221 f. / Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2013-03-27T17:00:44Z No. of bitstreams: 1 Tese Juliana Fonseca.pdf: 14472345 bytes, checksum: 164f08902adbe200b28632881de4d3b5 (MD5) / Approved for entry into archive by Ana Hilda Fonseca(anahilda@ufba.br) on 2013-06-04T17:31:12Z (GMT) No. of bitstreams: 1 Tese Juliana Fonseca.pdf: 14472345 bytes, checksum: 164f08902adbe200b28632881de4d3b5 (MD5) / Made available in DSpace on 2013-06-04T17:31:12Z (GMT). No. of bitstreams: 1 Tese Juliana Fonseca.pdf: 14472345 bytes, checksum: 164f08902adbe200b28632881de4d3b5 (MD5) Previous issue date: 2012 / CNRS,CAPES,CNPq / A pesquisa visou à preparação de catalisadores de ouro e/ou cobre para a reação de oxidação preferencial do monóxido de carbono (CO-PrOx). Em uma primeira etapa, nanopartículas de ouro e/ou cobre (1 m/m%) foram suportadas em um óxido de cério comercial. O cobre foi adicionado por impregnação em meio aquoso e o ouro em meio orgânico. Análises de DRX e medidas de área superficial específica mostraram que a impregnação dos metais não alterou as propriedades texturais do suporte, mas modificaram as suas propriedades redox. Medidas de capacidade de estocagem de oxigênio (OSC) e análises de redução à temperatura programada (TPR) mostraram que os metais aumentaram a redutibilidade da céria. Os testes catalíticos mostraram que, abaixo de 120 °C, houve um aumento da conversão do CO, alcançando 100% nos catalisadores contendo cobre e 98% no Catalisador Au/CeO2. Acima de 120 °C, a conversão do CO diminuiu em todos os catalisadores devido à reação reversa de WGS. Os testes catalíticos conduzidos em isoterma (100 °C) mostraram que os catalisadores contendo ouro foram os mais ativos, porém menos seletivos. A presença de CO2 diminuiu a conversão dos três catalisadores. A adição de H2O somente desativou o Catalisador CuOx/CeO2. Na segunda etapa da tese, foram sintetizados óxidos contendo cério e alumínio pelo método de auto-estruturação induzida por evaporação do solvente. Estes suportes apresentaram elevadas áreas superficiais específicas, favorecendo uma elevada dispersão do cério. Os difratogramas de raios X mostraram que a alumina era amorfa mesmo após a incorporação de pequenas quantidades de cério. Com a adição 15 e 20 mol% Ce, houve a formação de nanocristais de CeO2. As isotermas de adsorção de N2 a 77 K e as imagens de microscopia eletrônica de transmissão confirmaram o arranjo hexagonal mesoporoso da alumina. Esta estrutura desapareceu progressivamente com a introdução do cério. A análise de RMN das amostras mostrou a presença de picos de alumínio em coordenação tetra, penta e octaédrica. As análises de XPS dos sólidos contendo cério mostraram a presença de uma porcentagem alta de Ce3+, indicando que uma fase mista à base de cério e alumínio deve estar presente e apresenta uma elevada redutibilidade a uma temperatura superior àquela de redução da céria; além de capacidade de estocagem de oxigênio mais alta que a esperada ao se considerar o óxido misto: CeO2-Al2O3. A velocidade de troca de oxigênio (obtida nos experimentos de troca isotópica 18O2/16O) foi mais alta sobre a céria, mas as amostras contendo 10, 15 e 20 mol% de cério mostraram um número de átomos de oxigênio trocados superior ao da céria, indicando uma mobilidade de quase todos os átomos de oxigênio nos óxidos mistos (superfície+volume). Na terceira parte da tese, os óxidos contendo cério e alumínio (CeXAl) foram utilizados como suportes para catalisadores contendo 1 m/m% de ouro. O ouro foi depositado pelo método de impregnação em meio orgânico. Todos os catalisadores mostraram valores elevados de área superficial específica (de 198 a 337 m² g-¹). A redutibilidade, a capacidade de estocagem e a mobilidade do oxigênio dos catalisadores aumentaram com a presença do ouro e com o aumento do teor de cério nos suportes. No entanto, os valores de OSC e a mobilidade de oxigênio dos catalisadores contendo 10, 15 e 20 mol% Ce foram mais altos que aqueles obtidos com o Catalisador Au/CeO2. A atividade de oxidação do CO aumentou com o aumento do teor de cério nos suportes, o que foi relacionado com a mobilidade do oxigênio nestes sistemas. No entanto, na reação de CO-PrOx, os catalisadores contendo 5 e 10 mol% de cério apresentaram as conversões mais elevadas nas temperaturas entre 50 e 60 °C. Os catalisadores foram estáveis nos testes realizados a 100 °C durante 5 h. A adição de CO2 na mistura reacional desativou o Catalisador Au/CeO2, enquanto que os Catalisadores Au/CeXAl foram menos afetados. Em todos os catalisadores, a presença de vapor d’água não apresentou influência significativa nos desempenhos catalíticos. / Salvador

L'étude a porté sur la conversion en presence de catalyseurs bimétaliques supportes de trois molécules modèles de polyols (érythritol, xylitol et sorbitol) en phase aqueuse à 150-240 ° C sous 30-120 bar de H2 pour obtenir sélectivement des produits linéaires C4, C5 et C6 désoxygénés qui sont des précurseurs de polymèrs. L'activité catalytique dépend fortement de la nature du support utilisé (TiO2 vs ZrO2) et la plus grande sélectivité pour les produits désoxygénés linéaires voulus C4, C5 et C6 à une conversion de 80% est de 71, 66 et 54%, respectivement, en présence de catalyseur mixte à base de rhodium et du rhenium à 200 ° C sous 80-120 bar. Les caractérisations des catalyseurs par chimisorption de CO, MET-EDX, TGA-MS et XPS suggèrent une distribution et une réductibilité différentes des espèces de Re sur les nanoparticules Rh supportées en fonction du support permettant d'expliquer ces différences / The aim of our research project reports a study of heterogeneously catalyzed conversion of three polyol model molecules (erythritol, xylitol, and sorbitol) in aqueous phase at 150-240 °C under 30-120 bar of H2 to obtain selectively linear deoxygenated C4, C5, and C6 products used as precursors for polymer applications. The activity was strongly dependent on the nature of the support (TiO2 vs ZrO2) and the highest selectivity to the desired linear deoxygenated C4, C5, and C6 products at 80% conversion reached 71, 66, and 54%, respectively, in the presence of Rh–ReOx bimetallic catalysts at 200°C under 80-120 bar. The characterizations of the catalysts by CO chemisorption, TEM-EDX, TGA-MS, and XPS suggest a different distribution and reducibility of Re species over the supported Rh nanoparticles depending on the support that can explain these differences

Les catalyseurs Pt-Rh supportés ont montré des propriétés intéressantes en ouverture sélective des naphtènes. Les performances catalytiques de ces catalyseurs dépendent, entre autres, de l'interaction entre le rhodium et le platine. L'objectif de ces travaux portait sur l'étude de l'influence de la méthode de préparation sur les interactions Pt-Rh. Dans ce but, plusieurs voies reposant sur des stratégies de synthèse différentes ont été sélectionnées, des plus classiques, comme l'imprégnation, aux plus sophistiquées, comme la modification d'un catalyseur monométallique parent par ajout d'un second métal par réaction de surface, la formation des particules Pt-Rh au sein de microémulsion ou de microsuspension ou encore la réduction des précurseurs métalliques assistée par radiolyse. Les catalyseurs ont été caractérisés par diverses techniques telles que la chimisorption d'hydrogène, la microscopie électronique en transmission, la réduction en température programmée, l'adsorption de molécules sondes (CO ou NO puis CO) suivie par infrarouge ou encore par réactions modèles. Ces caractérisations ont permis de mettre en évidence que (i) les imprégnations classiques ou assistées par radiolyse mènent à un mélange de particules monométalliques et bimétalliques, (ii) les méthodes de modification de surface permettent le dépôt du second métal sur les sites spécifiques des particules métalliques préformées, (iii) la synthèse des particules métalliques en microsuspension ou microémulsion permet également l'obtention de particules bimétalliques, mais avec la présence d'alliages Pt-Rh de surface. / Pt-Rh supported catalysts have demonstrated interesting properties in selective ring opening of naphthenic molecules. Their catalytic performances depend on several properties like platinum-rhodium interaction. The aim of this work was to study the influence of the preparation method on Pt-Rh interactions. For this purpose, several preparation ways were selected, from the most classical ones, such as impregnation, to more sophisticated ways such as (1) surface modification of monometallic catalyst by addition of a second metal (surface reactions), (2) formation of Pt-Rh particles in microemulsion or in microsuspension, or (3) impregnation assisted by radiolysis. Catalysts were characterized by various techniques such as hydrogen chemisorption, transmission electron microscopy, temperature programmed reduction, adsorption of probe molecules (CO or NO then CO) followed by infrared spectroscopy, or model reactions.These characterizations allowed demonstrating that (i) the classical impregnation or the one assisted by radiolysis leads to monometallic and bimetallic particles, (ii) metal deposition on specific sites of preformed metallic particles can be obtained by surface modification of monometallic catalysts, (iii) the synthesis of metallic particles in microemulsion or microsuspension yields bimetallic entities with Pt-Rh alloy at the particle surface.

Les jasmonates de méthyle sont des oxylipines asymétriques impliquées dans les mécanismes de défense, de développement et de régulation des organismes photosynthétiques terrestres ou marins face à des stress biotiques et abiotiques. Parmi les quatre stéréoisomères, seuls l’épi-jasmonate et l’ent-épi-jasmonate de méthyle possèdent de bonnes propriétés organoleptiques mais aussi une forte activité phytohormonale permettant l’élicitation de métabolites secondaires bioactifs. En ciblant spécifiquement une hexokinase mitochondriale régulant le métabolisme des cellules cancéreuses, les jasmonates de méthyle constituent d’excellents candidats pour de nouveaux agents thérapeutiques. Dans la recherche constante de nouvelles molécules thérapeutiques issues du milieu naturel, notre laboratoire s’est donc focalisé sur la synthèse énantiosélective de l’épi-jasmonate et l’ent-épi-jasmonate de méthyle, au départ de diols bicycliques homochiraux monoprotégés dérivant du cyclooct-1,5-diène.Afin d’obtenir ces diols bicycliques énantiopurs, une stratégie innovante a consisté en l’étude de la réaction d’électrocyclisation du méso-époxyde dérivé du cyclooct-1,5-diène assistée par des ligands chiraux métallés diversement fonctionnalisés, les catalyseurs de Jacobsen. En mettant à profit notre savoir-faire sur les désymétrisations enzymatiques, une stratégie parallèle optant pour la résolution énantiosélective de diols homochiraux monocycliques, ou de diols bicycliques C2-symétriques nous a permis d’accéder à des silanyloxyindèn-5-ones chirales, précurseurs clé des cis-jasmonates de méthyle énantiopurs. Enfin, la synthèse racémique de deux jasmonoïdes clé, la (±)--jasmolactone, puis le (±)-épi-jasmonate de méthyle a été validée en 15 étapes à partir du cyclooct-1,5-diène. / Methyl jasmonates are asymmetric oxylipins involved in defensive, developmental and regulative mechanisms of terrestrial and marine photosynthetic organisms in response to biotic and abiotic challenges. Among the four stereoisomers, only methyl epi-jasmonate and ent-epi-jasmonate show good organoleptic properties but also phytohormonal activity allowing the elicitation of bioactive secondary metabolites. Because they specifically target a mitochondrial hexokinase regulating the metabolism of cancer cells, methyl jasmonates have become excellent candidates as new therapeutic agents. With a constant attention on new therapeutic agents derived from the natural environment, our laboratory has focused on the enantioselective synthesis of methyl epi-jasmonate and ent-epi-jasmonate using monoprotected homochiral diols derived from cyclooct-1,5-diene.In order to obtain these chiral bicyclic diols, an innovative strategy has involved the study of the chemo-stereoselective electrocyclization of the cyclooct-1,5-diene-derived meso-epoxide assisted by chiral metallated ligands known as Jacobsen’s catalysts. Taking advantage of our knowledge of enzymatic desymmetrization, a second strategy opting for the enantioselective resolution of monocyclic homochiral diols or C2-symmetric bicyclic diols led access to chiral silanyloxyinden-5-ones, key precursors to chiral methyl cis-jasmonates. Meanwhile, the racemic synthesis of (±)--jasmolactone and methyl (±)-epi-jasmonate was validated in 15 steps starting from cyclooct-1,5-diene.

During this PhD thesis, cobalt (Co) catalysts have been prepared, characterized and studied in the carbon monoxide hydrogenation (CO+H2) reaction (also known as “Fischer-Tropsch” (FT) reaction). In industry, the FT synthesis aims at producing long chain hydrocarbons such as gasoline or diesel fuels. The interest is that the reactants (CO and H2) are obtained from other carbonaceous sources than crude oil: natural gas, coal, biomass or even petroleum residues. As it is well known that the worldwide crude oil reserves will be depleted in a few decades, the FT reaction represents an attractive alternative for the production of various fuels. Moreover, this reaction can also be used to produce high value specialty chemicals (long chain alcohols, light olefins…).<p>Two different types of catalysts have been investigated during this thesis: cobalt with magnesia used as support or dispersant (Co/MgO) and cobalt with silica used as support (Co/SiO2). Each catalyst from the first class is prepared by precipitation of a mixed Co/Mg oxalate in acetone. This coprecipitation is followed by a thermal decomposition under reductive atmosphere leading to a mixed Co/MgO catalyst. On the other hand, Co/SiO2 catalysts are prepared by impregnation of a commercial silica support with a chloroform solution containing Co nanoparticles. This impregnation is then followed by a thermal activation under reductive atmosphere.<p>The mixed Co/Mg oxalates and the resulting Co/MgO catalysts have been extensively characterized in order to gain a better understanding of the composition, the structure and the morphology of these materials: thermal treatments under reductive and inert atmospheres (followed by MS, DRIFTS, TGA and DTA), BET surface area measurements, XRD and electron microscopy studies have been performed. Moreover, an original in situ technique for measuring the H2 chemisorption surface area of catalysts has been developed and used over our catalysts.<p>The performances of the Co/MgO and Co/SiO2 catalysts have then been evaluated in the CO+H2 reaction at atmospheric pressure. Chemical Transient Kinetics (CTK) experiments have been carried out in order to obtain information about the reaction kinetics and mechanism and the nature of the catalyst active surface under reaction conditions. The influence of several experimental parameters (temperature, H2 and CO partial pressures, total volumetric flow rate) and the effect of passivation are also discussed with regard to the catalyst behavior.<p>Our results indicate that the FT active surface of Co/MgO 10/1 (molar ratio) is entirely covered by carbon, oxygen and hydrogen atoms, most probably associated as surface complexes (possibly formate species). Thus, this active surface does not present the properties of a metallic Co surface (this has been proved by performing original experiments consisting in switching from the CO+H2 reaction to the propane hydrogenolysis reaction (C3H8+H2) which is sensitive to the metallic nature of the catalyst). CTK experiments have also shown that gaseous CO is the monomer responsible for chain lengthening in the FT reaction (and not any CHx surface intermediates as commonly believed). Moreover, CO chemisorption has been found to be irreversible under reaction conditions.<p>The CTK results obtained over Co/SiO2 are quite different and do not permit to draw sharp conclusions concerning the FT reaction mechanism. More detailed studies would have to be carried out over these samples.<p>Finally, Co/MgO catalysts have also been studied on a combined DRIFTS/MS experimental set-up in Belfast. CTK and Steady-State Isotopic Transient Kinetic Analysis (SSITKA) experiments have been carried out. While formate and methylene (CH2) groups have been detected by DRIFTS during the FT reaction, the results indicate that these species play no role as active intermediates. These formates are most probably located on MgO or at the Co/MgO interface, while methylene groups stand for skeleton CH2 in either hydrocarbon or carboxylate. Unfortunately, formate/methylene species have not been detected by DRIFTS over pure Co catalyst without MgO, because of the full signal absorption.<p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Les bisoxazolines de symétrie C2, ligands chiraux bidentates formés par deux cycles oxazolines séparés par un atome de carbone portant deux substituants identiques, font partie de ligands le plus utilisés en chimie de coordination et en catalyse asymétrique (homogène et hétérogène). Ce travail décrit la synthèse de treize ligands polytopiques chiraux comportant des unités bisoxazolines. Ces ligands ont été par la suite utilisés, d'une part, en tant que ligands chiraux pour la construction des catalyseurs auto-supportés de Cu(II)/ ligand polytopique (catalyseurs testés par la suite dans les réactions d' α-amination de β-cétoesters énantiosélective, de desymétrisation asymétrique par benzoylation de meso-diols, de dédoublement cinétique de rac-diols et dans la nitroaldolisation du nitrobenzaldehyde ou réaction de Henry); et d'autre part, en tant que briques deconstruction dans l'autoassemblage alterné et contrôlé de polymères de coordination métalloorganiques racémiques et énantiopurs. / Chiral C2-symmetric bis(oxazolines), bidentate ligands formed by two oxazoline rings separated by a carbon atom with two identical substituents, are one of the most popular types of chiral ligands which have already been successfully used in coordination chemistry and asymmetric catalysis (heterogeneous and homogeneous). This work describes the synthesis of thirteen polytopic chiral ligands bearing bis(oxazolines) moieties which have then been used, on the one hand, as chiral ligands for the construction of selfsupported Cu(II)/ polytopic ligand catalysts which were subsequently tested in the enantioselective α-hydrazination of β-ketoesters, the asymmetric desymmetrization of meso-diols by benzoylation and the kinetic resolution of rac-diols and the nitroaldolisation reaction (Henry reaction); and on the other hand, as organic building blocks for the controlled and alternate self-assembly of racemic and enantiopur metal-organic coordination polymers.

L’objectif de ce travail était de démontrer la possibilité de coupler sur un même catalyseur, la fonction de stockage et réduction des NOx (sur le baryum) avec un effet électrochimique reposant sur un système micropile. Ce système micropile est composé de nanoparticules catalytiques (Pt et Rh) déposés sur conducteur ionique par les ions O2- (YSZ) en contact avec un support conducteur électronique (SiC dopé) de façon à pouvoir générer, sous mélanges réactionnels, une force électromotrice capable de réduire électrochimiquement une partie des NOx sur le Pt et d’oxyder le CO, les hydrocarbures imbrûlés et H2 sur le Rh. L’effet micropile a été observé sur un catalyseur Pt/Ba (matériau de stockage)/YSZ/Rh enduit dans les canaux d’un filtre à particule en carbure de silicium dopé, en condition essence pauvre à 400°C et en condition Diesel à plus basse température (300°C). Une augmentation de la conversion des NOx d’environ 10% a été observé sur les catalyseurs micropile. L’effet électrochimique a été détecté par une surproduction de CO2, en milieu riche (très peu ou pas de O2) provenant de la réaction d’oxydation électrochimique du CO (produit par vaporeformage) en réagissant avec les ions O2- provenant de YSZ. De plus, des tests catalytiques ont montré que YSZ peut être utilisée comme matériau de stockage des NOx. En effet, un traitement réducteur préalable augmente fortement sa capacité de stockage des NOx / The main objective of this study was to demonstrate the coupling between NOx storage/reduction process on barium, with an electrochemical reduction of NOx (micro fuel cell effect) on the same catalyst. The micro fuel cell effect is ensured by a an electromotive force (potential) which is created between catalytic nanoparticules (Pt and Rh) in contact with an ionic conductor (YSZ) and an electronic conductor (doped SiC). The micro fuel cell effect was observed, during the regeneration phase of the catalysts (rich period), on a Pt/Ba/doped α-SiC-YSZ/Rh monolithic system under lean-burn gasoline conditions at 400°C with an enhancement of about 10 % of the NOx conversion over a complete cycle lean/rich. This electrochemical effect was characterized by the electrochemical oxidation of CO (produced by steam reforming) into CO2 by using O2- ions coming from YSZ. Under Diesel conditions, the micro fuel cell system was found to work at low temperature especially at 300°C. In the second part of the work, a new generation of NOx Storage and reduction catalyst was developed consisting only of noble metals (Pt and/or Rh) deposited on YSZ support (Ba free catalyst). The catalytic measurements revealed that YSZ can be used as a NOx storage material in lean burn conditions (Gasoline and Diesel) especially when it was previously reduced under hydrogen. The storage mechanism would take place on the oxygen vacancies created by the removal of O-2 ions from the YSZ structure

Plusieurs ligands dérivés de la D-glucosamine, conçus pour différentes réactions catalytiques,ont été synthétisés. Les ligands pour la catalyse homogène basés sur 1,2-glucodiamine ontété préparés, et utilisés dans des réactions d'alkylation allylique, d'hydrogénation et d'additionde Michael.La D-glucosamine a utilisee pour la preparation de catalysateur type de SPAC (SupportedAqueous Phase Catalyst). Ce catalysateur hétérogène été utilisé avec de très bons résultatsdans les réactions de couplage croisé de Suzuki Miyaura. Le catalyseur a également étérecyclé. Des essais de préparation de ligands greffés sur une matrice de silice de type SBA-15ont été réalisés ainsi que des ligands à base de poly (éthylène) glycol. / Several ligands derived from D-glucosamine, designed for different catalytic reactions havebeen synthesized. The ligands for homogeneous catalysis based on 1,2-glucodiamine wereprepared, and used in reactions of allylic alkylation, hydrogenation and Michael addition.Supported Aqueous Phase Catalyst (SAPC) system was prepared from D-glucosamine anduse with very good results in Suzuki Miyaura cross coupling reactions. Catalyst was alsorecycled. Attempt to prepare ligands grafted on SBA-silica matrix were made as well asligands containing poly(ethylene) glycol moiety.

Cette thèse décrit le développement de procédés utilisables pour valoriser des extraits de bois afin de préparer : (1) des combustibles (hydrocarbures) liquides ; (2) des matériaux poreux avec des applications potentielles dans les domaines de l’énergie et l’environnement, notamment isolation thermique, catalyse, piégeage et séparation de micropolluants. Les extraits de bois en question sont des lignines, associées ou non à des tannins. Les deux types de matériaux sont actuellement peu valorisés, et l’on montre qu’ils peuvent être source de valeur ajoutée au travers des procédés rapportés dans ce mémoire / The present thesis describes the development of processes which can be used for valorizing wood extracts in the aim of preparing: (1) liquid (hydrocarbon) fuels; (2) porous materials with potential energy and environmental applications, namely thermal insulation, catalysis, abatement or separation of micropollutants. The wood extracts in question are lignins, associated or not with tannins. Both kinds of materials are presently poorly valorized, and it is shown here that they can lead to high added-value products through the processes reported in this PhD dissertation

Les travaux de cette thèse sont centrés sur le développement de systèmes moléculaires en solution homogène pour la production photocatalytique de dihydrogène dans l'eau utilisant des catalyseurs de cobalt à ligands pentadentate tétrapyridinique ou tétra- et pentaaza macrocycliques. Associés au photosensibilisateur et à l’ascorbate comme donneur d’électron sacrificiel, les complexes à ligands macrocycliques présentent d’excellentes performances pour la production d’H2, bien supérieures à celles des complexes à ligands polypyridiniques en termes d’efficacité et de stabilité, en raison de la grande stabilité de leur état réduit «Co(I)». Enfin, [Ru(bpy)3]2+ a pu être substitué par un colorant organique très robuste du type triazatriangulénium conduisant à un système photocatalytique encore plus performant. Ces résultats démontrent que les colorants organiques sont une alternative viable aux photosensibilisateurs à base de métaux nobles, même en milieu aqueux acide. / The work of this manuscript is focused on the design of molecular systems in homogeneous solution for photocatalytic production of molecular hydrogen in water using cobalt catalysts with pentadentate tetrapyridinic and tetra- and pentaza macrocyclic ligands. In association with [Ru(bpy)3]2+ as photosensitizer and sodium ascorbate as sacrificial electron donor, the macrocycle based catalysts display high performances for H2 production, far exceeding those of the polypyridine based catalysts, both in terms of activity and stability, because of the stability of their reduced state «Co(I)». Finally, [Ru(bpy)3]2+ was successfully substituted with a robust organic dye belonging to the triazatriangulenium family, leading to an even more efficient photocatalytic system. These results demonstrate well that organic dyes are a truly efficient alternative to noble metal based photosensitizers, even in acidic aqueous medium.