Dissertationen zum Thema „Oxydes de plutonium – Synthèse (chimie)“
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Bardelle, Philippe. „Synthèse du mononitrure mixte d'uranium-plutonium par réduction des oxydes /“. Saclay : Commissariat à l'énergie atomique, 1989. http://catalogue.bnf.fr/ark:/12148/cb351007303.
Vigier, Jean-François. „Synthèse d’oxydes d’actinides en milieu chlorure fondu : études structurales et mécanismes réactionnels“. Electronic Thesis or Diss., Lille 1, 2012. http://www.theses.fr/2012LIL10051.
The study developed in this thesis concerns actinide oxides synthesis for nuclear fuel refabrication, and more specifically, the actinide (III) precipitation in molten salt LiCl-CaCl2 (30-70%mol) salt at 700°C using wet argon sparging. First, this conversion method is described for neodymium (III) and cerium (III) coconversion. The conversion rates are around 99.9%, and the obtained powders contain mixed oxychloride Ce1-xNdxOCl as main component, with a small amount of mixed oxide Ce1-xNdxO2-0.5x for the high cerium ratio. A second oxychloride CeIV(Nd0.7Ce0.3)IIIO3Cl is obtained in specific conditions and in very low quantity. The structure of this oxychloride is described in this study. The partially oxidative property of the conversion method induces the oxidation of a part of cerium (III) to oxidation state (IV). In the case of uranium (III) conversion by wet argon sparging, all the uranium is oxidized and give the oxide UO2 as single compound. The conversion rate for this element is over 99.9% in the molten chloride, but significant amount of uranium is lost by volatilization during the conversion. Finally, the U(III) and Pu(III) coconversion study shows the highest precipitation sensitivity of uranium (III) in comparison with plutonium (III), responsible of a successive conversion of the two elements, giving an oxide mixture of UO2 et PuO2 with quantitative conversion rate. Surprisingly, the conversion of Pu(III) in the same conditions led to a mixture of PuO2 and PuOCl, characteristic of a partial oxidation from Pu (III) to Pu (IV), in contrast with coconversion of U(III)-Pu(III)
Vigier, Jean-François. „Synthèse d’oxydes d’actinides en milieu chlorure fondu : études structurales et mécanismes réactionnels“. Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10051/document.
The study developed in this thesis concerns actinide oxides synthesis for nuclear fuel refabrication, and more specifically, the actinide (III) precipitation in molten salt LiCl-CaCl2 (30-70%mol) salt at 700°C using wet argon sparging. First, this conversion method is described for neodymium (III) and cerium (III) coconversion. The conversion rates are around 99.9%, and the obtained powders contain mixed oxychloride Ce1-xNdxOCl as main component, with a small amount of mixed oxide Ce1-xNdxO2-0.5x for the high cerium ratio. A second oxychloride CeIV(Nd0.7Ce0.3)IIIO3Cl is obtained in specific conditions and in very low quantity. The structure of this oxychloride is described in this study. The partially oxidative property of the conversion method induces the oxidation of a part of cerium (III) to oxidation state (IV). In the case of uranium (III) conversion by wet argon sparging, all the uranium is oxidized and give the oxide UO2 as single compound. The conversion rate for this element is over 99.9% in the molten chloride, but significant amount of uranium is lost by volatilization during the conversion. Finally, the U(III) and Pu(III) coconversion study shows the highest precipitation sensitivity of uranium (III) in comparison with plutonium (III), responsible of a successive conversion of the two elements, giving an oxide mixture of UO2 et PuO2 with quantitative conversion rate. Surprisingly, the conversion of Pu(III) in the same conditions led to a mixture of PuO2 and PuOCl, characteristic of a partial oxidation from Pu (III) to Pu (IV), in contrast with coconversion of U(III)-Pu(III)
Bardelle, Philippe. „Synthèse du mononitrure mixte d'uranium-plutonium par réduction des oxydes“. Aix-Marseille 3, 1988. http://www.theses.fr/1988AIX30049.
Hibert, Nicolas. „Synthèse et caractérisation structurale des complexes de plutonium à base de peroxyde“. Thesis, Lille, 2020. http://www.theses.fr/2020LILUR054.
In the framework of the improvement of the reused nuclear fuel manufacturing and the Pu multirecycling, U-Pu coconversion represent a potential alternative to the current mixing process of uranium and plutonium oxide powders. Compared to carbon-based U-Pu coconversion processes, the peroxide process has the advantage of, among others, leading to the absence of residual carbon in oxide powder. However, the current knowledge of plutonium peroxide is incomplete and scattered, hindering the plutonium conversion and U-Pu coconversion technological developments. Thus, the evaluation of the feasibility of this process requires a preliminary strengthening of the knowledge of plutonium peroxide physico-chemical properties. The first part of this work has been dedicated to the characterization of plutonium peroxide soluble complexes and salts. Molar extinction coefficient of soluble complexes have been estimated in order to quantify the plutonium loss in precipitation experiments. The experimental conditions enabling very high yield of precipitation of Pu and an easy-filterable powder have been determined. Moreover, a new database of plutonium peroxide salt properties has been established from the characterizations obtained. In the second part, syntheses carried out with mixed systems such as U-Pu and U-Th have led to obtaining a mix of uranyl peroxide and +IV actinide peroxide salt. The experimental conditions enabling very high yields for uranium and for plutonium and an easy-filterable powder have been determined. Then, thermal treatment of the precipitate has led to obtaining an oxide powder with a good ability to the manufacturing of sintered oxide pellet and which enables to demonstrate the feasibility of U-Pu conversion process at the laboratory scale
Legrand, Olivier. „Nouveaux oxydes d'ortho-hydroxyarylphosphines chiraux, synthèse et applications en catalyse asymétrique“. Aix-Marseille 3, 1999. http://www.theses.fr/1999AIX30046.
Fournier, Sabine. „Etude de la dissolution des oxydes mixtes (U,Pu)O2 à forte teneur en plutonium“. Montpellier 2, 2000. http://www.theses.fr/2000MON20203.
Xin, Baowei. „De la chimie douce, au milieu hydrothermal étendu au domaine supercritique, du réacteur fermé au dispositif en continu : synthèse d'oxydes métalliques nanostructurés“. Dijon, 2005. http://www.theses.fr/2005DIJOS015.
Estevenon, Paul. „Synthèse et caractérisation de silicates MSiO4 (M = Ce, Th, U, Np, Pu)“. Thesis, Montpellier, Ecole nationale supérieure de chimie, 2018. http://www.theses.fr/2018ENCM0013/document.
Actinides, and mainly plutonium, are the main contributors to the long-term radiotoxicity of spent nuclear fuel. In conditions representative for geological repository, the interactions between such radioelements and silicate species could influence the mobility of the actinides in the environment and thus, could affect the safety of the storage facilities. Especially, the formation of actinide silicate, AnSiO4, has to be considered carefully, since thorium and uranium silicate are ubiquitous in environmental silicate rich media and under reductive conditions. Because the chemistry of AnSiO4 is poorly known, their preparation is a prerequisite in order to determine thermodynamic data associated to their formation and to evaluate their stability under geological repository conditions.The first part of this work consisted in the preparation, under hydrothermal conditions, of ThSiO4, USiO4 and CeSiO4 as surrogates of PuSiO4. This study allowed us to determine the preponderant parameters which impact the formation of silicate phases, to establish optimized conditions for their synthesis as pure phases and then to propose potential mechanisms of formation. For all of these syntheses, the competition between the complexation of metal cations by silicate ions and their hydrolysis played a predominant role. Three different and efficient strategies have been identified for the formation of actinide silicates. The first one was characterized by the use of weakly acid reactive media to limit the hydrolysis of actinide in solution. The second involved the use of strong ligands to maintain the actinide in solution in weakly basic media. The third was developed with element oxidation states that also protected it against hydrolysis. The transposition of these strategies to the preparation of PuSiO4 allowed to determine the suitable synthesis conditions to form PuSiO4 and then to identify the differences in terms of reactivity between Pu(IV) and surrogate elements
Boyer, Jérémie. „Indolone-1 oxydes 2-substituées : synthèse et capacité de piégeage de radicaux“. Toulouse 3, 2004. http://www.theses.fr/2004TOU30014.
Nitrone compounds have been the subject of many developments since the discovery of their capacity to trap free radicals. This property of spin trapping coupled with electron paramagnetic resonance (EPR) analysis made it possible to highlight many redox mechanisms in chemistry and in biology. This memoir describes the synthesis and the radical trapping properties of a series of nitrones, the indolone-1-oxides. These indolone-1-oxides were synthesized in two different ways both starting from an arylaldehyde substituted by a nitro group in the ortho position. A series of eight compounds was obtained and tested for their capacities to trap free radicals. The spin trapping experiments were carried out initially by EPR on this series by testing various free radicals (hetero- or carbon-centered). The study made it possible to determine the capacity of indolone-1-oxides to trap various types of radicals giving particularly stable nitroxide adducts. Two of these nitrones spontaneously yielded nitroxide adducts in solution. The trapping properties were then evaluated by indirect methods measuring the capacity of the nitrones to protect or to delay the degradation of a molecular probe by radical attack. The first method evaluated the capacity of nitrones to inhibit the bleaching of b-carotene caused by lipoperoxyl radical attack in lipophilic medium. The second method followed the inhibition of the fluorescence decay of fluorescein undergoing radical attack initiated by 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH) in hydrophilic medium. The various methods used in this work show that the indolone-1-oxide series has, at very low concentrations, very good free radical trapping capacities. These nitrones will thus make good molecular tools for the study of redox mechanisms in biological systems
Gergely, Bernadett. „Synthèse et caractérisation de catalyseurs à base d'oxyde d'étain et de gallium“. Lyon 1, 2001. http://www.theses.fr/2001LYO10166.
Portehault, David. „Synthèse par chimie douce en milieu aqueux d'oxydes de manganèse nano-structurés : des matériaux pour batteries au lithium ?“ Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00812589.
Dutartre, Mathieu. „Oxydes de phosphines secondaires P-chirogéniques : nouvelle synthèse stéréosélective et applications“. Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS067/document.
A new stereoselective synthesis of phosphinous acid boranes is described by hydrolysis of aminophosphines boranes prepared by reaction of the oxazaphospholidine complex derived from ephedrine with organolithium reagents.By reaction with a strong acid, the phosphinous acid boranes lead to the corresponding P-chirogenic secondary phosphine oxides in very good yields (90%) and with complete retention of the configuration at the phosphorus atom. The secondary phosphine oxides have been used in asymmetric hydrogenation and intramolecular Heck cyclisation using rhodium and palladium complexes, respectively. In a second part, a new synthesis of P-chirogenic ortho-halogenophenyl phosphine oxides is described. The principle of this synthesis is based on the addition of secondary phosphine oxides to a benzyne, prepared in situ from dihalogenobenzene. The o-halogenophenylphosphine oxides were used to prepare many functionalized derivatives in ortho position by reactions such as homocoupling with copper or heterocoupling catalyzed by palladium complexes. In the last part, the synthesis of chiral copper clusters was performed using P-chirogenic monophosphines. The X-ray structure, circular dichroism, and the photophysical properties of the chiral clusters were presented
Maître, Alexandre. „Réactivité des mélanges oxydes-carbone dans la synthèse des carbures de titane et de zirconium : aspects cinétiques et technologiques“. Limoges, 1998. http://www.theses.fr/1998LIMO0037.
Larcher, Dominique. „Nouvelles voies de synthèse et caractérisation de matériaux d'électrodes positives pour accumulateurs au lithium“. Amiens, 1997. http://www.theses.fr/1997AMIE0118.
Taban, Caliskan Gülnur. „Synthèse et caractérisation de polyoxométallates organométalliques de molybdène et de tungstène en milieu aqueux“. Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1908/.
In this thesis, the reaction of [Cp*2M2O5] complexes with Na2M'O4 (M, M' = Mo, W) in different stoichiometric ratios has been investigated in an acidic aqueous medium. It is a mild and selective entry into well-defined Lindqvist-type organometallic mixed-metal Polyoxometalates. Using a 1:4 ratio leads to the neutral compounds [Cp*2MoxW6-xO17] (for x = 6, 4, 2, 0), of which the two mixed-metal systems [Cp*2Mo2W4O17] and [Cp*2Mo4W2O17] were not previously reported. The identity of the complexes is demonstrated by elemental analysis, thermogravimetric analysis and infrared spectroscopy. The molecular identity and geometry of compound [Cp*2Mo4W2O17] is further confirmed by a fit of the powder X-ray diffraction pattern with a model obtained from previously reported single-crystal X-Ray structures of [Cp*2Mo6O17] and [Cp*2W6O17], with which [Cp*2Mo4W2O17] is isomorphous. The formula of these compounds may also be written as [(Cp*M)2(M'O)4(µ2-O)12(µ6-O)]. The relative position of the M and M' atoms is perfectly defined by the nature of the starting materials, the M element from the organometallic reagent ending up selectively in the (Cp*M) positions and the M' element from the inorganic reagent occupying selectively the (M'O) positions. Thermal decomposition of these compounds yields the mixed-metal oxides Mo2/3W1/3O3 and Mo1/3W2/3O3 with an expected homogeneous distribution of the two metals. When the same synthetic procedure is carried out with [Cp*2M2O5] and Na2M'O4 (M, M' = Mo, W) in a 1:10 ratio, the anionic organometallic mixed-metal polyoxometalates [Cp*MM'5O18]- (M, M' = Mo, W) are obtained. This family was previously represented only by the homometallic Mo member, obtained by two different and less efficient synthetic strategies. All these compounds have been isolated as salts of nBu4N+, nBu4P+ and Ph4P+ cations. The compounds have been characterized by elemental analysis, thermogravimetric analysis, electrospray mass spectrometry, and infrared spectroscopy. The molecular identity and geometry of compounds Ph4P[Cp*Mo6O18] and Ph4P[Cp*WMo5O18] have been confirmed by single crystal X-ray diffraction. The compounds show characteristic M=O and M-O-M vibrations in the IR spectrum. As found for all POM derivatives, the terminal M'=Ot and M''=Ot vibrations (950-1000 cm-1) have higher frequency, than the M-Ob-M vibrations (750-890 cm-1). The 1H NMR spectra of the isolated products for the new anionic POM's show the Cp* signal at d 2. 2 (when linked to Mo) or 2. 4 (when linked to W), plus the resonances of the cation with suitable intensity for the 1:1 Cp*/cation stoichiometry. The 31P NMR spectrum of the phosphonium salts shows the expected cation resonance at d 23. 4 for Ph4P+ and d 35. 1 for Bu4P+. All anionic compounds were also investigated in terms of their thermal behavior by thermogravimetric analysis (TGA) in air. The salts with N-based cation (Bu4N+) lead to complete loss of the organic part, with formation of the mixed-metal trioxides Mx/6M'1-x/6O3 (x = 0, 1, 5, 6), with a relatively good match between experimentally observed and theoretical mass losses upon warming up to 500 °C. TGA of the salts with phosphonium cations (Bu4P+ and Ph4P+) gave indication of phosphorus loss or not depending on the anion, without a clear rationalization. All anions were also investigated by mass spectrometry using an electrospray injection method. The spectrum in negative mode showed the expected molecular ion with an isotopic pattern in good agreement with the simulation. The fragmentation pattern is not identical for each type of anion, but as a general feature, we can observe a loss of the Cp* fragment to yield [MM'5O18]-, followed by the subsequent loss of both MO3 and M'O3
Rataboul, Franck. „Synthèse d'un hydroxyde de zirconium supporté sur silice : application à la préparation de catalyseurs de la réaction de métathèse des alcanes“. Lyon 1, 2002. http://www.theses.fr/2002LYO10160.
Renard, Catherine. „Synthèse et étude structurale par diffraction X et microscopie électronique de nouveaux oxydes de nickel, ruthénium et platine à valence mixte“. Lille 1, 1997. http://www.theses.fr/1997LIL10139.
La structure de sr#4ru#3#,#1o#1#2 résulte d'un empilement compact (cchc)#2 de 8 couches sro#3. Des dimères d'octaèdres relies par les faces, partiellement occupes par le ruthénium impliquent une surstructure. L'étude en diffraction électronique indique la présence de défauts lies a ces occupations partielles. Enfin, trois nouveaux oxydes de platine : bi#2#,#5ni#0#,#5pt#3o#8, sr#1#,#2pb#0#,#8pt#4o#8 et sr#4pbpt#4o#1#2 ont été synthétisés et étudies. Les deux premiers sont isotypes de pb#2pt#4o#8. Le dernier présente une structure particulièrement originale, le platine est en environnement pyramidal a base carrée, son degré d'oxydation moyen vaut +3,5. Une étude par x. P. S. Met en évidence la coexistence de deux degrés d'oxydation du platine au sein des colonnes formées par les pyramides a base carrée
Chambon, Cébastien. „Densification et homogénéisation U/Pu au cours du frittage de combustibles oxydes mixtes élaborés à partir de poudres UO2, U3O8 et PuO2“. Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0847.
In order to manufacture mixed-oxide fuels, also known as MOX ((U,Pu)O2) for the next generation of nuclear reactors, the use of triuranium octoxide (U3O8) was considered in this study. This PhD work focuses on the impact of this addition on MOX sintering and on the dimensional stability of sintered pellets during annealing. Initial experiments revealed a de-densification phenomenon at high temperature in the pellets containing U3O8 synthesized from an oxalic route.This undesirable phenomenon was studied on an inactive surrogate: a cerium oxide synthesized from an oxalic route in order to develop experimental techniques and protocols. The relationship between the presence of carbon impurities in the powders and the de-densification phenomenon was proven. Moreover, this de-densification phenomenon was observed in situ for the first time by using X-ray microtomography during sintering.The study of MOX fuels confirmed the major role of carbon impurities. The microstructural evolutions, the quantification of the carbon species released during sintering and the analysis of gases trapped inside the porosity of the sintered material led to the determination of a de-densification mechanism. Finally, a thermomechanical modelling of the fuel behavior under the effect of pore pressurization allows consolidating the proposed mechanism. Based on these results, a new sintering cycle was proposed and the first trials successfully limited the impact of the de-densification phenomenon
Lemarchand, Alex. „Synthèse par chimie douce et étude structurale de nanocristaux d'oxydes métalliques“. Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0110/document.
The aim of this work was to synthesize small size (~1-3 nm) metal oxide nanocrystals namely titanium dioxide (TiO2), tin dioxide (SnO2) and zinc oxide (ZnO), and to study their structure. Syntheses were conducted via non-aqueous or even strictly non-hydrolytic sol-gel methods under kinetic control. The structural characterization was mainly carried out by X-Ray diffraction methods, transmission electronic microscopy and the study of pair distribution functions, obtained by X Ray total scattering, coupled with atomic scale modelling methods. In the case of TiO2, anatase nanocrystals were obtained with sizes ranging between 4 nm and 8 nm. The molar ratio of the oxygen donor with respect to titanium was shown to be an important parameter to control the nanoparticle size. In peculiar conditions we have been able to isolate an intermediate phase characterized by very small sized and poorly crystallized nanoparticles which the structure can be assimilated to a disordered brookite structure. Concerning SnO2, rutile-type nanocrystals were synthesized with sizes ranging between 2 nm and 4 nm. The use of an ether as oxygen donor led to the simultaneous formation of an organic polymeric phase and of primary nanoparticles characterized by an intermediate structure close but still different from the rutile-type structure. Moreover, the use of benzyl-type solvents in the presence of tin tetrachloride led to the formation of water in the system. Lastly, for ZnO, we have shown that using an organic base to induce the formation of the metal oxide network in a methanolic solution of zinc acetate in the presence of a strong complexing agent of the zinc allowed us to obtain wurtzite nanocrystals of ultrasmall sizes around 1 nm. Even for the smallest sizes, the nanoparticles exhibit a structure very close to that of wurtzite with an increasing disorder of the cationic network
Bouchmella, Karim. „Synthèse par procédé sol-gel non-hydrolytique de catalyseurs oxydes mixtes pour la métathèse d'oléfines“. Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20088.
The non-hydrolytic sol-gel synthesis (NHSG) of Re-Si-Al and Mo-Si-Al mixed oxides was proposed as an innovative one step route to heterogeneous olefin metathesis catalysts. Supported molybdenum oxide catalysts are receiving much attention as a result of their relatively low price, robustness and good activity at low temperature. Supported rhenium oxide catalysts are known to be highly active and selective even at room temperature. However, they are expensive and moderately stable because of the sublimation of the rhenium oxide. The NHSG synthesis used in this work is based on the one pot reaction of chloride precursors (ReCl5 or MoCl3, SiCl4, AlCl3) with diisopropylether (iPr2O) at 110 °C in dichloromethane. The simplicity of NHSG makes it attractive: multi-step procedures, expensive precursors, or reactivity modifiers are not needed. The mixed oxide catalysts exhibited well-controlled compositions and mesoporous textures, with high acid site densities. XRD, XPS and ToF-SIMS showed that the catalysts could be described as an amorphous silica-alumina matrix with well-dispersed Re or Mo surface species. In the case of Re-based catalysts, rhenium losses by sublimation during calcination were observed for the silica-rich formulations. The loss of rhenium could however be avoided by increasing the Al content. More importantly we demonstrate that Re sublimation during calcination of silica-rich formulations is suppressed when the whole preparation procedure (synthesis, washing, drying and calcination) is carried out in the absence of water. Particular attention was devoted to the study of the influence of the composition on texture, structure, acidity and surface properties, which were correlated with the catalytic performances. The performance of selected Re-Si-Al and Mo-Si-Al catalysts was evaluated in the metathesis of propene and in the cross-metathesis of ethene and trans-2-butene. The NHSG catalysts were compared to catalysts of similar compositions prepared by other more methods (impregnation, thermal spreading, flame spray pyrolysis). The catalysts prepared by NHSG have a high specific activity in the metathesis reaction
Rhers, Bouchra. „Synthèse, caractérisation de nouveaux complexes de tungstène et étude de leur greffage par voie COMS sur des surfaces oxydes : application en métathèse stéréo- et énantiosélective des oléfines“. Lyon 1, 2006. http://www.theses.fr/2006LYO10177.
Bouhoute, Yassine. „Nouveaux oxydes métalliques supportés : vers la compréhension des catalyseurs industriels de métathèse des oléfines par une approche combinant synthèse, RMN et DFT“. Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1316.
The aim of this thesis was to apply surface organometallic chemistry in order to prepare novel supported organometallic complexes bearing oxo ligands for olefin metathesis. The first approach consists of the utilization of an inorganic precursor (WOCl4) to obtain mainly (80%) the bis-siloxy species [(=SiO)2WOMe2] in two steps: grafting followed by alkylation with SnMe4. The latter material catalyzes isobutene self-metathesis to 2,3-dimethylbutene. Employing oxo organotungstene precursors results in materials that can be characterized by spectroscopic techniques (EXAFS, RAMAN, Solid-state NMR, DRIFT…) and offer a large variety to alter the spectator ligands. In fact, the first model of the industrial catalyst (=SiO)2W(=O)(CH2SiMe2)2 has been obtained by grafting of [WO(CH2SiMe3)3Cl] onto silica dehydroxylated at 200 °C. Elucidation of the surface structure by 17O MAS NMR along with DFT calculations suggest that there are most likely two co-existing geometries, trigonal bipyramidal (TPB) and square pyramide (SP), as the activation barrier is found to be low (<5 kcal.mol-1). This new surface species has shown a high activity in propene self-metathesis and low deactivation rate, at reflected by the high turn-over number of 24000 after 25 hours on stream. Furthermore, an original approach to access variety solid tungsten oxo catalysts expressed generally as [(=SiO)WO(CH2SiMe3)2OAr] has been developed and comprises a simple modification of the supported monopodal species [(=SiO)WO(CH2SiMe3)3] by desired phenol derivatives. Catalysts with electron withdrawing phenoxide ligands exhibit higher activity and stability in propene self-metathesis than their electron rich phenoxide homologue. The developed methodologies will be extended to molybdenum oxo alkyl complexes
Loubert, Gaël. „Etude de la précipitation quantitative de l’uranium(VI) et du plutonium(IV) en milieu acide nitrique par de nouveaux ligands organiques“. Thesis, Lille, 2018. http://www.theses.fr/2018LIL1R074.
Due to the uranium natural resource depletion and the high growth in energy requirements, the fourth-generation nuclear power plants, with FNR, which involve the uranium and plutonium recycling, can be a future appropriate industrial route. Nonetheless, these evolutions modify potentially the spent fuel reprocessing. Furthermore, U(VI) and Pu(IV) precipitation, without any valency adjustment, would provide an answer to the efficiency and safety demands. In this context, the present work is interested in new organic ligands research allowing the quantitative precipitation of uranium(VI) and plutonium (IV) in a concentrated acid medium. The whole studies led to the identification of new organic ligands, and these new ligands are able to massively precipitate uranium(VI) in a nitric acid medium. Among these identified molecules, the oxalic acid/NCP ligands association has been used to precipitate both of these two actinides. A determination of the precipitate has been done in order to identify the structures and the morphologies of the precipitate. The solubility measurements over time have allowed to assess the fast precipitating kinetic and the very low solubility of the precipitated component. Finally, the thermal treatment of the precipitate gives rise to the formation of actinides oxides whose properties match the requirements of the fuel shaping step. The extension of these results made it possible to offer an innovating conversion process of both actinides in a nitric acid medium and that without any valency adjustment, which fit to all the conditions of the requirement specifications of the spent fuel reprocessing for the fourth generation of nuclear reactors
Kourieh, Reem. „Synthèse et caractérisation de catalyseurs de type oxydes mixtes pour des applications environnementales“. Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00993106.
Kervazo, Sophie. „Computational actinide chemistry : structure, bonding and thermodynamics“. Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1R042/document.
The main question of this thesis is: do we have today the tools to efficiently describe the structure, the bonding and the thermodynamics of actinide systems? This broad question is answered thanks to three studies. The first two are directly applied to the plastic industry and the nuclear plant safety. The last one, more fundamental, concerns the benchmarking of newly developed theoretical approach on f-element systems.First, actinides and transition metal arene-coordinated alkyl cations have been recently proven to be efficient catalysts for ethylene polymerizations. Interestingly, thorium, uranium and zirconium alkyl cations’ catalytic activity depends on the solvent. To understand these behaviors and to confirm the tendency of these complexes to engage in unusual-arene coordination, relativistic DFT calculations combined with a characterization of the interaction thanks to the ETS-NOCV method are used. Second, in accident scenario along the reprocessing of spent nuclear fuel, plutonium can be released in various volatile forms (PuO2, PuO3 or PuO2(OH)2, …). The exploration of these scenarios by the use of simulations requires, among the various parameters, the knowledge of the thermodynamic properties of the possibly formed elements. Our in-silico study focusses on the determination of the enthalpies of formation of the former two species for which experimental uncertainties remain, using multi-configurational relativistic wavefunction method. The last part of the thesis focusses on the benchmark of the B2-PLYP functional for f-element systems, which turns out quite accurate with respect to the experimental data and the gold-standard CCSD(T) method
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
Dazzazi, Anass. „Synthèse et caractérisation de nanoparticules d'oxydes métalliques par voie organométallique : vers des applications biomédicales“. Toulouse 3, 2013. http://thesesups.ups-tlse.fr/1951/.
This manuscript describes a collaborative work between the University of Toulouse and the University of Rabat. This work is devoted to the development of metal oxide nanoparticles (gamma-Fe2O3 and ZnO) for biological applications (MRI or optical imaging). It focuses in particular on the development of methodologies for transforming hydrophobic nanoparticles prepared following organometallic chemistry to hydrophilic ones, and to study their properties. Methodologies of solvent exchange to transfer ZnO hydrophobic nanoparticles into water using Gémini ligand have been first developed. The well known "double layer" strategy turned to be much more complicated as expected. The use of amino-PEG surfactants leads to the direct formation of water-dispersible iron oxide nanoparticles. In a second step, the physical properties (optical or magnetic properties) of such nanoparticles were studied either in organic media or in water. In particular, we demonstrated that the optical properties of the ZnO nanoparticles are independent of the solvent but strongly depend on the surface state of the nanoparticles. The first example of a photocommutation of ZnO nanoparticles by a diarylethene photochromic dye has been described. Finally, ZnO nanoparticles stables in buffered solutions have been obtained and the first observation with a fluorescence microscope performed. The iron oxide nanoparticles have been tested as MRI contrast agents
Trolez, Yann. „Multi-rotaxanes cycliques et linéaires assemblés au cuivre(I)Copper(I) templated syntheses and dynamic properties of cyclic and linear multi-rotaxanes : synthèse et propriétés dynamiques“. Strasbourg, 2010. https://publication-theses.unistra.fr/public/theses_doctorat/2010/TROLEZ_Yann_2010.pdf.
Since some years, many efforts have been made for the functionalisation of rotaxanes. Recently, the synthesis of a [3]rotaxane containing two zinc(II) porphyrins, behaving as an adaptable receptor towards the complexation of bidentate substrates such as 4,4'-bipyridine, has been reported. The association constants with this type of compounds vary with the presence or not of Cu(I) in the system, but in all the studied cases, they are above 106. The PhD work presented here is to improve the system of adaptable receptor. First, the synthesis and the study of two new cyclic [4]rotaxanes assembled with Cu(I), containing or not porphyrins, are reported. These metalated [4]rotaxanes behave as molecular receptors thanks to π-donor/π-acceptor interactions or coordination bonds. Very surprisingly, the porphyrinic [4]rotaxane has completely lost its coordination properties after demetalation because of the collapse of the structure on itself due to the coordination of two of four triazoles belonging to the axles on Zn2+ of the porphyrins. Then, the syntheses and the studies of linear multi-rotaxanes for the elaboration of a symmetrical double molecular shuttle are reported. In extension to this project, a linear [5]rotaxane containing two types of coordinating units, one bidentate and the other tridentate, was synthesized. This compound showed a remarkable selectivity towards the coordination of cations Zn2+ and Li+. Indeed, the addition of two equivalents of each metallic cations induce the quantitative coordination of Zn2+ on the tridentate chelate and Li+ on the bidentate chelate
Najjar, Hend. „Les oxydes type-pérovskite La1-xMxMn1-yM’yO3+δ (M : Pr ; Eu ou M’ : Al, (0≤x,y≤1) ) : synthèse par combustion et études des propriétés physico-chimiques et catalytiques“. Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10058/document.
Combustion synthesis is a simple and safe-time process. It is based on redox reaction between fuel ( glycine) and oxidant agent (nitrates). A series of nanocristalline powders LaMnO3+δ were successfully obtained by varying glycine/nitrate ratio (r) from 0.43 to 0.8. The obtained specific areas range in 18-37 m²/g. Different desorbed oxygen species from these solids were identified: those weakly adsorbed to the surface (α1-O2) and those diffusing from the bulk (α2-O2 and β-O2 ). The desorption of α2-O2 and β-O2 causes respectively the reduction of Mn4+ to Mn3+ and Mn3+ to Mn2+. The use of fuel rich precursor enhances the specific surface area, the reducibility of manganese and the mobility of desorbed oxygen. This criterion allows interesting catalytic properties in CH4 deep oxidation. The LM0,53 catalyst obtained in stoichiometric conditions exhibits the best thermal stability.The combustion synthesis is also useful to obtain LaMn1-yAlyO3+δ oxides in a large range of Al content (0≤y≤ 1). The Al-substitution for Mn improves α2-O2 mobility. The best catalyst is obtained for the optimal fraction y=0.1 of Al due to their higher surface areas and superficial Mn concentration. A series of substituted lanthanum manganite in the A sublattice of the perovskite-type structure La1-xLnxMnO3+δ (Ln : Pr ;Eu, 0≤x≤1) were obtained by combustion synthesis. The α2-O2 mobility was improved by this substitution. A fraction of 20% was found to be optimum for catalytic activity in deep oxidation of methane
Ishak, Dridi Islem. „Synthèse stéréosélective et réactivité des 4-hydroxy-1-boryl-1-allénylsilanes. Synthèse et étude théorique de nouveaux dérivés de dimères benzimidazolo-1,3,5,2-triazaphosphorine-2-oxydes“. Thesis, Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=http://theses-intra.upmc.fr/modules/resources/download/theses/2019SORUS573.pdf.
This thesis has focused on two different topics. Firstly, the synthesis of 1-silylalleneborane was studied, for the first time, from acetylenic epoxide and a silylborane. This method allows the stereoselective and stereospecific preparation of allenylboranes through an anti SNi mechanism. Subsequently, propargylation of the aldehydes using allenes afforded stereoselective access to the corresponding 2-alkynyldiols-1,3. A six-member closed transition state has been proposed for this last transformation which proceeds via a SE2' type mechanism. The scope and limitations of these two reactions have been explored.Finally, the electrophilic and nucleophilic reactivity of imidates resulting from the condensation of 2-aminobenzimidazole on a variety of orthoesters was studied as a route for the preparation of N-benzimidazole dimers. We also studied the synthesis of [1,2a] benzimidazolo-1,3,5,2-triazaphosphorin-2-oxide dimers through the action of hexamethylphosphoramide on N-benzimidazole dimers, the evaluation of the antioxidant activity of these new compounds formed (amidic and phospho-nitrogen dimers) is in progress
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
Lecroq, William. „Etude de la formation de radicaux phosphorés et leurs applications en synthèse organique“. Thesis, Normandie, 2019. http://www.theses.fr/2019NORMC265.
This manuscript explores the reactivity of phosphorous radicals in organic chemistry.The development of a photo induced method for the synthesis of arylphosphonate derivatives by simply combining diaryliodonium salts with phosphites in acetonitrile is discussed. Mechanistic studies of this photo-induced process allowed us to propose a mechanistic pathway of the reaction, where a charge transfer complex is a key intermediate in the reaction.The reactivity of the phosphoranyl radicals was used for the study of the deoxygenation of amine N-oxydes, using an organophosphorous catalyst, which can be reduced by phenylsilane. Theoretical studies showed that the photo active species is the pyridine N-oxide, rearrange to form an oxaziridine. The utilization of phenylsilane for the deoxygenation of tertiary amine N-oxide at room temperature without visible light irradiation was discussed, allowing the discovery of a selective deoxygenation method for N,N-dioxides
Varnier, Olivier. „Synthèse et caractérisation de poudres de spinelle de magnésium et d'oxyde d'erbium par les voies sol-gel“. Montpellier 2, 1992. http://www.theses.fr/1992MON20032.
Henry, Natacha. „Nouveaux oxydes de métaux de transition à valence mixte ou inusuelle : les composés Bi2MxCu (II/III) (1-2x)O4 (M=Bi, Pb), Pb2V (III)V2(v)O8,5 et Pb3Mn (II)2Mn (IV)3V2O16“. Lille 1, 2000. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2000/50376-2000-288.pdf.
La filiation avec les phases a 2v 3o 9 (m = pb,sr,ba) permet d'envisager la preparation de nombreux vanadates par condensation des vo 4. _ l'oxyde pb 3mn 5v 2o 1 6 possede une structure resultant de la succession de couches compactes de formules o 4 et pbo 3. Des blocs pbo 3-o 4-o 4-pbo 3 sont separes par des couches lacunaires pbo 2. Les atomes de vanadium occupent les sites tetraedriques entre les couches pbo 3 et pbo 2. Les atomes de manganese occupent deux sites cristallographiques differents. Les distances interatomiques et les sommes des valences de liaison permettent d'attribuer sans ambiguite les degres d'oxydation +4 et +2 aux deux types de manganese. La structure est comparee a celles des phases du type magnetoplombite et pbv 6o 1 1
De, Campos Matthieu. „Valorisation de matière faiblement radioactive comme réactif dans la synthèse de matrices cimentaires“. Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1R016.
In the context of pressurized water nuclear reactors (PWRs), fuel fabrication generates low-level radioactive materials in the form of low-reactivity and relatively dense metal oxides. These materials, in the form of aggregates, are currently stored pending their reuse in nuclear fuel or in alternative solutions. This thesis studies their valorization as additives in the synthesis of cement matrices (pastes and mortars), for the development of shielding materials against ionizing radiation, such as γ rays. The state of the art (Chapter I) focuses on the generation of this weakly radioactive material in the French nuclear fuel cycle, on the photon-matter interactions, on cementitious matrices, and on the use of radioactive materials in cementitious matrices. The experimental work has required to develop miniaturized physico-chemical characterization methods adapted to radioactive materials (Chapter II), in order to compare them with formulations using non radioactive analogs. For the development of cement-based materials, a magnesium potassium phosphate cement (MKPC) and a pure Portland cement are used. Workability, setting time, mechanical compressive strength, dimensional stability, homogeneity of the microstructure and temperature resistance are optimized. For MKPC pastes, the mechanical strength depends on the MgO/KH2PO4 molar ratio (Chapter III). In order to optimize the integration of the dense metal oxides, MKPC are formulated at stoichiometry, although this composition, without additives, is characterized by significant swelling. The addition of powdered mineral additives (fly ash, dense metal oxides) enabled to inhibit swelling and avoid phase segregation. With Portland cement, the incorporation of metal oxides is performed on mortars, with a granular skeleton (Chapter IV), and it is carried out in two ways: either as a supplement to an optimized formulation, or by volume replacement of the fine parts of the granular skeleton. In both cases, compressive strengths are obtained with values above 50 MPa at 28 days, and a good resistance to temperatures up to nearly 250°C. A third incorporation method is possible, which requires the synthesis of cement/metal oxide granules. The fifth and last chapter compares the mechanical and shielding performances of cement matrices incorporating the dense metal oxides. It also quantifies the interactions of these metal oxides with the environment (by reactivity experiments in contact with cementitious waters at ambient temperature and pressure or beyond, and leaching tests). Depending on the performance of the two types of cement matrices developed, different uses are possible, e.g. waste encapsulation or structural and temperature resistant materials
Zhang, Jidong. „Utilisation des N-oxydes dérivés d'amino-alcools pour la synthèse de N-H pyrrolidines substituées en position 2, 3 ou 4 et pour l'α-fonctionnalisation d'amines secondaires“. Paris 11, 1989. http://www.theses.fr/1989PA112213.
Azomethine ylids generated from tertiary amine oxides by double deprotonation are the only azomethine ylids able to undergo intermolecular 3+2 cycloaddition with non-activated olefins. Thus, 3- or 4-substituted or 3, 4-disubstituted N-alkyl pyrrolidines can be obtained by a simple and direct method. It was important to develop this method for preparing N-H pyrrolidines found in natural products. In the first pan of this thesis, demethylation of N-methyl pyrrolidines was attempted using a variety of literature methods. However none of them appeared suitable for our purpose, mainly because of the lability of the 5 membered heterocyclic ring. Then, we looked for an amine oxide which could easily undergo 3+2 cycloaddition and whose N-alkyl group could be removed under mild conditions. We found that β-amino alcohol (protected) derived amine oxides gave good yields of the corresponding pyrrolidines. Hofmann elimination of the quatemary ammonium salt followed by debenzylation gave quantitatively the N-H pyrrolidines substituted in positions 2, 3 or 4. This methodology is used for the synthesis of a precursor of kainic acid and one of its analogues. In the second part, we propose an original and general method for functionalisation of secondary amines at α-position. β-amino alcohol (unprotected) derived amine oxides treated with t-butyllithium give oxazolidines after intramolecular trapping of the intermediate immonium by the alcoholate. Opening of the oxazolidine ring by a Grignard reagent and removal of the amino alcohol moiety (according to the sequence described above) give access to α-alkylated amines. Several exemples are reponed
Moog, Iona. „Sur des oxydes de cérium contenant du fer nanostructurés et de morphologies contrôlées“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00806578.
Girard, Vincent. „Etude des propriétés de regénération par voie oxydante d'oxydes métalliques sulfurés“. Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00944308.
Ben, Salem Roua. „Catalyseurs à base d'oxydes métalliques fluorés : synthèse, caractérisations et applications catalytiques“. Electronic Thesis or Diss., Lyon 1, 2023. https://n2t.net/ark:/47881/m6c53kx4.
This thesis work focuses on the synthesis of new fluorinated metal catalysts, using trifluoroacetic acid (TFAH) as fluorine precursor, their physico-chemical characterizations and the study of their acid-base properties in the gas and aqueous phases. The first synthesis is the anionic exchange between oxo/hydroxo supports of titanium, of niobium and of zirconium, with high specific areas, and a solution of TFAH. The fluorine retention, before and after calcination, is greater using the zirconium support. The presence of fluorine inhibits the basicity of the zirconia and generates Brønsted acidity due to the electron-withdrawing effect of fluorine and makes the catalyst’s surface more hydrophobic. Fluorinated zirconia produces selectively propene from isopropanol in gas phase and pyruvaldehyde from dihydroxyacetone in water. The second synthesis is new multi-step approach coupling the decomposition of an yttrium-based fluorine precursor Y(TFA)3(H2O)3 into YF3 NPs and their incorporation into TiO2. Various physico-chemical characterization techniques (XPS, XRD, 19F NMR) indicate that fluorine exists in the form of YF3 in the TiO2 matrix, stable at after calcination at 500°C. YF3 dispersed in TiO2 of high surface area catalyzes efficiently the conversion of dihydroxyacetone (DHA) in water
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
Trenque, Isabelle. „Synthèse et caractérisation d'oxydes métalliques ZnO au bénéfice de nouvelles stratégies d'élaboration d'absorbeurs IR“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-01017168.
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.
Trenque, Isabelle. „Synthèse et caractérisation d’oxydes métalliques ZnO au bénéfice de nouvelles stratégies d’élaboration d’absorbeurs IR“. Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR14905/document.
Thanks to its absorption / reflexion properties limited to the UV and the IR range, n-doped zinc oxide is a promising candidate for the elaboration of transparent and insulating films in smart windows. Nanostructured particles of Ga-doped zinc oxide were elaborated by polyol process. Polyol process was used in order to control the size and the morphology of the particles. Both experimental and theoretical data show that a maximum of IR absorption efficiency is obtained for a doping rate of 2.6 molar percent. Colloidal suspensions with high transmission in the visible range combined with significant absorption of the near infrared range were obtained using two strategies. The first one is the encapsulation of the Ga-doped ZnO particles by a fluoride shells with an intermediate refractive index between ZnO and the dispersion medium. The second one is the optimization of the dispersion state of nano-colloidal suspensions thanks to the adsorption of thioalkanes on the Ga-doped ZnO crystallite surfaces
Cherizol, Robenson. „Études des propriétés catalytiques des nanocatalyseurs d'argent et de cuivre supportés sur l'alumine pour la réduction des NOx“. Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28199/28199.pdf.
Popuri, Srinivasa Rao. „Etude expérimentale des relations structure-propriétés et des effets de dimensionnalité dans des oxydes de cobalt et de vanadium“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00927123.
Sturza, Mihai-Ionut. „Oxyfluorures de fer de type pérovskite : influence du sous-réseau anionique sur les structures et les propriétés physicochimiques“. Thesis, Lille 1, 2011. http://www.theses.fr/2011LIL10070/document.
The development of transition metal oxides with remarkable physical properties involves a strict control of the metal valence, usually resulting from complexes substitutions in the cationic subarray. An interesting alternative is the modification of the anionic subarray via F− for O2− substitution. The crystallochemistry of these two different species induces significant structural changes and leads to new polytypes. We have focused our attention on the Ba/Sr-Fe-O system in which the partial introduction of fluorine leads to the new compounds Ba/SrFeO3-δF1-y with evidence of polytypes related to perovskites 3C-,15R- and 6H-Ba/Sr(Fe,M)O3-δ.We show in an unprecedented way, the easy access to a large amount of vacancies within the pseudo-cubic phase Sr0.8Ba0.2Fe(O,F)~2.5 stable at room-temperature. The drastic effect of the incorporation of a small amount of fluorine passes through the local repartition of O/F/, creating constraints and shifting the tolerance factor into the pseudo-cubic range, for highly deficient compounds.In the case of Fe-based hexagonal perovskite (15R-BaFeFxO3-δ (0.15≤x≤0.35), 6H-Ba0.8Sr0.2FeFxO3-δ (0.15≤x≤0.25)) the partial incorporation of F- leads to extended disorder structures which show reversible removal/incorporation of oxygen and possible ionic conductivity, even at low temperature. From our structural characterizations, this phenomenon would be driven by a giant “breathing phenomenon” which accompanies the reorganization of the anionic (O,F) subarray versus temperature. We show that this partial introduction of fluorine leads to a drastic increase of the AFM ordering close to the highest values reported in iron oxides (TN ≈ 700 K)
Matar, Mohamad. „Exploration de nouvelles voies pour l'ignifugation des polymères“. Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0067/document.
In this study, we have tried to develop new formulations to improve the thermal stability and fire behavior of three polymer matrices widely used: the polyethylene (PE), the polystyrene (PS) and the polyamide 66 (PA 66). The intumescent system used consists to combine a classical flame retardants (ammonium polyphosphate (APP) and pentaeryhthritol (PER)) with a small amount of nanooxides whose properties can be adjusted in order to improve the compatibility of the melting mixture, or to change the degradation mechanism by a chemical (catalytic effect) or physical (insulating layer, viscosity, etc …) process. The total amount of additives has been set at 25wt%. An important part of this study was consecrated to the synthesis of oxides with different morphologies, porosities, structures and functionalities. In this regard, the mesoporous silica has an advantage of having a high surface area (700-1400 m²/g) and a pore size compatible with the polymer chains. By adapting the synthesis conditions, we have aimed to correlate between some parameters related to the prepared silicas (such as (1) the specific surface area (2) particle size (3) pore size (4) morphology and (5) the type of structure (usually SBA-15)) on the thermal stability and fire behavior of different polymer matrices. A comprehensive study has been conducted globally, regardless of the matrix, that the improvements provided by the mesostructured silicas are modest compared to those elicited by classical FR. However, the fire behavior has been improved (particularly LOI) by combining APP/PER system with 1-2wt% of SBA-15. The surface modification of SBA-15 by grafting a different organic functions (CTAB, amine, thiol, phenol, phosphonate, benzoic acid and diphenylphosphate), inorganic species (aluminum, phosphoric acid and tungstophosphoric acid) or metals (copper, nickel) have been the subject of an advanced characterizations in order to assess the amount and the thermal stability of the grafted species, well as the nature of the surface bonds. Other types of synthetic nanooxides (aluminophosphates, zirconium phosphate and titanate nanotubes) or commercial (CeO2, ZrO2, CeZr and CePr) have been also studied. Most of these particles in combination with APP/PER system have shown a slightly positive effect on the thermal stability and fire behavior of polymers. In mechanistic terms, the nanooxides have mainly an effect on enhancing the barrier effect. The analyses carried out by Py/GC/MS showed that the grafted oxides by acidic species catalyze the conversion of alkenes and dienes (resulting from the decomposition of PE) to aromatics. In the presence of SBA-15, the analysis of char (by XRD and FTIR) shows the formation of new crystalline phases which enhance the protective layer
André, Rémi F. „Tailored routes to metal-containing nanoparticles for hydrogenation reactions in solution : surface design for H2 activation“. Electronic Thesis or Diss., Sorbonne université, 2021. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2021SORUS190.pdf.
In this thesis work, the use of metal-containing nanoparticles such as carbides, oxides and phosphides is explored for colloidal catalysis. In an attempt to build a Frustrated Lewis Pair (FLP)-like catalytic system for H2 activation, the synergy with a molecular Lewis base is assessed. In the bibliographic introduction, the stakes and the challenges of H2 activation in solvent are presented, with an emphasis on the use of non-purely metallic catalysts for the hydrogenation of model compounds. In the first part, early transition metal carbides and hydrides are synthesized via solid-state metathesis. The influence of process parameters is explored to tune the phase speciation in the products. The most promising carbon-supported catalysts, Mo2C/C and W2C/C, are studied for gas phase and liquid phase hydrogenations of olefins. In the second part, cerium and indium oxides are obtained via hydrothermal pathways. The relevance of oxygen defects in CeO2-x is established for H2 gas phase activation and semi-hydrogenation of phenylacetylene in solvent. The last part is dedicated to the non-aqueous syntheses of molybdenum and tungsten oxides, and nickel carbide and phosphides. The syntheses mechanisms are studied by means of NMR for the organic species and XAS and XRD for the nature of the inorganic species. The catalytic activity of the unsupported nanoparticles is finally evaluated for the hydrogenation of nitrobenzene and phenylacetylene in various solvents
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