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The purpose of this thesis is to investigate „chemical looping water splitting‟ processes for hydrogen production which involves reducing a solid oxygen carrier material (such as iron oxide) by a reducing agent such as carbon monoxide, syngas or methane. Following this, a second step can be performed where water is used to oxidise the metal, thereby producing free hydrogen (without requiring any separation steps). These two steps (reduction and oxidation) can be repeated to perform redox cycles which would continuously utilise the solid oxygen carrier material. Initial experiments were performed using temperature programmed redox cycles to perform chemical looping water-gas shift and compare the performance of two perovskites (La0.6Sr0.4Co0.2Fe0.8O3-δ and La0.7Sr0.3FeO3-δ) against two supported metal oxides (60% Fe2O3/Al2O3 and 20% NiO/Al2O3). The best performing materials of the perovskites (La0.7Sr0.3FeO3-δ) and support metal oxides (60% Fe2O3/Al2O3) were further tested in isothermal chemical looping water-gas shift cycles over 150 redox cycles to assess material lifetime. The results showed that 60% Fe2O3/Al2O3 under these conditions had deactivated due to the formation of FeAl2O4 which led to lower hydrogen production. La0.7Sr0.3FeO3-δ gave high material stability and steady hydrogen production over more than 100 redox cycles. A nickel-containing perovskite La0.7Sr0.3Fe0.9Ni0.1O3-δ was synthesised and subjected to the same experimental conditions but this material showed no improvement compared to La0.7Sr0.3FeO3-δ in terms of hydrogen production, hydrogen purity and material stability. In an additional experiment 60% Fe2O3/Al2O3 and La0.7Sr0.3FeO3-δ were used as oxygen carrier materials in a three-step chemical looping process involving reduction by methane (to form syngas), water oxidation and air oxidation (to provide heat). 60% Fe2O3/Al2O3 gave good hydrogen purities during water oxidation but showed low material stability, whereas La0.7Sr0.3FeO3-δ showed no loss in material stability but gave low hydrogen purity, possibly due to carbon deposition during the reduction step.

This thesis describes investigations utilising isotopic hydrogen gas (D2 and DT) and covering several areas of chemistry. The initial studies involved the selective alpha-labelling of pyridine and other N-heterocyclics via new hydrogen-deuterium exchange catalysts, identified via a parallel-chemistiy screening process. The new catalysts and associated methodology are applicable to labelling with tiitium as well as deuterium and are a significant improvement upon existing labelling approaches. The remaining studies involved the application of isotopes to studies of the hydrogenation of unsaturated hydrocarbons. initially the hydrogenation, and isotopic exchange reactions, of simple imbranched C5 alkenes and alkynes with D2 gas were examined. Although many aspects of the hydrogenation chemistry of pentenes and pentynes have been studied there is an interest in obtaining close to 100% selectivity in the reactions of these important industrial feedstocks. The studies were subsequently extended to the hydrogenation of the less-volatile phenyl-C3 unsaturated hydrocarbons, allowing studies with DT gas as well as D2. The work carried out in these two chapters includes a comparison of a novel l%Pd/Al2O3 catalyst developed by Johnson Matthey (JM)/Synetix with a standard catalyst 5% Pd/C catalyst routinely used for the hydrogenation of double bonds. Although these investigations are still in their initial stages, the results obtained suggest that the JM catalyst could prove more selective than the commonly used Pd/C. The above DT studies also enabled an investigation of the application of a new development in 3H-NMR spectroscopy, the 3H cryo-probe. This new technology was shown to provide a significant advance for the analysis of tritiated compounds and mixtures containing low levels of radioactivity. The last investigations concerned the facile exchange of isotope during the hydrogenation of terminal alkenes. This process was shown to be general and could well provide a novel methodology for the tritium labelling of this class of compounds.

The thesis is divided into six chapters: Chapter one introduces an overview of deuterium and tritium properties, various labelling procedures as well as analytical methods for hydrogen isotopically labelled compounds. Chapter two describes the preparation of polymer supported transition metal catalysts, particularly rhodium trichloride catalyst, and then applications in the deuteriation and tritiation of aromatic compounds and selected drugs. 3H-NMR spectroscopy showed some aromatic compounds and drugs were labelled with 100% regiospecificity. The regiospecificity was improved when rhodium trichloride was supported on PVP polymer. Chapter three presents a new procedure for the specific incorporation of three tritium atoms into organic compounds. Chapter four describes the applications of a mild Lewis acid catalyst - boron trifluoride etherate in the deuteriation and tritiation of some aromatic compounds and drugs. 2H- and 3H-NMR spectroscopy analysis of the labelled compounds and drugs confirmed the exchange reaction was electrophilic. Chapter five describes a procedure for the synthesis of a deuteriated biocompatible polymer, 2H-PmMl2. When the procedure was adopted for the synthesis of the tritiated version, the polymer was labelled with very low specific activity. A microwave assisted procedure was investigated to see whether the deuteriation of the monomer, HEMA-PC could be achieved by this method. In chapter six NMR spectroscopy is employed to study methylation kinetics using methyl triflate as methylating reagent.

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La problématique de la première absorption (i.e. étape d’activation) de l’intermétallique FeTi, pour le stockage de l’hydrogène est souvent un frein pour son industrialisation. Le challenge réside dans la conception d’un « nouveau matériau » dont la première étape d’hydrogénation, s’effectue dans les mêmes conditions de température et de pression modérées, que lors de l’hydrogénation réversible. Une solution est de faire appel aux performances d’un élément dopant et/ou à la technique du broyage mécanique. Dans ce manuscrit, nous proposons l’utilisation de l’hafnium comme dopant. Ce projet complète les études qui ont été effectuées sur le zirconium (e.g. le zirconium commercial contient toujours une certaine quantité d’hafnium). L’ajout d’une faible quantité d’hafnium induit la formation d’une phase secondaire, « riche » en hafnium et en fer. Grâce à la présence de cette phase, la cinétique de première absorption est considérablement améliorée, et ce, sans traitement thermique préalable. L’étape d’activation comprend un seul mécanisme lorsque la taille des particules est faible. A contrario, un second mécanisme est mis en évidence, pour des particules de taille supérieure à 0,5 mm. La mécanosynthèse a permis non seulement d’obtenir la phase principale FeTi, mais aussi de favoriser la première absorption d’hydrogène. Des paramètres d’élaboration méticuleusement optimisés ont rendu possible la conception d’un matériau « modèle », par pulvérisation cathodique magnétron, sous forme de couche mince. Ce matériau modèle pourrait servir à étudier et à comprendre la diffusion de l’hydrogène à l’interface de la matrice FeTi et du dopant Zr ou Hf. / The issue of the first hydrogenation (i.e. activation process) of the intermetallic FeTi for the storage of hydrogen is often a brake for its use in industry. The challenge lies in the design of a "new material" whose first hydrogenation is carried out under the same conditions of moderate temperature and pressure, as during reversible absorption. Efficient solutions are to use a doping element and/or mechanical alloying process. In this work, we propose to use hafnium as a dopant. This project completes the studies that have been carried out on zirconium (e.g. commercial zirconium always contains a certain amount of hafnium). The addition of a small amount of hafnium induces the formation of a secondary phase, "rich" in hafnium and iron. Thanks to the presence of this phase, the kinetics of activation process is improved, without prior heat treatment. The activation process consists of a single step, when the particle size is small. However, a second step appears, for particles bigger than 0.5 mm. The mechanical alloying allowed the formation of the main phase FeTi, and also enhanced the activation process. An accurate control of deposition conditions allow us to design a ″model″ material by magnetron sputtering as thin layers. This ″model″ material can be used to study and understand the hydrogen diffusion, at the interface of the matrix (FeTi) and the dopant (Zr or Hf).

L’adsorption des gaz dans les solides micro/mésoporeux et la solubilisation des gazdans les liquides sont des phénomènes physiques très bien connus. En revanche, lasolubilisation des gaz dans un liquide confiné à l’intérieur d’un solide (système hybride) estun domaine très peu étudié, malgré des applications importantes, notamment dans l’extractiondu pétrole, les ciments ou encore les réacteurs catalytiques triphasiques. Nous avons montréexpérimentalement que la solubilité du CO2 et H2 augmente quand la taille de pores du solideest de l’ordre du nanomètre. Un des objectifs de cette thèse était d’optimiser le couple solidesolvant(système hybride) et les conditions de température et de pression pour augmenter lestockage de H2 pour les applications de stockages. Dans le système Aérogel/éthanol à 50 barset 0°C, la solubilité de H2 est 8,5 fois supérieure à la solubilité mesurée dans le liquide seul,représentant une masse de 6,2g d’hydrogène stocké par kg de solide. Le second objectif étaitde comprendre les paramètres clefs de ce phénomène apparent de « sursolubilité » dans lessystèmes hybrides. En comparant différents solides poreux (zeolithes, MOF, MCM, silice),nous avons montré le rôle majeur des propriétés d’interfaces. Les phénomènes desolubilisation ont été modélisés à l’échelle moléculaire par GCMC et validéesexpérimentalement. Il apparait que le mécanisme de sursolubilisation provient d’unestructuration en couche des molécules de solvants en interactions avec les parois dumésopore. / The adsorption of gases in micro/mesoporous materials and solubility of gases inliquids are physical phenomena well known. On the other hand, solubility of gases in liquidsconfined inside a solid (hybrid system) has not been entensively studied, despite the importantapplications such systems can have in the areas of oil extraction, cement and triphasiccatalytic reactors. We have shown experimentally that the solubility of CO2 and H2 increaseswhen the size of the pores of the solid is in the nanometer range. One of the objectives of thisthesis was to optimize the couple a solid and a solvent into a hybrid system and the conditionsin which to increase the H2 storage capacity. In an aerogel/ethanol hydrid system at 50 barand 0 ° C, the solubility of H2 is 8.5 times greater than the solubility measured in the singleliquid, representing a mass of 6.2 g of hydrogen stored per kg of solid. The second objectivewas to understand this apparent phenomenon of oversolubility and the key parameters in thehybrid systems. By comparing different porous solids (zeolites, MOFs, MCM-41 and silica),we have shown the major role of the properties of interfaces. The phenomena of solubilsationwas modelled by GCMC and experimentally validated. It appears that the mechanism ofoversolubilisation comes from structuring the solvent molecules in interactions with the wallsof the mesopore layered.

Cette thèse s’inscrit dans une volonté d’améliorer la compréhension des mécanismes fondamentaux de radiolyse de biomolécules par des ions accélérés, à l’échelle moléculaire. Ainsi, les ions étudiés ont été de différentes nature (H+, He2+, C6+) et de différentes énergies, correspondant à une gamme de densité de dépôt d’énergie allant de 0,3 à 1000 eV/nm.Dans le vivant, l’eau ayant une place prépondérante, la compréhension de la radiolyse de l’eau est essentielle. L’espèce la plus réactive produite en milieu aéré, le radical hydroxyle (HO•) a été quantifiée en utilisant une sonde spécifique, l’acide 3-coumarine-carboxylique.Les dégâts indirects aux biomolécules, via les espèces issues de la radiolyse de l’eau, ont été étudiés en solution aqueuse diluée sur deux systèmes : un acide aminé, la phénylalanine et une protéine, la myoglobine. Les effets directs de radiolyse ont été étudiés sur la myoglobine en gels concentrés hydratés. Les phénomènes de radiolyse ont été caractérisés pour décrire les mécanismes en jeu et les produits issus de la radiolyse de la phénylalanine ont été systématiquement identifiées et quantifiées. / The goal of this thesis is to achieve a better understanding of fundamental mechanisms of the radiolysis of biomolecules by accelerated ions, at the molecular scale. To do so, different type of ions have been used (H+, He2+, C6+) at various energies, corresponding to densities of energy deposition from 0,3 to 1000 eV/nm.The main component in biological systems is water. Therefore, the comprehension of the water radiolysis under ions irradiation is essential. One of the most reactive species produced in aerated conditions, the hydroxyl radical (HO•), has been quantified using a specific probe, the 3- carboxylic acid coumarin.Indirect effects of radiolysis on biomolecules, involving water radiolysis species, have been studied in dilute aqueous solutions on two different systems: phenylalanine, an amino acid, and a protein, myoglobin. Direct radiolysis effect were studied on concentrated hydrogels of myoglobin ad other proteins. Elucidation of radiolysis mechanisms and quantification of phenylalanine radiolysis products were systematically performed.