Orientador: Carlos Alberto Gasparetto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-08T22:28:21Z (GMT). No. of bitstreams: 1 Ohata_SueliMarie_D.pdf: 1133009 bytes, checksum: d9e555381242748bb00e413dc46b8c7d (MD5) Previous issue date: 2007 / Resumo: Os reatores de recirculação representam uma tecnologia alternativa muito atraente para o processo de hidrogenação, tecnologia esta ainda não totalmente desenvolvida para a hidrogenação de óleos vegetais. Os reatores convencionais utilizados no processo de hidrogenação possuem agitação mecânica, sistema de injeção de hidrogênio na base, e necessitam de condições mais severas de operação, como a temperatura e a pressão. Em um reator que opera num sistema de recirculação, um ejetor tipo Venturi e utilizado, o qual proporciona uma grande transferência de massa entre as fases presentes, dispensando a agitação mecânica, alem de requerer quantidades menores de catalisador, demandar menos hidrogênio e trabalhar com pressão, temperatura e tempo de reação menor. Foram encontradas poucas informações na literatura a respeito do processo de hidrogenação de óleos vegetais através do reator de recirculação, desta forma, o objetivo deste trabalho foi analisar o processo de hidrogenação de óleo de soja em um reator de recirculação através da modelagem e simulação. Para a formulação do modelo que descreve este sistema, foram considerados os fenômenos de transferência de massa, alem da cinética da reação. A partir das equações obtidas, propos-se uma metodologia para solucionar o sistema de equações diferenciais que descrevem o sistema. Foram propostos dois modelos para o estudo: reator em batelada, resolvido analiticamente e uma associação de um reator CSTR em serie com um PFR com dispersão axial, resolvido pelo método da colocação ortogonal. Ambos os modelos descreveram adequadamente o processo de hidrogenação nas condições estudadas / Abstract: Loop reactors represent a very attractive alternative technology to the hydrogenation process, but this technology was not totally developed for the hydrogenation of vegetable oils. The conventional reactors used for the hydrogenation process have mechanical agitation, system of injection of hydrogen in the basis and they need more severe conditions of operation, as the temperature and the pressure. In a reactor that operates in a system loop, an ejector type Venturi is used, which provides an high mass transfer rate between the present phases, without mechanical agitation, needs less catalyst, demands less hydrogen and works with lower values of pressure, temperature and time of reaction. There is very little information in the literature about the hydrogenation process of vegetable oils in a loop reactor, thus, the purpose of this study was to analyse of the process of hydrogenation of soybean oil in a loop reactor by modelling and simulation. For the formulation of the model that describes this system, the phenomena of mass transfer and kinetics of the reaction were considered. From the balance equations, a method was considered to solve the system of differential equations that describe the system. Two models of reactors were proposed for the study: batch reactor, solved analytically and an association of a reactor CSTR in series with a PFR with axial dispersion, solved by orthogonal collocation method. Both models described the process of hydrogenation appropriately in the studied conditions / Doutorado / Doutor em Engenharia de Alimentos

Este trabalho teve como objetivo a síntese e caracterização de sílicas mesoporosas suportadas com níquel para atuarem como catalisadores na hidrogenação de óleos vegetais. Foram escolhidas as sílicas mesoporosas ordenadas do tipo SBA-15 e FDU-1, sintetizadas a partir de TEOS como fonte de sílica e copolímeros triblocos como agentes direcionadores de estrutura em meio HCl. O Ni(NO3)2.6H2O foi utilizado como fonte de metal, cuja solução aquosa com a concentração de níquel desejada foi adicionada à sílica antes da remoção do molde polimérico, originando os precursores dos catalisadores. Após a impregnação, as amostras foram submetidas à calcinação sob atmosfera de ar, gerando o precursor na forma de óxido que ao ser tratado com H2 é reduzido Nio , forma ativa do catalisador. As técnicas de termogravimetria, termogravimetria derivada, difração de raios X a alto e baixo ângulo, isotermas de adsorção de nitrogênio e absorção atômica foram empregadas para a caracterização destes materiais. A TG/DTG foi utilizada para a simulação das melhores condições de calcinação/redução. As amostras foram calcinadas em um forno tubular com controlador de temperatura. Os ensaios de DRX confirmaram a fase NiO após calcinação e a fase Nio na redução, por termogravimetria. A difração por raios X, confirmou a presença da fase Ni . Os resultados dos ensaios de difração de raios X a baixo ângulo indicaram que com teores de Ni de até 10%, não há modificação na estrutura dos materiais SBA-15 e FDU-1. As isotermas de adsorção de nitrogênio são do tipo IV, características de materiais mesoporosos. Os teores de níquel foram medidos por absorção atômica. Os valores de áreas superficiais dos materiais com 10% de Ni foram superiores a 300 m2 /g, sugerindo que tais materiais são promissores para prosseguir com os estudos e efetivamente testá-los como catalisadores na hidrogenação de óleos vegetais / This work aimed at the synthesis and characterization of mesoporous silica supported with nickel to act as catalysts in the hydrogenation of vegetable oils. The SBA-15 and FDU-1 were chosen as mesoporous ordered silica types, synthesized from TEOS as a source of silica and tribloco copolymers as molded agents of the structure in the midst HCl. The Ni(NO3)2.6H2O was used as a source of metal, whose aqueous solution with the desired concentration of nickel has been added to the silica before the removal of mold polymer, forming the catalytic precursors. After impregnation, the samples were subjected to calcination under air atmosphere, creating the precursor in the oxided form which being treated with H2 is reduced to Nio , active form of the catalyst. The TG techniques, thermogravimetric derived, X-ray diffraction at high and low angles, nitrogen adsorption isotherms, and atomic absorption spectrometry were used to characterize these materials. The TG / DTG were used for the simulation of best calcination / reduction conditions. The samples were calcined in a tubular oven with temperature controller. The DRX tests confirmed the NiO phase after calcination and Nio phase in the reduction by TG. The SAXS results indicated that Ni levels up to 10% do not change the material structures such as SBA-15 and FDU-1. The nitrogen adsorption isotherms are the IV type, characteristics of mesoporous materials . The nickel levels were measured by atomic absorption spectrometry. Surface area values for materials with Ni10% were greater than 300 m2 / g, suggesting that such materials are promising to proceed with the studies and test them effectively as catalysts in the hydrogenation of vegetable oils

DME est un carburant propre qui contribue à diminuer les émissions de gaz à effet de serre; il est aussi une molécule plate-forme pour le stockage d'énergie. L'objectif de la thèse est le développement de matériaux catalytiques bifonctionnels pour la synthèse directe de DME à partir de CO2/H2 à partir de Cu/ZnO/ZrO2 comme le catalyseur de la synthèse de méthanol à partir de CO2/H2 et Al-TUD-1 comme le catalyseur de déshydratation du méthanol en DME. Dans cette thèse, Al-TUD-1 a été étudiée comme un catalyseur de la déshydratation du méthanol en DME pour la première fois. Son activité en déshydratation du méthanol en DME augmente avec la diminution du rapport Si/Al. Les catalyseurs bifonctionnels ont été préparés par un procédé de dépôt par co-précipitation. Le SMSI a été démontré et était bénéfique pour la dispersion de cuivre métallique, la surface de cuivre métallique augmente avec le rapport Si/Al. Dans le même temps, on a observé le blocage des sites acides d'Al-TUD-1 par le cuivre. Afin d'exposer les sites acides d'Al-TUD-1, la méthode de « core-shell » a été adoptée pour préparer le catalyseur bifonctionnel. Elle aide à libérer la fonction acide en empêchant son blocage par le cuivre. Cette méthode de synthèse a été bénéfique pour la stabilité des particules de cuivre métalliques, mais des faibles conversions de CO2/H2 ont été observées en raison de l'inaccessibilité du noyau. Un autre catalyseur bifonctionnel a été préparé par une méthode de mélange physique pour comparaison. L'optimisation du catalyseur bifonctionnel Cu/ZnO/ZrO2@Al-TUD-1 pour la synthèse directe de DME à partir de CO2/H2 a permis d'éclairer les principaux paramètres affectant le contact intime de deux fonctions catalytiques: surface et dispersion du cuivre, les propriétés acide et basic, la présence d'eau et l'accessibilité des sites actifs pour les réactifs. / DME is a clean fuel that helps to diminish the emissions of green house gases; it is as well a platform molecule for the energy storage. The objective of the thesis is the development of bifunctional catalytic materials for the direct DME synthesis from CO2/H2 based on Cu/ZnO/ZrO2 as the methanol synthesis from CO2/H2 catalyst and Al-TUD-1 as the methanol dehydration to DME catalyst. In this thesis, Al-TUD-1 was investigated as the methanol dehydration to DME catalyst for the first time. The methanol dehydration to DME performance increases with the decrease of Si/Al ratio. The bifunctional catalysts were prepared by co-precipitation deposition method. The SMSI was demonstrated and was beneficial for the metallic copper dispersion, the metallic copper surface area increases with the Si/Al ratio. In the same time the blockage of acid sites of Al-TUD-1 by copper was observed. In order to expose the acid sites of Al-TUD-1, the core shell method was adopted to prepare the bifunctional catalyst. It helps to free the acid function preventing its blockage by copper. This method of synthesis was beneficial for the stability of metallic copper particles, but performed low conversions of CO2/H2 due to the inaccessibility of the core. Another bifunctional catalyst was prepared by physically mixing method for comparison. The optimization of the bifunctional Cu/ZnO/ZrO2@Al-TUD-1 catalyst for the direct DME synthesis from CO2/H2 allowed enlightening the main parameters that affect the intimate contact of two catalytic functions: copper surface area and dispersion, acid and basic properties, water presence and the accessibility of the active sites for the reactants.

Abstract The subject of this thesis is the characterization of chemical reactions and adsorption by means of remote detection (RD) method of nuclear magnetic resonance (NMR). The thesis consists of three related topics: In the first one, novel RD NMR based methods for characterizing chemical reactions were presented. In the second topic RD NMR methods were used to study the performance of new kind of microfluidic reactors. The third project concentrated on the development of a novel way to quantify the adsorption of flowing gas mixtures in porous materials. Even though all the topics cover quite different areas of research, they have few common nominators: remote detection NMR, microfluidics and method development. Microfluidic devices are of interest for many areas of science (such as molecular biology, disease diagnosis, chemistry) as they offer great promises for future technologies. Small dimensions enable, among many other things, the benefits of small sample volumes, large surface to volume ratio, efficient heat exchange and precise control of flow features and chemical reactions. The efficient evolution of microfluidic processes requires also the development of new innovative ways to characterize the performance of microfluidic devices. In this work, remote detection NMR is utilized for the purpose. RD is a method where the encoding and detection of information are separated physically. In many cases, the encoding and detection are performed with two separate RF coils while a fluid is passing through the studied system. In the first part of the thesis work, we introduced the concept of remote detection exchange (RD-EXSY) NMR spectroscopy. We demonstrated that the RD-EXSY method can provide unique chemical information. Furthermore, the time-of-flight (TOF) information, which is a natural side product of the experimental setup used, can be converted into indirect spatial information, showing the active reaction regions in a microfluidic device. Additionally, we demonstrated that by applying the principles of Hadamard spectroscopy in the encoding of the indirect spectral dimension we were able to produce with high efficiency RD-EXSY TOF images with direct spatial information. This allows even more accurate characterization of the active regions. The second topic concentrates on the development of microfluidc hydrogenation reactors. In the project atomic layer depositon (ALD) method was used for the first time to deposit both catalyst nanoparticles and support material on the surface of wall-coated microreactors. As a model reaction continuous flow propene hydrogenation into propane was studied by means of remote detection NMR. Reaction yield, mass transport phenomena and the activity of the catalyst surface were determined from the RD NMR data. Thirdly we presented a novel method for gas adsorption measurements in porous materials using RD TOF NMR. Traditional adsorption measurements are carried out at static conditions for a single gas component, as multi-component adsorption measurements are challenging and time-consuming. We investigated adsorption of continuously flowing propane and propene gases as well as their mixture in packed beds of mesoporous materials. The unique time-of-flight information obtained using the RD NMR method was utilized in the determination of flow velocity, which was then converted into amount of adsorbed gas.

Abstract Carbon nanotubes are a promising material for various applications due to their unique collection of properties. However, carbon nanotube material as such is inert and insoluble, which hampers the true realization of its potential. In order to enhance the applicability of carbon nanotubes, their surface must be modified. This work concerned the chemical modification of single-walled carbon nanotubes (SWNT) by the Birch reduction, which is based on the reduction of the SWNT surface with the valence electron of alkali metal solvated in liquid ammonia. The reduction generates a SWNT anion, which reacts with electrophiles resulting in the covalent attachment of functional groups to the tube surface. In this work, aryl halides or alcohols were used as electrophiles to yield arylated or hydrogenated SWNTs, respectively. At first, the goal was to modify SWNTs as a filler material for polystyrene. The use of five halogenated ethenylphenyl derivatives as electrophiles revealed that the structure of electrophile affected the success of functionalization and the solubility of SWNTs in polystyrene-toluene solution. The most successful functionalization and solubilization of SWNTs were achieved with 1-chloro-4-ethenylbenzene. In the second part, liquid ammonia was replaced with a new solvent, 1-methoxy-2-(2-methoxyethoxy)ethane (diglyme) in order to avoid the restrictions, hazards and inconvenience of its handling. The work concentrated on the study of alkali metal reduction of SWNTs in diglyme by the use of arylation with 4-iodobenzoic acid or 4-chlorobenzoic acid and hydrogenation as model reactions. Li, Na or K was used as an alkali metal while naphthalene or 1-tert-butyl-4-(4-tert-butylphenyl)benzene was used in order to enhance the solvation of electrons. As a result, functionalization was simplified and enhanced. Electrophile affected the functionalization in such a way that arylation was significantly more successful than hydrogenation. The effect of alkali metal and electron carrier varied with electrophile. The most successful hydrogenation was achieved with the complex of Li and 1-tert-butyl-4-(4-tert-butylphenyl)benzene while arylation was the most successful with the complex of K and naphthalene. The solubility of SWNTs in water, ethanol, methanol and dimethylformamide was clearly improved by arylation whereas hydrogenation led to moderate improvement. / Tiivistelmä Hiilinanoputket ovat ainutlaatuisten ominaisuuksiensa vuoksi lupaava materiaali moniin sovelluksiin, mutta liukenemattomuus ja epäreaktiivisuus haittaavat niiden tehokasta hyödyntämistä. Käytettävyyttä voidaan parantaa kemiallisella modifioinnilla. Tässä työssä yksiseinäisiä hiilinanoputkia modifioitiin Birch-pelkistyksellä, joka perustuu putken pinnan pelkistykseen nestemäiseen ammoniakkiin solvatoituneella alkalimetallin valenssielektronilla. Pelkistyksessä hiilinanoputkesta muodostuu anioni, joka reagoi elektrofiilin kanssa johtaen funktionaalisten ryhmien kovalenttiseen sitoutumiseen putken pintaan. Tässä työssä hiilinanoputkia aryloitiin käyttämällä aryylihalideja elektrofiilinä tai vedytettiin käyttämällä alkoholia. Aluksi tavoitteena oli hiilinanoputkien modifiointi sellaiseen muotoon, että niitä voitaisiin käyttää polystyreenin täyteaineena. Viittä aryylihalidia käyttämällä havaittiin, että elektrofiilin rakenne vaikutti funktionalisoinnin määrään ja putkien liukoisuuteen polystyreeni-tolueeni-liuokseen. 1-Kloori-4-etenyylibentseenillä saavutettiin onnistunein arylointi ja paras liukoisuus. Työn toisessa osassa luovuttiin ammoniakin käytöstä siihen liittyvien rajoitteiden ja haittojen vuoksi. Keskityttiin hiilinanoputkien alkalimetallipelkistyksen tutkimiseen uudessa liuottimessa, 1-metoksi-2-(2-metoksietoksi)etaanissa (diglyymi). Mallireaktioina käytettiin arylointia 4-jodibentsoehapolla tai 4-klooribentsoehapolla ja vedytystä alkoholilla. Ammoniakin korvaaminen diglyymillä yksinkertaisti ja tehosti funktionalisointia. Reaktiot suoritettiin eri alkalimetalleilla (Li, Na tai K). Naftaleenia tai 1-tert-butyyli-4-(4-tert-butyylifenyyli)bentseeniä käytettiin elektronien solvatoinnin parantamiseksi. Elektrofiilin rakenne vaikutti funktionalisointiin siten, että aryylihalidi johti huomattavasti onnistuneempaan funktionalisointiin kuin alkoholi. Alkalimetallin ja elektroninkantajamolekyylin vaikutus vaihteli elektrofiilin mukaan. Litiumin käyttö 1-tert-butyyli-4-(4-tert-butyylifenyyli)bentseenin kanssa johti onnistuneimpaan vedytykseen. Kaliumin käyttö naftaleenin kanssa johti onnistuneimpaan arylointiin. Hiilinanoputkien liukoisuus vaihteli elektrofiilin mukaan. Arylointi paransi selkeästi hiilinanoputkien liukoisuutta veteen, etanoliin, metanoliin ja dimetyyliformamidiin. Vedytyksen vaikutus liukoisuuteen oli vähäisempi.

La réaction d'hydrogénation des alcènes est une réaction clé dans de nombreux procédés industriels permettant la production de produits de commodité et de spécialité. D’importants efforts de recherche ont donc été réalisés pour développer des systèmes catalytiques de plus en plus productifs et sélectifs. Parmi les nombreux catalyseurs homogènes et hétérogènes développés à ce jour, les complexes organométalliques d’Iridium(I), très prometteurs, ont été préparés depuis la découverte du catalyseur de Crabtree, [Ir(COD)(py)(PCy3)]BF4, pour répondre à des problèmes de sélectivité dans l'hydrogénation asymétrique ou celle d’oléfines tétrasubstituées fortement encombrées en conditions homogènes. Cependant, l'utilisation industrielle de ce complexe organométallique d’Ir (I) est limité par sa décomposition rapide en solution, qui conduit à la formation de complexes polynucléaires (hydrures pontés d'Iridium) très stables et inactifs en catalyse. Le but de ce travail de thèse a été de développer des matériaux catalytiques contenant des complexes Ir(NHC) isolés à la surface d’une silice contenant des fonctionnalités imidazolium parfaitement distribuées le long de ses canaux poreux. L'isolement des unités Ir(I) sur le support de silice devrait permettre d’empêcher les processus bimoléculaires de désactivation et faciliter la récupération du catalyseur. La préparation des matériaux catalytiques cible se fait grâce a la transformation des unités imidazolium contenues dans le matériau de départ en carbenes d’argent N-hétérocycliques, qui sont ensuite transmétallés en carbènes d’iridium avec le complexe [Ir(COD)Cl]2. Les matériaux obtenus ont été caractérisés par diverses techniques, notamment une technique de RMN très avancée : la RMN de l’état solide utilisant la polarisation nucléaire dynamique. Ceci a permis de mieux comprendre la structure moléculaire des sites de surface iridiés. Les performances catalytiques des complexes Ir-NHC supportés ont été testées dans réaction d’hydrogénation des alcènes et comparées à celles de leurs homologues homogènes. Divers substrats oléfiniques et différentes conditions de réaction ont été testées. Les résultats montrent que le catalyseur supporté est beaucoup plus stable et 50 fois plus actif en terme de vitesse et de productivité. Cette approche a été étendue au développement de catalyseurs d’iridium supportés sur polymère. Le support choisi a été un polyéthylene téléchélique contenant des fonctionnalités iodées terminales. Le solide obtenu après incorporation de l’iridium a été caractérisé par RMN et spectrométrie de masse (MALDITOF). Les performances catalytique de ce nouveau système ont été elles aussi comparées a celles de complexes homologues en solution / Alkene hydrogenation is a key in many bulk and fine chemicals production processes. Major efforts were therefore directed towards the preparation of ever more productive and selective catalysts. Among the large number of homogeneous and heterogeneous catalysts, promising Iridium (I) organometallic complexes were prepared since the discovery of the well-known Crabtree’s catalyst, [Ir(COD)(py)(PCy3)]BF4, to address selectivity issues in homogeneous asymmetric hydrogenation or hydrogenation of highly hindered tetrasubstituted olefins. However, the industrial use of Ir organometallic complexes as catalysts is limited by their fast decomposition leading to the formation of highly stable and inactive polynuclear iridium hydridebridged complexes. The goal of this PhD project was to elaborate supported Ir(I)-NHC catalytic material to prevent such bimolecular deactivation processes. The targeted supported Ir complexes were based on hybrid organic-inorganic material containing regularly distributed imidazolium units along the pore-channels of the silica framework. Beside the Ir-site isolation on the silica support, this catalytic system was also expected to ease catalyst recovery at the end of the hydrogenation. The preparation of the final systems relies on the preparation of supported silver carbenes first, and further transmetallation with an Ir-precursor, namely [Ir(COD)Cl]2. The materials were characterized by several techniques as for example advanced solid state NMR using Dynamic Nuclear Polarization to gain insight into the molecular structure of the Ir surface sites. Catalytic performances of the supported Ir-NHC complexes were tested in alkene hydrogenation and compared to those of homogeneous homologues. Several different substrates and reaction conditions were tested. The results showed that the supported catalyst was much more stable and 50 times more active in term of rate and productivity. A polymer supported Ir-complex was also elaborated using a telechelic polyethylene iodide as support. The polymeric materials were fully characterized by NMR and MALDI-TOF experiments and their catalytic performances were compared to those of molecular analogues and those of silica supported systems

Le travail décrit dans cette thèse vise à produire des nanostructures bien ordonnées présentant une forte activité catalytique sur la base d’ensembles de nanoparticules de ruthénium et de fullerènes/fullerènes fonctionnalisés. Le Chapitre 1 présente une analyse bibliographique sur l’utilisation des fullerènes en catalyse hétérogène, en mettant en avant leurs propriétés particulières telles que la stabilité thermique, une grande capacité d'adsorption d'hydrogène et la capacité d’obtenir diverses coordinations. Le Chapitre 2 décrit la synthèse et la caractérisation de nanostructures Ru@C60 obtenues par la réaction de décomposition par au dihydrogène du complexe [Ru(COD)(COT)] en présence de C60. L'effet du solvant et des rapports de Ru/C60 utilisés durant la réaction ont été étudiés. Plusieurs caractérisations d’objets sphériques Ru@C60 et des calculs DFT nous permettent de proposer une voie pour leur formation. Le Chapitre 3 présente la préparation de nouveaux nano-assemblages obtenus à partir de [Ru(COD)(COT)] et de fullerènes fonctionnalisés en utilisant la même méthode décrite dans le chapitre 2. Tout d'abord la synthèse de fullerènes fonctionnalisés C66(COOH)12 est détaillée, puis la synthèse et la caractérisation des nanostructures Ru@C66(COOH)12 ont été étudiés. Le Chapitre 4 décrit l'utilisation de ces nanomatériaux en catalyse. Nous avons préparé trois Ru@fullerene: Ru@C60 dans du dichlorométhane, T-Ru@C60 dans le toluène et Ru@C66(COOH)12. Ensuite, l'activité catalytique et la sélectivité des catalyseurs préparés Ru@C60, T-Ru@C60 et Ru@C66(COOH)12 ont été étudiées pour l'hydrogénation du nitrobenzène et du cinnamaldéhyde. Des calculs DFT ont permis de rationaliser les résultats obtenus pour l'hydrogénation sélective de nitrobenzène sur Ru@C60. / The work described in this thesis aims to produce well-ordered nanostructures presenting high catalytic activity, on the bases of the assembly of ruthenium nanoparticles and fullerene/functionalized fullerene. Chapter 1 provides a review on the use of fullerene and fullerene-based materials in heterogeneous catalysis, emphasizing their specific properties such as thermal stability, high capacity for hydrogen adsorption and the ability of various coordination modes. Chapter 2 describes the synthesis and characterization of Ru@C60 nanostructures produced by the decomposition reaction of [Ru(COD)(COT)] in the presence of C60. The effect of the solvent and ratios of Ru/C60 on the course of the reaction have been investigated. Several characterizations of spherical Ru@C60 objects and DFT calculations allow us to propose a pathway for their formation. Chapter 3 presents new nano-assembly preparation based on [Ru(COD)(COT)] and functionalized fullerene using the same method as they are described in chapter 2. First, the synthesis of functionalized fullerene C66(COOH)12 is detailed, and then the synthesis and characterization of Ru@C66(COOH)12 is studied. Chapter 4 describes the use of these nanomaterials in catalysis. We have prepared three Ru@fullerene catalysts, which are Ru@C60 in dichloromethane, T-Ru@C60 in toluene, and Ru@C66(COOH)12. Then, the catalytic activity and selectivity of the prepared catalyst Ru@C60, T-Ru@C60 and Ru@C66(COOH)12 are studied for the hydrogenation of nitrobenzene and cinnamaldehyde. DFT calculations allow to rationalize the results obtained for the selective hydrogenation of nitrobenzene over Ru@C60.

L'objectif de ce travail était double : obtenir des informations sur le lien structure/réactivité dans les nanoalliages et évaluer l'impact de l'addition d'or sur les propriétés catalytiques de métaux actifs en hydrogénation. Des nanoparticules bimétalliques Au-Pd et Au-Rh ont été synthétisées et supportées principalement sur des nanobâtonnets TiO2 rutile, caractérisées par différentes techniques d'analyse (DLS, UV-Vis, HR-(S)TEM, XRD, XPS et CO-FTIR), et évaluées dans deux réactions d'hydrogénation. Les catalyseurs modèles ont été principalement préparés par voie colloïdale suivie d'une immobilisation sur le support et d'un post-traitement consistant à éliminer le surfactant sans détruire la structure des nanoparticules. Les particules Au-Pd (3-5 nm) possèdent une structure alliée de type solution solide. La structure des particules Au-Rh (3-5 nm), système immiscible en volume, est plus hétérogène, avec différentes configurations en fonction du post-traitement effectué : coeur-coquille, ségrégation de phases de type « Janus » et alliage à l'échelle atomique en faible proportion. Les catalyseurs bimétalliques ont été testés en hydrogénation de la tétraline en présence de soufre et en hydrogénation sélective du cinnamaldéhyde, dans les deux cas sous haute pression d'hydrogène, et comparés à leurs homologues monométalliques. En hydrogénation du cinnamaldéhyde, un effet considérable du traitement post-synthèse sur l'activité et sélectivité est mis en évidence. Les catalyseurs fraichement synthétisés montrent une sélectivité élevée en hydrocinnamaldéhyde alors que les traitements de réduction et de calcination-réduction diminuent l'activité pour les échantillons AuRh les plus riches en Rh. En hydrogénation de la tétraline, l'alliage avec l'or a pour effet de diminuer l'activité mais d'améliorer la stabilité des systèmes à base de Pd et Rh en présence de soufre, en augmentant, par effet électronique, la barrière de chimisorption du soufre ou de sulfuration / The objectives of this work were to gain an insight into the structure-selectivity relationships in nanoalloys and to evaluate the impact of gold addition on the catalytic properties of active metals in hydrogenation reactions. For this purpose, bimetallic Au-Pd and Au-Rh nanoparticles were synthesized and supported (mostly) on rutile TiO2 nanorods before being structurally characterized by various techniques (DLS, UV-Vis, HR-(S)TEM, XRD, XPS, and CO-FTIR) and evaluated in two hydrogenation reactions. The model catalysts were mainly prepared using a colloidal method and immobilized on the support. Post-treatments were carried out in order to eliminate the surfactant used during the synthesis, with minimal impact on the nanoparticle structure. The influence of the synthesis parameters on the nanoparticle structure and catalytic properties was evaluated. The Au-Pd particles (3-5 nm) exhibit an alloyed solid solution structure. The structure of the bulk-immiscible Au-Rh particles (3-5 nm) is more heterogeneous, with several structural configurations depending on the post-treatment: core-shell, Janus-type phase segregation, and atomic-scale alloyed structure to a small extent. The catalysts were tested for tetralin hydrogenation in the presence of sulfur (0-100 ppm H2S) and for the selective hydrogenation of cinnamaldehyde, both under high hydrogen pressure. The bimetallic systems were compared to their monometallic counterparts. The post-synthesis treatments have a dramatic impact on activity and selectivity in cinnamaldehyde hydrogenation. The fresh catalysts exhibit a high selectivity toward hydrocinnamaldehyde, whereas reduction and calcination-reduction mainly decrease the activity of Rh-rich Au-Rh samples. For tetralin hydrogenation, gold decreases the activity but improves the stability of Pd and Rh-based systems in the presence of sulfur through electronic effects increasing sulfur chemisorption or sulfidation barriers

Orientadores: Sergio Gama, Pedro Jorge von Ranke / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-08T01:09:57Z (GMT). No. of bitstreams: 1 Carvalho_AlexandreMagnusGomes_D.pdf: 6808779 bytes, checksum: b779b54728ac489a69ae449f1e33d093 (MD5) Previous issue date: 2006 / Resumo: Este trabalho apresenta resultados de estudos estruturais, magnéticos e magnetocalóricos de alguns compostos à base de gadolínio, germânio e silício. Os estudos estruturais incluem análises por microscopia ótica e eletrônica, além de difração de raios-X. As análises magnéticas restringem-se a medidas de magnetização em função da temperatura e do campo magnético. Utilizando essas técnicas, são estudados compostos sob diferentes condições de processamento, tais como: amostras como fundidas; tratadas termicamente; pulverizadas e sinterizadas. Os compostos Gd5Ge4 e Gd5Ge2Si2 são também analisados magneticamente sob pressão hidrostática. Adicionamos hidrogênio aos compostos Gd5Si4, Gd5G e2Si2 e Gd5Ge2,1S i1,9 e substituímos Ge e Si por Sn no composto Gd5Ge2Si2, criando novas famílias de materiais, as quais também foram analisadas pelas técnicas supracitadas. Além do trabalho experimental, são apresentados resultados teóricos para o efeito magnetocalórico, utilizando o modelo de Landau-Devonshire. Apresentamos também resultados fenomenológicos para o composto Gd5Ge2Si2 sob pressão hidrostática, utilizando o Modelo de Acoplamento Spin-Rede (MASR) / Abstract: This work presents the results from structural, magnetic and magnetocaloric studies about some compounds based on Gd, Ge and Si. Structural studies include optical and electronic microscopy analyses, besides X-ray diffraction. Magnetic analyses are limited to measurements of magnetization as a function of temperature and magnetic field. Using these techniques, the compounds are investigated under different processing conditions, such as: as-cast, heat-treated, powdered and sintered samples. Gd5Ge4 and Gd5Ge2Si2 compounds are also analyzed through magnetic measurements performed under hydrostatic pressure. We have inserted hydrogen atoms into Gd5Si4, Gd5G e2Si2 and Gd5Ge2,1S i1,9 compounds and substituted Sn for Ge and Si in Gd5Ge2Si2 compound. Thus, new families of materials were developed, which are also investigated in this work using the techniques mentioned above. Besides the experimental work, theoretical results are presented for the magnetocaloric effect using the Landau-Devonshire model. We also present phenomenological results for Gd5Ge2Si2 compound under hydrostatic pressure using the Coupling Magnetic-Lattice Model / Doutorado / Física da Matéria Condensada / Doutor em Ciências

Des membranes polymères catalytiques ont été préparées via la polymérisation photo-amorcée de monomères acryliques à la surface de membranes support MicroPES(r). Des nanoparticules de palladium (PdNP) avec diamètre moyen compris entre 4 et 10 nm sont ensuite synthétisés et immobilisées dans ces gels polymères greffés. Cette thèse se focalise sur le greffage d'un gel de polymère neutre : (2-hydroxyethyl acrylate) (PHEA), pour négliger les contributions ioniques du réseau polymère sur la synthèse in-situ des PdNP. La stabilisation de PdNP dans le gel de PHEA greffé est possible par des moyens stériques étant donné que la distance entre des chaînes de polymère réticules (entre 0.3 à 2.5 nm) est plus petite que le diamètre moyen de PdNP. Une approche à la fois théorique et expérimentale, sur la base des mecanismes de nucléation et de croissance, permet la conception de PdNP de taille spécifique. La performance catalytique des membranes a été évaluée avec une configuration en filtration traversée. Sur la réaction de couplage de Suzuki-Miyaura, des conversions et sélectivités de 100 % ont été obtenues pour des temps de séjour de 10 secondes avec des membranes planes. Les réactions d'hydrogénation de plusieurs composés aromatiques ont également été testées. Des taux de conversion élevés ont été obtenus en quelques secondes avec des membranes planes en filtration avec des solutions saturés d'H2. Des taux de conversion élevés sont obtenus en seulement quelques minutes avec des membranes fibres creuses catalytiques en mode contacteur permettant une importante intensification du procédé. / Catalytic polymeric membranes are prepared via photo-grafting polymerization of neutral acrylic monomers onto the surface of a MicroPES(r) membrane support. Palladium nanoparticles (PdNP) of mean diameter of 4-10 nm are synthetized and immobilized within the grafted polymer gels. The research is focused on grafting a neutral polymer gel: poly (2-hydroxyethyl acrylate) (PHEA), to avoid any ionic contribution of the polymer network on the in-situ synthesis of PdNP. The stabilization of PdNP within the grafted PHEA is achieved by steric means as the distance between polymeric crosslinked chains (ca. 0.3 to 2.5 nm) is smaller than the mean diameter of PdNP. Both theoretical and experimental approaches are presented on the PdNP synthesis as an approach to conceive PdNP of specific sizes using nucleation and growth theories. Catalytic performance of the membranes is evaluated in flow-through configuration. Catalytic tests are performed on Suzuki-Miyaura cross-coupling reactions. Full conversion and selectivity within 10 seconds of residence time using flat sheet membrane are obtained. Hydrogenation of several aromatic compounds are also tested and high conversions were achieved within seconds of residence time using flat sheet membranes in flow-through configuration with H2-saturated solutions and within minutes using catalytic hollow fibers in contactor mode.