Made available in DSpace on 2014-12-17T15:01:51Z (GMT). No. of bitstreams: 1 JoseRS_TESE.pdf: 2480554 bytes, checksum: 063a0cad7c7f0aba30894e5fdff5f4a7 (MD5) Previous issue date: 2010-07-30 / The current natural gas production of 52 Mm3d-1 and the large projects for its expansion has been setting new boundaries for the Brazilian industry of oil and gas. So far, one of the biggest challenges regards to the logistics for gas transportation from offshore fields. Therefore, the transformation of natural gas into gasoline, diesel and/or olefins via Fischer-Tropsch synthesis would be an alternative to this matter. In this work, the production of hydrocarbons by Fischer-Tropsch synthesis in a slurry reactor was investigated and a perovskite-type catalyst (LayCu0,4Fe0,6O3 ? d) was used with y varying from 0 to 1 on a molar basis. In addition, Nb2O5 support was also applied in order to observe the selectivity of the produced hydrocarbons by the Fischer-Tropsch process. It is shown that the hydrogen conversion was influenced by the support as well as the different phases of the samples. The kinetic results for the CO2 production suffered great influence with the introduction of the Nb2O5 support throughout the series of samples studied. The catalysts allowed obtaining welldefined cuts of hydrocarbons in the range of C1-C6 and C17-C28, and these results were clearly influenced by the support and the lanthanum content. The higher olefin/paraffin ratio obtained was 1.8 when using a non-supported perovskite with y equal to 0.8. This would indicate the suitability of using this material for the production of olefins / A produ??o atual de 52 milh?es m?dia-1 de g?s natural e os grandes projetos para esta expans?o vem estabelecendo novas fronteiras para a ind?stria nacional de petr?leo e g?s, sendo um dos maiores desafios a log?stica para o transporte do g?s oriundo de campos offshore. Uma alternativa seria usar o g?s natural para a produ??o de gasolina, diesel e/ou olefinas atrav?s da s?ntese de Fischer-Tropsch. No desenvolvimento deste trabalho foi investigado a produ??o de hidrocarbonetos via s?ntese de Fischer-Tropsch em um reator slurry mediante uso de catalisadores do tipo perovskita, LayCu0,4Fe0,6O3?d, onde y sofreu varia??o de 0 at? 1 em base molar. A s?ntese dos catalisadores levou em considera??o o estudo da influ?ncia do teor de lant?nio e do suporte (Nb2O5) na atividade e seletividade da rea??o de Fischer-Tropsch, objetivando a produ??o de hidrocarbonetos. As convers?es de H2 foram sensivelmente influ?nciadas pela presen?a de fases existentes em cada amostra, assim como pelo suporte. Os resultados da cin?tica de produ??o de CO2 sofreram grandes influ?ncias com a introdu??o do suporte em toda a s?rie das amostras produzidas. Os catalisadores empregados permitiram a obten??o de cortes bem definidos de hidrocarbonetos na faixa de C1-C6 e C17-C28, sendo estes resultados claramente influenciados pelo suporte e pela varia??o do teor de lant?nio. A maior rela??o olefina/parafina obtida foi de 1,8 para a perovskita com y igual a 0,8 na amostra n?o suportada, viabilizando o uso deste material na produ??o de olefinas

nÃo hà / O presente trabalho tem como principal objetivo investigar as condiÃÃes mais adequadas para o estudo da difusividade de n-parafinas em um catalisador tÃpico para a sÃntese de Fischer-Tropsch (SFT), utilizando o mÃtodo cromatogrÃfico ZLC (coluna de comprimento zero), e avaliando-se a repetitividade e a reprodutibilidade desta metodologia. Objetiva, ainda, verificar o desempenho do catalisador em um reator de leito fixo, em escala piloto, e observar o efeito da difusÃo na seletividade a hidrocarbonetos de alta massa molar. O catalisador foi caracterizado, com Ãnfase nos ensaios de microscopia e anÃlise textural. Quanto à difusividade dos n-alcanos (n-C7, n-C9, n-C12, n-C16), foram utilizados dois sistemas ZLC, sendo um na Universidade Federal do Cearà (UFC) e o outro na Universidade de Edimburgo, empregando-se amostras de diferentes granulometrias (forma pà e pellet). Investigou-se, tambÃm, a influÃncia da temperatura, da vazÃo do gÃs de purga, da massa de catalisador e da concentraÃÃo do sorbato no gÃs de purga. Quanto à etapa reacional, esta ocorreu em uma unidade piloto para a SFT a 20 bar, nas temperaturas de 210 ÂC e 230 ÂC e em diferentes velocidades espaciais. O catalisador apresentou-se como mesoporoso, com um pouco de microporosidade, e com a fase ativa (Co) bem distribuÃda. Em relaÃÃo à difusividade efetiva, o diÃmetro de partÃcula mais adequado para o uso na coluna ZLC, dentre os testados, foi de 214 Âm para o catalisador na forma pÃ, com 5 mg de amostra. Comparando-se os experimentos realizados nas duas universidades, percebeu-se uma boa repetitividade, porÃm a reprodutibilidade, nÃo foi satisfatÃria. Observou-se ainda, a influÃncia da constante de Henry nos resultados obtidos para difusividade efetiva, em diferentes tamanhos de catalisador, entretanto, nÃo se perceberam mudanÃas significativas na difusividade efetiva em funÃÃo da variaÃÃo da temperatura e da concentraÃÃo de sorbato no gÃs de purga. Em se tratando da reaÃÃo, os resultados indicaram um forte efeito da temperatura na conversÃo de CO e na seletividade a C5+. O mecanismo difusivo à afetado pela difusividade de superfÃcie, e, a partir deste resultado, pode-se justificar o aumento da seletividade a metano com o incremento da relaÃÃo H2/CO. Com base nos resultados apresentados, o mÃtodo ZLC mostrou-se adequado para o estudo da difusividade efetiva de n-parafinas em um catalisador convencional para a SFT. / The main goal of the present research is to establish the most appropriate conditions for studying the diffusivity of n-paraffins in the presence of a typical catalyst for Fischer-Tropsch synthesis (FTS), by using the chromatographic method ZLC (zero length column) and evaluating the repeatability and reproducibility of this method. It also aims to verify the catalyst performance in a fixed bed reactor, at a pilot-scale, and observe the effect of diffusion in the selectivity of high molar mass hydrocarbons. At first, the catalyst characterization was done with emphasis on the microscopy studies and textural analysis with N2. Regarding the n-alkanes diffusivity (n-C7, n-C9, n-C12, n-C16), two ZLC equipments were used, one at the Federal University of Ceara (UFC) and the another one at the University of Edinburgh, with different particle size samples. This work has also evaluated the influence of temperature, the purge gas flow rate, the catalyst mass and sorbate concentration in the purge gas. The reaction step was done at a Fisher-Tropsch pilot-scale unit at 20 bar, with 210ÂC and 230ÂC in different space velocities. As a result, the catalyst was presented as mesoporous, with small microporosity, and with active phase (Co) well distributed. Concerning the effective diffusivity, the most appropriate particle diameter to be used at the ZLC column, among the tested diameters, is 214 Âm (dust form), with 5 mg of catalyst. Comparing the studies that were held at the two universities, it was noticed a good repeatability, however, the reproducibility was not satisfactory. It was observed a strong influence of the HenryÂs constant at the results of effective diffusivity, for different catalyst sizes; however, no significant changes at the effective diffusivity were noted due to temperature variation and sorbate concentration. Regarding the reaction, the results indicated a strong effect of temperature at the CO conversion and at the C5+ selectivity. The diffusive mechanism is strongly affected by the catalyst surface effects. Based on this result, the raise of methane selectivity by increasing H2/CO ratio can explained. As final result, the ZLC is found as a suitable method for surface diffusion estimation using typical Fischer-Tropsch catalyst.

A necessidade de produÃÃo de combustÃveis lÃquidos, principalmente diesel com baixos teores de enxofre para atender recentes legislaÃÃes ambientais, impulsionou a pesquisa sobre a reaÃÃo de sÃntese de Fischer-Tropsch (SFT), que utiliza a polimerizaÃÃo entre monÃxido de carbono (CO) e hidrogÃnio (H2) em diversos tipos de reator e de catalisador. Foram realizadas vÃrias simulaÃÃes da reaÃÃo de sÃntese de Fischer-Tropsch em reator tubular de leito fixo com catalisador de ferro avaliando-se o efeito de determinadas condiÃÃes operacionais na distribuiÃÃo de produtos, de acordo com o modelo desenvolvido para a distribuiÃÃo das massas moleculares dos hidrocarbonetos formados. As condiÃÃes operacionais foram avaliadas de modo favorecer a formaÃÃo de diesel e graxa, que por sua vez podem ser craqueadas visando à produÃÃo de combustÃveis lÃquidos. Um planejamento experimental e uma posterior anÃlise estatÃstica foram executados de forma a apontar as condiÃÃes operacionais que mais influenciam na formaÃÃo de produtos especÃficos como gasolina, diesel e graxas, assim como na conversÃo do gÃs de sÃntese em hidrocarbonetos. Os resultados obtidos mostraram a adequaÃÃo da modelagem adotada com dados experimentais existentes na literatura / In this work, a fixed-bed tubular reactor was modeled and simulated for the Fischer-Tropsch synthesis carried out using iron-based catalysts. The model has considered the fluid-dynamics of the fixed-bed reactor and the polymerization reaction of the Fischer-Trospch synthesis. Several simulations were carried out with the mathematical model to study the effects of the operating conditions on the product distribution and on the yield into hydrocarbons. The simulations were analyzed aiming the optimization of the system toward the production of diesel and wax fractions, which can be later cracked to produce a higher amount of liquid products. The simulations were carried out following a factorial design to identify the operating conditions that most influence the production of each specific product fraction, as gasoline, diesel and waxes, and in the yield of synthesis gas into hydrocarbon

A síntese de Fischer-Tropsch é um processo de conversão do gás de síntese (CO + H2) em hidrocarbonetos de cadeias longas. Os catalisadores clássicos para a hidrogenação do CO são, principalmente, o Fe e o Co suportados em diferentes óxidos. O desempenho catalítico do catalisador é influenciado pelo tamanho, dispersão e grau de redução das partículas metálicas. Estudos recentes mostram uma promissora aplicação de materiais à base de nanofibras de carbono na catálise heterogênea. Estes materiais apresentam algumas vantagens em relação aos suportes catalíticos tradicionais, tais como: uma baixa interação metal-suporte, elevada área superficial, ausência de poros fechados, alta condutividade térmica, elevada inércia química e hidrofobicidade. Neste trabalho foram fabricados suportes catalíticos macroscópicos à base de nanofibras de carbono, empregando o método de vapor deposição, a partir da decomposição do etano. Os catalisadores foram preparados pela impregnação incipiente do Co e de promotores na superfície do suporte. Foram empregados os metais nobres, Ir, Pt e Ru, como promotores catalíticos, com o objetivo de incrementar a redutibilidade e a atividade do catalisador. Todos os catalisadores foram caracterizados por Quimissorção de CO, Fisissorção de N2, Redução a Temperatura Programada (TPR), Espectroscopia Fotoeletrônica de Raios X (XPS) e Microscopia Eletrônica de Transmissão (MET). Os catalisadores foram, então, testados na síntese de Fischer-Tropsch, utilizando um reator de leito fixo e fluxo contínuo, com análise simultânea dos produtos gasosos e controle sistemático da temperatura, pressão e vazão dos reagentes. Finalmente, foram analisados os produtos líquidos obtidos na reação com objetivo de conhecer a influência dos promotores na seletividade dos hidrocarbonetos formados. / Fischer-Tropsch synthesis is a process of converting the syngas (CO + H2) to long-chain hydrocarbons. The traditional catalysts for the CO hydrogenation are Fe and Co supported on different oxides. Catalytic performance of the catalyst is influenced by size, dispersion and degree of reduction of metal particles. Recent studies show a promising application of materials based on carbon nanofibers in heterogeneous catalysis. These materials have some advantages compared to traditional catalyst supports, such as a low metal support interaction, high surface area, no closed pores, high thermal conductivity, high chemical resistance, and hydrophobicity. In this work, based on macroscopic carbon nanofiber catalyst supports have been manufactured by employing the method of chemical vapor deposition from ethane decomposition. Catalysts were prepared by incipient wetness impregnation of Co and promoters on the support surface. Noble metals, Ir, Pt and Ru were used as catalytic promoters, with the aim of increasing the reductibility and catalyst activity. All catalysts were characterized by CO Chemisorption, N2 Physisorption, Temperature Programmed Reduction (TPR), X-ray Photoelectron Spectroscopy (XPS), and Transmission Electron Microscopy (TEM). The catalysts were then tested in the Fischer-Tropsch synthesis using a fixed bed reactor, continuous flow, with simultaneous analysis of gaseous products and systematic temperature control, pressure, and flow rate of the reactants. Finally, the liquid products obtained in the reaction were analyzed in order to determine the influence of promoters on the selectivity of hydrocarbons formed.

Ce travail concerne la mesure et la caractérisation du transfert thermique à la paroi externe d’un faisceau de tube de refroidissement inséré dans des colonnes à bulles type « slurry ». La valeur du coefficient de transfert de chaleur est estimée à partir des équations de la chaleur. Une colonne de 0,15 m de diamètre et de 4 m de haut, équipée de deux tubes en U (3 cm de diamètre externe), a été utilisée pour mettre au point la métrologie nécessaire. L’eau a servi de fluide de refroidissement. Le mélange diphasique air-huile Syltherm XLT®, puis le mélange triphasique air-huile Syltherm XLT®-microbilles d’alumine poreuses (dS ~ 80 μm), ont servi de fluides modèles. L’incertitude de nos mesures a été estimée à environ 8 %. En système diphasique, les variations du coefficient de transfert de chaleur avec la vitesse superficielle du gaz ont pu être corrélées par une loi semblable à celle de Deckwer (1980). Cependant, la valeur de la constante de corrélation semble dépendre de l’orientation du faisceau de tubes par rapport à l’axe de la colonne. Un tel comportement n’a jamais été rapporté dans la littérature. L’écart du faisceau à un faisceau idéal (i.e. parfaitement droit et symétrique) peut être un paramètre crucial pour le transfert de chaleur. En système triphasique, la valeur du coefficient ne varie pas de façon significative jusqu’à une concentration massique d’environ 18,8 %, avant de diminuer d’environ 10 % pour une concentration massique de 21,3 %. Ce résultat est surprenant. Les variations rapportées dans la littérature sont en effet souvent contradictoires, mais toujours continues dans la gamme de concentrations testée. La métrologie mise au point a été implantée dans une colonne de 1 m de diamètre et de 5 m de haut, équipée de 24 tubes en U (6 cm de diamètre externe). Celle-ci est jugée représentative d’un réacteur pour le procédé Fischer-Tropsch. Les premiers résultats indiquent que la caractérisation thermique de l’installation sera plus délicate que pour la petite colonne / This work investigates the measure and characterisation of heat transfer in slurry bubble column reactors equipped with a bundle of cooling tubes. The value of the shell-tube heat transfer coefficient is estimated at thermal steady-state regime using heat transfer equations. A 15 cm in diameter, 4 m high bubble column, equipped with a two U-tubes (3 cm O.D.) bundle has been used to assess the metrology selected. The cooling fluid was water. Air-Syltherm XLT® heat transfer fluid and air-Syltherm XLT® heat transfer fluid-porous alumina particles (dS ~ 80 μm) were successively used as shell fluids. The uncertainty of our measures has been estimated to be around 8 %. The variations of the shell-tube heat transfer coefficient with superficial gas velocity can be modelled using the well-known correlation by Deckwer (1980). However, a smaller constant value than indicated by Deckwer et al. (1980) was obtained and it was found to be dependent upon the orientation of the tube bundle relatively to the column axis. This has never been reported in the literature and implies that any difference relatively to the ideal tube bundle – perfectly straight and symmetric – might be critical for heat transfer. Addition of solid particles has little effect on heat transfer for solid concentrations below 18.8 %w/w. A further increase up to 21.3 %w/w induced a 10 % decrease of the value of the shell-tube heat transfer coefficient. This was surprising, as existing literature results display continuous variations of the heat transfer coefficient values in the range of solid concentrations tested, even though trends of variation could be opposite. The assessed metrology was implemented into a 1 m in diameter, 5 m high bubble column equipped with a 24 U-tubes (6 cm O.D.) bundle. This pilot plant was considered to be large enough to mock up a slurry bubble column reactor for the Fischer-Tropsch process. First results indicate that thermal characterisation will be more complex than for the smaller diameter column

In this work, carbonaceous deposits on spent HTFT catalysts were investigated. This research was required in order to better understand the observed loss in productivity observed in the industrial reactors, with the aim of improving the economy of the HTFT process. A host of complementary techniques were employed to systematically determine the composition of a typical catalyst recovered from a reactor. Spent HTFT catalysts are comprised of magnetite and a mixture of iron carbides as well as adsorbed hydrocarbon products (soft carbon) and hard carbon. Reaction initiates at the particle surface and along the promoter-rich grain boundaries toward the core of the grains. A partially reacted particle would therefore have a core-shell structure, with magnetite representing the unreacted region of the catalyst. The reacted region consists of a porous carbonaceous matrix with soft carbon and carbide crystallites nestled in this matrix. The hard carbonaceous species is a mixture of polymeric carbon and polycyclic aromatic hydrocarbons. The particle structure is linked to the sample preparation method and an alternative method yielding catalyst particle with uniformly distributed promoter elements could be beneficial. Investigating carbonaceous species is a complex process, and development of a fresh methodology would aid in the quest for insight into the nature of carbonaceous species in various systems. A new approach which entails a combination of the traditional techniques combined with MALDI-TOF MS enabled a deeper investigation. Additional aspects such as the molecular weight distributions along with known information about crystallinity and morphology of the catalyst provide a comprehensive study of carbonaceous material. Polymeric carbon and very large polycyclic aromatic hydrocarbons constitute hard carbon and can be observed with minimal sample preparation procedures. The evolution of the HTFT catalysts was investigated as a function of time-on-stream. This enabled us to study the effects of increasing amounts of hard carbon on the activity and the chemical and physical properties of the catalysts. The catalyst activity was found to decrease with increasing hard carbon content, although the effect of carbon deposition cannot be distinguished from phase transformation (oxidation) which occurs simultaneously. A method to quantify the amount of hard carbon, which progressively builds up on the catalyst, was demonstrated. This required a great deal of method development, which provides a platform for future investigations of these catalysts. Importantly, it allows predictions of the amounts of carbon that will be deposited after a certain reaction time. This allows more efficient regulation of catalyst replacement. The production of fine carbon-rich particles in the industrial reactor poses a major problem in the process. Carbon deposition leads to an increase in particle diameter with time on-stream. Permissible levels of hard carbon were identified, beyond which the mechanical strength of the catalyst particles deteriorate. This leads to break-up of the particles and therefore fines formation. The surface area and pore volume generally increase with progressive deposition of hard carbon, while the bulk density of the catalyst material exhibits a linear decrease with carbon build-up. A mechanism is proposed for hard carbon formation which apparently occurs through the dissociative adsorption of CO to form a carbon monolayer. This is followed by polymerisation of the carbon atoms. Meta-stable interstitial carbides are formed at the iron-carbon interface. Owing to a carbon concentration gradient between the top of the surface and the bottom of the metal or carbide particle, carbon diffusion across the crystal (carbide decomposition) and grows as a PAH molecule lifting the iron carbide away from the particle. As this corrosion process is intrinsic to iron-based catalysts, a catalyst that contains sulphur is proposed for future development.

Lower C2–C4 olefins are important commodity chemicals usually produced by steam cracking of naphtha or fluid catalytic cracking of vacuum gas oil. The Fischer–Tropsch synthesis of lower olefins (FTO) with iron-based catalysts uses synthesis gas as an alternative feedstock. Nanostructured carbon materials are widely applied as supports for the iron nanoparticles due to their weak interaction with the metal species, facilitating the formation of catalytically active iron carbide. Numerous synthetic approaches towards carbon-supported FTO catalysts with various structures and properties have been published in recent years but structure-performance relationships remain poorly understood. We apply ordered mesoporous carbon (CMK-3) as a support material with well-defined pore structure to investigate the relationships between calcination/activation conditions and catalytic properties. After loading of iron and sodium/sulfur as the promoters, the structures and properties of the FTO catalysts are varied by using different calcination (300–1000 °C) and activation (350 or 450 °C) temperatures followed by FTO testing at 1 bar, 350 °C, H2/CO = 1. Carbothermal reduction of iron oxides by the support material occurs at calcination temperatures of 800 or 1000 °C, leading to a higher ratio of catalytically active iron(carbide) species but the catalytic activity remains low due to particle growth and blocking of the catalytically active sites with dense graphite layers. For the samples calcined at 300 and 500 °C, the formation of non-blocked iron carbide can be enhanced by activation at higher temperatures, leading to higher catalytic activity. Olefin selectivities of ∼60%C in the formed hydrocarbons with methane of ∼10%C are achieved for all catalysts under FTO conditions at low CO conversion. The influence of the calcination temperature is further investigated under industrially relevant FTO conditions. Promoted CMK-3-supported catalysts obtained at low calcination temperatures of 300–500 °C show stable operation for 140 h of time on stream at 10 bar, 340 °C, H2/CO = 2.

Orientador: Reginaldo Guirardello / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-18T13:21:06Z (GMT). No. of bitstreams: 1 Yamada_ShinobuTomas_D.pdf: 3876142 bytes, checksum: 951723c2abec9e70853595542ea18fe3 (MD5) Previous issue date: 2011 / Resumo: Esta tese apresenta a cinética e a fluidodinâmica do processo Fischer Tropsch realizado nos softwares científicos Fortran (Formula Translation) e CFX (Fluidodinâmica Computacional) da AEA Technology plc. O presente trabalho é uma simulação computacional de um sistema catalítico, multifásico, multicomponente e não isotérmico com topologia tridimensional, baseado em catalisador de cobalto suportado, recheio de esferas de aço e meio reacional formado por pseudocomponentes, gás combustível - GLP, nafta - gasolina - diesel, ceras de baixo - médio - alto peso molecular e vapor de água, além do gás de síntese (CO + H2) não convertido. As modelagens da cinética de reação e do balanço de massa estão estruturadas na linguagem de programação Fortran com modelos matemáticos da tecnologia Fischer Tropsch e as modelagens dos balanços de energia, momento e turbulência pelo software computacional CFX, com geometria baseada no Reator Arge Sasol em Leito Fixo composto por cinco domínios (recheio - meio reacional - entrada - saída - parede) e um subdomínio (catalisador), configuradas numa malha com mais de cinco milhões de elementos e um milhão de nós. A cinética é o modelo esquematizado por Sarup-Wojciechowski (1989) com a constante cinética definida pela expressão modificada da lei de Arrhenius. A modelagem da fluidodinâmica é tratada pelas equações de Navier Stokes e turbulência através do modelo k-? e "disperse phase zero equation", complementados pela biblioteca de propriedades fisico-químicas Diadem DIPPR, artigos científicos e experimentos em planta piloto realizados na Unidade de Industrialização do Xisto - Petrobras, São Mateus do Sul - (PR) / Abstract: This thesis presents the fluid dynamics and the kinetics of Fischer Tropsch Process in a fixed bed reactor accomplished in the scientific software Fortran (Formula Translation) and CFX (Computational Fluid Dynamics) of AEA Technology plc. The current work is a computational simulation of the catalytic system, multiphase, multicomponent and non isothermal with 3D topology, that is based on the cobalt supported catalyst, column random packing and the reaction mean treated on pseudo components concept, fuel gas - PLG, naphtha - gasoline - diesel oil, low - medium - high molecular weight waxes and water steam, besides non converted syngas (CO + H2). The kinetics reaction modelling and mass balance are structured in Fortran programming language with mathematic models of Fischer Tropsch technology. Also the energy balance, momentum and turbulence phenomena are structured by CFX, with geometry based on the Arge Sasol Fixed Bed Reactor consisted for five domains (packing - reaction media - in- out - wall) and one subdomain (catalyst), configured in a mesh with more than five million of elements and one million of nodes. The kinetic models are schematized by Sarup-Wojciechowski (1989) equation and the kinetic constant defined according to a modified expression of the Arrhenius law. The modelling of the fluid dinamics are considered on the Navier Stokes fundamental equations and turbulence phenomena through k-? and "disperse phase zero equation", complemented by the physical-chemicals library property Diadem DIPPR, scientifc articles and data referred to pilot plant experiments performed in the Unidade de Industrialização do Xisto - Petrobras, located in São Mateus do Sul - (PR) / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

Orientador: Reginaldo Guirardello / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-27T12:37:15Z (GMT). No. of bitstreams: 1 Freitas_AntonioCarlosDaltrode_D.pdf: 6856921 bytes, checksum: 9a39352c311e27b7f5ddb44084565f2e (MD5) Previous issue date: 2015 / Resumo: Há um crescente interesse por fontes alternativas de energia limpa, segura e renovável, e por tecnologias de transformação destas fontes em combustíveis. Dentre esses processos, a reação de gaseificação utilizando água supercrítica (SCWG), visando a produção de hidrogênio e a reação de síntese de Fischer-Tropsch (FT) visando a produção de combustíveis líquidos, vêm ocupando papel de destaque. Nesse contexto, essa tese teve como objetivo realizar a análise termodinâmica das reações envolvidas na transformação de biomassa em combustíveis, utilizando para isso, técnicas de otimização global. Foram aplicadas as metodologias de minimização da energia de Gibbs para sistemas com pressão e temperatura constantes e de maximização da entropia para sistemas com pressão e entalpia constantes. Os problemas foram formulados na forma de programações lineares e não lineares, e as metodologias propostas foram implementadas e resolvidas no software GAMS. Primeiramente foi realizada a análise termodinâmica da transformação de diferentes fontes renováveis de energia, tais como etanol, glicerol, glicose, celulose, lignina, bagaço de cana de açúcar e biomassa microalgal, em hidrogênio ou gás de síntese por meio da reação de SCWG. Posteriormente o uso do gás de síntese produzido, foi termodinamicamente avaliado visando a produção de combustíveis líquidos, por meio da reação de síntese de Fischer-Tropsch. Com esse trabalho, contribuímos com uma maior elucidação das condições reacionais mais favoráveis para cada um dos processos analisados, estudando ainda estratégias para se obter uma maior conversão dos reagentes e aumentar a produtividade dos compostos de interesse, além de verificar o comportamento energético dos sistemas associados / Abstract: There is a growing interest in alternative sources of clean, safe and renewable energy, and in technologies for processing these sources into fuels. Among these processes, the supercritical water gasification (SCWG) reaction, for hydrogen production, and the Fischer-Tropsch (FT) synthesis reaction, for liquid fuels production, have occupied a prominent role. In this context, this thesis performed the thermodynamic analysis of reactions involved in the transformation of biomass into fuels, using for it, global optimization techniques. Methodologies are applied to minimize Gibbs energy, in systems with constant pressure and temperature, and maximize the entropy, in systems with constant pressure and enthalpy. The problems are formulated in the form of linear and nonlinear programming, and the proposed methodologies are implemented and solved in the software GAMS. The thermodynamic analysis of the transformation of different sources such as ethanol, glycerol, glucose, cellulose, lignin, sugarcane bagasse and microalgal biomass in hydrogen or syngas, through the SCWG reaction are performed first. Later, the use of syngas produced are thermodynamically evaluated for the production of liquid fuels by the Fischer-Tropsch synthesis reaction. With this work we contribute to a further elucidation of the more favorable reaction conditions for each of the cases examined, also considering strategies to increase the conversion of reactants and the productivity of the desired products, as well as the realization of the energy characterization of the processe / Doutorado / Engenharia Química / Doutor em Engenharia Química

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