Dissertations / Theses on the topic 'Hydrogène – Synthèse (chimie) – Stockage'
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Gagnon-Thibault, Évelyne. "Synthèse et caractérisation de matériaux polymères poreux pour le stockage d'hydrogène." Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/29167/29167.pdf.
Depardieu, Martin. "Chimie intégrative pour la synthèse de matériaux fonctionnels avancés." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0316/document.
Hierarchical porosity in solid foams allows the combination of the advantages offered by the different scales of structuration : macropores allow high porous volume and easy diffusion of reagents, while mesopores and micropores allow confinement and high specific surface areas. Integrative chemistry, associating soft matter and soft chemistry, offers a variety of synthetic pathways to generate such materials. We used emulsions and surfactants to template sol-gel chemistry in order to obtain silica foams bearing hierarchical porosity. These silica foams were employed as hard templates to synthesize carbon foams, used as electrodes in lithium-sulfur batteries bearing high capacities. We then explored the impact on performances of loading them with metallic nanoparticles. We also studied the potential of those carbon foams for hydrogen storage, and we obtained cycling capabilities with LiBH4 after loading them with metallic nanoparticles. Finally, the silica foams were used as a support for bacterial growth. Indeed, when bacteria grow in a confined medium, the kinetics of growth and their final concentration can be totally different than what is observed in classical cultures, which is of high interest for applications such as biocatalysis
Fang, Wenhao. "Production d’hydrogène par transformation du bioéthanol sur catalyseurs à base de nickel." Electronic Thesis or Diss., Lille 1, 2013. http://www.theses.fr/2013LIL10026.
The potential benefits of hydrogen economy based on renewable energy sources (biomass) have drawn much attention. Hence studies on H2 production from catalytic transformation of bio-ethanol are very interesting and promising. Two types of Ni-based catalysts, CeNiXOY and NiXMg2AlOY, are studied for H2 production from ethanol through two routes, steam reforming and oxidative steam reforming (H2O/EtOH = 3). Numerous physico-chemical characterizations of the catalysts allow proposing active sites and possible mechanism. The CeNiXOY and NiXMg2AlOY nano-compounds are able to store different hydrogen species in particular hydride species. Once in situ treated in H2 at proper temperature, these mixed oxides become nano-oxyhydrides with the presence of anionic vacancies, O2- species and cations in close interactions which are highly active and efficient catalysts for ethanol steam reforming. The Ni12Mg2AlOY catalyst allows obtaining a low-temperature high-yield H2 production of 3 mol molEtOH-1 at 300 °C without the formation of CO. The Ni3Mg2AlOY and CeNi1OY catalysts are able to produce a very high H2 production of about 5 mol molEtOH-1 at 650 °C. In the presence of O2, CeNiXHZOY and NiXMg2AlHZOY oxyhydrides (30 mg) enable to completely convert ethanol with about 45 mol% H2 production with the oven temperature at only 60 °C, showing remarkable stability for 75 h on stream. This self-sustainable reaction is driven by the energy released from the strong exothermic reaction between the hydride species stored in the catalysts with O2, at the same time hydride species are continuously formed from ethanol to make the reaction sustainable
Bououdina, Mohamed. "Étude d'alliages et d'hydrures dérivés des phases de laves ZrCr2(1-x)M2x (M=éléments 3d et molybdène) : Synthèse, études structurale et thermodynamique en relation avec les propriétés de stockage de l'hydrogène." Grenoble 1, 1995. http://www.theses.fr/1995GRE10056.
Yu, Zhewei. "Equilibrium and kinetics studies of hydrogen storage onto hybrid activated carbon-metal organic framework adsorbents produced by mild syntheses." Thesis, Nantes, Ecole des Mines, 2016. http://www.theses.fr/2016EMNA0236/document.
Since the last 15 years, the porous solids such as Metal-Organic Frameworks (MOFs) have opened new perspectives for the development of adsorbents for hydrogen storage. The structure and the pore networks of these materials are especially adapted to the adsorption of gases. The chromium (III) terephthalate-based MIL-101(Cr) is a very stable material which exhibits good adsorption uptakes for hydrogen (H2), carbon dioxide (CO2) and methane (CH4).In this study, syntheses were carried out by different ways and several mineralizing agents such as hydrofluoric acid (HF), acetic acid (CH3COOH) and sodium acetate (CH3COONa) have been tested. Moreover, Activated Carbon (AC) has been introduced in the framework to create an AC incorporated composite material with an enhanced specific surface area. Conventional techniques such as powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and nitrogen (N2) adsorption isotherms at 77 K were used for materials characterizations.In the aim to evaluate hydrogen storage capacities of these materials, hydrogen adsorption isotherms were measured at 77 K via both volumetric and gravimetric methods, and the obtained results are in good agreement. A hydrogen uptake value of 13.5 wt% has been measured at 77 K and 100 bar for the composite material which shows a great improvement of hydrogen capacity compared to the pristine MIL-101(Cr) (8.2 wt%).Finally, hydrogen adsorption kinetics has been measured at 77 K using volumetric method. The obtained results were compared to the Linear Driving Force (LDF) and a temperature dependent diffusion model was also considered to take into account the temperature variations which occur during the adsorption process
Clémençon, Damien. "Mg(BH4)2 : synthèse, nano-confinement et catalyse." Thesis, Amiens, 2019. http://www.theses.fr/2019AMIE0047.
This PhD thesis concerns the field of hydrogen storage and more specifically solid-sate hydrogen storage materials. Magnesium borohydride, Mg(BH4)2, is a compound of strong interest because of its high hydrogen gravimetric capacity (14.8 %) and was the subject of this study. The literature on the decomposition of this compound is actually very inconsistent and reveals numerous contradictions. Different synthesis routes of Mg(BH4)2 were studied during the thesis in order to produce the purest possible compound and at a lower cost. A mechanical milling-assisted metathesis reaction produced Mg(BH4)2 from NaBH4 and MgCl2 precursors with an excellent yield. The hydrogen desorption properties of Mg(BH4)2 were then improved by a dual approach of catalytic additions and nano-confinement into mesoporous carbons. Core-shell Ni-Pt nanoparticles of about 1.9 nm in diameter were used as catalysts. These particles were dispersed in a carbon having mesoporous channels of 4 nm in diameter prepared by hard templating of SBA-15 silica. The results showed that the combined effect of both nano-confinement and catalysis allows the final decomposition temperature of Mg(BH4)2 to be reduced by more than 100°C while obtaining faster hydrogen desorption kinetics
Tharcis, Marion. "Synthèse et caractérisation d'assemblages supramoléculaires organisés par liaisons hydrogène dans l'eau." Paris 6, 2011. http://www.theses.fr/2011PA066058.
Guillet, François. "Développement et optimisation d’un système de stockage d’énergie et de production d’hydrogène basé sur l’électrochimie et la chimie du zinc." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI029.
Hydrogen is an energy carrier and a potential asset for helping to lower carbon levels of energetic uses. Water electrolysis is a way of production and a good compromise to generate a large quantity of cheap and low-environmental-impact hydrogen. Compression is used to store hydrogen but electrolysers are technologically limited to reach high pressures. One solution to overcome this problem is decoupling electrolysis. It aims at separating the hydrogen and oxygen production in two steps through mediation oxydizer/reducer. Ergosup company has developed ZHYNCELEC process, using different technologies such as zinc as mediator. The first step is zinc electrodeposition which increases the acidity of solution and lead to an oxygen formation. This step is inspired by industrial zinc electro winning. The second step is the reaction between the metallic deposition and electrolyte producing hydrogen and making the dissolution of zinc. The purpose of this study is the optimisation of ZHYNCELEC process.This work can be divided in three axes of study. First, the selection of the different electrode materials. They are chosen by electrochemical performances and durability. Secondly, electrolyte composition optimization. The key factors are zinc concentration, acid concentration and the possibility of additives presences. The final axe concerns the processing aspect and the operative conditions like temperature, current density, maximal hydrogen pressure and reactor geometry. These three axes cannot be studied separately because of the interaction between the different parameters, which forces at compromising following the aim of the application of the process
Petit, Jean-Fabien. "Etude de la stabilité thermique de l’ammoniaborane : de la synthèse aux caractérisations thermogravimétriques et spectroscopiques." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS256.
Boron and nitrogen based-materials offer a great potential and interest in energy applications and in particular in the field of hydrogen storage. The ammonia borane (NH3BH3) was revealed, in the mid 2000s, as a material with high gravimetric (19.6%m) and volumetric (140 g.L-1) capacities in hydrogen. During the analysis of the literature we realized that all studies on ammonia borane treated on its thermal destabilization, so we chose an original approach by focusing our work on the thermal stabilization of ammonia borane. My thesis work focused on the synthesis of ammonia borane to identify the best synthesis parameters (boron and nitrogen precursors, solvent, and temperature) for the highest possible onset temperature. Indeed, by varying some precursors we observed a change in the onset temperature and therefore in the thermal stability of the ammonia borane. After determining the best synthesis parameters we undertook thermal and thermolytic studies to understand which factor(s) is(are) responsible for the stabilization's differences. For this, we performed thermogravimetric analysis coupled to mass spectrometer studies to determine the dehydrogenation mechanism and studies in isothermal conditions to verify the stability of our ammonia boranes. Thirdly we performed a spectroscopic study by XPS and solid state MAS-NMR of boron 11 and nitrogen 15. These studies allowed us to identify a new mechanism of dehydrogenation of ammonia borane for experiments in isothermal conditions
Zhao, Weigang. "Synthèse et caractérisation de matériaux carbonés microporeux pour le stokage de l'hydrogène." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0093/document.
This thesis describes the preparation, the characterisation and the performances in terms of hydrogen storage capacity of activated carbons designed for such application. The objective was to develop materials that might be able to meet or approach the storage capacity targeted by the US Department of Energy for 2015, i.e. 5.5 wt. % with respect to the whole storage system. With this aim in view, the researches reported here focused on: (1) investigation and understanding of experimental conditions for preparing such adsorbents; (2) optimization of their porous texture for hydrogen storage; (3) correlations between hydrogen storage capacity and textural parameters (surface area, pore volumes and pore size distributions); (4) investigation of materials doping by nitrogen and metal nanoparticles. Storage capacities of 6.6 % in weight with respect to adsorbent at 77K and 4 MPa on one hand, and of 1 wt. % at 298K and 20 MPa on the other hand, were obtained in the present thesis, among the highest reported so far in the open literature
Garric, Joachim. "Conception, synthèse et étude de nouvelles capsules hélicoïdales : des pelures de pomme moléculaires." Bordeaux 1, 2005. http://www.theses.fr/2005BOR13057.
Fort, Océane. "Synthèse d’additifs supramoléculaires pour le renfort du bitume." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS067.
Due to a steady increase of the traffic in recent years together with an increase in the speed and load of the vehicles, the roadways are more and more stressed. This has the consequence of reducing their service life. Improving the properties of bitumen, an essential material in the production of roads, is therefore a current issue. Several additives are developed in order to improve the properties of bitumen (hardness, resistance to rutting, etc.). Unfortunately, the addition of these molecules (mainly polymers) into bitumen is leading to an increase in viscosity and therefore to an increase in the processing temperatures. In this context, we have investigated a new class of additive based on supramolecular chemistry, organogelators, that are able to improve the mechanical performance of bitumen at service temperatures (0 – 70 °C) while limiting the increase in viscosity at high temperatures (150 – 180 °C) to limit energy costs. Structural parameters of several organogelators have been adjusted to optimize mechanical properties. Moreover, addition of a polymer end-capped with two cohesive segments has allowed improving the resistance to high deformation. Finally, the mechanisms responsible for the self-assembly of the organogelators as well as the structure/property relationship are understood through extensive multiscale characterizations
Luminati, Darzac Magali. "Cryptophanols, bis-cryptophanes, nouveaux cyclotrivératrylènes fonctionnalisés. Synthèse, applications et propriétés complexantes." Lyon, École normale supérieure (sciences), 2002. http://www.theses.fr/2002ENSL0217.
Porcher, Jean-Philippe. "Synthèse de complexes bioinspirés de Mo et W catalyseurs pour la réduction des protons." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066301/document.
Enzymes containing molybdenum or tungsten within their active sites appear to be present in all form of life. Most of them are oxotransferase or hydroxylase. They contain one or two pyranopterin-dithiolene cofactor, also called Moco, in which the metal is coordinated by the dithiolene moiety. The molybdenum cofactor is highly unstable and mimicking the active site of these enzymes is challenging. A new strategy for the synthesis of a pyranopyrazine dithiolene ligand (qpdt) has been developed in our laboratory. The corresponding molybdenum complex (Bu4N)2[MoO(qpdt)2] was synthesized and characterized extensively. This unique Mo-enzyme biomimetic complex demonstrated its potential for H2 production. This complex was shown to be active for the photoreduction of protons in acidic conditions (pH = 4), in the presence of the catalyst, the photosensitizer Ru(bpy)32+, ascorbic acid in exces and gave excellent activities of 500 TON with a high stability in aqueous organic media. Moreover, the electroreduction of protons by this complex in acetonitrile showed a remarkable rate constant value of 1030 s-1 at 1.3 V. (vs Ag/AgCl). To valorize this very original ligand qpdt, (Et4N)[Ni(qpdt)2] and (Et4N)2[Co(qpdt)2]2 bisdithiolene complexes were synthesized and characterized. Preliminary studies of theses complexes have shown a potential for the photoreduction and the electroreduction of protons. These results open new directions for the search of proton reduction catalysts. This first biomimetic complex should also be exploited to understand the chemistry of this class of oxidoreductase that is still not well understood
Torchy, Séverine. "Transfert d'hydrogène sous irradiation micro-ondes." Lille 1, 2000. http://www.theses.fr/2000LIL10069.
Crouzet, Camille. "Procédés géo-inspirés pour la valorisation de déchets industriels ferreux et la synthèse de phosphates pour le stockage de l'énergie." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAU019.
Two areas of research relatively different were investigated during this Ph.D thesis at the boundary between process engineering, geosciences and material sciences through the valorization of ferrous byproducts and the synthesis of iron phosphates for energy storage applications. The common thread of this work was the use of our knowledge in redox and natural hydrothermal processes as a geo-inspiration source for the development of novel industrial processes.In the first and main part of this manuscript, we propose a novel valorization path for ferrous wastes and byproducts through the recovery of iron oxides and the production of hydrogen. This process is inspired from natural hydrogen production observed in mid-Atlantic ridges where ferrous iron content of magmatic minerals is oxidized by liquid water leading, among others, to hydrogen production and magnetite (Fe3O4) formation. Applying the same oxidation process to ferrous byproducts (metal Fe or ferrous iron FeO) enables the development of a novel valorization path. A first study is conducted on the identification of hydrothermal oxidation mechanism of reagent grade FeO and the influence of mild acetic acid on oxidation kinetic. This process is then applied to steel slag, a steel-making byproduct mainly composed of calcium but also of 15 to 25 %w FeO. The major result of this study was found in the characterization of magnetite as nanoparticles, a highly valuable product. In addition, we propose to complete the valorization process of steel slag by performing mineral CO2 sequestration (at room and high temperature).The second part of this Ph.D manuscript is dedicated to the synthesis of iron phosphates for energy storage applications. For mobile applications, this storage is nowadays mainly performed by lithium batteries. For these devices, a particular interest is given to lithium iron phosphates as positive electrode material for their ability to insert and disinsert lithium in its olivine related structure, modifying its chemical composition from LiFe2+PO4 (LFP) to Fe3+PO4 (FP). The main goal of this second part is to propose a novel synthesis path for FP through a two-step process with 1) the synthesis of a sarcopside related material Fe2+3(PO4)2 (a pseudo-olivine structured rare mineral) and 2) its isostructural oxidation in air to form the targeted FP material. This oxidation step leads to the partial solid migration of iron (exsolution mechanism) from the core to the surface and its precipitation as hematite, Fe2O3. For the sake of new materials as positive electrode, this process is then applied to the oxidation of maricite NaFe2+PO4 into Na3Fe3+2(PO4)3
Alasmar, Eliane. "Systèmes ternaires à base de magnésium : synthèse, structure, propriétés physiques, stockage et/ou production d’hydrogène." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0023/document.
The use of fossil fuels (non-renewable energy) is responsible for the increase of the concentration of greenhouse gases in the atmosphere. Among the considered alternatives, hydrogen is seen as the most attractive energy vector. Production and storage of hydrogen is one of the key challenges in developing the hydrogen economy.The first objective of this thesis deal with the synthesis and characterization of magnesium-based ternary compounds in the RE-TM-Mg ternary system (with RE = Rare Earth and TM = transition metals) which could be good candidates for hydrogen storage. These compounds could also have other applications than the hydrogen storage in the future such as light structured material. The NdNiMg15 compound has been the subject of a completed study. This phase crystallizes with a tetragonal symmetry (a= 10.0602(1) and c= 7.7612(2) Å and a space group P4/nmm). It showed an antiferromagnetic ordering at 9 K and a reversible hydrogen storage capacity of 4 %mass. This phase exhibited a hardening effect respect to magnesium compound.The second objective of this thesis concerns the hydrogen production by hydrolysis of i) RE-TM-Mg ternary compounds, which could be considered as an economic and energetic possibility to valorize the waste of these compounds and ii) RE-TM-Mg ternary mixtures prepared by ball milling. The grinding creates defects thus promoting the corrosion of the metals. In addition, the hydrogen production by hydrolysis of the Mg-NdNiMg15 composites (70, 80 and 90 %mass. Mg) was carried out and compared with that of the NdNiMg15 compound (64 %mass. Mg). The main corrosion mechanism determined from the electrochemical measurements of the composites is the galvanic corrosion
Debeusscher, Sylvanie. "Stockage et caractérisation de l'hydrogène dans les oxydes mixtes à base de cérium-nickel et zirconium ou aluminium." Electronic Thesis or Diss., Lille 1, 2008. http://www.theses.fr/2008LIL10122.
The mixed oxides based on cerium-nickel and zirconium or aluminium are able to store large quantities of hydrogen, To determiine nature, reactivity and properties of hydrogen species (spill-over, direct desorption), the solid were studied by different physicochemical techniques in the dried, calcined and partially reduced states: XRD, porosity, TGA, TPR, TPA, TPD, chemical titration and inelastic neutron scattering (INS). Solids are mainly mesoporous with a common pore size at 4 nm, They are constituted of CeO2 phase, Ce-Ni or Ce-Ni-Zr solid solution and of Ni(OH)2 in the dried state and NiO in the calcined state. The Ni species are in various environments and the strong interactions between the cations in solid solution and at different particles interface influence their reducibility and the creation of anionic vacancies. Activation in H2 in temperature is determining for hydrogen storage in the solid while calcination step is not necessary. INS Analyses evidence that the hydrogen species inserted during treatment in H2 are H+( OH-), hydride H- and H* (metallic nickel) species, present in various chemical environments, in particular for hydride species. All kinds of hydrogen species participate to the reaction during the chemical titration in agreement with the proposed hydrogenation mechanism. The study of the adsorption of hydrogen shows that this step is fast and in quantity of the same order as that measured by chemical titration. The direct desorption of H2 is very low, linked to the presence of hydrogen in interaction with metallic nickel (H*-·). Desorption of water is also observed, in parallel, corresponding to the elimination of groups. The hydride species are not desorbed. These various observations allow connecting hydrogen species properties with their localization in the structure and to model active sites
Benchakar, Mohamed. "Synthèse et caractérisation de nouveaux composés bidimensionnels, les MXènes, pour le stockage et la conversion de l'énergie." Thesis, Poitiers, 2020. http://www.theses.fr/2020POIT2271.
Hydrogen is the most promising energy vector for the future energy grid implementation. It can be obtained from different methods of production. However, an eco-friendly hydrogen with a high purity can only be produced using water electrolysis. Furthermore, the design of low cost, active and stable electrodes is required for the development of large scale electrolysis systems. In this context, 2D materials are of upmost interest for the development of catalysts in reason of their high surface to volume ratio, conferring them unique properties far from those of their bulk counterparts. In this way, MXene family (discovered in 2011) is a good candidate. Their intrinsic properties (high electronic conductivity, hydrophilicity, versatile chemistry) reinforces the passion they arouse and make these materials as promising candidates for the design of efficient catalysts. In this work, several Ti3C2Tx MXenes were first synthesized using different etching agents and characterized in order to elucidate the hydration chemistry, composition, structure, surface chemistry and macroscopic properties. This MXene, which nevertheless exhibits a low catalytic performance toward hydrogen and oxygen evolution reactions, has been used as a support for cobalt-based layered double hydroxides. The presence of numerous terminal groups on the MXene surface allows obtaining a good dispersion of the active phase. In addition, MXene ensures the good electronic conductivity of the electrode which promotes the charge transfer. The structural properties of the resulting material (Co-LDH@ Ti3C2Tx) were studied and correlated to its good catalytic activity toward oxygen evolution reaction in alkaline medium. This performance could be associated to the electronic interaction occurring between the active phase and the MXene. Further, Mo2CTx MXenes were also synthesized, characterized and used as a precursor for the synthesis of a MoS2/Mo2CTx two-dimensional heterostructure. This innovative material was obtained by topotactic transformation (sulfurization) of Mo2CTx. This composite has proven to be an excellent catalyst toward hydrogen evolution reaction in alkaline medium. This high activity could be attributed to the intimate contact existing between the MoS2 and Mo2CTx phases on one hand, allowing an activation of the 2D sulfide basal plane and to the presence of weakly coordinated atoms on the other hand, allowing the water activation at low overpotentials.Thus, efficient and stable MXene-based catalysts have been developed for oxygen and hydrogen evolution reaction. The prospects for this work are numerous considering the chemistry richness of these new 2D materials in order to obtain more efficient electrodes
Krieger, Jean-Philippe. "Réarrangements de cycles et activation de liaisons C-H : synthèse de macrocycles." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066765.
There is currently a growing interest for macrocycles as scaffolds in medicinal chemistry. Therefore, the development of new and efficient strategies toward this class of compounds represents a major challenge. In the first part of our research work, we have been interested in the synthesis of functionalized paracyclophanes incorporating heteroatoms, capitalizing on a Diels-Alder/retro-Diels-Alder reaction sequence from tricyclic dienes and acetylenic dienophiles. The tricyclic dienes precursors could be quickly assembled from simple and readily available building blocks, using a reliable sequence involving a Sonogashira cross-coupling, the semi-hydrogenation of an alkyne and a six-pi electron electrocyclization. The resulting tricyclic dienes were engaged in an intermolecular Diels-Alder/retro-Diels-Alder reaction sequence to provide paracyclophanes possessing a trisubstituted aromatic ring. An intramolecular version of this sequence was devised which enabled access to unique paracyclophanes with a cage architecture incorporating a tri- or tetrasubstitued aromatic ring. The second part of our investigations was devoted to the development of transition metal-catalyzed C-H activation mediated macrocyclizations. In the presence of a ruthenium(II) complex as the catalyst, the cyclization of Omethylhydroxamic acids substituted by a carbon chain possessing a remote alkyne could be achieved and provided an efficient access to macrocyclic isoquinolones. A similar transformation was applied to alpha,betaunsaturated hydroxamic acids derivatives substituted by an acetylenic chain, using a catalytic system based on a rhodium(III) complex, to afford macrocyclic pyridones
Kilig, Huriye. "Synthèses de thiacalix[4]arenes et leurs utilisations en tectonique moléculaire." Université Louis Pasteur (Strasbourg) (1971-2008), 2002. http://www.theses.fr/2002STR13139.
Smari, Imen. "Synthèse et réactivité en catalyse de nouveaux hétéroaromatiques." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S012/document.
This thesis work dealing with the activation / functionalization of CH bonds for the formation of derivatives of heteroaryl. We sum so interested in the reactivity of derivatives of 4-formylpyrazole for pallado-catalyzed via CH bond activation couplings. The formyl C4 is used to control the regioselectivity of the arylation. Subsequently, we investigated the reactivity of 2-bromofluorènes in these coupling reactions. The third part focuses on the synthesis of aminothiophenes and pyrrolyl-thiophene. The originality of our approach is the use of these compounds as a precursor in pallado-catalyzed reactions. Finally, the last part is devoted to the reactivity of 3-bromobenzothiophene in pallado-catalysed reactions without cleavage of the C-Br bond C3 benzothiophene
Ati, Mohamed. "Synthèse, structures et propriétés des composés LiMSO4F (M = métal 3d) en tant que matériaux d'électrode positive pour batteries à ions Li." Amiens, 2013. http://www.theses.fr/2013AMIE0118.
This thesis has focused on the synthesis and characterization of new fluorosulfates compounds, namely LiMSO4F (M = 3d metals) as a new electrode materials for LIBs through different sustainable synthetic approaches. Among them, LiFeSO4F appears as a serious candidate for positive electrodes. Therefore, we tried, first, to obtain it using different synthesis methods (ionothermal, solvothermale, and solid-state process). Our structural and electrochemical investigations show its nice stability over cycling with attractive performances (3. 6 V vs. Li; Qth = 151 mAh/g). Afterward, our investigations of the other members of this family using other 3d metals (Co, Ni, Mn and Zn) revealed that both LiMnSO4F and LiZnSO4F crystallize in two differents structures namely triplite and sillimanite, respectively. Hence our motivation to study the solid solutions of LiMyFe1-ySO4F based on Mn and Zn. Surprisingly, the LiMyFe1-ySO4F (M = Mn, Zn) triplite type structure show a higher redox potential compare to the two others polymorphs (tavorite and sillimanite) in the range of 3. 9 V vs. Li. To our knowledge, this is the highest redox potential reported for Fe3+/Fe2+, so far. Moreover, these solid solutions powders show a nice stability over cycling with nominal capacities close to the theoretical ones. Thereafter, we prepared LiFeSO4F in the triplite type structure without adding Mn or Zn. The latter shows good electrochemical performances with nice structural stability during cycling. At last, we investigated a non lithied hydoryfluorosulfate compound (FeSO4F1-yOHy) as a new positive electrode material for lithium metal polymer batteries. This material was prepared using a solid-state process at 290°C and the electrochemical measurements show that it has nice performances with a redox potential located between 3. 2 and 3. 58 V vs. Li, as function of the amount of OH in the structure
Vidal-Letourneur, Véronique. "Synthèse et caractérisation du complexe bis(siloxy)hydruro-tantale supporté sur silice : application à la métathèse des alcanes." Lyon 1, 1997. http://www.theses.fr/1997LYO10300.
Arab, Sofiane. "Développement d'un procédé de synthèse de méthanol à partir de CO2 et H2." Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0240/document.
As the result of fossil resources increasing scarcity, and geopolitical tensions due to energy supply securing, some countries are gradually moving to renewable and low carbon energy resources to reduce significantly their energy dependency. The electricity production from solar and wind energy are intrinsically responsible for intermittency issues that periodically lead to a gap between production and consumption. Transforming the unused excess of electricity production to chemicals may be an interesting solution for optimal exploitation of these resources. This thesis aims at investigating some means of developing new methanol process synthesis from CO2 stemming from industrial sources and H2 produced by the excess of electricity through water electrolysis. The envisioned methanol unit should be able to operate under variable regime. Initially, heat and mass transfer for two reactor technologies of methanol synthesis have been studied by using criteria described in literature. Then, a heterogeneous reactor model has been grounded in the results of heat and mass transfer analysis obtained previously. The reactor model was used to carry out a large parametric analysis of the reactor. In a second step, the reactor survey has been extended to the methanol loop to learn about the effect on the global reactor performances after its integration in the methanol loop. Once the phenomena involved in methanol process have been understood in steady regime, a transient model of the methanol loop has been developed and used to investigate the process dynamics such as the required time to start the process or to move from an operating state to another. The current and medium term electricity availability has been assessed in order to estimate the number of transitions per year undergone by the methanol unit. Based on these observations, reactor designs and operating strategies have been suggested so that they lower the impact of transitions on methanol unit. A whole chapter has been dedicated to evaluate some alternatives to develop and to improve the process of methanol synthesis. Some reactor designs have been suggested and their ability to convert hydrogen to methanol has been simulated. Although the reactor design proposals are only at the concept stage, some of them arouse more interest, and merit further evaluation. Finally, a decision support tool has been presented and used to choose the most appropriate reactor technology for the process of methanol synthesis
Batisse, Nicolas. "Fluoration pour la synthèse de matériaux à base de carbone pour le stockage de l'énergie." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2011. http://tel.archives-ouvertes.fr/tel-00822122.
Sahnoun, Sophian. "C-H fonctionnalisation de purines : synthèse d’inhibiteurs potentiels de la HSP90." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA114803/document.
Resistance to current treatments of cancer encourages finding new therapeutical targets. The heat shock protein 90 (hsp90) is a molecular chaperon which regulates the folding of many client proteins associated with all of the six hallmarks of cancer, and helps maintaining their proper conformation. Consequently, the hsp90 has become an exciting new target in cancer drug discovery since the inhibition of its ATPase activity leads to depletion of these client proteins via the proteasomal pathway. PU3 and PU24S are purine-based hsp90 inhibitors functionalized on C-8 position. In the aim to identify more active compounds and/or new subfamilies of inhibitors, we have developed new metal-catalyzed C-H activation processes of various heterocycles including purines and other azoles. These new and simple approaches have allowed the access to numerous C-8 functionalized purines bearing (het)aryl, alkenyl and benzyl moieties
Salameh, Chrystelle Mounir. "Synthèse de matériaux nitrures fonctionnels à base de bore ou d'aluminium pour des applications en énergie (production et stockage de l'hydrogène)." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20157/document.
Porous inorganic materials are of great interest owing to their potential in energy applications. The general objective of the present thesis concerns the development of functional (carbo)nitrides for hydrogen generation and storage (material design, elaboration, properties and applications). The PDCs route, which offers a large number of opportunities in chemistry and ceramic sciences, has been applied to produce functional (carbo)nitrides materials. Firstly, we prepared porous binary systems such as AlN and BN by replicating the structure of CMK-3 and that of activated carbon. After pyrolysis and removal of the template, we demonstrated the feasibility of producing nitrides with tailored porosity. Moreover, by coupling the PDCs route with the aerogel technology, we succeeded in preparing polymer-derived AlN and BN aerogels. We assessed the potential of these porous AlN and BN materials in nanoconfinement of two chemical hydrides, namely sodium alanate and ammoniaborane, respectively. In both cases, the nanoconfinement destabilized the network of the hydride and favored the release of H2 at low temperature. Besides, in the case of nanoconfined ammoniaborane, no evolution of undesired gaseous by-products was observed, which means that pure hydrogen was produced in our conditions. Secondly, we prepared porous quaternary systems through the association of AlN/BN with Si-based ceramics. In particular, we investigated the preparation of SiAlCN with tailored porosity by using two approaches: the “molecular building block” and “single-source precursor” approaches. Concerning the former, we investigated the preparation of ordered mesoporous materials to be used as catalytic supports for hydrolysis of alkaline solution of sodium borohydride. We succeeded in generating high amounts of H2 with attractive kinetics. Concerning the latter approach, the work was focused on the investigation of the chemistry of SiAlCN and SiBCN materials with a particular focus on the elaboration of SiAlCN microcellular foams by a sacrificial processing route
Debeusscher, Sylvanie. "Stockage et caractérisation de l'hydrogène dans les oxydes mixtes à base de cérium-nickel et zirconium ou aluminium." Thesis, Lille 1, 2008. http://www.theses.fr/2008LIL10122/document.
The mixed oxides based on cerium-nickel and zirconium or aluminium are able to store large quantities of hydrogen, To determiine nature, reactivity and properties of hydrogen species (spill-over, direct desorption), the solid were studied by different physicochemical techniques in the dried, calcined and partially reduced states: XRD, porosity, TGA, TPR, TPA, TPD, chemical titration and inelastic neutron scattering (INS). Solids are mainly mesoporous with a common pore size at 4 nm, They are constituted of CeO2 phase, Ce-Ni or Ce-Ni-Zr solid solution and of Ni(OH)2 in the dried state and NiO in the calcined state. The Ni species are in various environments and the strong interactions between the cations in solid solution and at different particles interface influence their reducibility and the creation of anionic vacancies. Activation in H2 in temperature is determining for hydrogen storage in the solid while calcination step is not necessary. INS Analyses evidence that the hydrogen species inserted during treatment in H2 are H+( OH-), hydride H- and H* (metallic nickel) species, present in various chemical environments, in particular for hydride species. All kinds of hydrogen species participate to the reaction during the chemical titration in agreement with the proposed hydrogenation mechanism. The study of the adsorption of hydrogen shows that this step is fast and in quantity of the same order as that measured by chemical titration. The direct desorption of H2 is very low, linked to the presence of hydrogen in interaction with metallic nickel (H*-·). Desorption of water is also observed, in parallel, corresponding to the elimination of groups. The hydride species are not desorbed. These various observations allow connecting hydrogen species properties with their localization in the structure and to model active sites
Dubouis, Nicolas. "Understanding the role of electrolytes solvation structure for electrochemical energy storage applications." Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS089.
This thesis aims at understanding the role of the electrolyte, and more specifically the role of solvation structures, for electrochemical storage applications. First, this manuscript reviews the most recent advances on the comprehension on the role of the water molecule for the generation of hydrogen in electrolyzers. Then, we set up a strategy, which consists in studying the reactivity of water in an organic inert matrice in order to better understand how non-covalent interactions can tune the water reactivity. Coupling electrochemical measurements with molecular simulations and spectroscopies, we sketch a “molecular” picture of the water environment in these electrolytes and draw a structure-reactivity correlation. Then, we study the cathodic stability of water in aqueous superconcentrated electrolytes employed for aqueous batteries. Studying these systems, we describe that when two salts sharing the same cation but anions with very different properties (size, geometry) are mixed with water, aqueous biphasic systems can form. Finally, we use this intrinsic non-compatibility between small inorganic anions with large organic anions. Indeed, we demonstrate that the utilization of organic superconcentrated electrolytes can nearly suppress the dissolution of VX3 (X = Cl, Br, I) compounds usually observed in diluted electrolytes, allowing us to expand intercalation electrochemistry to the layered halides family
Bourque, Jean-Sébastien. "Production de biohydrogène par digestion anaérobie dans un réacteur UASB." Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25724/25724.pdf.
Dhaher, Sameh. "L'étude du stockage solide de l'hydrogène et des complexes sigma-dihydrogène." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30230.
Adopting clean and emission- free energy cycle using hydrogen as an energy carrier could be the solution in order to curb the ill effects of energy crisis and global warming on the planet. Thus, the lack of efficient hydrogen storage devices has stimulated the search of new systems. In this manuscript, the dehydrogenation of the bis-dihydrogen ruthenium complex without additives at the ruthenium center has been reported in Chapter II. The unusual and rare dimeric complex bearing two phosphido bridges was accessed from thermolysis of the bis(dihydrogen) complex RuH2(H2)2(PCyp3)2. The complex was characterized by NMR, IR, UV-Visible, X-ray, neutron structure and DFT calculations. Surprisingly, the complex shows a reversible up take and release of H2 at room temperature in solution as well as in the solid state. This is one major criteria for designing a solid hydrogen storage material. The activation of the H-H bond has been subjected to a detailed study in Chapter III. Several novel ruthenium complexes bearing fac-coordinating ligands, 1,3,5-triaminocyclohexane (tach) and 1,4,7-triazacyclononane (tacn) and different anions have been prepared. DFT investigation has been deployed throughout these studies for a fine-level examination of H-H bond activation. An attractive goal in the context of hydrogen storage is to combine magnesium hydride, MgH2 or MOFs to organometallic complexes. This is the purpose of the fourth chapter. Doping magnesium hydride with ruthenium or nickel precursors shows promising results
Couillaud, Samuel. "Synthèse, structure, propriétés physiques et réactivité vis-à-vis de l’hydrogène de nouveaux composés ternaires à base de magnésium." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14288/document.
Nowadays, the decrease of fossil fuel resources, and the increase of energy requirements and concentration of greenhouse gases in the atmosphere induces the development of new energies. The use of hydrogen as energetic vector is a solution. Indeed, it is abundant and its combustion is highly energetic (3 times more than petrol). However, its utilisation is limited by problems of production, storage and use. In this work, we have focused on the problem of solid hydrogen storage. It allows for high volumetric capacity (≈ 140 g/L) but is restricted by low weight capacity and by slow sorption kinetics. Because magnesium is potentially a good candidate according to its high weight capacity (7.6 %wt), we have chosen to work on the ternary compounds RE-M-Mg (RE = Rare earth, M = transition metal). The goal was double: to keep the good capacity of the magnesium and to decrease the enthalpy of formation of the hydride. The RE4NiMg system (with RE = Y and Gd) and the derived solid solutions were studied. An irreversible hydrogen uptake of 2.5% wt and a magnetic properties change from antiferromagnetic to spin glass behaviour were observed.A more exploratory work allowed us to discover two new magnesium rich compounds: LaCuMg8 and Gd13Ni9.5Mg77.5. Both lead to a phase mixture induced by their decomposition during the first absorption. This mixture allows a very significant improvement of the hydrogen sorption properties of magnesium
Fang, Wenhao. "Production d’hydrogène par transformation du bioéthanol sur catalyseurs à base de nickel." Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10026/document.
The potential benefits of hydrogen economy based on renewable energy sources (biomass) have drawn much attention. Hence studies on H2 production from catalytic transformation of bio-ethanol are very interesting and promising. Two types of Ni-based catalysts, CeNiXOY and NiXMg2AlOY, are studied for H2 production from ethanol through two routes, steam reforming and oxidative steam reforming (H2O/EtOH = 3). Numerous physico-chemical characterizations of the catalysts allow proposing active sites and possible mechanism. The CeNiXOY and NiXMg2AlOY nano-compounds are able to store different hydrogen species in particular hydride species. Once in situ treated in H2 at proper temperature, these mixed oxides become nano-oxyhydrides with the presence of anionic vacancies, O2- species and cations in close interactions which are highly active and efficient catalysts for ethanol steam reforming. The Ni12Mg2AlOY catalyst allows obtaining a low-temperature high-yield H2 production of 3 mol molEtOH-1 at 300 °C without the formation of CO. The Ni3Mg2AlOY and CeNi1OY catalysts are able to produce a very high H2 production of about 5 mol molEtOH-1 at 650 °C. In the presence of O2, CeNiXHZOY and NiXMg2AlHZOY oxyhydrides (30 mg) enable to completely convert ethanol with about 45 mol% H2 production with the oven temperature at only 60 °C, showing remarkable stability for 75 h on stream. This self-sustainable reaction is driven by the energy released from the strong exothermic reaction between the hydride species stored in the catalysts with O2, at the same time hydride species are continuously formed from ethanol to make the reaction sustainable
Slostowski, Cédric. "Synthèse solvothermale supercritique de nanostructures d'oxyde de cérium." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00954292.
Cantin, Thomas. "Conception en milieu superacide de dications chiraux pour la synthèse de composés fluorés et/ou hétérocycliques azotés." Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2290.
Thanks to their exceptional acidity, superacid allow access to polycationic superelectrophiles by polyprotonation. These highly reactive species are capable of being trapped by very weak nucleophiles and can be used to develop new synthetic methodologies that do not exist under “classical” conditions.In the first part of this work, the design of chiral cations in HF/SbF5 media for their exploitation for stereocontrolled reactions was studied. The generated chiral ammonium-carboxonium superelectrophiles could be observed by low temperature in situ NMR experiments and analysed by X-ray diffraction of single-crystals. The reactivity of these species could be evaluated in the context of diastereoselective hydrofluorination reactions and Friedel-Crafts type cyclizations.In a second part, the superelectrophilic activation of alpha-aminonitriles allowed to develop a new reactivity of these compounds. The formation of ammonium-nitrilium dications was demonstrated by in situ NMR analysis at low temperature and crystallization in superacidic conditions HF/SbF5. This new methodology allowed the synthesis of novel chiral unsaturated piperidinones from amino acid derivatives.Finally, preliminary results of a new methodology of inert Csp3-H bonds functionalisation are presented in a third part. From unsaturated sulfonamides, nitrogen-containing heterocyclic compounds could be selectively synthesized under HF/SbF5 superacidic conditions without external activator
Sebaoun, Laure. "Conception, synthèse et études structurales de foldamères aromatiques repliés en feuillet." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00956734.
Graux, Lionel. "Nouveaux complexes de ruthénium (II) associés aux Oxydes de Phosphine Secondaire (OPS) : Synthèse, caractérisation et application en catalyse." Electronic Thesis or Diss., Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4366.
The past decade has witnessed a renewed interest for Secondary Phosphine Oxides (SPO) in catalysis as preligands of transition metals. While the coordination chemistry and catalytic activity of these species have been mainly studied with palladium and platinum, only few examples with ruthenium have been reported so far.We investigated the synthesis of new ruthenium(II) complexes associated to one or two phosphinous acid ligand (PA) (SPO tautomer) which were fully characterised. Then we were interested in the role played by the ligand during the catalytic cycle. The use of different ruthenium sources allowed us to isolate [Ru]/SPO complexes (oxygen coordinated) and [Ru]/PA complexes (phosphorous coordinated). We evaluated the catalytic activities of these well-defined complexes in C-H bond activation and cycloisomerisation from alkynes or ynamides. During the course of these studies, the influence of ligand stereoelectronic parameters in the catalytic process have been demonstrated.Moreover, in a side project, we explored a new reactivity of ynamides with cyclic 1,3-diketones catalysed by palladium, cationic gold or ruthenium complexes. This reactivity gives access to alpha-alkoxysubstituted enamides
Rolland, Dalon Edouard de. "Borides and borophosphides at the nanoscale : liquid-phase synthesis and electrocatalytic water splitting properties." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS261.
Transition metal borides and phosphides present interesting properties in electrocatalysis for the production of dihydrogen. In these materials, the p-block element modifies the electron density of the metal atoms, which not only makes these materials resistant to oxidation and corrosion, but also modifies the catalytic properties. The development of catalysts requires the design of objects with a high surface/volume ratio, i.e. at the nanoscale. It is therefore essential to develop synthesis routes adapted to obtaining these materials and to the search for new compounds. In particular, combining boron with phosphorus and/or one or more transition metals in the same compound could lead to profound changes, notably in the electron density of the metal sites and the geometry of surface sites, due to the formation of specific crystalline structures constrained by the presence of covalent bonds. In view of the properties of the binary phases, all the modifications in terms of morphology, geometry and composition make it possible to control the reactivity and (electro)catalytic properties. This thesis work focused on the development of transition metal borides and borophosphides, with the objectives of morphological control on the nanometric scale, the development of new compounds, including metastable ones, and the characterisation of their electrocatalytic properties. The synthesis approaches chosen are based on two pillars. Firstly, molten salts, which enable synthesis to be carried out in the liquid state and at temperatures intermediate between those of solid-state chemistry and those of colloidal routes. Thus, the reaction media are homogeneous, enabling greater reactivity between soluble or dispersed precursors, and limiting the coalescence of particles. The other pillar is the use of metallic nanoparticles as nanoreactors in which boron and/or phosphorus are incorporated, so as to maintain the morphology of the particles. In this way, we obtain pure-phase nanomaterials in the case of nickel and iron borides, with a degree of control over composition and morphology that has never been achieved before. This control could only be achieved by understanding the formation mechanisms of the corresponding compounds and nano-objects. This understanding was achieved by developing in situ monitoring of the syntheses using X-ray diffraction under synchrotron radiation. We were thus able to identify reaction intermediates in the form of amorphous nanoparticles, the nature of which was elucidated using total X-ray scattering coupled with the pair distribution function. By extension, this particular synthesis route also enables us to search for rare or never reported phases that may exhibit significant electrocatalytic activity for the dissociation of water. The choice of compositional domains of interest, guided by machine learning to minimise formation energies, led to the synthesis of nanoparticles of a bimetallic boride of nickel and cobalt boron. We have also made progress in studying new synthesis routes for nickel borophosphide ternary phases, which are rare and difficult to obtain. Finally, we explored a route for synthesising metal nanoparticles without organic surface ligands, in order to avoid secondary reactions or competitive diffusion mechanisms within the metals from the ligands during molten salt synthesis. Based on work demonstrating the colloidal stability of nanomaterials in molten salts, we describe a rapid and simple method for synthesising metal nanoparticles based on molten salts using nickel as a case study
Graux, Lionel. "Nouveaux complexes de ruthénium (II) associés aux Oxydes de Phosphine Secondaire (OPS) : Synthèse, caractérisation et application en catalyse." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4366/document.
The past decade has witnessed a renewed interest for Secondary Phosphine Oxides (SPO) in catalysis as preligands of transition metals. While the coordination chemistry and catalytic activity of these species have been mainly studied with palladium and platinum, only few examples with ruthenium have been reported so far.We investigated the synthesis of new ruthenium(II) complexes associated to one or two phosphinous acid ligand (PA) (SPO tautomer) which were fully characterised. Then we were interested in the role played by the ligand during the catalytic cycle. The use of different ruthenium sources allowed us to isolate [Ru]/SPO complexes (oxygen coordinated) and [Ru]/PA complexes (phosphorous coordinated). We evaluated the catalytic activities of these well-defined complexes in C-H bond activation and cycloisomerisation from alkynes or ynamides. During the course of these studies, the influence of ligand stereoelectronic parameters in the catalytic process have been demonstrated.Moreover, in a side project, we explored a new reactivity of ynamides with cyclic 1,3-diketones catalysed by palladium, cationic gold or ruthenium complexes. This reactivity gives access to alpha-alkoxysubstituted enamides
Prunier, Hélène. "Synthèse et étude des propriétés structurales thermodynamiques et catalytiques de nanoparticules bimétalliques Au-Cu par microscopie électronique en transmission corrigée d'abérrations." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC122/document.
The emergence of new materials, structured at the nanoscale, with controlled properties, has opened new prospects regarding materials around us. In particular for metals and alloys, it seems crucial to connect their structural properties to their chemical and physical properties in order to optimise their use.Within this context, this thesis is focused on the synthesis and the characterisation of Au-Cu bimetallic alloy nanoparticles by transmission electron microscopy. On the basis of the bulk phase diagram, we especially studied particles with nominal compositions Au3Cu, AuCu et AuCu3.The first part of this work is dedicated to the synthesis of nanoparticles in two different ways. The chemical way is based on the polyol process and leads to nanoparticles exhibiting a cubic shape, and a systematically rich Au content. On the other hand, nanoparticles obtained by Pulsed Laser Deposition (PLD), a physical method of synthesis, display a well-controlled and tuneable composition. From a structural point of view, the annealing of the particles leads to chemical order and the stabilisation of L10 and L12 structures. However, we reveal that this phase transition is blocked in nanostructures with crystal defects. Moreover, we establish the evolution of the lattice parameter of the particles as a function of the composition and we demonstrate that, as in the bulk case, it is in agreement with Vegard’s law.In the second part, the nanoparticles synthesised via the physical method are studied using environmental transmission electron microscopy, i.e. in conditions close to those usually applied in catalytic reactors. Experiments performed at high temperature highlight that the dissolution of Au and Au-Cu nanoparticles occurs in a two-step process: fusion occurs first and is followed by evaporation for nanoparticles with a mean diameter of 10 nm.Coupling heating with gas flow (H2 or O2) in higher pressure condition than those usually reached allows us to study the thermodynamic behaviour of the nanoparticles in oxidative or reductive conditions. Most Notably, we show that oxidation-reduction cycles performed on nanoparticles with a diameter larger than 20 nm leads to a Kirkendall effect and the reversible formation of hollow particles (doughnuts).This cross-disciplinary thesis is a pioneering work towards understanding the bimetallic Au-Cu alloy system at atomic scale
Behloul, Chakib Rafik. "Méthodes de conception de réacteurs multifonctionnels (réacteur-échangeur-séparateur) : application à la synthèse directe de DME à partir de CO₂ et d’H₂." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0249.
The depletion of resources and the accumulation of pollutant gases in the atmosphere are nowadays of growing concern. The current energy transition requires that certain material and energy transformation processes be partially modified or profoundly reconsidered to fit more sustainable operating conditions. Low-carbon electricity and hydrogen can substitute fossil fuels, leading to an energy mix with a low greenhouse gas (GHG) footprint. In addition to hydrogen, the production of alternative fuels and high value-added products is another way to support the energy transition.Looking for optimal, sustainable and economical processes is therefore a major challenge that process engineers are facing. The present work has thus focused on the intensification of mass and energy transformation processes, through multifunctional units, which take advantage of the synergies between elementary functions of transformation (reaction, transfer, separation, etc.) within an intensive equipment. The concept of multifunctional reactors, coupling several elementary functions, has been a real success when historical demonstrators were created (Eastman-Kodak process, etc.), but their implementation has not been generalized, due to a lack of practical design methodology.This work focuses on the implementation of some intensification methodologies to understand and improve the performance of a process involving balanced exothermic reactions. The dimethyl ether (DME) direct synthesis from CO₂ and H₂ is considered as a case study. Different exploratory ways for the DME direct synthesis process development have been investigated based on modeling and simulation. Reactor- Heat exchanger, multifunctional reactor (reactor-heat exchanger-membrane separator), hybrid elementary block processes and a process involving the cooled reactor in a conventional process environment in the presence of additional unit operations and recycle loop are studied from different angles. Different optimization cases and strategies have been addressed which differ by the decision variables and the solving method. The different methodologies applied have demonstrated the relevance of the solutions obtained and the opening towards process innovation.At the equipment level, the profiles optimization represents the heart of the methodology. The results demonstrate the potential of multifunctional reactors: a CO₂ conversion per pass of 98%, a DME yield of 95% and the possibility to remove a distillation column are obtained. In order to assess the maximum achievable performance in a multifunctional reactor, a hybrid process of elementary blocks has been optimized. At the process scale, the reactor behavior has been studied to further understand the impact of the reactor integration in a recycle loop and to estimate the local and global effects on the multiple performance criteria. Based on various criteria (overall DME yield, overall CO₂ conversion, TRL, etc.), the comparison of the different designs revealed that a reduction of the equipment number by a factor of 11 is possible in the case of a multi-functional reactor choice
Villagra, Angel Eduardo. "Photo-dissociation de l'eau et photo-réduction du CO₂ assistées par co-catalyse moléculaire." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS282/document.
The main objective of this research work was to put into evidence the co-catalytic effect of organo-metallic molecular complexes containing transition metals as reactive centers, adsorbed at the surface of doped semiconductors with photo-activity with regard to water photo-dissociation and carbon dioxide photo-reduction, in view of practical applications in photochemistry and photo-electrochemistry. First, appropriate materials (two photoactive semiconductors and two molecular co-catalysts) have been identified and selected (results are presented in chapter I). Then, we have designed, constructed and optimized a specific test bench that can be used for the continuous detection and titration of reaction products (results are presented in chapter II). Product analysis was achieved by coupling a gas-phase chromatograph to the photo-electrochemical reactor. Then, photoactive semiconductors and molecular co-catalysts have been elaborated/synthesized and their intrinsic properties have been measured (results are presented in chapter III). Finally, the co-catalytic activity of molecular complexes has been put into evidence and several performance indicators such as reaction kinetics and turn-over frequency have been measured (results are presented in chapter IV)
Tsiamantas, Christos. "Synthesis and structure-stability relationship of aromatic helical foldamers." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0029/document.
At the molecular level, the functions of helical patterns are often directly associated with the stability of thesearchitectures, (in α-helices). For example, upon removal of such an entity from the protein’s tertiary structure,the peptidic helix becomes flexible and thus inactive. In order to control the rigidity of these architectures,several strategies have been used and the construction of completely artificial well folded molecules known asfoldamers is one them. Our group mainly focuses on helical aromatic oligoamide foldamers and to dateseveral studies have been carried out to investigate factors affecting the helical stability; the influence ofoligomer length, solvent effects and the effect of aliphatic linkers within a helical aromatic sequence.In the present study we investigate the helical propensity of five commonly used aromatic monomers infoldamer synthesis and by using NMR spectroscopy, X-ray crystallography and dynamic chiral HPLC weevaluate their contribution in helical stability. Additionally, inspired by the role of disulfide bonds in proteins wedecided to explore their effect on helical stability. For this reason intra- and inter-molecularly disulfide bondedcompounds were designed and synthesized. Their stability was studied using NMR spectroscopy, chiral HPLCand CD experiments.Finally, the synthesis of mono-disperse helical strings of polymeric dimensions through a convergent, segmenttripling strategy has been developed. This protection/deprotection free synthesis was carried out byconnecting oligomeric blocks via a labile anhydride functionality
Li, Chen. "CH bond activation of methane and unsaturated molecules by a transient eta2-cyclopropene complex of niobium : synthesis, characterization and mechanistic studies." Thesis, Toulouse, INSA, 2015. http://www.theses.fr/2015ISAT0029/document.
Chapter 1 reports a literature summary of the different ways of cleaving a hydrocarbon C-H bond, mostparticularly methane, with both early and late transition metal complexes. For early transition metals ourattention is focused on three mechanisms: i) the σ-bond metathesis, ii) the α-H abstraction/1,2-CH bond addition and iii) the β-H abstraction/1,3-CH bond addition.Chapter 2 challenges the problem of the activation of a CH bond of methane by a transient η2-cyclopropene complex of niobium. High pressure solution NMR, isotopic labelling studies and kinetic analyses of the degenerate exchange of methane in the methyl complex [TpMe2NbCH3(c-C3H5)(MeCCMe)] (1) are reported. Stoichiometric methane activation by the mesitylene complex [TpMe2Nb(CH2-3,5-C6H3Me2)(c-C3H5)(MeCCMe)] (2) giving 1 is also realized. Evidence is provided that these reactions proceed via an intramolecular abstraction of a β-H of the cyclopropyl group from either methane or mesitylene from 1 or 2, respectively, yielding the transient unsaturated η2-cyclopropene intermediate [TpMe2Nb(η2-c-C3H4)(MeCCMe)] (A). This is followed by itsmechanistic reverse 1,3-CH bond addition of methane yielding the product.Chapter 3 explores the reactivity of complex 1 towards heteroaromatics, unsaturated hydrocarbons, pentafluorobenzene and ferrocene (FcH) via the β-H abstraction/1,3-CH bond activation mechanism. Compound 1 is able to selectively activate the C-H bond of furan, thiophene, 1-cyclopentene, phenylacetylene, pentafluorobenzene and ferrocene, yielding the corresponding products [TpMe2NbX(c-C3H5)(MeCCMe)] (X = 2-C4H3O, 2-C4H3S, 1-C5H7, PhC≡C C6F5, Fc) which have been isolated and characterized by 1H, 13C NMR spectroscopy, electrochemical studies and X-ray diffraction analysis
Pang, Liuqing. "Multi-metal nano-materials as efficient electrocatalysts." Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1I013.
Hydrogen (H2) has been considered as the most promising and renewable energy carrier. With the advantages of low cost and high efficiency, electrochemical water splitting is a promising approach to produce H2 with high purity. However, the practical application of water splitting for mass production of H2 is greatly hindered by a higher applied bias voltage and a lower electrode stability required in an electrolyzer arising from two half reactions in water splitting, namely, cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER). Currently, Pt-group metals are the most effective catalysts for HER while the benchmark catalysts for OER are Ir/Ru-based compounds. However, high cost and scarcity of these metals limit their widespread use. Therefore, enormous efforts have been dedicated to the development of nano-scale non-noble metal catalysts with high dispersibility, large specific surface area, and electrocatalytic activity for water splitting. In this thesis, we have explored high-efficiency, high-stability, low-price electrocatalysts using a simple and environmentally friendly process. Firstly, we prepared new PtRu2 nanoparticles supported on sulphur- and nitrogen-co-doped crumbled graphene with trace amounts of iron (PtRu2/PF) electrocatalyst by one-step hydrothermal process. The PtRu2/PF catalyst achieved a current density of 10 mA·cm-2 at a low overpotential value of only 101 mV for HER at pH=1 and a current density of 10 mA cm-2 at an overpotential of only 238 mV for the OER in alkaline solution. Interestingly, this catalyst was also efficient for methanol oxidation reaction (MOR) in acidic solution and oxygen reduction reaction (ORR) in 0.1 M KOH solution. Secondly, we described the preparation of a hybrid material consisting of cobalt oxide decorated on nitrogen-doped MoS2 supported on carbon fibers (CoO/N-MoS2/CF) through a two-step process combining hydrothermal technique and electrochemical deposition. The CoO/N-MoS2/CF achieved a current density of 10 mA cm-2 at an overpotential of only 78 mV for the HER and a current density of 50 mA cm-2 at 458 mV for the OER in 1.0 M KOH. Additionally, the CoO/N-MoS2/CF delivered a maximum current density of 53 mA cm-2 at an applied cell voltage of 1.5 V for a two-electrode water splitting. Thirdly, we showed for the first time the extraordinarily capacity of perforated gold nanoholes (Au NHs) electrodes for electrochemical water splitting under illumination with light. The strong plasmonic electromagnetic enhancement, which occurs under illumination of the perforated Au NHs electrode, facilities the dissociation of water into H2. The overpotential for the HER occurs on such plasmonic electrodes at a current density of 100 mA cm-2 was 205 mV, largely improved compared to the reference material, Pt. The fast electrocatalytic behavior of the interface was attested by a low Tafel slope of 33 mV dec-1. All of these materials were characterized by a variety of different techniques, such as SEM, TEM, XRD, XPS, Raman and electrochemical measurements
Lemort, Lucille. "Élaboration et caractérisation d'alliages hydrurables de type ABx (A=Pr, Nd, La, Mg ; B=Ni; x=3, 3.5, 3.8, 5) en vue de leur utilisation comme matière active pour électrode négative d'accumulateurs NiMH." Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00599399.
Liu, Xiu. "Production d'hydrogène par reformage à sec de méthane sur catalyseurs au Ni à base de CeO2, CeO2 modifiée avec Zr ou Al, et nano-matériaux Mg-Al-O." Electronic Thesis or Diss., Centrale Lille Institut, 2021. http://www.theses.fr/2021CLIL0032.
The demand for hydrogen, as a chemical product and as energy is increasing, but the main hydrogen production methods are unsustainable and not environmentally friendly. Hydrogen production from renewable resources (such as biogas mainly composed of CH4 and CO2) is required. Dry reforming of methane (DRM) is a promising method to produce H2 and CO from greenhouse gases. In this thesis, Ni-based CeNiXOY, CeZr0.5NiXOY, CeAl0.5NiXOY, and AlMg2NiXOY catalysts are studied in dry reforming of methane reaction. The effect of reaction temperature, Ni content, in situ H2 pretreatment, mass of catalyst, calcination, and CO2/CH4 ratio are studied. Moreover, long duration stability tests are reported on some chosen samples. The optimized catalytic performance associated with resistance to carbon formation is obtained on partially reduced catalysts. Various physicochemical characterizations are used to analyze the properties of the catalysts, such as XRD, Raman, XPS, and H2-TPR. Some chosen catalysts are also characterized after DRM reaction to analyze their evolution. Finally, an active site involving Ni species in close interactions with other cations is proposed. It is related to a partially reduced catalyst involving anionic vacancies, O2- species, and cations
Jacques-Lefebvre, Steve. "Vers la synthèse d'hélices organiques fonctionnalisées avec des nucléobases." Thèse, 2007. http://hdl.handle.net/1866/7840.