Neste trabalho foi sintetizada e caracterizada uma série de porfirinas e FeP correspondentes contendo substituintes NO2 nas posições orto- ou grupos COOH nas posições para- dos anéis meso-fenis, e a atividade catalítica destes compostos na oxidação de hidrocarbonetos foi investigada, tanto em sistemas homogêneos quanto em sistemas suportados. As porfirinas H2(TNMCPP), H2(DNDCPP) e H2(MNTCPP) foram sintetizadas pela reação de pirrol com a mistura de 2-nitrobenzaldeído e 4-carboxibenzaldeído, em meio de ácido propiônico e nitrobenzeno, sendo em seguida isoladas e purificadas através de cromatografia preparativa em sílica gel tendo como eluente a mistura DCM : ACT : HAc (8 : 2 : 0,1). A inserção de ferro nas porfirinas bases livre foi feita pela reação com FeBr2.2H2O em meio de DMF. A caracterização das porfirinas bases livre e das correspondentes FeP envolveu diferentes técnicas como: TLC, eletroforese em gel de agarose, análise elementar, UV/Vis, IV, RMN 1H, FAB MS, susceptibilidade magnética e EPR. Utilizou-se as porfirinas H2(TNPP) e H2(TCPP) e FeP correspondentes como padrões de comparação, tornando a série completa. A purificação e caracterização destas porfirinas mostraram-se bastante complexas devido à presença de grupos ionizáveis resultando em grandes diferenças de solubilidade na série e efeitos de agregação. Estes efeitos foram mais pronunciados para as porfirinas contendo maior número de grupos COOH. O estudo da atividade catalítica da série de FeP foi desenvolvido inicialmente em meio homogêneo, utilizando diferentes substratos como: (Z)-cicloocteno, cicloexeno, cicloexano e adamantano. As FeP sintetizadas mostraram-se catalisadores eficientes e seletivos para a hidroxilação de alcanos e epoxidação de alcenos. A estabilidade da Fe(TNMCPP)Cl foi investigada em reações com múltiplas adições de oxidante. Observou-se uma alta estabilidade para este catalisador em solução, com bons rendimentos em epóxido para até sete ciclos consecutivos, e um alto número de turnover (1142). A Fe(TNMCPP)Cl foi ancorada na APS através de ligação covalente (peptídica) entre o grupo COOH da FeP e o grupo NH2 da sílica funcionalizada. Esta FeP foi selecionada por possuir apenas um grupo capaz de reagir com a sílica e, ao mesmo tempo, a proteção estérica de três grupos NO2 substituintes nas posições orto-, constituindo um sistema interessante do ponto de vista catalítico. Este sistema mostrou-se bastante eficiente na oxidação do (Z)-cicloocteno. O número máximo de turnover catalítico para esta FeP suportada foi de 595 após três adições sucessivas de oxidante. A Fe(TNMCPP)Cl foi ancorada na APS também por atração eletrostática, porém este sistema mostrou-se menos eficiente como catalisador na oxidação do (Z)-cicloocteno. / In this work, a series of porphyrins and corresponding FeP containing NO2-substituents in the ortho- or COOH-groups in the para- meso-phenyl rings were synthesized and the catalytic activities of such compounds were investigated in both homogeneous and heterogeneous systems. H2(TNMCPP), H2(DNDCPP) and H2(MNTCPP) porphyrins were synthesized through the mixed co-condensation of pyrrole and different benzaldehydes (2-nitrobenzaldehyde and 4-carboxybenzaldehyde) in propionic acid and nitrobenzene media. The porphyrins were then isolated and purified through silica gel chromatography, having a solvent mixture DCM : ACT : HAc (8 : 2 : 0,1). The characterization of the free-base porphyrins and the corresponding FeP was carried out through TLC, electrophoresis on agarose gel, elemental analysis, UV/Vis, infra red, RMN 1H, FAB MS, magnetic susceptibility and EPR. H2(TNPP) and H2(TCPP) and corresponding FeP were used for comparison, thus completing the porphyrin series. The purification and characterization of these porphyrins proved to be very complex due the presence of ionic groups. This resulted in different solubilities throughout the series, as well as aggregation effects. Such effects were more pronounced with porphyrins containing a greater number of COOH groups. The study of the catalytic activities of the FeP was initially carried out in homogeneous system, by using various substrates: (Z)-cyclooctene, cyclohexene, cyclohexane and adamantane. The synthesized FeP were efficient and selective catalysts for alkane hydroxilation and alkene epoxidation. The stability of Fe(TNMCPP)Cl was investigated by multiple oxidant addition. A high stability was observed for this catalyst in homogeneous system, since it led to good epoxide yields up to the seventh cycle and an excellent turnover number of 1142. Fe(TNMCPP)Cl was supported on APS through covalent binding of the peptidic type between COOH groups in the FeP and NH2 group on the funcionalized silica. This FeP was chosen for the study since it has only one group that is capable of reacting with the silica, at the same time that it presents sterical hindrance confered by the three NO2 groups in the ortho-position. This is a very interesting system from the catalytical point of view. Such system proved to be very efficient in the oxidation of (Z)-cyclooctene. The maximum catalytic turnover attained with this supported FeP was of 595, after three sucessive additions of oxidant. Fe(TNMCPP)Cl was also supported on APS though electrostatic binding, but this system was a less efficient catalyst for (Z)-cyclooctene oxidation.

Made available in DSpace on 2016-08-19T12:56:40Z (GMT). No. of bitstreams: 1 Dissertacao Debora.pdf: 2922945 bytes, checksum: a0781d0cbab272005bd65274fd6cdf1c (MD5) Previous issue date: 2012-04-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aims to prepare, characterize and study materials type perovskite (Ba3BB‟2O9 and Ba2BB‟O6) as catalysts for the reaction of NOX and CO conversion, seeking other alternatives for catalytic converters. The compounds were prepared using a polymeric precursor method, calcined at 500, 700 and 900 ° C in the period of two hours. Characterized by X-ray diffraction, infrared by transformed of Fourier, Raman and Microscopy electronic of scanning spectroscopy. According to DRX, the method favors the formation of perovskite phases treated at 400 °, 500 °, 700 ° and 900 ° C, obtaining the desired compounds in the presence of the secondary phase. In the analysis of infrared spectroscopy, verified the presence of a characteristic vibrational, that to correspond the connection between the metal-oxygen, which becomes more intense when occurs the increase in the heat treatment. This behavior has been confirmed by the stretching associated with internal vibration of the oxygen of the octahedron in 360 cm-1 and 410 cm-1 of the A1g(O) e 2Eg(O) observed in the sample belonging to the order of 1:2. For catalytic activity toward conversion reaction of the gases mentioned, were more active for CO, highlighting the perovskite Ba3CaNb2O9 where the conversion was directly proportional to the formation of the structure of the compound and the reduction of the presence of secondary phase. / Objetivo deste estudo foi preparar, caracterizar e estudar materiais tipo perovskita (Ba3BB‟2O9 e Ba2BB‟O6) como catalisadores para reação de conversão de NOX em N2 e CO em CO2, buscando desenvolver conversores catalíticos alternativos. Os compostos foram preparados pelo método do precursor polimérico, calcinados a 500, 700 e 900°C, no período de duas horas. Os compostos foram caracterizados estruturalmente por difração de raios X, infravermelho por transformada de Fourier e espectroscopia Raman e morfologicamente por microscopia eletrônica de varredura. De acordo com os resultados de difração de raios X, o método favoreceu a formação das fases de perovskitas tratadas nas temperaturas de 500, 700 e 900°C, obtendo compostos desejados na presença de fase secundária. Nas análises de espectroscopia na região do infravermelho, verificamos a presença de um modo vibracional característico, que corresponde à ligação entre metal-oxigênio, que se torna mais intenso à medida que ocorre o aumento da temperatura de tratamento térmico. Tal comportamento foi confirmado pelos estiramentos associadas com a vibração interna do oxigênio do octaedro em 360 cm-1 e 410 cm-1 do A1g(O) e 2Eg(O) observados nas amostras pertencentes ao ordenamento 1:2. Para atividade catalítica frente à reação de conversão dos gases citados, foram mais ativos para CO, ressaltando a perovskita de Ba3CaNb2O9 onde a conversão foi diretamente proporcional a formação da estrutura do composto e a diminuição da presença da fase secundária.

Orientador: Gustavo Paim Valença / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-23T11:37:38Z (GMT). No. of bitstreams: 1 Vesga_PabloMiguelCoha_M.pdf: 3148003 bytes, checksum: e990cb6467a80b515b813438a624fd7d (MD5) Previous issue date: 2013 / Resumo: Reações de desidrogenação e desidratação no etanol são de grande interesse, já que levam à produção de compostos que são utilizados na indústria química, farmacêutica e cosmética. No presente trabalho, catalisadores de magnésio e molibdênio suportados na peneira molecular MCM-41 foram utilizados no estudo das reações de desidrogenação e desidratação de etanol. Os catalisadores foram preparados através da impregnação por umidade incipiente de nitrato de magnésio e heptamolibdato de amônia, com teores de 0,5% a 2,0% em massa para o magnésio e de 3,0% para o molibdênio. O Mg após a impregnação se apresentou como óxido de Mg e o Mo como óxido de Mo ou carbeto de Mo. Os materiais foram secados, calcinados e caracterizados através de Microscopia Eletrônica de Varredura (MEV), Energia Dispersiva de Raios-X (EDS), Difração de Raios X (DRX), Adsorção Física de Nitrogênio, Análise Infravermelho, Análise Termogravimétrica (TGA). Depois de calcinados, os catalisadores foram carregados no reator, pré-tratados e então testados nas reações de conversão de etanol entre 200 °C e 300 °C. Os produtos da reação foram analisados por cromatografia gasosa (CG). Houve produção de metano, propano, propeno, acetaldeído, éter etílico, 1,3-butadieno, acetato de etila, etano e eteno. A pressão parcial do etanol foi mantida fixa em 7870 Pa. A temperatura que mais favoreceu a reação foi 300 °C e o catalisador que apresentou maior conversão foi aquele possuía 0,5% de Mg e 3,0% de Mo, este último metal na forma de carbeto de Mo. Dos catalisadores testados, os que apresentaram maiores atividades catalíticas foram os que possuíam menor porcentagem de Mg devido a algumas propriedades como maior área superficial. Os catalisadores que possuíam carbeto de Mo favoreceram mais as reações que aqueles que tinham óxido de molibdênio, demonstrando mais uma vez que é um excelente composto para ser usado em reações, especialmente de desidrogenação / Abstract: Dehydrogenation and dehydration reactions with ethanol are interesting, because of these processes produce compounds that are highly used in the chemical, pharmaceutical, cosmetic and biological industries. At present, MCM-41 catalysts impregnated with magnesium and molybdenum are used to study ethanol dehydration and dehydrogenation reactions. The catalysts were prepared by impregnating magnesium nitrate and ammonium heptamolibdate in the silica supports, with a theoretical metal content of 0,5% to 2,0% for magnesium and 3,0% for molybdenum; the Mg was used in oxide form while the Mo was in oxide and carbide form. The solids were dried, calcinated and characterized by Scanning Electron Microscopy (SEM), EDS Analysis, X-Ray Diffraction (XRD), Nitrogen Adsorption, Thermo-Gravimetric Analysis (TGA), Infra-red Analysis (FT-IR). After calcination, the catalyst was loaded into the reactor to undergo pretreatment before being tested in ethanol reactions at low temperatures (473 - 573 K). The gases products of reaction were analyzed by Gas Chromatography (GC). The products were methane, propane, propeno, acetaldehyde, ether ethylic, 1,3-butadiene, ethyl acetate, ethane and ethylene. The partial pressure of ethanol was always the same and maintained at 7870 Pa. The optimal temperature for the reaction was found to be 573 K and the catalyst that had the biggest conversion of ethanol was MCM-41 with 0,5% Mg and 3,0% Mo, with the Mo in carbide form. Of the catalysts tested, those which showed higher catalytic activity were those that had the lowest percentage of Mg due to some properties such as a higher surface area. Catalysts impregnated with Mo carbide had more favorable reactions than those with molybdenum oxide, once again showing that it is an excellent compound for use in reactions, especially dehydrogenation reactions / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

En vue du changement climatique et de la transition énergétique, le présent travail s’intègre dans le projet ANR VItESSE2 portant sur le stockage d’énergie électrique renouvelable et la valorisation du CO2 par hydrogénation en méthanol sur des catalyseurs au cuivre. Au cours de cette thèse, une méthode analytique pour la mesure des surfaces de cuivre par chimisorption de N2O a été mise au point. À partir de tests catalytiques sous 50 bar, des modèles cinétiques pour des catalyseurs Cu/ZnO/Al2O3 et Cu/ZnO/ZrO2 ont été élaborés. Pour l’étude mécanistique, un montage infrarouge en réflexion diffuse a été développé afin d’étudier différents catalyseurs pour la synthèse de méthanol et pour la réaction du gaz à l’eau. Le montage a servi pour des tests catalytiques in situ à 34 bar sous flux réactionnel. L’étude a été complétée par des expériences de désorption thermoprogrammée de différentes molécules sonde. Les résultats suggèrent que le catalyseur Cu/ZnO/ZrO2 est plus sélectif pour le méthanol que Cu/ZnO/Al2O3 et qu’un mode de préparation favorisant les interactions Cu–ZnO–ZrO2 peut être bénéfique pour l’activité catalytique. / In view of the climate change and the energy transition, this work is part of the ANR project VItESSE2 about renewable electric energy storage and CO2 valorization by methanol hydrogenation on copper catalysts. During this thesis, an analytical method for copper surface measurement by N2O chemisorption was developed. Based on catalytic tests at 50 bar, kinetic models for Cu/ZnO/Al2O3 and Cu/ZnO/ZrO2 catalysts were elaborated. For the study of the mechanism, a diffuse reflection infrared setup was developed in order to study different catalysts for methanol synthesis and water-gas shift reaction. The setup was used for in situ catalytic tests at 34 bar under reaction flow. The study was complemented by temperature programmed desorption experiments with different probe molecules. The results suggest that the Cu/ZnO/ZrO2 catalyst is more selective for methanol than Cu/ZnO/Al2O3 and that a preparation method which favors Cu–ZnO–ZrO2 interactions can be beneficial for catalytic activity.

De nombreuses mesures pour réduire les émissions anthropiques de gaz à effet de serre et plus particulièrement de CO2, existent déjà, elles restent cependant insuffisantes. C’est dans ce cadre qu’a vu le jour le projet ANR VItESSE2 visant à développer un procédé de conversion de CO2,issu de certaines industries, en méthanol par réduction à l’hydrogène produit par électrolyse de l’eau à partir d’électricité fournie par des énergies faiblement émettrices de CO2 (énergie nucléaire et les énergies renouvelables). Ce procédé permet aussi d’assurer, une fonction de gestion du système électrique en reliant la production d’hydrogène aux quantités d’électricités disponibles sur le réseau. Les principaux objectifs de la thèse sont la synthèse et la caractérisation de catalyseurs performants ainsi que la mise au point des conditions réactionnelles conduisant à la meilleure productivité en méthanol. L’optimisation des systèmes catalytiques a permis de développer un catalyseur de type CuO-ZnO-ZrO2 compétitif par rapport aux catalyseurs commerciaux actuellement sur le marché. / Numerous measures to reduce anthropogenic emissions of greenhouse gases, especially CO2, already exist; however they are still insufficient. It is in this context that the ANR project VItESSE2 emerged to develop a method for converting CO2 produced by industries. The aim of this project is to transform CO2 into methanol, by reduction with hydrogen produced by water electrolysis using electricity provided by decarbonised energies (nuclear and renewable energies). This process also allows to secure a management function of the electrical grid by connecting the production of hydrogen to the available quantity of electricity in the network. The main objectives of this thesis are the synthesis and the characterization of efficient catalysts for CO2 hydrogenation into methanol and the development of reaction conditions leading to improved methanol productivity. The optimization of catalyst systems allowed to develop a CuO-ZnO-ZrO2 catalyst competitive in relation to commercial catalysts currently on the market.

Les catalyseurs à base de nanoparticules de Pd sont largement utilisés dans l’industrie des oléfines. Ceux-ci permettent d’hydrogéner les sous produits de la réaction tel que l'acétylène (C2H2) qui peut empoisonner et désactiver le catalyseur. Toutefois, le Pd, bien que très actif pour la réaction d’hydrogénation, est peu sélectif. Ainsi, l'acétylène et l'éthylène (qui sont des hydrocarbures insaturés) interagissant avec le Pd peuvent être hydrogénés en éthane (C2H6), qui est un produit toxique. Ainsi, un effort considérable est consacré à l’amélioration de la sélectivité des catalyseurs à base de Pd. Ce travail de thèse rentre dans ce cadre. Il consiste à décrire à l’échelle moléculaire les sites actifs du catalyseur au Pd et à identifier les mécanismes réactionnels qui peuvent avoir lieu. Le but étant de comprendre comment les propriétés intrinsèques du catalyseur au Pd varient avec la taille, la forme, les supports d'oxyde et l'incorporation d'additifs métalliques, afin d'améliorer leur sélectivité. L'hydrogénation de l'éthylène en acétylène est étudiée en tant que réaction prototype.Pour atteindre ces objectifs, la Théorie de la Fonctionnelle de la Densité, via une approche périodique à l’aide du code VASP, a été appliquée à plusieurs modèles de catalyseurs de Pd. Ces modèles constitués de nanoparticules de quelques atomes (Pdn, n=1,2,..,7, 13, and 55) et de surface semi-infinie de Pd(111) ont permis d’étudier l’effet de la forme et de la taille sur les propriétés magnétiques et sur la réactivité du Pd. L’étude de la réactivité a concerné essentiellement les mécanismes d’adsorption de C2H2 et C2H4. Ensuite, étant donné que, dans les conditions réelles, les catalyseurs sont stabilisés sur des supports oxyde de type TiO2, la surface de ce dernier a été considérée dans nos modèles. Ainsi, les propriétés électroniques et la réactivité des nanoparticules libres et supportées ont pu être comparées pour mettre en évidence l’effet du support. Enfin, dans le but d’améliorer la sélectivité du Pd, et de prédire un catalyseur performant, des additifs de type métaux de transition (M avec M=Au, Ag, Cu, Co, Ni, Fe etc..) ont été considérés. En effet, en misant sur les effets de synergie qui peuvent se produire pour des couples bimétalliques grâce aux modifications des densités électroniques, il a été possible de prédire des combinaisons de métaux (PdM) dont les propriétés électroniques sont différentes de celles des éléments pris séparément. L’étude des chemins réactionnel et l’identification des barrières d’activation semblent indiquer que les systèmes Pd-Fe et Pd-Co sont des candidats intéressants. / The catalysts based on Pd nanoparticles are widely used in the olefin purification industry. This allows to hydrogenate the by-products of the reaction such as acetylene (C2H2), which can poison and deactivate the catalyst. Although Pd-based catalysts are very active for the hydrogenation reaction, they have a low selectivity. Thus, acetylene and ethylene (which are unsaturated hydrocarbons) interacting with the Pd-catalysts may be hydrogenated to ethane (C2H6), which is a toxic product. Considerable effort is devoted to improve the selectivity of catalysts based on Pd. The present thesis is within this framework. It describes at the molecular level the active sites of Pd-model catalysts and identifies the reaction mechanisms. The goal is to understand how the intrinsic properties of Pd catalyst vary with different size and shape, oxide supports and incorporation of metal additives, in order to improve their selectivity. The hydrogenation of ethylene to acetylene is studied as a prototype reaction. To achieve the goal, periodic Density Functional Theory approach, as implemented in the VASP code, was applied to several Pd-catalysts models. These models include nanoparticles of few atoms (Pdn, n=1,..,7, 13, and 55) and semi-infinite Pd surface (111). They were used to study the effect of the shape and size on the magnetic and electronic properties, and their influence on the reaction pathways. The first step in the reaction mechanism is the adsorption of C2H2 and C2H4. Therefore, the adsorption mechanism was also examined for various magnetic isomers of Pdn structures. Because in the real conditions, the catalysts are often stabilized on TiO2 oxide supports, the surface of the latter was considered in our models. Thus, the electronic properties and reactivity of free and supported Pd-nanoparticles could be compared to reveal the effect of the support. Finally, in order to improve the selectivity of Pd, and predict an effective catalyst, transition metals additives (M = Au, Ag, Cu, Co, Ni, Fe etc...) have been considered. Indeed, building on the synergies that can occur for bimetallic couples through changes in electron densities, it was possible to predict combinations of metals (PdM) whose electronic properties are different from those of their monometalic counterpart. The study of reaction pathways and identification of activation barriers suggest that Pd-Fe and Pd-Co systems are the best candidates.

The anthropogenic carbon dioxide (CO2) emission into the atmosphere, mainly through the combustion of fossil fuels, has resulted in a balance disturbance of the carbon cycle. Overwhelming scientific evidence proves that the escalating level of atmospheric CO2 is deemed as the main culprit for global warming and climate change. It is thus imperative to develop viable CO2 capture and sequestration (CCS) technologies to reduce CO2 emissions, which is also essential to avoid the potential devastating effects in future. The drawbacks of energy-cost, corrosion and inefficiency for amine-based wet-scrubbing systems which are currently used in industry, have prompted the exploration of alternative approaches for CCS. Extensive efforts have been dedicated to the development of functional porous materials, such as activated carbons, zeolites, porous organic polymers, and metal-organic frameworks (MOFs) to capture CO2. However, these adsorbents are limited by either poor selectivity for CO2 separation from gas mixtures or low CO2 adsorption capacity. Therefore, it is still highly demanding to design next-generation adsorbent materials fulfilling the requirements of high CO2 selectivity and enough CO2 capacity, as well as high water/moisture stability under practical conditions. Metal-organic frameworks (MOFs) have been positioned at the forefront of this area as a promising type of candidate amongst various porous materials. This is triggered by the modularity and functionality of pore size, pore walls and inner surface of MOFs by use of crystal engineering approaches. In this work, several effective strategies, such as incorporating 1,2,3-triazole groups as moderate Lewis base centers into MOFs and employing flexible azamacrocycle-based ligands to build MOFs, demonstrate to be promising ways to enhance CO2 uptake capacity and CO2 separation ability of porous MOFs. It is revealed through in-depth studies on counter-intuitive experimental observations that the local electric field favours more than the richness of exposed nitrogen atoms for the interactions between MOFs and CO2 molecules, which provides a new perspective for future design of new MOFs and other types of porous materials for CO2 capture. Meanwhile, to address the water/moisture stability issue of MOFs, remote stabilization of copper paddlewheel clusters is achieved by strengthening the bonding between organic ligands and triangular inorganic copper trimers, which in turn enhances the stability of the whole MOF network and provides a better understanding of the mechanism promoting prospective suitable MOFs with enhanced water stability. In contrast with CO2 capture by sorbent materials, the chemical transformation of the captured CO2 into value-added products represents an alternative which is attractive and sustainable, and has been of escalating interest. The nanospace within MOFs not only provides the inner porosity for CO2 capture, but also engenders accessible room for substrate molecules for catalytic purpose. It is demonstrated that high catalytic efficiency for chemical fixation of CO2 into cyclic carbonates under ambient conditions is achieved on MOF-based nanoreactors featuring a high-density of well-oriented Lewis active sites. Furthermore, described for the first time is that CO2 can be successfully inserted into aryl C-H bonds of a MOF to generate carboxylate groups. This proof-of-concept study contributes a different perspective to the current landscape of CO2 capture and transformation. In closing, the overarching goal of this work is not only to seek efficient MOF adsorbents for CO2 capture, but also to present a new yet attractive scenario of CO2 utilization on MOF platforms.

No description available.

Ces travaux de thèse s'inscrivent dans le cadre du projet CHEMLIVAL qui vise à valoriser la lignine en composés aromatiques fonctionnalisés (fonction : aldéhydes, acides carboxyliques, phénols) pour des applications en chimie fine ou polymères. Pour ce faire, nous avons étudié la valorisation de la lignine par voie d'oxydation catalytique hétérogène en milieu alcalin, une méthodologie respectueuse de l'environnement, pour la production de composés aromatiques telle que la vanilline ou la syringaldéhyde. Précédés par une caractérisation poussée des lignines utilisées dans cette étude, une optimisation des paramètres de la réaction (température, pression, catalyseurs…) ainsi que des suivis cinétique ont été réalisés. Ainsi des résultats comparables, voire supérieurs, à ceux décrits dans la littérature ont été obtenus. Ces travaux ont montré que la nature de la lignine ainsi que le procédé d'extraction lié à celle-ci avaient une grande influence sur les rendements en composés aromatiques. De plus, les résultats obtenus ont permis de proposer un schéma réactionnel d'oxydation de la lignine. L'utilisation d'un catalyseur (Pt/TiO2) a montré un effet bénéfique sur les rendements en composés aromatiques, probablement via un nouveau mécanisme d'oxydation de la lignine métallo-initié qui reste encore à élucider / This work is part of the CHEMLIVAL project aiming at the lignin valorization into functionalized aromatics compounds (functions : aldehydes, carboxylic acids, phenols) for fine chemistry or polymer applications. With this in mind, we studied lignin valorization through heterogeneous catalytic oxidation in alkaline media, an environmental friendly approach, for the production of aromatic compounds such as vanillin or syringaldehyde. After an extensive characterization of the different lignin samples used, we proceeded to an optimization of the conditions parameters (temperature, pressure, catalysts…) and kinetics study. As a results, yields similar or even higher than those reported in the literature were obtained. This work demonstrated that the lignin source as well as its extraction process has a great influence over the aromatic yields. Furthermore, the results acquired allowed us to propose a reaction scheme for lignin oxidation. The use of a catalyst (Pt/TiO2) was found to be beneficial for the production of aromatic compounds probably due to metallo-initiated mechanism that still needs to be identified

Cette thèse en partenariat avec Total Petrochemicals, porte sur deux grands axes: la préparation de nouveaux catalyseurs pour la polymérisation d'éthylène et l'analyse des propriétés des polyéthylènes obtenus. Face au grand nombre de combinaisons à tester et à la diversité de polymères produits, des méthodes de travail haut-débit sont indispensables pour la comparaison et la distinction de produits d'intérêt. Ainsi, le développement d'une nouvelle méthode de préparation de catalyseurs et de polymérisation en parallèle a permis de comparer directement et visuellement plusieurs complexes catalytiques suivant leur activité. Des méthodes d'analyse en parallèle ont également conduit à la comparaison de polyéthylènes produits suivant leur densité, leur température de fusion et leurs masses moléculaires. La détermination des masses moléculaires en parallèle a nécessité la conception d'un prototype de chromatographie planaire et le développement d'une nouvelle méthode d'analyse. L'ensemble de ces travaux en haut-débit a fourni un grand nombre d'informations. Le traitement statistique de cette banque de données permet d'apporter un outil de comparaison multi-paramètres et d'aide à la compréhension des relations catalyseur/propriétés de polymères. / This thesis in partnership with Petrochemicals Total, is composed of two main axis: preparation of new catalysts for ethylene polymerization and analysis of the properties of polyethylenes obtained. Face to a large number of combinations being tested and the diversity of produced polymer, high-throughput methods are essential for the comparison and the distinction of products of interest. Thus, the development of a new method for the preparation of catalysts and for polymerization in parallel leads to compare directly and visually several catalytic complexes according to their activity. Methods of analysis in parallel also led to the polyethylene comparison produced according to their density, melting point and molecular masses. The determination of the molecular masses in parallel required the design of a planar prototype of chromatography and the development of a new method of analysis. The whole of this work in highthroughput provided a large number of information. The statistical processing of this data bank brings a tool of multivariate comparison and helps to the comprehension of the relations catalyst/polymer properties.