El Capítulo I trata la actual crisis energética y hace una breve introducción sobre el uso del hidrógeno como vector energético, mencionando los diferentes métodos que pueden utilizarse para la producción/purificación de hidrógeno a partir de recursos renovables. También incluye una breve descripción del papel que puede jugar la biomasa como alternativa a los combustibles fósiles, y su conversión a biocombustibles y productos químicos de valor añadido. El reformado catalítico de glicerol para la producción de gas de síntesis o corrientes ricas en hidrógeno se presenta como una ruta potencial, alternativa y prometedora que ha llamado la atención en los últimos años. Esta reacción se suele llevar a cabo sobre catalizadores basados en metales soportados en materiales estables. En el Capítulo II se estudia el efecto de la adición de Sn sobre las propiedades y la estabilidad de catalizadores de Pt soportado en carbón en la reacción de reformado glicerol en fase gas. Para ello, se preparó y caracterizó una serie de catalizadores con diferentes relaciones atómicas Pt/Sn. El alto precio de los metales nobles motiva la búsqueda y empleo de metales más baratos y abundantes que también tengan un buen comportamiento catalítico en esta reacción. Por ello, en el Capítulo III se emplearon catalizadores basados en Ni promovidos por óxido de cerio para el reformado de glicerol. Por otro lado, se hace necesario optimizar el uso del CeO2 debido a su limitada disponibilidad y sus extensas aplicaciones. Así, en este trabajo se dispersó CeO2 sobre carbón activado de alta área superficial, obteniendo gran superficie de óxido de cerio expuesta al mismo tiempo que se redujo su consumo. También se estudió el efecto de la presencia de estaño en estos catalizadores. Se obtienen diversas ventajas al realizar el reformado de glicerol en fase líquida. Así, se obtienen corrientes más ricas en H2 con menor cantidad de CO. Esto se debe a las moderadas temperaturas y altas presiones empleadas, que favorecen la reacción de desplazamiento del gas de agua. También se suprime la necesidad de evaporar la disolución acuosa de glicerol, por lo que el requerimiento energético es menor y se evitan reacciones indeseadas de descomposición térmica. De este modo, en el Capítulo IV se hace un estudio comparativo sobre las propiedades catalíticas de tres muestras, Pt/CeO2, Ni/CeO2 y Pt-Ni/CeO2, en la reacción de reformado de glicerol en fase líquida. Además, se empleó espectroscopía de reflectancia total atenuada in situ para obtener información relevante sobre los intermedios de reacción y la evolución de los catalizadores durante la reacción, permitiendo así proponer los caminos de reacción más probables. Para obtener corrientes de hidrógeno suficientemente puro para su uso es las pilas de combustible, la corriente obtenida después del reformado debe ser procesada en varias etapas, entre las que se incluyen la eliminación del CO por medio de la reacción de desplazamiento del gas de agua (water-gas shift, WGS). En el Capítulo V se estudia la serie de catalizadores de Ni promovidos por CeO2 soportados en carbón en la reacción de desplazamiento del gas de agua a bajas temperaturas. Para este estudio se emplearon diferentes corrientes de entrada, tanto ideales (sólo CO y H2O) como reales (CO, CO2, H2 y H2O). Por último, en el Capítulo VI, el catalizador que presentó mejor comportamiento catalítico en el apartado anterior fue estudiado en mayor profundidad, relacionando sus propiedades con la actividad catalítica, sometiéndolo finalmente a ensayos de estabilidad en condiciones más demandantes.

Abstract: With the worldwide dependence on non-renewable fossil fuels and increasing concerns over their impact on our planet through greenhouse gas emissions finding an alternative source of clean energy is a global imperative. The solar energy is one source of renewable energy resources, and It has the highest potential to contribute substantially to the future of carbon-free power needs. Solar to hydrogen has attracted much attention in the past decade due to its abundance and the spotlessness of hydrogen as fuel for energy usage. However, practically the requirements to convert solar energy to hydrogen, require a stable photocatalyst that’s able to operate efficiently over a wide range of the UV-VIS spectrum. Organic semiconductors have been widely used in hydrogen evolution due to their earth abundance, aqueous stability, and optical absorption that can be tuned to the UV-VIS spectrum. In chapter 3, The effect of different sacrificial regents on hydrogen evolution activity was systemically investigated by using poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) nanoparticles dispersion large and small diameter with Sodium dodecyl sulfate (SDS) as stabilizer. Ascorbic acid (AA), diethylamine (DEA), triethanolamine (TEOA), and triethylamine mixed with methanol (TEA/MeOH) were chosen as sacrificial reagents. The results indicate that the large diameter give improved efficiency with ascorbic acid, and the small diameter improved activity in the presence of diethylamine. The results indicated that the comparison between different sacrificial reagents is difficult because, the conditions of every experiment is different to another, depending on (the type of photocatalyst used, solubility, activity..) so to date, there is no clear concurrence in which sacrificial reagent is better than others. Photocatalysts formed from a single organic semiconductor typically suffer from inefficient intrinsic charge generation, which leads to low photocatalytic activities. In chapter 4, To overcome this limitation, we have used BTR, O-IDTBR, and PC71BM in binary and tertiary heterojunction nanoparticles between non fullerene donors’ small molecules and fullerene acceptor. The resulting photocatalyst display unprecedentedly a high hydrogen evolution rate over 12000 μmolh-1g-1 under AM 1.5g illumination.

Cette thèse porte sur la catalyse supportée sur nanotubes de carbone. Plusieurs aspects ont été étudiés, électrocatalyse pour la production d'hydrogène à partir d'eau, catalyse pour la synthèse organique et électrocatalyse de la réaction de réduction de l'oxygène. Différents catalyseurs ont été synthétisés à partir d'assemblages supramoléculaires de molécules amphiphiles autour de nanotubes de carbone ou d'adhésion de molécules polyaromatiques à la surface des nanotubes et ont impliqué l'utilisation de catalyseur moléculaire ou nanoparticulaire. L'utilisation de ces catalyseurs pour les différents types de réactions mentionnés plus haut ont abouti à des résultats intéressants. / This PhD thesis deals with the catalysis supported on carbon nanotubes. Several aspects have been studied such as electrocatalysis for hydrogen production form water, catalysis for organic synthesis and electrocatalysis of the oxygen reduction reaction. Many different catalysts have been synthesized based on supramolecular assembly of amphiphilic molecules around carbon nanotubes or assembly of polyaromatic molecules at the surface of the nanotubes. These catalysts are made of metallic complexes or metallic nanoparticles. These catalysts have been successfully used to perform the reactions mentioned above.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23578号 / 工博第4933号 / 新制||工||1770(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 江口 浩一, 教授 陰山 洋, 教授 阿部 竜 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

No description available.

Statistically based experimental designs were applied to optimise medium constituent for biogas production utilizing N-­‐acetylglucosamine as a carbon source for Clostridium beijerinckii and Clostridium paraputrificum. The important medium constituents influencing total biogas produced, identified by the Plackett and Burman method, were FeSO4.7H2O and initial pH for C. beijerinckii cultures whilst for C. paraputrificum cultures N-­‐acetylglucosamine, L-­‐ cysteine.HCl.H2O and MgCl2. A one factor L-­‐cysteine.HCl.H2O optimization design was applied to investigate the ideal concentration of L-­‐cysteine.HCl.H2O required to achieve an anaerobic environment for optimum C. beijerinckii total biogas production. The Method of Steepest Ascent was then employed to locate the optimal area of the significant medium variables. Using the Box-­‐behnken method, experimental results showed that there were significant linear effects of independent variables, N-­‐acetylglucosamine for C. beijerinckii cultures and for C. paraputrificum cultures N-­‐acetylglucosamine, L-­‐cysteine.HCl.H2O and MgCl2 on total biogas volume. Significant curvature or quadratic effects of N-­‐ acetylglucosamine and L-­‐cysteine.HCl.H2O were identified for C. paraputrificum cultures. There were no significant interaction effects between medium constituent variables on resulting biogas volume. The optimal conditions for the maximum volume of biogas produced for C. beijerinckii cultures were 21 g/l of N-­‐ acetylglucosamine, 0.1 g/l of FeSO4.7H2O and initial pH of 6.11 and for C. paraputrificum were 29 g/l of N-­‐acetylglucosamine, 0.27 g/l of L-­‐ cysteine.HCl.H2O and 0.4 g/l of MgCl2. Using this statistical optimization strategy, the total biogas volume from N-­‐acetylglucosamine utilization increased from 150 ml/l to 6533 ml /l in the C. beijerinckii cultures and 100 ml/l to 5350 ml/l in the C. paraputificum cultures. The maximum yield of bio-­‐hydrogen by C. paraputrificum from N-­‐acetylglucosamine was 2.55 mol of H2 / mol of N-­‐ acetylglucosamine and by C. beijerinckii was 2.43 mol of H2 / mol of N-­‐ acetylglucosamine.

As reserves of conventional crude oil are depleted, there is a growing need to develop unconventional oils such as heavy oil and bitumen from oil sands. In terms of recoverable oil, Canadian oil sands are considered to be the second largest oil reserves in the world. However, the upgrading of bitumen from oil sands to synthetic crude oil (SCO) requires nearly ten times more hydrogen (H₂) than the conventional crude oils. The current H₂ demand for oil sands operations is met mostly by steam reforming of natural gas. With the future expansion of oil sands operations, the demand of H₂ for oil sand operations is likely to quadruple in the next decade. As natural gas reforming involves significant carbon dioxide (CO₂) emissions, this sector is likely to be one of the largest emitters of CO₂ in Canada. <br> <br>In the current H₂ plants, CO₂ emissions originate from two sources, the combustion flue gases from the steam reformer furnace and the off-gas from the process (steam reforming and water-gas shift) reactions. The objective of this study is to develop a process that captures CO₂ at minimum energy penalty in typical H₂ plants. <br> <br>The approach is to look at the best operating conditions when considering the H₂ and steam production, CO₂ production and external fuel requirements. The simulation in this study incorporates the kinetics of the steam methane reforming (SMR) and the water gas shift (WGS) reactions. It also includes the integration of CO₂ capture technologies to typical H₂ plants using pressure swing adsorption (PSA) to purify the H₂ product. These typical H₂ plants are the world standard of producing H₂ and are then considered as the base case for this study. The base case is modified to account for the implementation of CO₂ capture technologies. Two capture schemes are tested in this study. The first process scheme is the integration of a monoethanolamine (MEA) CO₂ scrubbing process. The other scheme is the introduction of a cardo polyimide hollow fibre membrane capture process. Both schemes are designed to capture 80% of the CO₂ from the H₂ process at a purity of 98%. <br> <br>The simulation results show that the H₂ plant with the integration of CO₂ capture has to be operated at the lowest steam to carbon (S/C) ratio, highest inlet temperature of the SMR and lowest inlet temperatures for the WGS converters to attain lowest energy penalty. H₂ plant with membrane separation technology requires higher electricity requirement. However, it produces better quality of steam than the H₂ plant with MEA-CO₂ capture process which is used to supply the electricity requirement of the process. Fuel (highvale coal) is burned to supply the additional electricity requirement. The membrane based H₂ plant requires higher additional electricity requirement for most of the operating conditions tested. However, it requires comparable energy penalty than the H₂ plant with MEA-CO₂ capture process when operated at the lowest energy operating conditions at 80% CO₂ recovery. <br> <br>This thesis also investigates the sensitivity of the energy penalty as function of the percent CO₂ recovery. The break-even point is determined at a certain amount of CO₂ recovery where the amount of energy produced is equal to the amount of energy required. This point, where no additional energy is required, is approximately 73% CO₂ recovery for the MEA based capture plant and 57% CO₂ recovery for the membrane based capture plant. <br> <br>The amount of CO₂ emissions at various CO₂ recoveries using the best operating conditions is also presented. The results show that MEA plant has comparable CO₂ emissions to that of the membrane plant at 80% CO₂ recovery. MEA plant is more attractive than membrane plant at lower CO₂ recoveries.

Cette étude examine une approche alternative à l'utilisation de deux déchets provenant des activités agricoles et d'élevage développés en Colombie. Lisier de porc et de mucilage café ont été utilisés pour évaluer une co-digestion anaérobie processus axé sur la production d'hydrogène. En outre, les objectifs couvert une nouvelle étape dans le but de fermer le cycle des déchets fois. La thèse a été menéeen trois phases : 1. Evaluation de la productiond'hydrogène à partir de la co-digestion de mucilage café et du lisier de porc pendant la fermentation sombre ; 2. Évolution dans le temps de rétention par la surveillance des micro-organismes par qPCR et d'autres paramètres incluiding pH, le potentiel d'oxydo-réduction, et une pression partielle d'hydrogène ; 3. Traitement de l'effluent de processus de production d'hydrogène par digestion anaérobie avec production de méthane. Les résultats expérimentaux ont montré que les mélanges de deux déchets sont en mesure de produire de l'hydrogène. Un ratio substrat de 5:5, ce qui a été associé à un rapport C/N de 53, a été adapté pour la production d'hydrogène. En outre, la stabilité et l'optimisation du processus ont été évalués par l'augmentation du taux de charge organique influent. Ce fut la meilleure condition expérimentale en termes de taux moy en volume d'hydrogène cumulatif de production et de rendement qui étaient 2661 NmL, 760 NmL H2/Lwdet 43 NmL H2/gDCO, respectivement. Cette performance a été préservé au fil du temps, ce qui a été vérifié par la culture discontinue répétitive pendant 43 jours. Deux tendances ont été identifiées au cours du temps de rétention associée à l'hydrogène cumulatif similaire, mais avec des différences de phase de latence le temps et le taux de production d'hydrogène. T. thermosaccharolyticum était le genre dominant au cours de la tendance à court lié à la plus courte phase de latence de temps et plus le taux de production d'hydrogène. Les tendances de long ont été associées à une diminution de Bacillus sp. concentration au début des expériences, et avec le concours possible pour des substrats solubles entre T. thermosaccharolyticum et Clostridium sp. La troisième phase a montré que l'utilisation d'une deuxième phase pour produire du méthane était utile d'améliorer le traitement des déchets tant. Enfin, l'énergie totale produite à la fois pour les biocarburants ont montré des niveaux similaires avec d'autres processus. Cependant,l'hydrogène a été d'environ 10% de l'énergie totale produite dans le processus. En outre, les deux gaz peuvent être mélangés pour produire biohythane qui améliore les propriétés de biogaz. / This research investigates an alternative approach to the use of two wastes from agricultural and livestock activities developed in Colombia. Swinemanure and coffee mucilage were used to evaluatean anaerobic co-digestion process focused on hydrogen production. In addition, the aims covered a further stage in order to close the cycle of the both wastes. The thesis was conducted in three phases : 1. Evaluation of hydrogen production from the co-digestion of coffee mucilage and swine manure during dark fermentation ; 2. Trends over retention time through the monitoring of microorganisms by quantitative PCR and other parameters incluiding pH, oxidation reduction potential, and hydrogen partial pressure ; 3. Treatment of the effluent from hydrogen production process by anaerobic digestion with methane production. The experimental results showed that mixtures of both wastes are able to produce hydrogen. A substrate ratio of 5:5, which was associated with a C/N ratio of 53, was suitable for hydrogen production. Moreover, the stability and optimization of the process were evaluated by increasing the influent organic load rate. This wasthe best experimental condition in terms of average cumulative hydrogen volume, production rate and yield which were 2661 NmL, 760 NmLH2/Lwd and 43 NmL H2/gCOD, respectively. This performance was preserved over time, which was verified through the repetitive batch cultivation during 43 days. Two trends were identified over retention time associated with similar cumulative hydrogen, but with differences in lag-phase time and hydrogen production rate. T.thermosaccharolyticum was the dominating genus during the short trend related to the shortest lag phase time and highest hydrogen production rate. The long trends were associated with a decrease of Bacillus sp. concentration at the beginning of the experiments and with the possible competition for soluble substrates between T.thermosaccharolyticum and Clostridium sp. The third phase showed that the use of a second stage to produce methane was useful enhancing the treatment of both wastes. Finally, the overall energy produced for both biofuels (Hydrogen andmethane) showed similar levels with other process. However, hydrogen was around the 10% of the overall energy produced in the process. In addition, both gases could be mixed to produce biohythane which improves the properties of biogas.

Doctor of Philosophy / Department of Chemical Engineering / Keith L. Hohn / The autothermal reforming and partial oxidation of hexadecane via Pt/Ni bimetallic nanoparticles on various ceria-based supports were investigated. Nanoparticles with Pt/Ni molar ratios ranging from 0/100 to 10/90 were loaded on ceria-based supports including cerium oxide, gadolinium-doped cerium oxide and cerium-doped zirconium oxide. The effect of the Pt/Ni molar ratio and the promotional effect of the support were studied by comparing the hydrogen yield. TPR and XPS analysis showed that there was a strong interaction between Ni and the CeO₂-ZrO₂ support, which led to enhancement of catalyst performance when the Pt/Ni ratio was low. The strong interaction between Ni and CeO₂-ZrO₂ support was induced by the formation of a solid solution between NiO and ZrO₂. In the case of bimetallic catalysts loaded on Gd₂O₃-CeO₂, no significant improvement in the catalytic activity of autothermal reforming was achieved until the Pt/Ni ratio reached 10/90. With C-snarf-1 as a pH-sensitive fluorescent probe, the local acidity on the surface of gradient aluminosilicate thin films and in the pore structure of mesoporous silicate films was explored. The single molecule emission ratio (I₅₈₀/I₆₄₀) of C-snarf-1 on the gradient aluminosilicate films showed similar results as previously reported for aluminosilicate mesoporous films. As the Al/Si ratio increases, the emission ratio declines, indicative of increased material acidity. In the case the mesoporous silicate films, much broader distributions of emission ratios were observed and are suggestive of significant heterogeneity in the pore structure of these films. The average emission ratio increased with a rise in pH until pH 6 or 7. A further rise in pH leads to a decline in emission ratio. Molecules with high mobility showed a narrow distribution and slightly lower average emission ratio when compared to data from all detected molecules. This observation implies a reduced heterogeneity for mesopores in which the molecules rapidly diffuse. The narrow distribution and lower average value of emission ratio at low pH, combined with the decrease in emission ratio induced by an increase in ionic strength may further indicate that the interaction between dye molecules and the pore surface impacts the emission ratio of the dye molecules.

Le but de ces travaux était de développer des membranes conductrices protoniques de type phosphonique par PECVD radio-fréquence en décharges continue et pulsée à partir du mono-précurseur diméthyl allylphosphonate. De telles membranes sont pressenties comme pouvant avantageusement remplacer la membrane Nafion® ou les membranes conventionnelles de type sulfonique ou phosphonique classiquement utilisées dans les dispositifs piles à combustible ou électrolyseur de type PEM. Ainsi, une étude paramétrique visant à établir des corrélations entre les propriétés des films et les paramètres de dépôt a été menée. Il ressort de cette étude paramétrique que l’utilisation d’une décharge pulsée est favorable à une vitesse de croissance plus élevée et une densité des films plus faible que le mode de décharge continue, favorisant ainsi la conduction protonique. Nous avons également démontré que les dépôts réalisés en mode de décharge pulsée présentent de meilleures capacités de sorption et de rétention d’eau, ce qui est bénéfique pour l’application visée qui est la (photo-)électrolyse de l’eau. Par ailleurs toutes les membranes phosphoniques plasma préparées sont stables d’un point de vue rétention d’eau et réseau covalent jusqu’à au moins 250 °C, ce qui garantit leur utilisation dans des systèmes pouvant fonctionner jusqu’à 120 °C. Par la suite les membranes phosphoniques plasma ont été intégrées en cellule d’électrolyse de l’eau, associées au Nafion® en tant qu’électrolyte. Les caractérisations électrochimiques en cellule ont montré que les membranes phosphoniques plasma sont suffisamment compétitives pour être envisagées dans le futur comme électrolytes solides à part entière dans des AME « tout solide ». / The purpose of this work was to develop phosphonic-type proton conductive membranes by radio-frequency PECVD in a continuous or pulsed discharge from the single precursor dimethyl allylphosphonate. Such membranes could advantageously replace the Nafion® membrane or conventional sulfonic-type or phosphonic acid-type membranes, more classically used in PEM fuel cells and electrolysis devices. A parametric study was carried out in order to establish correlations between the properties of the films and the deposition parameters. It appears that the use of a pulsed discharge promotes better films properties, namely higher growth rate and lower density, than the continuous discharge, thus promoting proton conduction. It was also noticed that the deposits prepared in a pulsed discharge have the highest sorption and water retention capacities, which is particularly beneficial for the intended application i.e. the (photo-) electrolysis of water. Furthermore, all the plasma phosphonic membranes prepared are stable in terms of water retention and covalent network up to at least 250 °C, which ensures their use in systems able to operate up to 120 °C. Subsequently the plasma phosphonic membranes, deposited on the Nafion® as mechanical support, were integrated as electrolyte membrane into a water electrolysis cell. It turns out that plasma phosphonic membranes are competitive enough to be envisaged in the future as integral solid electrolytes in solid membrane-electrodes assemblies.