenyl and dimethyl-diphenyl functionalised derivatives of DTBPMB have also been explored, although only a monophosphine was isolated due to difficulties in obtaining an intermediate di(chloromethyl) precursor in both synthetic pathways, although this now appears to have been overcome.

In recent years so called "superacidic" metal oxides have attracted a lot of attention, primarily because of their ability to catalyse hydrocarbon isomerisation reactions at low temperatures. In this study, two particular classes of "superacidic" metal oxides - sulfated haematite and molybdated zirconia - have been examined for their efficacy in methane oxidation. To date, there have been few studies, which have aimed at investigating the potential of this class of oxides for hydrocarbon oxidation reactions, which is surprising in view of their well known ability to activate paraffins. Sulfation has been employed for iron oxide catalysts prepared from a number of oxyhydroxide and hydroxide precursors. Although, as has been shown, iron oxide catalysts prepared by different routes exhibit different reaction pathways during methane oxidation, sulfation has been found to produce a number of general effects such as increased surface area, suppression of low temperature total oxidation and the enhancement of oxidation activity at higher temperatures producing low levels of selective partial oxidation products. TEM examination demonstrates that the morphology of the different iron oxide samples are related to that of their precursors and is little effected by sulfation, except in the case of iron oxide samples prepared from a goethite precursor where the influence of sulfation on porosity is evidenced. Powder x-ray diffraction indicates that all the materials are in the haematite polymorph following calcination and that the sulfation again produces little effect, except for modifying the particle size and crystallinity in some cases. However, in the case of haematite produced from goethite, sulfation causes an anisotropic effect on the width of powder diffraction reflections. Further investigation has demonstrated that this is highly calcination temperature dependent, and whilst Mossbauer spectroscopy indicates that cationic disorder contributes to this effect HRTEM has shown it to be primarily due to the presence of mesoporous dimension voids running axially along the acicular Fe₂O₃ crystallites. It is proposed that sulfation causes this effect by hindering the Fe³⁺ cation migration during the transformation of goethite to haematite and this is associated with bridging C₂v complexation of SO₄²⁻ as evidenced in the sulfated goethite precursor. The catalytic activity of a series of zirconia-supported molybdenum catalysts with different loadings in the range 2, 5 and 10wt% were evaluated for both the partial and complete oxidation of methane. The catalytic performance of these materials has been shown to depend markedly on molybdenum content and it has tentatively been suggested that the formation of a monolayer species over the zirconia support is of importance in the reaction. Molybdation increases surface area and quantitative powder X-ray diffraction has indicated that this is associated with an increasing proportion of the metastable tetragonal phase of zirconia with increasing M0 O3 content. Hydrogen TPR studies indicate that molybdate undergoes a two stage reduction process and that Mo species on monoclinic zirconia are more susceptible to reduction. Laser Raman spectroscopy studies have indicated that the nature of the molybdenum oxo species is a function of loading, with polymolybdate species being replaced by XRD invisible molybdenum trioxide crystallites as MoO₃ content is increased. No direct relationship between MoO₃ formation or ZrO₂ polymorph on catalytie performance could be discerned and it is proposed that at reaction temperatures, which are significantly above the Tamman temperature of MoO₃ molybdenum oxo species are highly mobile forming monolayer type entities. Consistent with this, a catalyst with close monolayer MoO₃ content is found to possess a much higher efficacy than catalysts with sub- and super- monolayer contents. Finally, "superacidic" metal oxides have been screened for efficacy in methane combustion and the results determined under differential reaction conditions have been compared with those of materials reported to have high efficacy in the literature. It is found that, consistent with their potential enhancement of methane activation, modification of catalysts by literature methods so as to introduce "superacidity" generally promotes methane oxidation performance. However, supporting low levels of platinum on "Superacidic" oxides generally suppresses their performance, which is the opposite effect to that observed on their base oxides, which may imply a direct interaction of platinum with the aetive sites of reaction.

This thesis concerns the catalytic asymmetric synthesis of epoxides. An introduction highlights the utility of chiral epoxides in asymmetric synthesis. The important methods that have been developed towards the construction of this influential functional group are also described.

The properties of the perfluoropolymer sulphonic acid resin, sold under the trade name of Nafion have been examined. The use of Nafion as a support for transition metal catalysts has been studied in the context of alternative support systems. It has been demonstrated that transition metal complexes are readily incorporated into Nafion, provided they are either ionic in nature or contain ligands which are organic acid anions or ligands which can be protonated. Nafion used as a support has been successfully recycled and forms of Nafion with modified functional groups have been successfully synthesised. In order to explore the scope of Nafion as a catalyst support, a range of reactions has been investigated, the main purpose being comparison between the performance of a catalyst used homogeneously to its performance supported in Nafion. The hydroesterification of ethene to methyl propanoate was studied using several palladium complexes as catalysts. The ejects of temperature, CO pressure, catalyst loading and ligand to metal ratio on yields of product were recorded, using the most effective of the supported palladium catalyst systems. Yields of methyl propanoate using Nafion supported complex as catalyst were higher than the same catalyst used unsupported under comparable conditions. The hydrogenation of cyclohexene, dimethyl maleate and nitrotoluene was accomplished using the complexes [Ir(COD)(PPh(_2)Me)]PF(_6), [Rh(NBD){Fe(C(_5)H(_4)PPr(_2))(_2)}]BF(_4) and [RhCl(Ph(_2)P-NC(_5)H(_10))(_3)]. Yields of hydrogenation products using Nafion supported complexes were comparable or higher than yields obtained homogeneously. The hydrofonnylati n of hexene was carried out using a series of complexes of the form [Rh(NBD)L(_2)]BF(_4) where L represents a phosphine. Yields of aldehydes and normal to branched ratios were slightly lower using Nafion supported complexes in comparison to the homogeneous case. The production of substituted pyridines from propyne and acetonitrile was attempted using cobalt complexes coordinated to modified cyclopentadiene rings without success.