No / In this paper, hydrodesulfurization (HDS) of crude oil in the three-phase slurry reactor over cobalt – molybdenum catalyst (CoMo / ɣ- AL2O3) is studied. Effects of space velocity and length of reactor on the conversion rate and catalyst effectiveness for HDS process have been investigated. Kinetics of the reaction rate for this process is primarily and Arrhenius equation for the rate constant is used. The results show that the effectiveness factor for catalyst along the length of reactor is decreased about 83%. By increasing liquid velocity from 4 to 10 1/s, the conversion of sulfur components is decreased about 22% at the temperature of 523 K. At the same temperature, by increasing liquid velocity from 36 to 84 1/s conversion is reduced to 25%. The results of the variation of the dimensionless reaction rate against conversion show that with increasing conversion, the reaction rate decreases and the reaction is stopped when the conversion is 100%.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A reaÃÃo de sÃntese de Fischer-Tropsch tem merecido grande atenÃÃo pelo seu interesse tecnolÃgico e cientÃfico. Este interesse està associado a conversÃo do gÃs natural em produtos lÃquidos de alta qualidade (gasolina e diesel) e elevado valor agregado. No presente trabalho à descrito a metodologia empregada na sÃntese e caracterizaÃÃo de catalisadores de ferro usados na sÃntese de Fischer-Tropsch, com Ãnfase nos catalisadores suportados em sÃlica e catalisadores industriais (utilizados na sÃntese de amÃnia) promovidos com potÃssio e cobre. Pretende-se com esta discussÃo, identificar possÃveis vias para o desenvolvimento de catalisadores mais ativos e seletivos, variando a composiÃÃo do promotor estrutural para fins de otimizar a distribuiÃÃo dos produtos em fraÃÃes de hidrocarbonetos especÃficos (gasolina, diesel e graxa). A reaÃÃo foi conduzida em um reator de leito de lama. O estudo seguiu um planejamento experimental do tipo fatorial quadrado com ponto central e os resultados foram analisados baseados na metodologia dos grÃficos de superfÃcie de respostas. Os efeitos das diferentes condiÃÃes operacionais (temperatura e pressÃo) e dos diferentes teores de potÃssio na distribuiÃÃo dos produtos lÃquidos foram comparados baseados nos cromatogramas, nÃmero mÃdio de carbono (Nn) e no grau de dispersÃo dos produtos. Para todos os catalisadores de ferro empregados neste trabalho, observou-se um aumento no Ãndice que representa o comprimento da cadeia de hidrocarboneto (Nn) com o aumento do teor de potÃssio. Indicando um maior grau de polimerizaÃÃo para os catalisadores de ferro suportados com 18K em ralaÃÃo aos outros (12K, 6K e industrial). Os resultados mostram que, para catalisadores suportados, em pressÃes elevadas (25 e 30atm) favorecem a produÃÃo de graxa, enquanto a seletividade para hidrocarbonetos lÃquidos à favorecida a baixa pressÃo (20atm) e baixa temperatura (240ÂC). Para os catalisadores industriais, observou-se um aumento na fraÃÃo graxa em baixas temperaturas (240-255ÂC) e elevadas pressÃes (30atm). Contudo, os resultados de todas as corridas para o catalisador suportado e o industrial promovido e nÃo-promovido apresentaram quantidades significativas de n-parafinas com no mÃximo 35 Ãtomos de carbono que pode ser causados atravÃs das limitaÃÃes geomÃtricas e espaciais dentro dos poros do catalisador que tambÃm podem explicar o motivo pelo qual o Ãndice de dispersÃo da distribuiÃÃo de hidrocarbonetos serem mais baixos para um maior nÃmero de carbonos mÃdio. / The Fischer-Tropsch synthesis has been focus of attention of the scientific and industrial community. This interest is related to the conversion of natural gas into high quality liquid products, such as gasoline and diesel, which have high commercial value. In this work the methodology applied to synthesize and characterize iron-based catalyst used in the Fischer-Tropsch synthesis was described. Emphasis was given to catalysts supported in silica and to industrial catalysts (used in the synthesis of ammonia) impregnated with potassium and copper. The catalysts were tested to identify more active and selective catalysts, changing the amount of structural promoter in order to optimize the product distribution of specific hydrocarbons (gasoline, diesel, wax). The reaction was carried out in a slurry phase reactor. The experiments followed a 22 factorial experimental planning with central point and the results were analyzed based on the surface response methodology. The effects of the operating conditions (temperature and pressure) and of the amount of potassium in the catalyst on the liquid product distribution were compared based on the chromatographs, number average number of carbons (Nn) and distribution dispersion. In all iron based catalyst used in the research, the number average number of carbons (Nn) increased with increasing amount of potassium in the catalyst formulation. This result indicates that the catalyst with 18 K supported in silica showed the highest degree of polymerization in comparison with all other catalysts produced in this research. The results showed that for the catalyst supported in silica high pressures (25 to 30 atm) favor the production of wax, while higher selectivity towards liquid fuels was favored by low pressure (20 atm) and low temperature (240ÂC). For the industrial catalyst, an increase in the wax cat was observed at low temperatures (240-255ÂC) and high pressures (30 atm). The experiments carried out with the both catalysts (silica-supported and alumina-supported) have presented significant amounts of n-paraffins with a maximum of 35 carbons and low dispersion of the product distribution which can be caused by space limitations within the catalyst pores.

Made available in DSpace on 2014-12-17T15:01:24Z (GMT). No. of bitstreams: 1 MarcioBDB_DISSERT.pdf: 1427541 bytes, checksum: 4ea4ab1aa3dd7faa960c62967facffc8 (MD5) Previous issue date: 2010-09-30 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / This work aims at the implementation and adaptation of a computational model for the study of the Fischer-Tropsch reaction in a slurry bed reactor from synthesis gas (CO+H2) for the selective production of hydrocarbons (CnHm), with emphasis on evaluation of the influence of operating conditions on the distribution of products formed during the reaction.The present model takes into account effects of rigorous phase equilibrium in a reactive flash drum, a detailed kinetic model able of predicting the formation of each chemical species of the reaction system, as well as control loops of the process variables for pressure and level of slurry phase. As a result, a system of Differential Algebraic Equations was solved using the computational code DASSL (Petzold, 1982). The consistent initialization for the problem was based on phase equilibrium formed by the existing components in the reactor. In addition, the index of the system was reduced to 1 by the introduction of control laws that govern the output of the reactor products. The results were compared qualitatively with experimental data collected in the Fischer-Tropsch Synthesis plant installed at Laborat?rio de Processamento de G?s - CTG?S-ER-Natal/RN / O presente trabalho tem como objetivo a implementa??o e adapta??o de um modelo computacional de equil?brio de fases visando o estudo do processo Fischer- Tropsch em reator leito de lama a partir de g?s de s?ntese (CO + H2) para a produ??o seletiva de hidrocarbonetos (CnHm), com ?nfase na avalia??o da influ?ncia das condi??es operacionais sobre a distribui??o dos produtos formados durante a rea??o. O modelo em quest?o leva em conta efeitos do equil?brio de fases de modo rigoroso num tambor flash reativo, uma cin?tica detalhada que prev? a forma??o de cada componente do sistema reacional, bem como malhas de controle do processo para as vari?veis press?o e n?vel da fase lama. O sistema de equa??es obtido ? do tipo Alg?brico Diferencial, e foi resolvido utilizando-se o c?digo computacional DASSL (Petzold, 1982). A inicializa??o consistente do sistema de equa??es foi feita com base na condi??o de equil?brio de fases inicial formado pelos componentes j? existentes no reator, sendo o ?ndice do sistema reduzido a 1 pela introdu??o das leis de controle que regem a sa?da de produtos do reator. Os resultados obtidos foram comparados qualitativamente com os dados experimentais coletados na planta de s?ntese de Fischer- Tropsch instalada no Laborat?rio de Processamento de G?s do CTG?S-ER em Natal/RN

Made available in DSpace on 2014-12-17T15:01:51Z (GMT). No. of bitstreams: 1 AristidesFSJ_TESE.pdf: 1616188 bytes, checksum: 162e291640cf71e1607267c17f431e17 (MD5) Previous issue date: 2010-10-15 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The wet oxidation of organic compounds with CO2 and H2O has been demonstrated to be an efficient technique for effluent treatment. This work focuses on the synthesis, characterization and catalytic performance of Fe-MnO2/CeO2, K-MnO2/CeO2/ palygorskite and Fe/ palygorskite toward the wet oxidative degradation of phenol. The experiments were conducted in a sludge bed reactor with controlled temperature, pressure and stirring speed and sampling of the liquid phase. Experiments were performed on the following operating conditions: temperature 130 ? C, pressure 20.4 atm, catalyst mass concentration of 5 g / L initial concentration of phenol and 0.5 g / L. The catalytic tests were performed in a slurry agitated reactor provided with temperature, pressure and agitation control and reactor liquid sampling. The influences of iron loaded on the support (0.3; 7 and 10%, m/m) and the initial pH of the reactant medium (3.1; 6.8; 8.7) were studied. The iron dispersion on the palygorskite, the phase purity and the elemental composition of the catalyst were evaluated by X-Ray Difraction (XRD), Scanning Electron Microscopy (SEM) and X-Ray Flourescence (XRF). The use of palygorskite as support to increase the surface area was confirmed by the B.E.T. surface results. The phenol degradation curves showed that the Fe3+ over palygorskite when compared with the other materials tested has the best performance toward the (Total Organic carbonic) TOC conversion. The decrease in alkalinity of the reaction medium also favors the conversion of TOC. The maximum conversion obtained from the TOC with the catalyst 3% Fe / palygorskite was around 95% for a reaction time of 60 minutes, while reducing the formation of acids, especially acetic acid. With products obtained from wet oxidation of phenol, hydroquinone, p-benzoquinone, catechol and oxalic acid, identified and quantified by High Performance Liquid Chromatography was possible to propose a reaction mechanism of the process where the phenol is transformed into the homogeneous and heterogeneous phase in the other by applying a kinetic model, Langmuir-Hinshelwood type, with evaluation of kinetic constants of different reactions involved. / A oxida??o ?mida de compostos org?nicos a CO2 e H2O tem demonstrado ser uma t?cnica interessante no tratamento de efluentes. Este trabalho tem como objetivo a s?ntese e caracteriza??o dos catalisadores Fe-MnO2/CeO2, K-MnO2/CeO2/paligorsquita e Fe/paligorsquita, assim como, a avalia??o na degrada??o oxidativa do fenol. Os experimentos foram realizados em um reator de leito de lama, com controle de temperatura, de press?o e de velocidade de agita??o e com coleta de amostras da fase l?quida. Os Experimentos foram executados nas seguintes condi??es operacionais: temperatura de 130 oC, press?o de 20,4 atm, concentra??o m?ssica do catalisador de 5 g/L e concentra??o inicial do fenol de 0,5 g/L. Os par?metros avaliados foram: teor de ferro impregnado (0,3; 7 e 10% em massa) e o pH do meio reacional (3,1; 6,8 e 8,7). Os resultados da caracteriza??o por DRX, MEV e FRX mostraram a dispers?o do ferro na paligorsquita, a pureza das fases e, finalmente, a composi??o dos elementos que constituem o catalisador. O uso da paligorsquita como suporte eleva a ?rea especifica superficial do catalisador que foi confirmada por an?lise BET. As curvas de degrada??o do fenol indicam que o catalisador Fe3+ suportado em paligorsquita tem um papel preponderante na convers?o de Carbono Org?nico Total (COT) quando comparado aos demais catalisadores. A diminui??o da alcalinidade do meio reacional favorece tamb?m a convers?o de COT. A convers?o m?xima de COT obtida com o catalisador 3% Fe/paligorsquita, foi em torno de 95 % para um tempo de rea??o de 60 minutos, reduzindo ao mesmo tempo a forma??o de ?cidos, em especial o ?cido ac?tico. Com os produtos obtidos da oxida??o ?mida do fenol, hidroquinona, p-benzoquinona, catecol e ?cido ox?lico, identificados e quantificados por Cromatografia L?quida de Alta Efici?ncia, foi poss?vel propor um mecanismo do processo reacional onde o fenol ? transformado em fase homog?nea e os demais em fase heterog?nea. Aplicou-se um modelo cin?tico, tipo Langmuir- Hinshelwood, com avalia??o das constantes cin?ticas das diferentes rea??es envolvidas

En raison de la raréfaction des ressources de pétrole et des variations des prix avec le contexte géopolitique, la réaction de catalyse de Fischer-Tropsch qui permet la production d’hydrocarbures à partir du mélange syngas des gaz CO et H2 en présence d’un catalyseur à base de fer ou de cobalt, présente aujourd’hui un regain d’intérêt tant de la part des industriels que des académiques. Bien que découverte en 1923 par les allemands Franz Fischer et Hans Tropsch, les mécanismes qui entrent en jeu lors de cette réaction et les paramètres importants des propriétés des catalyseurs demeurent encore incertains. Dans ce contexte, les travaux présentés dans cette thèse visent à étudier l’impact de paramètres tels que la structure cristallographique et la forme de nano-objets de cobalt, phase active du catalyseur pour cette réaction. Ceci passe par la synthèse de catalyseurs modèles à base de nano-objets de cobalt et l’étude de leurs propriétés catalytiques. Dans un premier temps, la préparation d’un catalyseur à base de cobalt présentant une structure cristallographique hcp et une morphologie anisotrope a été réalisée, via une voie de synthèse par décomposition d’un précurseur organométallique de cobalt, conduisant à la formation de nano-objets de cobalt anisotropes. Puis, des tests catalytiques ont été réalisés en réacteur slurry, en collaboration avec un partenaire industriel, l’IFP-EN. Cela a permis la réalisation de tests Fischer-Tropsch en conditions proches des conditions industrielles réelles. Ces études ont permis de mettre en évidence la très grande stabilité de ces catalyseurs en comparaison à des catalyseurs de référence.Enfin, différents catalyseurs à base de cobalt, supportés sur des supports originaux de type macrostructurés permettant une meilleure gestion des échanges thermiques de la réaction, ont été préparés et leurs propriétés catalytiques étudiées sur un réacteur de type lit-fixe, mis en œuvre durant cette thèse. / Due to the decreasing the oil resources, and because of the the fluctuations of the price as a result of the geopolitical context, the Fischer-Tropsch synthesis, that enables the production of hydrocarbons form the syngas mixture (CO and H2) in the presence of a catalyst based on cobalt or iron, has recently gained a renewed interest from industrial as well as form the academic communities. Although this reaction was discovered in 1923 by the Germans Franz Fischer and Hans Tropsch, the mechanisms that come into play during this reaction and the crucial properties of the catalyst properties remain uncertain. In this context, the work presented in this thesis, aims to investigate the impact of parameters such as the crystallographic structure and the shape of the cobalt nano-objects, which is the active phase of the catalyst for this reaction. For this purpose, model cobalt nano-objects were synthetized and their catalytic properties were studied. As a first step, a cobalt based catalyst exhibiting an hcp crystallographic structure and an anisotropic shape was prepared via a synthetic route involving the decomposition of an organometallic precursor of cobalt and leading to the formation of anisotropic cobalt nano-objects. Catalytic tests were then conducted in a slurry reactor, in collaboration with an industrial partner, IFP-EN. This collaboration allowed performing catalytic studies under conditions that are very close to the actual industrial conditions. These studies revealed an increased stability of these catalysts compared to reference catalysts that deactivate with time. Finally, several cobalt-based catalysts, supported on innovative supports, such as macrostuctured supports, allowing a better control of the exothermicity, were prepared and their catalytic properties studied on a fixed-bed reactor that was set up during the course of this thesis work.