This thesis focuses on the assembly of non-conventional templated polyoxotungstates, specifically on the 6A group anions such as SO32-, SeO32- and TeO66-, which results in the discovery of 40 new polyoxotungstate compounds from the traditional Dawson-like cluster {SW18} to the nanoscale cluster {Se8W119} cluster. This study demonstrated that the identification and isolation of discrete building blocks to produce versatile and modular species can be assembled in a controlled manner, and it still represents a fundamental objective in the development of inorganic chemistry from the molecule to the nano world. The assembly of Iso-polyoxotungstate fragments can be affected by a few key reaction variables including, but not limited to, pH, temperature, ionic strength, type of cations and solvents. Carefully screening and controlling the reaction conditions can result in the isolation of the different aggregate behaviour of building blocks such as {W11} units. Further, the use of synthetically innocent anions appears to be important in the assembly of Iso-polyoxtungstate with pentagonal units. The Dawson-Like type X ⊂ {W18O54} (X= SIV, SeIV or TeVI) clusters can be reasonably designed and were isolated in a “one-pot” procedure by using a “shrink wrapping” strategy. These clusters are fully characterized by XRD, ESI-MS/CSI-MS and chemical analysis, IR, as well as by preliminary electrochemical studies. The effects of organo-cation, ionic strength and pH are investigated, especially in tungstoselenite and tungstotellurate chemistry. The synthetic methodology is also developed, the combination of building block strategy and solvent & cation exchange methods lead to the isolation of a series of new polyoxotungstate compounds including an “in-situ” reduction product {TeIVW18}, the thermochromic {Se2W18} cluster, and the organic soluble lacunary cluster {Se2W19}. These discoveries lead to a general new polyoxometalate building block approach and start a new field in polyoxotungstate synthesis.

This study provides a comprehensive understanding of the fine particle grinding process in stirred media mills. Calcium carbonate was chosen as the feed material. The experiments were firstly conducted in a laboratory scale vertically stirred media mill under various grinding conditions. The operating variables including specific energy, rotational speed, solids concentration, grinding media type, chemical additives (dispersant) were investigated. Then, the process was scaled up to a pilot scale mill. The performance of the pilot scale mill was compared to the laboratory scale mill regarding the product size (e.g. d80 ) and instantaneous power draw. Positron Emission Particle Tracking technology (PEPT) was used as a tool to study the motion of the grinding media in the laboratory scale stirred media mill. Some new stirrers were proposed and analysed. The PEPT results obtained under different operating conditions were demonstrated and analysed. The Discrete Element Method (DEM) based on the Hertz-Mindlin contact model was implemented to simulate the motion of the grinding media in both laboratory scale and pilot scale mills. A new type of stirrer is accepted by Imerys and used to produce the calcium carbonate in the industrial scale of grinding process. The energy saving is obtained up to 3 %compared to the standard stirrer currently used.

The production of high premium fuel is an issue of priority to every refinery. The trans-hydrogenation process was devised to convert two low value refinery cracked products to premium products; the conversion processes involve the combination of dehydrogenation and hydrogenation reactions as a single step process. The low value refinery products (i.e. alkanes and alkynes or alkadienes) have been converted to alkenes (olefins) by trans-hydrogenation using catalysts system based on VOx, CrOx and Pt all supported on alumina. Although trans-hydrogenation has been disclosed in many patents over decades, only little academic literature is available. The success of the process over various catalysts has been claimed in many of these patents. However, further studies are still required to ascertain the actual reaction mechanism, mitigating carbon deposition and catalyst deactivation, and the role of different catalysts to optimize the reaction desired products. The current research work evaluates the potential of CrOx/Al2O3, K-CrOx/Al2O3, Pt/Al2O3 and K-Pt/Al2O3 to investigate the trans-hydrogenation of the pentane (P)/1-hexyne (1HY) system, the pentane (P)/1,5-hexadiene (1,5-HD) system and the pentane (P)/2,4-Hexadiene (2,4-HD) system over a range temperatures (523-773 K). The fresh catalysts were first characterised by N2 adsorption using the BET method, X-ray diffraction, Raman spectroscopy, Thermogravimetric analysis, Temperature programme oxidation (TPO), Temperature programmed reduction (TPR), Electron paramagnetic resonance (EPR), Atomic absorption spectroscopy (AAS) and colorimetric analysis. The Free energy (ΔG) for the reaction of pentane with 1-hexyne, 1,5-hexadiene and 2,4-hexadiene shows that trans-hydrogenation is thermodynamically favoured at most temperatures for the reaction of pentane with 1-hexyne, however this is not always the case when hexadienes are the hydrogen acceptors. When 2,4-HD is the acceptor, ΔG is +ve at all the reaction temperatures tested. When pentane or hexyne/hexadiene or a 5:1 mixture was passed over the catalyst, in the temperature range of 523K -773 K, it was found that trans-hydrogenation process had taken place but many of the products are alkylated olefinic and alkylated hydrocarbons. Regarding all systems previously mentioned above, the ratio of olefin to alkylated olefin products was ~50:50 at 773K, however, this ratio was found to vary at other temperatures. The lowest ratio of ~10:90 was obtained at 523K. Dissociation of the hydrocarbon reactant was also observed leading to production of cracked products such as CH4, C2H4 and subsequent formation of a carbonaceous overlayer on the catalyst surface. This was not the case with the 2,4-hexadiene reactant, the trans-hydrogenation is poor, as expected from the free energies. The trans-hydrogenation process was shown to improve the conversion of pentane when co-fed with the hexyne to ~26% and to ~90% when co-fed with 1,5HD using the chromia catalyst at 773K, both values are much higher than the equilibrium conversion of the pentane dehydrogenation. Higher conversions of the pentane were subsequently obtained with other catalysts, but the chromia/alumina and K-CrOx/Al2O3 catalyst exhibits greater trans-hydrogenation activity. With the 2,4HD acceptor, very low conversions of pentane were obtained with all the catalysts: in general conversions lower than when the pentane was run alone were obtained. The products observed were unique for each catalyst. However, it was observed that for each catalyst, only the distribution of the products changed with temperature. This also accounted for changes in both the cracking products and the carbon laydown on the catalyst. The deactivation regeneration cycles shows very similar conversion of both reactants. There is a small deactivation observed for the longer time run; however these were not very significant. It was observed that some of the major products were consumed with time, but are used for the formation of other major products. However, this is more prominent with pentane/hexyne run using the CrOx/Al2O3 catalyst.

Modern society increasingly depends on reliable and secure energy supplies for economic growth and social prosperity. Thus, it is crucial to implement a low-carbon energy carrier based on renewable energy sources to ensure energy security and tackle climate change. Hydrogen (H2) is undoubtedly one of the most promising energy carriers to achieve a low-carbon energy future scenario. However, before the hydrogen economy can become completely viable, the safe and compact storage of H2 is an issue that must be overcome. This thesis concentrates on the development of potential “modular” solid state H2 storage solutions for portable power applications. A wide range of potential H2 storage materials was investigated with the aim of providing an improved performance in the form of a low desorption onset temperature, fast desorption kinetics and a high H2 gravimetric capacity. This research work focused on the study of light metal hydride – hydroxide systems, in particular the nanostructured MgH2-Mg(OH)2 system, and ammonia borane (AB) composites, specifically AB within a porous carbon-based matrix composites. The nanostructured MgH2-Mg(OH)2 “modular” H2 release system was investigated as a candidate exothermic filler material combined with an industrial MgH2 matrix to produce a novel solid state H2 storage hybrid tank. It was postulated that the heat of the reaction of the exothermic filler material could initiate and propagate a reaction in the matrix hydride and additionally contribute to the H2 yield. Detailed information about the thermodynamic and kinetic behaviour of the MgH2-Mg(OH)2 system, under operational conditions, was obtained. The thermal decomposition of this system was found to be a two-step process, associated with two H2 releases, resulting from: 1) almost simultaneous decomposition of Mg(OH)2 and hydrolysis of MgH2 at 616 K (exothermic event) and 2) decomposition of unreacted MgH2 at 743 K (endothermic event). The formation of a MgO layer on the unreacted MgH2 resulting from the previous hydrolysis was found to retard the H2 release. The formation of MgH2-MgO core-shell structures was investigated and confirmed by kinetic measurements, ex-situ Scanning Electron Microscopy / Energy Dispersive X-ray Spectroscopy (SEM/EDX) analysis and ex-situ Powder X-ray Diffraction (PXD) experiments. Kinetics measurements performed under operational conditions proved the H2 release of the system to be very slow (≈ 20 hours at 573 K). The mechanism for H2 evolution of this system was elucidated by in-situ Powder Neutron Diffraction (PND) performed at the Institut Laue-Langevin (ILL) in Grenoble, confirming the observations by thermal analysis methods and ex-situ PXD experiments. The use of additives (graphite and silicon carbide) was investigated to enhance the kinetic and thermodynamic properties in the system. The incorporation of SiC proved to be successful in improving the H2 release of the first step. However, no further kinetic improvements were observed by incorporating additives. Besides, the H2 capacity was slightly reduced by the introduction of 10 wt. % of C/SiC and traces of water were released alongside H2. AB-based nanocomposites and nanoconfined samples were also investigated with the aim of synthesising novel solid-state H2 storage materials with enhanced desorption properties. Highly ordered mesoporous carbons (FDU-25, CGY-1), activated carbons (AX21, Sigma AC, MAST Carbon TE7), and graphene (Angstron, Alfa), were employed to prepare nanocomposites (via ball milling or solution impregnation) in different ratios. A double-solution impregnated composite with a 2:3 weight ratio of AB to activated carbon (AC) showed the best performance with a dehydrogenation onset of 353 K and the suppression of borazine and boron-based by-products. The use of an external NiCl2 filter absorbed any released gaseous ammonia and no by-products were detected with a mass spectrometer sensitivity of 100 ppb. The nanoconfinement of AB in AC hosts was investigated by simultaneous Small Angle X-ray Scattering (SAXS) and Wide Angle X-ray Scattering (WAXS) at the Elettra synchrotron in Trieste. The results confirm that the nanoconfinement of ammonia borane was successfully induced and central to the performance improvements of the H2 storage material. To underpin the validity of the results and allow a quantitative comparison of the performance of these new developed materials with previously assessed systems, the reproducibility and repeatability of the measurements was ensured by means of intra and inter-laboratory comparisons. This was accomplished by using the facilities at the European Commission Joint Research Centre (JRC), Energy Storage Unit in Petten (The Netherlands) and the laboratories of the School of Chemistry in University of Glasgow (UK).

New energy materials have been investigated, including hydrogen storage materials and dilute nitride semiconductors. The two potential hydrogen storage materials to have been investigated are di-sodium amide borohydride (Na2NH2BH4) and lithium sodium borohydride (LiNaBH4). Additionally, the homoepitaxial growth of InNSb and GaNSb across a range of growth temperatures and rates has been examined and the effect of annealing GaNSb layers grown on GaAs has also been studied. It has been shown that Na2NH2BH4 undergoes a first order phase transition between a low temperature orthorhombic phase and a high temperature cubic phase. There is a large coexistence region between the two phases of -10°C to 70°C. The relative percentages of each of these phases in this region are dependent on whether the sample is been heated or cooled and the rate of change of the temperature, leading to a discrepancy in the overall volume of the sample between heating and cooling. It has also been proved that there is a metastable cubic phase of the sample that is seen when this material is first formed and cooled. Phase pure samples of LiNaBH4 have been synthesised from mixtures of sodium borohydride and lithium borohydride, with varying amounts of lithium inclusion. This lithium inclusion has resulted in some disorder in the sodium borohydride structure of the samples up to temperatures of 200°C, which disorder is increased as the amount of lithium increases. The inclusion of lithium has reduced the hydrogen desorption temperature by c.a.10% from 550°C for pure sodium borohydride to 504°C for the sample with the most lithium inclusion. Both InNSb and GaNSb exhibit a linear relationship between growth temperature and amount of nitrogen inclusion, with both more nitrogen being included and a greater maximum growth temperature seen in the GaSb-based material. In both types of material higher growth rates have resulted in less nitrogen inclusion at a given temperature. It has been shown that the increased amount of nitrogen inclusion has improved the quality of the grown layer. Annealing of hetroepitaxially grown GaNSb has increased the amount of substitutional nitrogen in these layers by allowing interstitial nitrogen to diffuse on to the crystallographic B site of the material, at higher temperatures this effect has been reversed. Increased nitrogen incorporation has resulted in a reduction in the crystal quality of these layers, differing from the effects seen in the homoepitaxial layers.

The majority of work presented covers an investigation in to vegetable oil based monomers for use in low ‘volatile organic compounds’ (VOC) or VOC free paints. Chapter 1 provides an introduction to recent EU legislation into the reduction of VOCs in a wide variety of paints and coatings. This is followed by an overview of vegetable oil based chemistry and subsequently the use of vegetable oils within materials, specifically coatings. Chapter 2 discusses the synthesis of a selection of vegetable oil derived monomers using a number of different diamines and aminoalcohols to produce fatty amides with methacrylate, styrene and maleate functionalisation. A selection of 3 vegetable oils with varying degrees of unsaturation (soybean oil, rapeseed oil and cocoa butter) were trialled to see the effect the starting oil had on the subsequent monomers. Removal of some or all of the unsaturation within the fatty chains of the triglycerides and monomers was carried out, primarily as a way to potentially reduce yellowing often found in paints derived from a vegetable oil source. Chapter 3 introduces the technique of emulsion polymerisation, followed by the incorporation of a selection of the methacrylate monomers synthesised in the previous chapter into polymer latexes. Comparisons of the latex properties are made and the results of a variety of tests (DSC, MFFT, hardness, yellowing ability) described. Comparisons between unsaturated and epoxidised derivatives are made and conclusions drawn. Chapter 4 focuses on the preparation of polyurethanes (PU) from a small library of renewable diols. These were synthesised using both cocoa butter and rapeseed oil with diethanolamine, followed by epoxidation of the residual unsaturation in some cases. These were reacted with MDI and a variety of commercial diols (PEGs and 1,4-butanediol) and their physical properties (tensile strength, Young’s modulus, swelling and cross-linking density) and thermal properties analysed by a variety of methods (TGA, DSC). Chapter 5 describes the BF3.Et2O catalysed ring-opening of a small range of epoxidised oils derived from rapeseed and cocoa butter to give higher molecular weight pre-polymers/oligomers suitable as polyols for PU synthesis. Two approaches to the monomers are described. Chapter 6 describes the experimental conditions and chemical analysis of the all the key reactions and processes described in the thesis.

The work presented in this thesis represents the chemical modifications of unsaturated plant oils to yield oligomeric/polymeric polyols suitable for polyurethane synthesis. Chapter 1 provides the introduction to the chemistry of polyurethanes, plant oils and plant oil based polyols. Chapter 2 focus on making oligomeric polyols from unsaturated plant oils through epoxidation and subsequent epoxide ring opening oligomerization that yielded oligomeric polyols. The properties of these oligomeric polyols were influence by the level of unsaturation of the plant oils. In addition, catalyst loading, monomer concentration and reaction time play vital role in determining the properties of the oligomeric polyols. Plant oil based polyols were also prepared by epoxide ring opening with renewable polyhydric alcohols that provide a variety of plant oil based polyols for polyurethane synthesis. Chapter 3 focus on the synthesis of polyurethanes (PU) from various types of plant oil based polyols as well as the evaluation of the mechanical properties of these synthesized PU. The tensile test of the PU shows that the mechanical properties were related to the structure and functionalities of the plant oil based polyols. The bulk of Chapter 4 discusses the copolymerization of epoxidized plant oils with tetrahydrofuran and the use of these copolymers for the synthesis of PU. The properties of the copolymers were related to the epoxidized oils used in the reaction and therefore influence the mechanical properties of the PU synthesized from them. Finally, Chapter 5 is a collection of work on the one-pot oligomerization of unsaturated fatty acid and plant oils with and without catalyst as well as the synthesis of PU based on these polyols.

The work described in this thesis was carried out on the synthesis of silicon carbide using microwave processing and aimed to develop procedures to reduce processing complexity and cut processing times. Si-C/SiO2-C systems were first studied due to the ready availability at reasonable cost of the starting powders and the excellent microwave absorption properties of carbon. Silicon carbide was synthesised from silicon or silica combined with activated carbon or graphite via microwave heating over timescales from minutes to seconds without the need for inert atmospheres or subsequent purification. In the reactions performed in a MMC, graphite was found fundamental not only as a microwave susceptor, but also as a reductant, preventing the oxidation of silicon carbide. Another important beneficial factor was water, used as a binder in the pellet making process, it minimised the intergrain void space between particles and possibly acted as a polar liquid microwave susceptor. It was found the carbide morphology and phase purity can be controlled by the microwave cavity used, the power applied and hence by the heating rate. Short irradiation times (ca. 5 minutes) in a multimode cavity using silicon and activated carbon powders produced single phase β-SiC nanofibres as small as 5 nm in diameter while large crystallites of β-SiC can obtained in ~1 minute using high power, single mode cavity microwave techniques. Furthermore, similar microwave cavity systems shown that the removal of the susceptor, starting from silica and carbon mixtures, is possible and the successful conversion to silicon carbide can be performed using loose powders. This represented a major step with respect to designing a flow process and reducing carbon contamination. Studies of microwave processing of silicon carbide were then extended to x-aerogels, to probe whether the produced silicon carbide would mimic the porous microstructures offered by the precursor. This indeed resulted in the production of porous silicon carbide (in 15 minutes) and also sintered crystallites of micrometre sizes (after 3.5 minutes) whether MMC or SMC systems were employed.

Pentaerythritol is an important industrial chemical for use in paints and coatings, primarily, but also in fuels, explosives, medicine and polymers. The current process for this material is over 50 years old and is a multi-step process involving 3 homogeneous aldolizations and a crossed Cannizzaro reaction, generating 1.5 tonnes of waste for every 4 tonnes of product. This is also very energy inefficient. We are currently developing a radically different concept, shown below. This will deliver an integrated heterogeneous catalytic process with no waste and a high energy and materials efficiency. Methanol/ Dehydrogenation Base Hydrog Ethanol Catalyst Catalyst Catalyst Pentaerythritol The initial step, CH3OH HCHO + H2, will involve the use of Ag/SiO2 catalysts. This will be in the absence of O2, which differs from the current oxidative dehydrogenation process used to produce HCHO, i.e. a direct dehydrogenation. This step has been optimised by investigation of different surface properties to determine how surface area and dispersion will affect the overall adsorption and consequently the methanol/ethanol conversion and product yields. Deactivation of these catalysts has also been touched on by use of in-situ temperature programmed oxidation’s. Base catalysis involving an aldol type reaction of 2 aldehydes, HCHO and CH3CHO, will give the methylolated aldehyde intermediate. This will then undergo a final hydrogenation to the desired product. Any unreacted aldehydes will, therefore, be hydrogenated back to starting materials and consequently recycled. It will be attempted to couple all three reactions to explore how the catalysts perform when used in succession.

This thesis explores three routes to alleviating the economic barriers to proton exchange membrane fuel cells through reducing, recycling and removing platinum group metals (PGMs). The reduction of PGM content is explored using electrochemistry to assess the novel materials produced when combining fullerene based compounds with electron beam lithography. This technique yields the potential to precisely control the distance between platinum (or other metal) atoms embedded within carbon materials. It is shown that the material alters the onset potential of proton reduction compared to glassy carbon and the methodology for study is developed. The recycling of PGMs is demonstrated by testing the electrochemical behaviour and particle structure of deposited palladium within biomass produced through biohydrometallurgy. Electron microscopy and electrochemistry is used to investigate the biohydrometallurgy process and how the substrate, leachate and reducing agent effect both the particles produced and the electrochemistry observed. Concluding that the un-processed materials may function as future electrocatalysts without further processing steps. The removal of PGM content is investigated, through the electrochemical characterisation of the adsorbed layers and solutions of phosphomolybdic acid, singularly substituted vanadophosphomolybdic acid and doubly substituted vanadophosphomolybdic acid. Describing the complicated multi-electron, multi-step redox chemistry of the potential mediator species, with specific focus on electrode material and the effect of pH.