La transesterificación de ácidos grasos ha sido el método comúnmente empleado en la modificación de aceites vegetales para su implementación como biodiesel en motores de combustión interna. Las variables que intervienen en la reacción de transesterificación para la obtención del biodiesel son: tipo de materia prima, alcohol, catalizador y concentración del mismo, entre otras. Las propiedades y la calidad del biodiesel no sólo están determinadas por las variables del proceso de producción sino también por la composición de ésteres alquílicos de ácidos grasos (FAAE) que lo componen. Las muestras de biodiesel B100 (libre de aditivos) fueron producidas a partir de distintas materias primas como aceite de girasol, maíz, soja y uva. Se optimizó el proceso de producción catalizado por una base y empleando metanol. La calidad de las muestras de biodiesel obtenidas en el laboratorio fue evaluada según la norma argentina IRAM 6515-1:2006. Además, se desarrolló un método espectrométrico UV-VIS para la determinación de la estabilidad oxidativa del biodiesel mediante la oxidación acelerada de los FAAE asistida por ultrasonidos. Los valores de tiempo de inducción determinados mediante el método propuesto para todas las muestras de biodiesel, estuvieron en concordancia con los valores medidos a través del método de referencia Rancimat®. Además, se propuso el desarrollo de un método simple y rápido para la determinación del contenido de Na, K, Ca, Mg, P y 20 metales pesados en muestras de biodiesel, mediante espectrometría de emisión óptica con plasma de acoplamiento inductivo (ICP OES), usando un multinebulizador Flow Blurring® prototipo de dos boquillas y la calibración online por estándar interno. El análisis de las muestras fue realizado sin necesidad de emplear ningún tipo de pretratamiento. La precisión a corto y largo plazo fue estimada a través de la desviación estándar relativa, las mismas fueron aceptables. Los porcentajes de recuperación para los componentes mayoritarios (Na, K, Ca, Mg y P) estuvieron entre un 95% y un 106%. / Transesterification of fatty acids has been the method commonly employed in the modification of vegetable oils for implementation as biodiesel in internal combustion engines. The variables involved in the transesterification reaction for obtaining biodiesel are: type of raw material, alcohol, catalyst and concentration of it, among others. The properties and the quality of biodiesel are not only determined by the variables of the production process but also by the composition of fatty acid alkyl esters (FAAE). Samples of Biodiesel B100 (without additives) were produced from different raw materials such as sunflower oil, corn, soybeans and grape seeds. The production process performed via base-catalyst transesterification using methanol, was optimized. The quality of biodiesel samples obtained in the laboratory was evaluated according to Argentina IRAM 6515-1: 2006. Further, a UV-VIS spectrometric method for determining the oxidative stability of biodiesel by an accelerated ultrasonic assisted oxidation of FAAE, was developed. The induction time values determined by the proposed method for all samples of biodiesel, were in accordance with those measured by the Rancimat® reference method. Furthermore, the development of a simple and fast method for the determination of Na, K, Ca, Mg, P and 20 heavy metals in biodiesel samples by optical emission spectrometry with inductively coupled plasma (ICP OES) using a two nozzles Flow Blurring® multinebulizer prototype and calibration on-line by internal standard, was proposed. The analysis of samples was conducted without using any pretreatment. Short-term and long term precision was estimated using the relative standard deviation. The precision values were acceptable. The recovery values for major components (Na, K, Ca, Mg and P) were between 95% and 106%.

La producción de biodiesel ha crecido durante los últimos años a nivel mundial, en respuesta al paulatino agotamiento de los recursos fósiles y a los efectos ambientales causados por el uso de los combustibles convencionales. Este biocombustible se obtiene a nivel industrial casi en su totalidad a partir de aceites de semillas. Sin embargo, la gran demanda energética, el agotamiento de los suelos y la utilización de semillas para fines alimenticios plantean la necesidad de nuevas fuentes de materia prima alternativa y sustentable. Muchas especies de microalgas, comúnmente denominadas oleaginosas, pueden almacenar altos contenidos de aceites, lo cual las convierte en una fuente potencial para la producción de este biocombustible. Algunas especies del género Nannochloropsis han sido propuestas para tal fin debido a su capacidad de acumular altos contenidos de lípidos, particularmente lípidos neutros, los cuales son la materia prima ideal para la producción de biodiesel. En Argentina, a diferencia de otras energías renovables, las investigaciones en este campo se encuentran en una etapa incipiente. Sobre la base de estos antecedentes, el objetivo general de esta Tesis fue evaluar el potencial de una cepa marina nativa de Nannochloropsis, aislada de la costa atlántica sur, como materia prima para la producción de biodiesel. Particularmente, los objetivos específicos fueron: la identificación a nivel de especie de la cepa en estudio a través de su caracterización morfológica y molecular; la optimización de técnicas para la determinación de la densidad celular, la concentración de pigmentos fotosintéticos y el contenido de lípidos neutros en cultivos a escala de laboratorio; el análisis del efecto de distintas condiciones ambientales (temperatura [15ºC y 25ºC], intensidad de luz [100 y 300 μmol fotón m-2 s-1] y fotoperiodo [12:12 h y 16:8 h de luz y oscuridad) y de la carencia de nitrógeno sobre parámetros de crecimiento, producción de biomasa y cantidad, productividad y calidad lipídica, con especial énfasis sobre la fracción de los lípidos neutros. Además, se evaluó el crecimiento de la cepa en estudio en un fotobiorreactor columnar de 25L y con un medio de cultivo (SWES) de menor costo que el empleado en experiencias de laboratorio (f/2). Los estudios morfológicos y ultraestructurales con microscopios óptico y electrónico y el análisis de los genes nuclear y cloroplástico, 18s rADN y rbcL respectivamente, permitieron identificar a la cepa en estudio como Nannochloropsis oceanica. La cepa fue depositada en el cepario Culture Collection of Autotrophic Organism (CCALA), República Checa, bajo la denominación Nannochloropsis oceanica CCALA 978. Se elaboró un modelo estimador de la densidad celular a través de lecturas de densidad óptica, el cual permite monitorear el crecimiento de N. oceanica CCALA 978 en forma rápida. Con respecto a la optimización de métodos para la determinación de pigmentos, el metanol asistido con congelado y descongelado rápido fue el método más efectivo para la extracción de clorofila a y carotenoides totales. El pre-tratamiento de las células con dimetilsulfóxido 5% y la tinción con el fluorocromo rojo Nilo se presentó como una técnica adecuada para la detección in situ de los lípidos neutros por espectrofluorimetría. Asimismo, la relación entre las intensidades de fluorescencia de la clorofila a y del rojo Nilo se propone como un índice para la estimación del tiempo de acumulación máxima de los lípidos neutros y consecuentemente, para la determinación del tiempo de cosecha de la biomasa. El efecto de las variables ambientales sobre los parámetros de crecimiento indicó que a mayor temperatura (25º C), mayor intensidad de luz (300 μmol fotón m-2 s-1) y con un fotoperíodo de 16:8 h L:O, la especie mostró un aumento de la velocidad de crecimiento (0,85 div d-1) a escala de laboratorio. Sin embargo, la producción de biomasa (680 mg L-1) no se incrementó en respuesta a la intensidad de luz más alta. Bajo las condiciones ambientales testeadas en este estudio, el contenido de lípidos totales (LT) de N. oceanica CCALA 978 fue en general alto (24-34%), y esto se debió a una alta proporción de los lípidos neutros (LN), los cuales representaron entre un 82% y 91% de los LT. No obstante, los mayores contenidos lipídicos se obtuvieron, cuando las células crecieron en un medio de cultivo carente de nitrógeno, a ambas intensidades de luz y un fotoperíodo de 16:8 h L:O (LT: 36% peso seco de biomasa [ps] y LN: 32% ps). Bajo estas condiciones, se alcanzaron productividades de LT y LN de 48 mg L-1 d-1 y 43 mg L-1 d-1, respectivamente. Con respecto a la calidad de los lípidos, los ácidos grasos saturados (AGS) y monoinsaturados (AGM) fueron las clases predominantes dentro de los LN, bajo todas las condiciones testeadas, representando conjuntamente entre el 90-96% de los ácidos grasos totales. Los AGS-LN aumentaron a 25°C, 16:8 h L:O y 300 μmol fotón m-2 s-1, mientras que los AGM-LN disminuyeron en respuesta a estas variables. Los ácidos grasos poliinsaturados (AGP) fueron la fracción minoritaria en todas las condiciones de cultivo testeadas. La composición de los ácidos grasos fue similar en todas las condiciones de cultivo probadas, tanto en los lípidos totales como en los lípidos neutros, siendo los principales ácidos grasos el ác. palmítico (C16:0), el ác. palmitoleico (C16:1), el ác. oleico (C18:1n9c) y el ác. eicosapentaenoico (C20:5n3). El ácido palmítico fue el componente mayoritario de los AGS, tanto en los LT como en los LN, e incrementó de manera significativa en función de la mayor temperatura, la mayor intensidad lumínica y la mayor duración de las horas de luz empleados. Dentro de los AGM, el ácido palmitoleico fue el más abundante en todas las condiciones de cultivo en los LT y LN. Se observó un disminución significativa con la temperatura más alta empleada (25°C) y la mayor duración de las horas de luz (16:8 h L:O). El ácido eicosapentaenoico fue el principal componente de los AGP en los LT y LN. Sin embargo, sus valores no superaron el 5%. En relación a los parámetros de calidad del aceite, el índice de Yodo, el número de cetano y el contenido de ácido linolénico estuvieron dentro de los límites establecidos por el estándar de calidad europeo EN14214. Estas características permiten inferir que los aceites de N. oceanica CCALA 978 se presentan como una materia prima adecuada para la producción de biodiesel. En la experiencia de cultivo de N. oceanica CCALA 978 en el fotobiorreactor columnar, se obtuvo un crecimiento sostenido de la cepa con el medio SWES, alcanzando 1,11 g L-1 de biomasa. Sin embargo, la intensidad de luz empleada y el diseño del fotobiorreactor constituyeron un impedimento para maximizar la producción de biomasa. De acuerdo con los resultados obtenidos, se concluye que la cepa nativa Nannochloropsis oceanica CCALA 978 es una microalga oleaginosa y robusta, y por lo tanto se la puede proponer como una fuente microalgal potencialmente útil de aceites para procesos de producción de biodiesel. Además, la información derivada de este trabajo representa una base para la implementación de nuevas estrategias de cultivos con fines bioenergéticos, tendientes a incrementar la biomasa, los contenidos de lípidos y las productividades lipídicas, condiciones indispensables para lograr un proceso potencialmente rentable. / In recent years, biodiesel production has grown worldwide in response to the gradual depletion of fossil resources and the environmental disturbances caused by the use of conventional fuels. Biodiesel is industrially obtained almost entirely from seed oils. However, the high energy demand, the depletion of soils and the use of seeds for food purposes raise the need for new sources of alternative sustainable feedstocks. Many species of microalgae, called oleaginous, can store high oils contents that turn them into a potential source for the production of biodiesel. Some species of Nannochloropsis genus have been proposed for this purpose due to ability to accumulate high lipid contents, in particular neutral lipids, which are considered the ideal feedstock for biodiesel production. Unlike other renewable energies in Argentina, research in this field is at early stage. Based on this background, the overall objective of this Thesis was to evaluate the potential of a native marine Nannochloropsis strain, isolated from the south Atlantic coast, as feedstock for biodiesel production. The specific objectives were followings: identification at specific level of the strain under study by both morphological and molecular characterization; optimization of techniques to determine the cell density, photosynthetic pigments concentration and neutral lipid content at laboratory scale; analysis of the effect of different environmental conditions (temperature [15ºC and 25ºC], light intensity [100 y 300 μmol photon m-2 s-1] and photoperiod [12:12 h and 16:8 h of light:darkness]) and the nitrogen deprivation on growth, biomass production, lipid quantity, lipid productivity and lipid quality, with special emphasis on the neutral lipids fraction. In addition, the growth of the strain under study was evaluated in a 25L columnar photobioreactor, with a culture medium (SWES) cheaper than the one used in laboratory experiments (f/2). Both morphological and ultrastructural studies of light and electron microscopes and the analysis of nuclear and chloroplast genes, 18S rDNA and rbcL respectively, allowed identifying the strain under study as Nannochloropsis oceanica. The strain was deposited in the Culture Collection of Autotrophic Organism, Czech Republic (CCALA) as Nannochloropsis oceanica CCALA 978. An estimation model for cell density was developed through optical density readings. In this way, the growth of N. oceanica 978 CCALA could quickly be monitored. Regarding methods to determine pigment concentration, methanol assisted with rapid freezing and unfreezing was the most effective method for the extraction of chlorophyll a and total carotenoids. Pre-treatment of the cells with 5% dimethyl sulphoxide and the staining with Nile red proved to be a suitable technique for in situ detection of the neutral lipids by espectrofluorimetry. Besides, the ratio between the fluorescence intensities of Chlorophyll a and Nile red was proposed as an index for the estimation of the maximum neutral lipid accumulation period and, consequently, for the determination of the biomass harvesting time. The effect of environmental variables on growth parameters indicated that under higher temperature (25°C), higher light intensity (300 μmol photon m-2 s-1) and a photoperiod of 16:8 h L:D, the species showed increased growth rate (0.85 div d-1) at laboratory scale. However, the biomass production (680 mg L-1) did not increase in response to higher light intensity. Under environmental conditions tested in this study, the content of total lipids (TL) in N. oceanica CCALA 978 was generally high (24-34%). This was due to a high proportion of neutral lipids (NL), which represented between 82% and 91% of TL. However, higher contents were obtained when the cells were grown in a culture medium devoid of nitrogen, at both light intensities and 16:8 h L:D photoperiod (TL: 36% dry weight of biomass [dw] and NL: 32% dw). Under these conditions, the highest productivities of 48 mg L-1 d-1 (TL) and 43 mg L-1 d-1 (NL) were obtained. Regarding the quality of lipids, under all conditions tested, saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) were the predominant classes within NL, representing both SFA-NL and MUFA-NL 90-96% of total fatty acids. The SFA-NL increased at 25°C, 16:8 h L:D and 300 μmol photon m-2 s-1, while the MUFA-NL decreased in response to these variables. Polyunsaturated fatty acids (PUFA) were the minority class in all tested culture conditions. For all these tests, the fatty acid composition was similar in both TL and NL, being the major fatty acids following: palmitic (C16:0), palmitoleic (C16:1), oleic (C18:1n9c) and eicosapentaenoic (C20:5n3). Palmitic acid was the major component of the SFA, in both TL and NL, and it significantly increased in response to higher temperature and light intensity and longer daylight hours employed. Within MUFA, palmitoleic acid was the most abundant in the TL and NL in all culture conditions. This fatty acid decresed significantly under the highest temperature (25°C) and the longest daylight hours (16:18 h L:D) employed. Eicosapentaenoic acid was the main component of PUFA on TL and NL. However, its values did not exceed 5% under all conditions probed. In regard to oil quality parameters, iodine index, cetane number and content of linolenic acid were within the limits set by European quality standard EN14214. These features allow us to infer that the oils of N. oceanica CCALA 978 constitute a suitable feedstock for the production of biodiesel. Respecting culture experience of N. oceanica CCALA 784 in the columnar photobioreactor, sustained growth of the strain was obtained with the SWES medium, reaching 1.11 g L-1 of biomass. However, both employed light intensity and photobioreactor design were an impediment to maximize biomass production. According to these results, it is concluded that the native strain of Nannochloropsis oceanica CCALA 978 is an oleaginous robust microalga. Therefore, it can be proposed as a potentially useful oil source for biodiesel production processes. In addition, the obtained information represents a basis for the implementation of new strategies for bioenergy cultures, aimed to increase biomass, lipid content and lipid productivities, which are requisites to achieve a potentially profitable process.

En la presente tesis, se investigó la síntesis de ésteres metílicos de ácidos grasos mediante la transesterificación catalítica empleando aceite de soja refinado y materias primas ácidas de bajos costos. Se evaluó el comportamiento de diferentes compuestos de zinc con propiedades ácido-base, en términos de actividad y estabilidad en el medio de reacción.En primera instancia se estudiaron las sales laminares hidroxiacetato e hidroxinitrato de zinc. El hidroxinitrato de zinc presentó buenos resultados en términos de actividad y estabilidad en la transesterificación de aceite de soja a 100° C, posibilitando su uso en ciclos catalíticos consecutivos, mostrando además una buena tolerancia al contenido acuoso. Hidroxiacetato de zinc presentó baja estabilidad en el medio de reacción. A continuación, se evaluó el potencial catalítico de los carboxilatos de zinc, con diferentes longitudes. Las sales de zinc de ácidos grasos de cadenas largas mostraron elevados rendimientos con buena estabilidad y tolerancia al agua, con la posibilidad de uso en reacciones consecutivas. Estos compuestos se solubilizan en el medio de reacción a la temperatura de trabajo, y se recuperan fácilmente debido a que cristalizan a temperatura ambiente. A temperaturas mayores, se observó la transformación de estos materiales a glicerolato de zinc en el medio de reacción. Los resultados obtenidos en la esterificación de ácidos grasos, mostraron que las sales carboxílicas de zinc presentan buena actividad. No obstante, se evidenció que durante la reacción se produce un intercambio de ligandos carboxilatos entre la sal carboxílica y el ácido a esterificar. Así mismo, la transesterificación de materias primas con 10-22 % de ácido oleico, mostraron que el oleato de zinc es capaz de esterificar los ácidos grasos libres y transesterificar triglicéridos en forma simultánea, con una notable actividad y selectividad. El desarrollo de esta tesis también incluye el estudio del glicerolato de zinc como potencial catalizador. Esta sal mostró ser activa, selectiva y estable en la transesterificación de aceite de soja refinado, y además presentó buena tolerancia a la presencia de agua. El uso del glicerolato de zinc en la transesterificación de materias primas ácidas, presentó una notable actividad con un máximo rendimiento a FAME a tiempos de reacción cortos. Este resultado se debe a la formación en el medio de reacción de un sistema catalítico altamente eficiente (glierolato/carboxilato de zinc), que opera en condiciones de reacción moderadas con elevada actividad y selectividad. / In the present thesis, the synthesis of methyl esters of fatty acids by catalytic transesterification using refined soybean oil and low-cost acid raw materials was studied. The behavior of several zinc compounds with acid-base properties were evaluated in terms of their activity and stability in the reaction medium. First, the layered salts zinc hydroxyacetate and hydroxynitrate were studied. Zinchydroxynitrate exhibited good results in terms of activity and stability in the transesterification of soybean oil at 100 °C, being possible to use it in consecutive catalytic cycles, also showing good tolerance to aqueous content. Zn hydroxyacetate presented low stability in the reaction medium. Then, the catalytic potential of zinc carboxylates with different chain lengths was evaluated. At 100 °C, the zinc salts of long-chain fatty acids showed high FAME yields with good stability and tolerance to water, with the possibility of reuse. These compounds dissolved in the reaction medium at low operating temperature, and can be easily recovered because they crystallize at room temperature. At higher temperatures, a transformation of the materials into zinc glycerolate was observed in the reaction medium. The results obtained in the esterification of fatty acids showed that zinc carboxylic salts presented good activity. However, it was observed that during the reaction a carboxylate shift occurred between the carboxylic salt and the acid to be esterified. In addition, the transesterification of raw materials with 10-22 % oleic acids showed that zinc oleate can simultaneously esterificate the free fatty acids and transesterificate triglycerides, with notable activity and selectivity. The development of this thesis also included the analysis of zinc glycerolate as a potential catalyst. This salt showed to be active, selective and stable in the transesterification of refined soybean oil, and it also presented good tolerance to the presence of water. The use of zinc glycerolate in the transesterification of acid raw materials exhibited a notable activity with maximum FAME yield at short reaction times. This result is a consequence of the formation of a highly efficient catalytic system (Zn glycerolate/Zn carboxylate) in the reaction medium, which operates under moderate reaction conditions with high activity and selectivity.

This dissertation includes two process modeling studies -- (1) predictive modeling of large-scale integrated refinery reaction and fractionation systems from plant data – hydrocracking process; and (2) integrated process modeling and product design of biodiesel manufacturing. \r\n1. Predictive Modeling of Large-Scale Integrated Refinery Reaction and Fractionation Systems from Plant Data -- Hydrocracking Processes: This work represents a workflow to develop, validate and apply a predictive model for rating and optimization of large-scale integrated refinery reaction and fractionation systems from plant data. We demonstrate the workflow with two commercial processes -- medium-pressure hydrocracking unit with a feed capacity of 1 million ton per year and high-pressure hydrocracking unit with a feed capacity of 2 million ton per year in the Asia Pacific. This work represents the detailed procedure for data acquisition to ensure accurate mass balances, and for implementing the workflow using Excel spreadsheets and a commercial software tool, Aspen HYSYS from Aspen Technology, Inc. The workflow includes special tools to facilitate an accurate transition from lumped kinetic components used in reactor modeling to the boiling point based pseudo-components required in the rigorous tray-by-tray distillation simulation. Two to three months of plant data are used to validate models' predictability. The resulting models accurately predict unit performance, product yields, and fuel properties from the corresponding operating conditions.\r\n2. Integrated Process Modeling and Product Design of Biodiesel Manufacturing: This work represents first a comprehensive review of published literature pertaining to developing an integrated process modeling and product design of biodiesel manufacturing, and identifies those deficient areas for further development. It also represents new modeling tools and a methodology for the integrated process modeling and product design of an entire biodiesel manufacturing train. We demonstrate the methodology by simulating an integrated process to predict reactor and \r\nseparator performance, stream conditions, and product qualities with different feedstocks. The results show that the methodology is effective not only for the rating and optimization of an existing biodiesel manufacturing, and but also for the design of a new process to produce biodiesel with specified fuel properties. / Ph. D.

Crude glycerol is the major byproduct of the biodiesel industry. In general, for every 100 pounds of biodiesel produced, approximately 10 pounds of crude glycerol are created. Because this glycerol is expensive to purify for use in food, pharmaceutical, or cosmetics industries, biodiesel producers must seek alternative methods for its disposal. Using crude glycerol as a carbon source for fermentation is a promising alternative use for this waste material. In this project, we propose to use crude glycerol in the fermentation of the microalga Schizochytrium limacinum, which is a prolific producer of docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid with proven beneficial effects on treating human diseases such as cardiovascular diseases, cancers, and Alzheimer's. The first part of this study provided "proof-of-concept" that Schizochytrium limacinum was capable of utilizing crude glycerol while producing DHA. The results show that pretreated crude glycerol was a viable carbon source for algal growth and DHA production, with 75 g/L to 100 g/L of glycerol being the optimum concentration range. In addition to glycerol concentration, temperature, trace metal levels, ammonium acetate concentration, and NH4Cl concentration also had significant effects (P < 0.1) on algal DHA production. Optimizing these factors using response surface methodology led to a DHA yield of 4.91 g/L and a DHA productivity of 0.82 g/L-day. The second part of this study investigated the effects of impurities within the glycerol on DHA production and algal biomass composition, with a goal of ensuring that the algal biomass produced from crude glycerol can be safely utilized as an ingredient in omega-3 fortified foods or animal feed additives. Crude glycerol samples obtained from different biodiesel producers were tested. All the samples contained methanol, soaps, and various elements including calcium, phosphorus, potassium, silicon, sodium, and zinc. Both methanol and soaps in the glycerol negatively influence algal DHA production. The two impurities can be removed from the culture medium by evaporation through autoclaving (for methanol) or by precipitation through pH adjustment (for soap). The results showed that the crude glycerol-derived algal biomass contained 45-50% lipid, 14-20% protein, and 25% carbohydrate, with 8-13% ash content. Palmitic acid (C16:0) and DHA (C22:6) were the two major fatty acids in the algal lipid. ICP analysis showed that that boron, calcium, copper, iron, magnesium, phosphorus, potassium, silicon, sodium, and sulfur were present in the algal biomass, but no heavy metals (such as mercury) were detected. The crude glycerol-derived algal biomass had a high level of DHA and a nutritional profile similar to glucose-derived commercial algal biomass, suggesting a great potential for using crude-glycerol derived algae in omega-3 fortified food or feed. Overall, this study shows that crude glycerol can be used as a safe and effective substrate for algal culture to produce high levels of omega-3 fatty acids. With the rapid expansion of the biodiesel industry, there is an urgent need to develop new markets for large quantities of crude glycerol. This research provides an exciting opportunity to utilize a large quantity of this low grade glycerol. / Master of Science

En raison des problèmes environnementaux associés à l'utilisation des combustibles fossiles, qui augmentent les émissions de gaz à effet de serre et causent les changements climatiques, et pour satisfaire le besoin mondial de carburants durables et surmonter une éventuelle crise énergétique, une part important de l'attention de la communauté scientifique est aujourd’hui consacrée à la découverte de sources d’énergie renouvelables. L'une des meilleures alternatives est le diesel vert qui pourrait être produit à partir d'huiles végétales (aucune quantité nette de dioxyde de carbone n'est rejetée dans l'atmosphère). Ces types d'huiles sont convertis en diesel vert par réaction d'hydrotraitement à haute température et pression en présence d'un catalyseur hétérogène qui joue un rôle essentiel dans ce processus. Ces catalyseurs hétérogènes, qui peuvent être bi- ou monométalliques, sont constitués d'un support et d'un composé métallique actif. Les caractéristiques du support telles que la surface spécifique, le volume des pores et le diamètre des pores ont un effet déterminant sur les propriétés finales du catalyseur formé. Ils peuvent déterminer la quantité de la charge de phase active optimale et peuvent être adaptés à la taille moléculaire du réactif. Dans cette thèse, un support d'alumine-γ mésoporeuse a d’abord été synthétisé en utilisant un polymère tensioactif par voie sol-gel et accompagné d'un auto-assemblage induit par évaporation (EISA). L'isopropoxyde d'aluminium (Al(O-i-Pr)₃) et le copolymère tribloc (Pluronic P123) ont été respectivement utilisés comme source d'aluminium et agent directeur de structure. La température de calcination optimale et le rapport massique P123/Al(O-i-Pr)₃ respectivement de 700ºC (avec 3 h de temps de trempage) et 0.98 permettent la production de γ-alumine avec des propriétés texturales appropriées. À l'étape suivante, 15% en poids de MoO₃ et 3% en poids de NiO ou CoO ont été imprégnés sur le support préparé pour former NiMo/γ-alumine et CoMo/γ-alumine respectivement après calcination. Suite à une sulfuration ex-situ, l'hydrotraitement de l'huile de canola a été effectué dans un réacteur continu pour la production de diesel vert. Une plage de température de 325 à 400°C et une de LHSV de 1 à 3 h⁻¹ ont été étudiées tandis que les autres paramètres opérationnels ont été maintenus constants à P: 450 psi et H2/huile: 600 mLmL⁻¹. Les deux catalyseurs ont permis la production de diesel vert (principalement C15-C18) tandis que NiMo a montré une activité légèrement supérieure à un LHSV plus élevé. La température optimale et le LHSV se sont révélés être 325ºC et 1 h⁻¹. Finalement, des catalyseurs Ni/γ-alumine (réduite) respectueux de l'environnement avec structure mésoporeuse ont été synthétisés par des procédés sol-gel (une étape) et d'imprégnation (deux étapes). Une teneur en oxyde de nickel plus faible a été observée dans un catalyseur dérivé du sol-gel par rapport aux produits imprégnés, ce qui est dû à l'incorporation de nickel dans le réseau de l'alumine. Après la réduction, du nickel métallique a été formé dans les deux catalyseurs. L'hydrotraitement de l'huile de canola a été effectué sur les deux catalyseurs (température: 400°C, P: 500 psi, LHSV: 0.5 h⁻¹, H2/huile: 600 mLmL⁻¹) et des hydrocarbures normaux, principalement C15-C18. Il a été observé que la conversion des triglycérides était initialement plus élevée pour le catalyseur imprégné et, après un temps en ligne de 300 min, elle tombe à des valeurs inférieures à celles du catalyseur sol-gel, ce qui montre la plus grande stabilité au fil du temps de ce dernier. / Owing to environmental issues concerning fossil fuels usage which increase the greenhouse gas emissions and cause climate change, and to satisfy the global need for sustainable fuels and overcome possible energy crisis much attention is devoted to the finding of sustainable energy sources. One of the best alternatives is green diesel which could be produced from vegetable oils (no net amount of carbon dioxide is released into the atmosphere). These kinds of oils are converted to green diesel via hydrotreating reaction at high temperature and pressure in the presence of a heterogeneous catalyst which plays an essential role in this process. These heterogeneous catalysts which could be bi- or monometallic, consist of a support and an active metal compound. The characteristics of the support such as specific surface area, pore volume and pore diameter have a determining effect on the final properties of the formed catalyst. They can determine the amount of optimum active phase loading and should be adapted to the reactant molecular size. In this thesis first, the γ-alumina support was one-pot synthesized via polymeric template assisted sol-gel and evaporation-induced self-assembly process. Aluminum isopropoxide (Al(O-i-Pr)₃) and triblock copolymer template (Pluronic P123) were respectively used as aluminum source and structure directing agent. The optimum calcination temperature and P123/Al(O-i-Pr)₃ mass ratio were respectively found to be 700ºC (with 3 h of soaking time) and 0.98 enabling the production of γ-alumina with appropriate textural properties. In the next step, 15% wt. MoO₃ and 3% wt. NiO or CoO were impregnated on the prepared support to respectively form NiMo/γ-alumina and CoMo/γ-alumina after subsequent calcination. Following an ex-situ sulfidation, the hydrotreatment of canola oil was performed in a continuous reactor to result in green diesel production. Temperature range of 325 to 400ºC and LHSV of 1 to 3 h⁻¹ were studied while the other process parameters were kept constant at P: 450 psi and H2/oil: 600 mLmL⁻¹. Both catalysts are promising for green diesel (mainly C15-C18) production while NiMo showed a slightly higher activity at higher LHSV. The optimum temperature and LHSV were found to be 325ºC and 1 h⁻¹. Finally, the environmentally friendly Ni/γ-alumina (reduced) catalysts with mesoporous structure were synthesize through sol-gel (one-step) and impregnation (two-step) methods. Lower bulk nickel oxide content was detected in sol-gel derived catalyst compared to impregnated ones which is due to the incorporation of nickel inside the alumina framework. After the reduction, metallic nickel was formed in both catalysts. Canola oil hydrotreatment was performed over both catalysts (temperature: 400ºC, P: 500 psi, LHSV: 0.5 h-1, H2/oil: 600 mLmL⁻¹) and normal hydrocarbons, mainly C15-C18, were produced. The triglyceride initial conversion was observed to be higher over the impregnated catalyst while after a time on stream of 300 min, it falls to values lower than that of the sol-gel catalyst, showing the higher stability over time of the latter.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第25267号 / 工博第5226号 / 新制||工||1996(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 高岡 昌輝, 教授 藤原 拓, 准教授 大下 和徹, 教授 西村 文武 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Resumo: Estudos têm sido realizados em relação à utilização de biodiesel em motores alternativos de ciclo Diesel, porém pouco material é encontrado quando se utiliza este combustível em turbinas a gás. Este trabalho analisou os parâmetros de desempenho e emissões de poluentes para várias misturas de biodiesel/querosene de aviação em um turboeixo Rover 1/S60. Os testes mostraram que não houve alterações significativas na operação do turboeixo. O estudo mostrou, também, que houve decréscimo de eficiência térmica e aumento de consumo de combustível com a utilização de misturas mais ricas em biodiesel. As emissões de poluentes também decresceram com o aumento de teor de biodiesel na mistura. / Abstract: Several tests have been performed comparing diesel and several kinds of esthers (biodiesel), most in reciprocating engines but also in micro-gas-turbines. This work studies a stationary turboshaft Rover 1/S60 performance and pollution emissions in the utilization of several blends of aviation kerosene and biodiesel. The tests also show that no significative changes occurred in turboshaft operation. This study also shows an increase of fuel consumption and a decrease in thermal efficiency and a decrease of pollutant species emission as the higher biodiesel proportion at blends are used at turboshaft operation. / Orientador: João Andrade de Carvalho Junior / Coorientador: Pedro Teixeira Lacava / Banca: Petronio Masanobu Tanisho / Banca: Luiz Daré Neto / Mestre

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Development of analytical methods to characterise biodiesel has become central to the overall success of the marketing of biodiesel fuel. In this regard, different bodies including the American Society for Testing and Materials (ASTM) and the European normalization (EN) have come up with various methods to determine important biodiesel parameters such as total glycerol, methanol and the fatty acid methyl esters (FAMEs), etc. Various studies have been conducted on the parameters mentioned above using a variety of instrumentation and sample preparations. The best methods reported are those that have been adopted by both the ASTM and EN standards. The purpose of this study was to develop alternative analytical methods to both the recommended ASTM and EN methods and, in some cases, to make modifications to both standards (ASTM D 6571 and EN 14214) and methods to determine total and bound glycerol, the ester content and also methanol content in biodiesel. Moreover, water washing after transesterification and the effect this practice has on biodiesel cold flow properties such as kinematic viscosity, cloud and pour point and density were evaluated. The possibility of using the iodine value to predict the feedstock source of an unknown biodiesel was also investigated. Six different vegetable oil samples were transesterified with methanol and used for this study. The six samples used were palm, crown, sunflower, waste vegetable oil (wvo), peanut and rapeseed biodiesel. Quantitative results indicated that the use of programmable temperature volatilisation (PTV) for total glycerol did not produce the required repeatability of between 1-4% relative standard deviation(RSD) for total glycerol analyses in biodiesel with precision of 25%, 86%, 25% and 56% for free glycerol (FG), monoglycerides (MG), diglycerides (DG), and triglycerides (TG) respectively. The standard requires a relative standard of between 1-4% As an alternative to the method using gas chromatography, normal phase high performance chromatography (HPLC) with binary gradient elution was used to determine the bound glycerol content. This method proved accurate and repeatable with RSD % of 0.33, 1.12, and 1.2 for TG, DG and MG respectively. Following the EN14103 protocol (European standard ester determination), the Zebron ZBWAX column which is comparable to the specification recommended by EN14103 but afforded the determination of ester content from the esters of myristic acid (C14:0) to behenic acid (C22:0) with reproducibility with RSD % of 6.81, 1.91, 7.27, 0.64, 1.18, 1.55, 6.03, 1.96, and 5.21 for methyl esters of myristic, palmitic, stearic, oleic, linoleic, linolenic, arachidoic, gadoleic and behenic acid respectively. Solid phase micro extraction (SPME) using GC-MS was developed as an alternative to both the EN14110 and ASTM D93 protocols for determining the methanol content in biodiesel. For this method, polyethylene glycol fibre (PEG) was used together with a deuterated methanol internal standard and a DB-FFAP (60m×0.25um×0.25um) column. Less volume of sample was required as compared to the EN14214 method. This method was found to be sensitive, accurate and repeatable with a RSD % of 4.82. The Iodine number of biodiesel decrease compared to their corresponding feed stock and therefore predicting the feed stock of an unknown biodiesel was going to be difficult .Results from this study indicated that it is not possible to predict the feed stock source of an unknown biodiesel from its iodine value. The effect of water washing after phase separation on biodiesel cold flow properties such as kinematic viscosity, density, cloud and pour point depended on the type of biodiesel produced. We observed that water washing after transesterification caused an increase in all the cold flow properties of sunflower biodiesel, whereas only the densities and kinematic viscosities increased in the case of palm and waste vegetable oil biodiesel. The cloud and pour point of the latter two diesel samples remained unchanged after water washing. Thus, the effect of water washing on biodiesel cold flow depended on the type of biodiesel. Blending a highly saturated biodiesel (fewer numbers of double bonds) with a less saturated biodiesel (higher number of double bonds) resulted in an improvement of both the pour and cloud points of the resultant biodiesel blend. / AFRIKAANSE OPSOMMING: Die ontwikkeling van analitiese metodes om biodiesel te karakteriseer word tans as ‘n kernmaatstaf gesien om biodiesel suksesvol te bemark. Hiervoor het verskeie liggame wat die Amerikaanse Vereniging vir Toetsing van Materiale (AVTM) en die Europese Normalisering (EN) insluit met verskeie standaard analitiese metodes vorendag gekom om belangrike biodiesel parameters soos bv. totale gliserol, metanol en vetsuur metielesters te meet. Om hierdie parameters te bepaal is van ‘n wye verskeidenheid toetse met verskillende instrumente en monsterbereidings gebruik gemaak. Die beste metodes is deur beide die AVTM en EN aanvaar. Die doel van hierdie studie was om metodes te ontwikkel wat as alternatiewe kan dien tot die wat deur die AVTM en EN voorsgeskryf is. In sommige gevalle is aanpassings tot beide die standaarde (AVTM en EN) en metodes aangebring om die totale en gebonde gliserol-, esteren metanolinhoud te bepaal. Verder is die effek van ‘n water wasstap na transesterifikasie op biodiesel se kouevloei eienskappe gevalueer wat eienskappe soos kinematiese viskositeit, vertroebelingspunt, gietingspunt en digtheid insluit. Die moontlike gebruik van die Jodiumpunt om die bron van die voerstof van ‘n onbekende diesel te bepaal is ook ondersoek. In hierdie studie is ses verskillende oliemonsters van plantaardige oorsprong gebruik wat d.m.v. metanol getransesterifiseer is. Hierdie monsters het palm-, kroon-, sonneblom-, afvalplant-, grondboontjie- en raapsaadolie ingelsuit. Tydens die studie is programmeerbare temperatuur vervlugtiging (PTV) vergelyk met inkolom inspuiting soos deur AVTM D6584/EN14214 vir totale gliserol analise voorgeskryf. Kwantitatiewe resultate het getoon dat die PTV metode nie die verlangde akkuraatheid van ‘n relatiewe standaardafwyking (RS) van 1-4% vir beide vrye en gebonde gliserol kon handhaaf nie. Die akkuraatheid was in die omgewing van 25%, 86%, 25% en 56% vir vrye gliserol (VG), monogliseriede (MG), digliseriede (DG) en trigliseriede (TG), onderskeidelik. Normale fase hoë werkverrigting vloeistofchromatografie met ‘n binêre elueeringsgradiënt is as alternatief tot gaschromatografie (GC) ondersoek om die gebonde gliserolinhoud te bepaal. Al was die GC metode meer sensitief, het die vloeistofchromatografie metode ‘n hoë graad van akuraatheid en herhaalbaarheid getoon met RS% waardes van 0.33, 1.12 en 1.2 wat vir TG, DG en MG, onderskeidelik, verkry is. ‘n Zebron ZB-WAX kolom is vir die EN14103 protokol gebruik. Behalwe vir ‘n groter lengte kon hierdie kolom met spesifikasies soos deur EN14103 voorgeskryf vergelyk word. Met die gebruik van hierdie kolom kon die esterinhoud van miristiensuur (C14:0) tot behensuur (C14:0) bepaal word. ‘n Hoë graad van herhaalbaarheid met RS% waardes van 6.81, 1.91, 7.27, 0.64, 1.18, 1.55, 6.03, 1.96 en 5.21 vir die metielesters van miristien-, palmitien-, stearien-, oleïn-, linoleïn-, linoleen-, aragidoon-, gadoleïen- en behensuur is onderskeidelik verkry. Om die metanolinhoud van die biodiesel te bepaal is soliede fase mikroekstraksie (SFME) m.b.v. gaschromatografie-massaspektrometrie (GC-MS) as alternatiewe tot EN14110 en AVTM D93 ontwikkel. In hierdie metode is daar van poliëtileenglikolvesels (PEG) en gedeutereerde metanol saam met ‘n DB-FFAP kolom (60 mm x 0.25 mm x 0.25 mm) gebruik gemaak. Hierdie metode het ‘n kleiner monstervolume as die EN14214 metode benodig en was sensitief, akkuraat en hehaalbaar wat tot ‘n RS% waarde van 4.82 gelei het. Op grond van die Jodiumwaarde van biodiesel en hul ooreenstemmende voerstowwe het hierdie studie bevind dat die Jodiumwaarde nie gebruik kan word om die voerstof van ‘n onbekende diesel kan voorspel nie. Die effek van ‘n water wasstap na faseskeiding op verskeie kouevloei eienskappe soos kinematiese viskositeit, vertroebelingspunt, gietingspunt en digtheid het van die tipe diesel afgehang. Dit is bevind dat ‘n water wasstap na transesterifikasie ‘n toename in al die kouevloeieienskappe van sonneblomdiesel tot gevolg gehad het. In teenstelling hiermee het slegs die kinematiese viskositeit en digtheid van palm- en afvalplantdiesel vermeerder terwyl hul vertroebelings- en gietingspunte onveranderd gebly het. Die hipotese dat ‘n water wasstap na transesterifikasie tot swak kouevloei eienskappe lei is dus as onwaar bevind aangesien hierdie eienskappe deur die tipe biodiesel bepaal word. Deur ‘n hoogs versadigde biodiesel (lae aantal dubbelbindings) met ‘n minder versadigde biodiesel (hoë aantal dubbelbindings) te vermeng het tot ‘n verbetering van beide die vertroebelings- en gietingspunte gelei. / Centre for Renewable and Sustainable Energy Studies

published_or_final_version / abstract / toc / Mechanical Engineering / Master / Master of Philosophy