Dans ce travail de recherche, des oxydes mixtes dopés par des métaux nobles ont été préparés et mis en œuvre dans la réaction d'oxydation catalytique du chlorure de vinyle (VC). Les catalyseurs d'oxyde composite de Co-Ce ont été préparés par des procédés sol-gel et testés pour l'activité d'oxydation du VC. L'analyse XPS a certifié que l'introduction de Ce favorisait la présence d'espèces de Co2 + et de Ce3 +, ce qui modifie l'environnement de coordination du réseau d'oxygène et génère plus de vacations d'oxygène. Les oxydes de cobalt modifiés par Ru ont été préparés et étudiés pour l'oxydation du VC. L'analyse XPS montre que le Ru4 + et le Co2 + modifie la concentration des espèces oxygènes sur la surface. Une proportion relative élevée de Co2+ et de Ru4+ perturbe également les lacunes en oxygène. Cela impacte l'activité catalytique et diminue la quantité de sous-produits chlorés. Des mousses cellulaires mésostructurées de phosphate de cobalt-SiO2 (CoPO-MCFs) ont été synthétisées avec succès par la méthode de croissance in situ. Les analyses XPS confirment une augmentation d'espèces d'oxygène de surface pour ce système catalytique. L'énergie apparente d'activation confirme cette tendance. L'influence de la morphologie des particules de Co3O4, sur l'activité catalytique du méthyl benzène et du chlorure de vinyle a été étudiée. Le Co3O4 cubique a montré une meilleure activité et une meilleure stabilité que celle de Co3O4 sphérique. La structure cubique, avec Co2 + exposée à la surface, est le site actif de l'oxydation / In this research works, composite oxides, noble metal supported oxides and noble supported MCFs were prepared, and their catalytic performances were investigated for the catalytic oxidation of vinyl chloride (VC). The Co-Ce composite oxide catalysts were prepared by citrate sol-gel methods, and tested for the activity of VC oxidation. The catalyst with high performance is the molar ratio of Co/Ce=7:3. The XPS analyse certified that the Ce introduction favored the presence of Co2+ and Ce3+ species, which changed the coordination environment of the oxygen lattice and generated more oxygen vacancies. At last, this catalyst exhibited a good performance and stability during 110 h of time on stream at 300 oC. Ru-modified cobalt oxides were prepared and studied for the VC oxidation. The XPS analyse certified that the Ru4+ will be in synergy with Co2+ concentration and this would also change the chemical coordination of oxygen on the surface. High relative proportion of Co2+ and Ru4+ will also devote to oxygen defects or vacancies. This would increased the catalytic activity and decrease the amount of chlorinated by-products.A novel heterostructured material, cobalt phosphate-SiO2 mesostructured cellular foams (CoPO-MCFs), was successfully synthesized by the in-situ growth method. The XPS confirmed a higher amount of surface oxygen species. The activation energy calculated from Arrhenius plots showed a lower value for VC oxidation. The influence of Co3O4 morphology, including cube and sphere, on catalytic activity of methylbenzene and vinyl chloride was studied. The Co3O4 cube had shown better activity and stability than that of the Co3O4 sphere. The cube structure, with Co2+ exposed on the surface, acted as the active site of the oxidation

Mechanical properties of (woven carbon fiber / vinyl ester matrix) composites can be greatly improved if the interphase between the reinforcing high-strength low-weight fiber and the thermoset resin is made more compliant. In order to improve the adhesion of the vinyl ester matrix to the carbon fiber, a thermoplastic coating such as poly(vinyl pyrrolidone) (PVP) can be used as an intermediate between the matrix and the fiber. The extent of mutual diffusion at the (sizing material / polymer matrix) interphase plays a critical role in determining the mechanical properties of the composite. In this research, the molecular interdiffusion across a poly(vinyl pyrrolidone))/vinyl ester monomer (PVP/VE) interface is being investigated by Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR) spectroscopy. The ATR method which can be used to characterize the transport phenomena, offers several advantages, such as the ability to monitor the diffusion <I>in situ</I> or to observe chemical reactions. In order to separate the effects of the vinyl ester monomer diffusion and the crosslinking reaction, ATR experiments were carried out at temperatures below the normal curing temperature. Diffusion coefficients were determined by following variations in infrared bands as a function of time, and fitting this data to a Fickian model. The values of the diffusion coefficients calculated were consistent with values found in the literature for diffusion of small molecules in polymers. The dependence of diffusion coefficients on temperature followed the Arrhenius equation. Hydrogen bonding interactions were also characterized. The diffusion model used in this study, however, does not seem to be appropriate for the particular (PVP/VE) system. Because the glass transition temperature of the PVP changed as diffusion proceeded, one would expect that the mutual diffusion coefficient did not stay constant. In fact, it was shown that the Tg can drop by 140oC during the diffusion process. A more suitable model of the (PVP/VE) system should take into account plasticization, hydrogen bonding, and especially a concentration dependent diffusion coefficient. Further analysis is therefore needed. / Master of Science

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第19197号 / 農博第2136号 / 新制||農||1034(附属図書館) / 学位論文||H27||N4943(農学部図書室) / 32189 / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 西尾 嘉之, 教授 木村 恒久, 教授 髙野 俊幸 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

No description available.

This work is an in-depth study of a system with an approach designed to determine the electrode processes and the factors or conditions which control them.

Processos industriais de polimerização em emulsão são usualmente realizados em reatores tipo tanque agitado em batelada (ou semi-batelada) ou em contínuo (CSTR). Reatores contínuos tem a vantagem de serem comparativamente de menor porte, e propiciarem melhor controle da qualidade do produto pela redução de variações de batelada a batelada. Reatores tipo CSTR podem exibir oscilações periódicas e autosustentadas de conversão, de tamanho e concentração de partículas. Estas oscilações podem ser minimizadas nos reatores tubulares pulsados devido à diminuição da dispersão axial em relação aos reatores do tipo CSTR. Na presente tese, desenvolveu-se um novo tipo de reator tubular, a Coluna Pulsada de Pratos Perfurados, CPPP, para uso no processo de polimerização contínua do acetato de vinila em emulsão. O reator é operado com escoamento pulsado e contém pratos perfurados como dispositivos internos. Inicialmente foram realizados ensaios de distribuição de tempos de residência, em um reator montado em vidro, com o objetivo de caracterizar o escoamento no reator CPPP quanto ao grau de mistura axial. Os dados foram interpretados usando o modelo de escoamento pistonado com dispersão axial. Valores do coeficiente de dispersão axial foram medidos e correlacionados para diferentes condições de freqüência e amplitude de pulsação, vazão, espaçamento entre pratos, e viscosidade do fluido. Verificou-se que o grau de mistura axial pode ser variado em faixas relativamente amplas pela manipulação da freqüência e amplitude de pulsação. Foi também montado um reator em aço inox e encamisado, com as mesmas dimensões, onde foram realizados ensaios de polimerização em emulsão de acetato de vinila, medindo-se a conversão e a distribuição de tamanhos de partículas (DTP), na saída do reator em regime transiente e permanente, e também ao longo do reator em regime permanente. Verificou-se que as condições operacionais (tempo médio de residência e grau de dispersão axial) influenciam várias características do produto, como, a conversão, tamanho médio e concentração de partículas, porém, não influencia, significativamente, a viscosidade da emulsão produzida, para a receita da reação de polimerização e as condições operacionais estudadas. Os resultados experimentais foram interpretados usando um modelo matemático do reator, o qual foi estabelecido com base em um modelo cinético publicado na literatura para o processo de polimerização em emulsão de acetato de vinila em batelada. Tal modelo foi adaptado incluindo-se os termos convectivos e dispersivos nas equações de balanço de massa, e resolvido numericamente. Foram ajustados apenas dois parâmetros neste modelo, para todas as condições operacionais estudadas e os resultados simulados reproduziram adequadamente o comportamento das principais variáveis de processo para a condição de regime permanente. O novo tipo de reator contínuo apresentado neste trabalho mostrou-se ser possível obter altas conversões em tempos médios de residência da ordem ou mesmo inferiores aos do processo em batelada e atingir regime permanente de operação em um a dois tempos médios de residência. O reator é eficiente, robusto, construtivamente simples, de fácil limpeza e manutenção, e mostrou-se promissor para utilização industrial em processo de polimerização em emulsão de acetato de vinila. / Industrial emulsion polymerization processes are usually carried out in stirred tanks operated in batch/semibatch or in continuous mode (CSTR). In comparison to batch processes, continuous reactors present several advantages such as lower volumes and better quality control by reducing batch-to-batch variations. Continuous emulsion polymerization in CSTR may exhibit sustained oscillations in conversion, particle size and particle concentration. Such oscillations may be reduced in pulsed tubular reactors due to less axial mixing. In this thesis a new type of tubular reactor, called Pulsed Sieve Plate Column, PSPC, was developed for the continuous process of vinyl acetate emulsion polymerization. This reactor is operated using oscillatory pulsed flow and uses perforated plates as internals. Residence time distribution runs were carried out in a glass reactor in order to characterize the axial mixing and flow patterns in the PSPC. The data were treated using the axially dispersed plug flow model. Axial dispersion coefficient was measured for different conditions of pulse frequency and amplitude, flow rate, plate spacing and viscosity. It was found that the degree of axial mixing can be varied in wide ranges by manipulating pulsation frequency and/or amplitude. Vinyl acetate continuous emulsion polymerization runs were carried out in a jacketed stainless steel reactor (with the same size of the glass reactor). Monomer conversion and particle size distribution was measured both at the reactor exit in transient state and along the reactor length at steady-state. It was found that average residence time and degree of axial mixing affect process and product quality variables, such as monomer conversion, mean particle size and concentration, but did not affect the viscosity of the emulsion produced, for the recipe and conditions used. A mathematical model for the reactor was developed. The model used, based on a well-known kinetic model previously developed in the literature for batch emulsion polymerization, was adapted to the continuous tubular reactor by adding the dispersion and convective terms to the balance equations. The model was numerically solved. Only two parameters were adjusted in this model and the simulated results showed excellent agreement with the experimental results, for steady state conditions. The proposed tubular reactor allows to reach high monomer conversion with similar or even lower residence time than those in batch processes and reaches steady state operation in just one to two mean residence times. The reactor is efficient, easy-to-built, easy-to-clean, robust and promising for use in industrial continuous emulsion polymerization of vinyl acetate.

Processos industriais de polimerização em emulsão são usualmente realizados em reatores tipo tanque agitado em batelada (ou semi-batelada) ou em contínuo (CSTR). Reatores contínuos tem a vantagem de serem comparativamente de menor porte, e propiciarem melhor controle da qualidade do produto pela redução de variações de batelada a batelada. Reatores tipo CSTR podem exibir oscilações periódicas e autosustentadas de conversão, de tamanho e concentração de partículas. Estas oscilações podem ser minimizadas nos reatores tubulares pulsados devido à diminuição da dispersão axial em relação aos reatores do tipo CSTR. Na presente tese, desenvolveu-se um novo tipo de reator tubular, a Coluna Pulsada de Pratos Perfurados, CPPP, para uso no processo de polimerização contínua do acetato de vinila em emulsão. O reator é operado com escoamento pulsado e contém pratos perfurados como dispositivos internos. Inicialmente foram realizados ensaios de distribuição de tempos de residência, em um reator montado em vidro, com o objetivo de caracterizar o escoamento no reator CPPP quanto ao grau de mistura axial. Os dados foram interpretados usando o modelo de escoamento pistonado com dispersão axial. Valores do coeficiente de dispersão axial foram medidos e correlacionados para diferentes condições de freqüência e amplitude de pulsação, vazão, espaçamento entre pratos, e viscosidade do fluido. Verificou-se que o grau de mistura axial pode ser variado em faixas relativamente amplas pela manipulação da freqüência e amplitude de pulsação. Foi também montado um reator em aço inox e encamisado, com as mesmas dimensões, onde foram realizados ensaios de polimerização em emulsão de acetato de vinila, medindo-se a conversão e a distribuição de tamanhos de partículas (DTP), na saída do reator em regime transiente e permanente, e também ao longo do reator em regime permanente. Verificou-se que as condições operacionais (tempo médio de residência e grau de dispersão axial) influenciam várias características do produto, como, a conversão, tamanho médio e concentração de partículas, porém, não influencia, significativamente, a viscosidade da emulsão produzida, para a receita da reação de polimerização e as condições operacionais estudadas. Os resultados experimentais foram interpretados usando um modelo matemático do reator, o qual foi estabelecido com base em um modelo cinético publicado na literatura para o processo de polimerização em emulsão de acetato de vinila em batelada. Tal modelo foi adaptado incluindo-se os termos convectivos e dispersivos nas equações de balanço de massa, e resolvido numericamente. Foram ajustados apenas dois parâmetros neste modelo, para todas as condições operacionais estudadas e os resultados simulados reproduziram adequadamente o comportamento das principais variáveis de processo para a condição de regime permanente. O novo tipo de reator contínuo apresentado neste trabalho mostrou-se ser possível obter altas conversões em tempos médios de residência da ordem ou mesmo inferiores aos do processo em batelada e atingir regime permanente de operação em um a dois tempos médios de residência. O reator é eficiente, robusto, construtivamente simples, de fácil limpeza e manutenção, e mostrou-se promissor para utilização industrial em processo de polimerização em emulsão de acetato de vinila. / Industrial emulsion polymerization processes are usually carried out in stirred tanks operated in batch/semibatch or in continuous mode (CSTR). In comparison to batch processes, continuous reactors present several advantages such as lower volumes and better quality control by reducing batch-to-batch variations. Continuous emulsion polymerization in CSTR may exhibit sustained oscillations in conversion, particle size and particle concentration. Such oscillations may be reduced in pulsed tubular reactors due to less axial mixing. In this thesis a new type of tubular reactor, called Pulsed Sieve Plate Column, PSPC, was developed for the continuous process of vinyl acetate emulsion polymerization. This reactor is operated using oscillatory pulsed flow and uses perforated plates as internals. Residence time distribution runs were carried out in a glass reactor in order to characterize the axial mixing and flow patterns in the PSPC. The data were treated using the axially dispersed plug flow model. Axial dispersion coefficient was measured for different conditions of pulse frequency and amplitude, flow rate, plate spacing and viscosity. It was found that the degree of axial mixing can be varied in wide ranges by manipulating pulsation frequency and/or amplitude. Vinyl acetate continuous emulsion polymerization runs were carried out in a jacketed stainless steel reactor (with the same size of the glass reactor). Monomer conversion and particle size distribution was measured both at the reactor exit in transient state and along the reactor length at steady-state. It was found that average residence time and degree of axial mixing affect process and product quality variables, such as monomer conversion, mean particle size and concentration, but did not affect the viscosity of the emulsion produced, for the recipe and conditions used. A mathematical model for the reactor was developed. The model used, based on a well-known kinetic model previously developed in the literature for batch emulsion polymerization, was adapted to the continuous tubular reactor by adding the dispersion and convective terms to the balance equations. The model was numerically solved. Only two parameters were adjusted in this model and the simulated results showed excellent agreement with the experimental results, for steady state conditions. The proposed tubular reactor allows to reach high monomer conversion with similar or even lower residence time than those in batch processes and reaches steady state operation in just one to two mean residence times. The reactor is efficient, easy-to-built, easy-to-clean, robust and promising for use in industrial continuous emulsion polymerization of vinyl acetate.

Aldol cyclotrimerizations have been used to achieve the rational chemical synthesis of both fullerenes and fullerene fragments in the past. Under certain conditions this reaction produces the corresponding cyclotetramer which has sometimes been regarded as an undesired byproduct. This work details efforts to synthesize and use these cyclotetramers toward a synthesis of a C240 fullerene fragment. One principal focus in this work is tridecacyclene, a cyclic tetramer of acenaphthylene given its name by our group for its thirteen rings. Relatively low yields for the synthesis of tridecacyclene and its derivatives drove us to investigate the mechanism of its formation and attempt to optimize its production. During this process, novel dione products were isolated from the attempted cyclotetramerization of two dimeric species. Characterization of these products by X-ray crystallography gave valuable insight into the reaction pathway, leading us to a new proposed mechanism of formation for the cyclotetramerization products observed in these aldol reactions. β-hydroxy-α-diazoketones are suitable progenitors to vinyl cation intermediates whose use in chemical synthesis is relatively unexplored. As part of an extensive project to develop the chemistry of vinyl cations for use in carbon-carbon bond forming reactions to build important molecular scaffolds, a range of β-hydroxy-α-diazoketones containing a pendent nucleophilic alkene were synthesized. Treatment of these compounds with Lewis acids gave either lactone or cyclopentenone products depending on the substrate used. Proposed herein is a mechanism involving a key acylium intermediate which, depending on the position of the pendent alkene, results in different product outcomes. In a collaborative effort to further investigate the known anti-cancer properties of fusarochromanone, a fungal metabolite that is isolated from Fusarium-infected feed from cold climates, a large-scale synthesis of this natural product was explored. An efficient, scalable synthesis of the previously prohibitively expensive amidochromanone starting material has been achieved and its elaboration to fusarochromanone has been demonstrated.

Fluorine atom plays a very important role in pharmaceuticals, agricultural chemicals, and medical imaging and it has become one of the most popular area in organic chemistry. For example, in modern medicinal chemistry introducing fluorine atom could potentially improve absorption, metabolism and potency of drug candidates. As a result, methods that allow the selective and efficient formation of the carbon-fluorine bond are highly desirable. An evolving approach is the utilization of transition-metals to catalyze the nucleophilic substitution of fluoride ion. This thesis described several novel and efficient methods to generate allylic and benzylic C-F bonds using rhodium/iridium catalyst.

No description available.