Os grandes campos de petróleo offshore recentemente descobertos na camada pré-sal, localizada no sudeste do Brasil, representam um avanço significativo da participação brasileira nas reservas mundiais de hidrocarbonetos, que ainda são a principal matriz energética mundial. Nesse cenário, torna-se importante o desenvolvimento da produção desses campos. Um dos principais desafios tecnológicos da exploração desses campos é o processamento do gás natural associado, que possui altos teores de dióxido de carbono CO2. Esse contaminante deve ser separado para possibilitar a injeção no reservatório e/ou o escoamento desse gás através de dutos submarinos, dadas as restrições na legislação ambiental. Nas plantas de processamento instaladas no convés de grandes embarcações, são previstas instalações para a separação do CO2 e a remoção de umidade do gás a fim de evitar a formação de hidratos e a corrosão acentuada das linhas de escoamento, pois tanto a injeção quanto a exportação do gás são realizadas em condições de pressão e temperaturas extremas. Nesse contexto, o conhecimento acurado das condições em que se forma uma fase aquosa líquida é importante para garantir a viabilidade técnica e de segurança dessas operações. Considerando a relevância do assunto e as limitações da literatura para os cenários enfrentados no pré-sal brasileiro, esse trabalho tem o objetivo de fazer um estudo abrangente do equilíbrio de fases em sistemas contendo hidrocarbonetos em fase gasosa com altos teores de CO2 e traços de água, visando à obtenção de modelo para cálculo do ponto de orvalho da água. O uso de modelos rigorosos baseado na teoria dos fluidos associativos (PC-SAFT) mostrou-se adequado para o cálculo das condições de saturação em amplas faixas de pressão e temperatura. Com base em dados experimentais publicados foi possível fazer um ajuste preciso dos parâmetros de interação binária da equação de estado PC-SAFT. Como resultado, obteve-se um modelo capaz de descrever o comportamento de fases em misturas de hidrocarbonetos com composição próxima das encontradas no pré-sal brasileiro. / The giant offshore petroleum fields recently discovered in the pre-salt layer on the southeast of Brazil represent a significant increment in the Brazilian share of the global hydrocarbon reserves, which is still the most important energetic matrix. In this scenario, the development of production for these petroleum fields becomes important. One of the main technological challenges posed by these fields is the processing of the associated gas, which contains high amounts of carbon dioxide (CO2). Due to environmental laws, this contaminant must be separated to allow the injection back into the reservoir and/or the gas flow through subsea pipelines. The gas processing plants installed on large vessels comprise facilities that remove CO2 and moisture from natural gas, to prevent hydrate formation and severe corrosion throughout the pipelines, as both gas injection and gas exportation are performed in extreme pressure and temperature conditions. Thus, the accurate knowledge of conditions in which aqueous liquid phases are formed is important to ensure the technical viability and operational safety of these operations. Considering the relevance of this subject and the limitations of published works for the Brazilian pre-salt scenario, this work presents a comprehensive study on the phase equilibrium in systems with hydrocarbons in gas phase with high content of CO2 and traces of water, aiming at developing a model to calculate the dew point of water. The use of a rigorous method based on the associating fluid theory (PCSAFT) has shown to be appropriate to calculate the saturation condition for a large range of pressure and temperature. Based on the experimental data published, the fitting of the binary interaction parameter from the PC-SAFT equation of state was carried out. The resulting model was able to describe the phase behavior of hydrocarbon mixture with composition similar to those found in the Brazilian pre-salt.

Os grandes campos de petróleo offshore recentemente descobertos na camada pré-sal, localizada no sudeste do Brasil, representam um avanço significativo da participação brasileira nas reservas mundiais de hidrocarbonetos, que ainda são a principal matriz energética mundial. Nesse cenário, torna-se importante o desenvolvimento da produção desses campos. Um dos principais desafios tecnológicos da exploração desses campos é o processamento do gás natural associado, que possui altos teores de dióxido de carbono CO2. Esse contaminante deve ser separado para possibilitar a injeção no reservatório e/ou o escoamento desse gás através de dutos submarinos, dadas as restrições na legislação ambiental. Nas plantas de processamento instaladas no convés de grandes embarcações, são previstas instalações para a separação do CO2 e a remoção de umidade do gás a fim de evitar a formação de hidratos e a corrosão acentuada das linhas de escoamento, pois tanto a injeção quanto a exportação do gás são realizadas em condições de pressão e temperaturas extremas. Nesse contexto, o conhecimento acurado das condições em que se forma uma fase aquosa líquida é importante para garantir a viabilidade técnica e de segurança dessas operações. Considerando a relevância do assunto e as limitações da literatura para os cenários enfrentados no pré-sal brasileiro, esse trabalho tem o objetivo de fazer um estudo abrangente do equilíbrio de fases em sistemas contendo hidrocarbonetos em fase gasosa com altos teores de CO2 e traços de água, visando à obtenção de modelo para cálculo do ponto de orvalho da água. O uso de modelos rigorosos baseado na teoria dos fluidos associativos (PC-SAFT) mostrou-se adequado para o cálculo das condições de saturação em amplas faixas de pressão e temperatura. Com base em dados experimentais publicados foi possível fazer um ajuste preciso dos parâmetros de interação binária da equação de estado PC-SAFT. Como resultado, obteve-se um modelo capaz de descrever o comportamento de fases em misturas de hidrocarbonetos com composição próxima das encontradas no pré-sal brasileiro. / The giant offshore petroleum fields recently discovered in the pre-salt layer on the southeast of Brazil represent a significant increment in the Brazilian share of the global hydrocarbon reserves, which is still the most important energetic matrix. In this scenario, the development of production for these petroleum fields becomes important. One of the main technological challenges posed by these fields is the processing of the associated gas, which contains high amounts of carbon dioxide (CO2). Due to environmental laws, this contaminant must be separated to allow the injection back into the reservoir and/or the gas flow through subsea pipelines. The gas processing plants installed on large vessels comprise facilities that remove CO2 and moisture from natural gas, to prevent hydrate formation and severe corrosion throughout the pipelines, as both gas injection and gas exportation are performed in extreme pressure and temperature conditions. Thus, the accurate knowledge of conditions in which aqueous liquid phases are formed is important to ensure the technical viability and operational safety of these operations. Considering the relevance of this subject and the limitations of published works for the Brazilian pre-salt scenario, this work presents a comprehensive study on the phase equilibrium in systems with hydrocarbons in gas phase with high content of CO2 and traces of water, aiming at developing a model to calculate the dew point of water. The use of a rigorous method based on the associating fluid theory (PCSAFT) has shown to be appropriate to calculate the saturation condition for a large range of pressure and temperature. Based on the experimental data published, the fitting of the binary interaction parameter from the PC-SAFT equation of state was carried out. The resulting model was able to describe the phase behavior of hydrocarbon mixture with composition similar to those found in the Brazilian pre-salt.

Thermodiffusion is one of the mechanisms in transport phenomena in which molecules are transported in a multicomponent mixture driven by temperature gradients. Thermodiffusion in associating mixtures presents a larger degree of complexity than non-associating mixtures, since the direction of flow in associating mixtures may change with variations in composition and temperature. In this study a new activation energy model is proposed for predicting the ratio of evaporation energy to activation energy. The new model has been implemented for prediction of thermodiffusion for acetone-water, ethanol-water and isopropanol-water mixtures. In particular, a sign change in the thermodiffusion factor for associating mixtures has been predicted, which is a major step forward in modeling of thermodiffusion for associating mixtures. In addition, a new model for the prediction of thermodiffusion coefficients for linear chain hydrocarbon binary mixtures is proposed using the theory of irreversible thermodynamics and a kinetics approach. The model predicts the net amount of heat transported based on an available volume for each molecule. This model has been found to be the most reliable and represents a significant improvement over the earlier models. Also a new approach to predicting the Soret coefficient in binary mixtures of linear chain and aromatic hydrocarbons using the thermodynamics of irreversible processes is presented. This approach is based on a free volume theory which explains the diffusivity in diffusion-limited systems. The proposed model combined with the Shukla and Firoozabadi model has been applied to predict the Soret coefficient for binary mixtures of toluene and n-hexane, and benzene and n-heptane. Comparisons of theoretical results with experimental data show a good agreement. The proposed model has also been applied to estimate thermodiffusion coefficients of binary mixtures of n-butane & carbon dioxide and n-dodecane & carbon dioxide at different temperature. The results have also been incorporated into CFD software FLUENT for 3-dimensional simulations of thermodiffusion and convection in porous media. The predictions show the thermodiffuison phenomenon is dominant at low permeabilities (0.0001 to 0.01), but as the permeability increases convection plays an important role in establishing a concentration distribution. Finally, the activation energy in Eyring’s viscosity theory is examined for associating mixtures. Several methods are used to estimate the activation energy of pure components and then extended to mixtures of linear hydrocarbon chains. The activation energy model based on alternative forms of Eyring’s viscosity theory is implemented to estimate the thermodiffusion coefficient for hydrocarbon binary mixtures. Comparisons of theoretical results with the available thermodiffusion coefficient data have shown a good performance of the activation energy model.

Thermodiffusion is one of the mechanisms in transport phenomena in which molecules are transported in a multicomponent mixture driven by temperature gradients. Thermodiffusion in associating mixtures presents a larger degree of complexity than non-associating mixtures, since the direction of flow in associating mixtures may change with variations in composition and temperature. In this study a new activation energy model is proposed for predicting the ratio of evaporation energy to activation energy. The new model has been implemented for prediction of thermodiffusion for acetone-water, ethanol-water and isopropanol-water mixtures. In particular, a sign change in the thermodiffusion factor for associating mixtures has been predicted, which is a major step forward in modeling of thermodiffusion for associating mixtures. In addition, a new model for the prediction of thermodiffusion coefficients for linear chain hydrocarbon binary mixtures is proposed using the theory of irreversible thermodynamics and a kinetics approach. The model predicts the net amount of heat transported based on an available volume for each molecule. This model has been found to be the most reliable and represents a significant improvement over the earlier models. Also a new approach to predicting the Soret coefficient in binary mixtures of linear chain and aromatic hydrocarbons using the thermodynamics of irreversible processes is presented. This approach is based on a free volume theory which explains the diffusivity in diffusion-limited systems. The proposed model combined with the Shukla and Firoozabadi model has been applied to predict the Soret coefficient for binary mixtures of toluene and n-hexane, and benzene and n-heptane. Comparisons of theoretical results with experimental data show a good agreement. The proposed model has also been applied to estimate thermodiffusion coefficients of binary mixtures of n-butane & carbon dioxide and n-dodecane & carbon dioxide at different temperature. The results have also been incorporated into CFD software FLUENT for 3-dimensional simulations of thermodiffusion and convection in porous media. The predictions show the thermodiffuison phenomenon is dominant at low permeabilities (0.0001 to 0.01), but as the permeability increases convection plays an important role in establishing a concentration distribution. Finally, the activation energy in Eyring’s viscosity theory is examined for associating mixtures. Several methods are used to estimate the activation energy of pure components and then extended to mixtures of linear hydrocarbon chains. The activation energy model based on alternative forms of Eyring’s viscosity theory is implemented to estimate the thermodiffusion coefficient for hydrocarbon binary mixtures. Comparisons of theoretical results with the available thermodiffusion coefficient data have shown a good performance of the activation energy model.

Les composés soufrés sont répandus dans divers secteurs industriels comme la chimie. La conception et/ou l'optimisation des procédés impliquant ces composés nécessite de connaître leurs propriétés thermodynamiques (corps purs et mélanges). Etant donnée la complexité des mélanges et pour des raisons économiques, des modèles thermodynamiques « prédictifs » sont souvent privilégiés. Le développement et la validation de ces modèles nécessitent des données expérimentales. Notre étude bibliographique ciblant les sulfures (R-S-R'), les 1-mercaptans (R-SH) et leurs éventuels solvants (les n-alcanes et les 1-alcools) nous a permis de mettre en évidence un manque de données concernant ces composés. De plus nous avons également observé un manque de techniques expérimentales adaptés, et de ce fait le besoin de développer un nouveau dispositif expérimental.Au cours de cette thèse, nous avons conçu un dispositif expérimental innovant permettant la mesure des équilibres liquide-vapeur à des pressions comprises entre 0,1 et 10 bar. Ce dispositif est basé sur la méthode « statique-analytique ». Nous avons mis en place deux adaptations spécifiques aux échantillonneurs capillaires ROLSITM pour permettre l'échantillonnage à ces pressions. De nouvelles données des mélanges binaires et ternaires d'intérêt ont été ainsi mesurées.Le modèle thermodynamique prédictif choisi est PC-SAFT couplé avec une méthode de Contribution de Groupes (GC-PC-SAFT). Un terme polaire a été introduit. Le travail s'est focalisé sur l'étude de deux familles représentatives de composés soufrés : les sulfures et les 1-mercaptans. Le modèle GC-PC-SAFT a montré sa capacité de bien corréler et prédire les propriétés thermodynamiques des corps purs. L'ajustement des paramètres s'est appuyé sur les données de la littérature et celles obtenues par le nouvel équipement. Les diagrammes de phases des mélanges binaires (sulfure + n-alcane, sulfure + 1-alcool, 1-mercaptan + n-alcane et 1-mercaptan + 1-alcool) et ternaires (1-mercaptan + n-alcane + 1-alcool) ont été prédits. / Sulfur compounds are widespread in various industrial fields. Design and/or optimization of the processes involving these compounds require accurate knowledge of thermodynamic properties of the concerned mixtures. Considering the complexity of industrial mixtures and for economical reasons, one may look to thermodynamic models with predictive features. To develop and validate these models, a minimum number of experimental data are required. Our literature review on sulfides (R-S-R'), 1-thiols (R-SH) and their possible solvents (n-alkanes and 1-alkanols) has shown a lack of data and of adapted experimental method. This observation leads to the need of developing a new experimental apparatus.In this work, we designed an innovative experimental apparatus for vapor-liquid-equilibrium measurements in the pressure range of [0.1 – 10] bar. The new apparatus is based on the “static-analytic” method. The key improvements are the two adaptations made for ROLSITM capillary samplers to achieve phase sampling in this pressure range. After validating the newly developed apparatus, new data of binary and ternary mixtures of interest were measured in order to develop a new predictive thermodynamic model focusing on sulfur compounds.The proposed predictive model is the PC-SAFT equation of state combined with a group contribution method (GC-PC-SAFT). We incorporated a polar term into PC-SAFT and investigated two representative families of sulfur compounds: sulfides and 1-thiols. The GC-PC-SAFT model proved reliable in correlating and predicting thermodynamic properties of pure compounds. Model parameters were fitted to the data found in the literature, as well as to those obtained through the new apparatus. Phase diagrams of some binary (sulfide + n-alkane, sulfide + 1-alkanol, 1-thiol + n-alkane and 1-thiol + 1-alkanol) and ternary (1-mercaptan + n-alkane + 1-alcool) mixtures were predicted.

Le remplacement des solvants organiques classiques par une nouvelle génération de solvants moins toxiques, moins inflammables et moins polluants est un défi majeur pour l'industrie chimique. Les liquides ioniques, sels liquides qui satisfont ces critères, sont envisagés comme alternatives. Le but de ce travail est d'évaluer le comportement des liquides ioniques en présence de gaz à effet de serre (CO2, N2O et CH4) ou de composés organiques. Dans un premier temps, une étude théorique présente les performances du modèle thermodynamique PC-SAFT sur la représentation des équilibres liquide-vapeur de systèmes constitués de dioxyde de carbone et de liquide ionique. Ensuite, l'étude de la solubilité du méthane, du dioxyde de carbone et du protoxyde d'azote dans divers liquides ioniques a été effectuée sous basse ou haute pression. Ce travail propose un modèle basé sur le concept de contribution de groupes afin de prédire la constante d'Henry du CO2 dans les liquides ioniques. Enfin, une étude sur les équilibres liquide-vapeur des systèmes binaires rencontrés dans la désulfuration des essences a été effectuée. Les données expérimentales ont permis d'évaluer les performances de l'équation PC-SAFT à représenter les équilibres entre phases de systèmes {composés soufrés / aromatiques + liquide ionique} / The replacement of conventional organic solvents by a new generation of solvents less toxic, less flammable and less polluting is a major challenge for the chemical industry. Ionic liquids have been widely promoted as interesting substitutes for traditional solvents. The purpose of this work is to evaluate the behavior of ionic liquids in the presence of greenhouse gases (CO2, CH4 and N2O) or organic compounds. Firstly, a theoretical study presents the performance of the thermodynamic model PC-SAFT in the representation of vapor-liquid equilibrium of systems containing ionic liquids and carbon dioxide. Then, the solubility study of methane, carbon dioxide and nitrous oxide in various ionic liquids was performed at high or low pressure. The group contribution concept is proposed in this study in order to predict the Henry's law constant of carbon dioxide in ionic liquids. Finally, a study on the vapor-liquid equilibrium of binary systems encountered in gasoline desulfurization was carried out. Experimental data were used to evaluate the performance of PC-SAFT equation of state to represent phase equilibrium of systems {sulfur / aromatic compounds + ionic liquid}

Knowledge of thermodynamic fluid properties, such as density and phase behavior, is important for the design, operation, and safety of several processes including drilling, extraction, transportation, and separation that are required in the petroleum. The knowledge is even more critical at extreme temperature and pressure conditions as the search for more crude oil reserves lead to harsher conditions. Currently, there is dearth of experimental data at these conditions and as such, the predictive capability of the existing modeling tools are unproven. The objective of this research is to develop a fundamental understanding of the impact of molecular architecture on fluid phase behavior at temperatures to 523 K (250 °C) and pressures to 275 MPa (40,000 psi). These high-temperature and high-pressure (HTHP) conditions are typical of operating conditions often encountered in petroleum exploration and recovery from ultra-deep wells that are encountered in the Gulf of Mexico. This PhD study focuses on the fluid phase behavior of a low molecular weight compound, two moderately high molecular weight compounds, three asymmetric binary mixtures of a light gas and a heavy hydrocarbon compound with varying molecular size. The compounds are selected to represent the family of saturated compounds found in typical crude oils. Furthermore, this study reports experimental data for two "dead" crude oil samples obtained from the Gulf of Mexico and their mixtures with methane from ambient to HTHP conditions. A variable-volume view cell coupled with a linear variable differential transformer is used to experimentally measure the high-pressure properties of these compounds and mixtures. The reported density data compare well to the limited available data in the literature with deviations that are less than 0.9%, which is the experimental uncertainty of the density data reported in this study. The phase behavior and density data obtained in this study are modeled using the Peng-Robinson (PR), the volume-translated (VT) PR, and the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equations of state (EoS). The EoS pure component parameters, typically obtained from the open literature, are derived from fitting the particular EoS to, critical point, or to vapor pressure and saturated liquid density data, or to HTHP density data. For the density data reported here, the PREoS provided the worst predictions, while the VT-PREoS gives an improved performance as compared to the PREoS. However, the PC-SAFT EoS provided the best HTHP density predictions especially when using HTHP pure component parameters. The situation is however reversed in the modeling performance for the phase behavior data whereby the PC-SAFT EoS with HTHP parameters provided the worst vapor-liquid equilibria predictions. Better predictions are obtained with the PC-SAFT EoS when using parameters obtained from fit of the vapor pressure data and is comparable to the PREoS predictions. This reversal in performance is not surprising since the phase behavior data occur at moderately low pressures. The performance of the PC-SAFT EoS is extended to the experimental density data reported for the dead crude oil samples and their mixtures with methane. The PC-SAFT EoS with either set of pure component parameters yield similar predictions that are within 3% of the reported crude oil density data. However, when using the HTHP parameters, the PC-SAFT gives a good representation of the slope of experimental data, which is crucial in the calculation of second-derivative properties such has isothermal compressibility. The PC-SAFT EoS is also employed to model the crude oil HTHP density data for both the dead crude oils and their mixtures with methane using correlations for both the Low-P parameters and the HTHP parameters. The Low-P parameters are derived from fitting the PC-SAFT EoS to pure compound vapor pressure and saturated liquid density data, while the HTHP parameters are obtained from fitting the PC-SAFT EoS to pure compound HTHP liquid density data. Interestingly, the PC-SAFT EoS with the Low-P parameters provided better HTHP density predictions that are within 1.5% of the experimental data for the dead oils than the HTHP parameters that are within 2 to 4% of the data. Density predictions for the dead oil mixtures with methane are however comparable for both sets of parameters and are within 1% on average. However, the PC-SAFT EoS with HTHP parameters clearly provided better representation of the isothermal property, a derivative property obtained from density data, within 10% while predictions with the Low-P parameters can be as high as 37%. The successful completion of the thesis work expands the current knowledge base of fluid phase behavior at the extreme operating conditions encountered by engineers in the petroleum industries. Furthermore, the reported HTHP experimental data also provide a means to scientists and researchers for the development, improvement, and validation of equations with improved modeling performance.

Nesse trabalho, a equação de estado PC-SAFT é combinada com um método de contribuição de grupos (GC) para estimação dos seus parâmetros. Para tanto, foram utilizados dados experimentais dos componentes puros (pressão de vapor e volume específico do líquido) e em mistura (equilíbrio líquido-vapor - VLE e coeficiente de atividade em diluição infinita - IDAC). Através de uma análise de sensibilidade, verificou-se que o parâmetro volume de associação poderia ser mantido constante, reduzindo o número de parâmetros a serem estimados. O objetivo principal foi estudar misturas que apresentassem associação cruzada ou forte interação entre os compostos. Com os parâmetros estimados, avaliou-se o desempenho do modelo GC-PC-SAFT no cálculo de propriedades de n-alcanos, 1-álcoois, aminas, clorofórmio e acetona. Os desvios médios obtidos no cálculo do equilíbrio líquido-vapor (VLE), entre as diferentes misturas estudadas, mostraram que a estratégia adotada para a estimação do parâmetro energia de associação apresentou bons resultados, com desvios relativamente baixos para a maioria dos casos estudados. Para IDAC, as predições foram muito semelhantes àquelas obtidas por outros modelos. Os resultados de VLE são importantes, pois fornecem informações sobre as concentrações intermediárias de uma mistura, enquanto que o IDAC fornece uma medida eficiente do grau de não-idealidade da mistura. Essas propriedades foram escolhidas com o objetivo de conseguir uma melhor representação das misturas, buscando eliminar a necessidade de parâmetros de interação binária. Os resultados obtidos revelam que o modelo GC-PC-SAFT proposto pode ser utilizado para predizer o equilíbrio líquido-vapor com uma precisão satisfatória para sistemas binários entre os diferentes compostos estudados, sem nenhum parâmetro de interação binária. / In this work, the PC-SAFT EoS is combined with a group contribution method (GC) for parameter estimation. To achieve this, experimental data for pure components (vapor pressure and liquid volume) and mixtures (vapor-liquid equilibria - VLE and infinite dilution activity coefficient -IDAC) has been used. Through sensitivity analysis, it has been found that the association volume parameter could be set constant, thus reducing the amount of parameters that needed to be estimated. The aim of this work was to study mixtures that presented cross association or strong component interaction. With the estimated parameters, GC-PC-SAFT performance in properties calculation of n-alkanes, 1-alcohols, amines, chloroform and ketone has been evaluated. The average deviations obtained in the calculation of vapor-liquid equilibria (VLE), in the different mixtures considered, have shown that the strategy for association energy parameter estimation has presented good results, with relatively low deviations for most of the cases. For IDAC, the predictions presented very similar results to those obtained by other models. VLE results are important because they provide information about mixtures’ intermediary concentrations, whereas IDAC offers an efficient measure of mixtures’ degree of non-ideality. These properties have been chosen with the aim of getting a better representation of the mixtures, seeking to eliminate the need for binary interaction parameters. The obtained results show that GC-PC-SAFT can be used to predict vapor-liquid equilibria for binary systems among the different studied components with satisfactory accuracy with no binary interaction parameter.

Nesse trabalho, a equação de estado PC-SAFT é combinada com um método de contribuição de grupos (GC) para estimação dos seus parâmetros. Para tanto, foram utilizados dados experimentais dos componentes puros (pressão de vapor e volume específico do líquido) e em mistura (equilíbrio líquido-vapor - VLE e coeficiente de atividade em diluição infinita - IDAC). Através de uma análise de sensibilidade, verificou-se que o parâmetro volume de associação poderia ser mantido constante, reduzindo o número de parâmetros a serem estimados. O objetivo principal foi estudar misturas que apresentassem associação cruzada ou forte interação entre os compostos. Com os parâmetros estimados, avaliou-se o desempenho do modelo GC-PC-SAFT no cálculo de propriedades de n-alcanos, 1-álcoois, aminas, clorofórmio e acetona. Os desvios médios obtidos no cálculo do equilíbrio líquido-vapor (VLE), entre as diferentes misturas estudadas, mostraram que a estratégia adotada para a estimação do parâmetro energia de associação apresentou bons resultados, com desvios relativamente baixos para a maioria dos casos estudados. Para IDAC, as predições foram muito semelhantes àquelas obtidas por outros modelos. Os resultados de VLE são importantes, pois fornecem informações sobre as concentrações intermediárias de uma mistura, enquanto que o IDAC fornece uma medida eficiente do grau de não-idealidade da mistura. Essas propriedades foram escolhidas com o objetivo de conseguir uma melhor representação das misturas, buscando eliminar a necessidade de parâmetros de interação binária. Os resultados obtidos revelam que o modelo GC-PC-SAFT proposto pode ser utilizado para predizer o equilíbrio líquido-vapor com uma precisão satisfatória para sistemas binários entre os diferentes compostos estudados, sem nenhum parâmetro de interação binária. / In this work, the PC-SAFT EoS is combined with a group contribution method (GC) for parameter estimation. To achieve this, experimental data for pure components (vapor pressure and liquid volume) and mixtures (vapor-liquid equilibria - VLE and infinite dilution activity coefficient -IDAC) has been used. Through sensitivity analysis, it has been found that the association volume parameter could be set constant, thus reducing the amount of parameters that needed to be estimated. The aim of this work was to study mixtures that presented cross association or strong component interaction. With the estimated parameters, GC-PC-SAFT performance in properties calculation of n-alkanes, 1-alcohols, amines, chloroform and ketone has been evaluated. The average deviations obtained in the calculation of vapor-liquid equilibria (VLE), in the different mixtures considered, have shown that the strategy for association energy parameter estimation has presented good results, with relatively low deviations for most of the cases. For IDAC, the predictions presented very similar results to those obtained by other models. VLE results are important because they provide information about mixtures’ intermediary concentrations, whereas IDAC offers an efficient measure of mixtures’ degree of non-ideality. These properties have been chosen with the aim of getting a better representation of the mixtures, seeking to eliminate the need for binary interaction parameters. The obtained results show that GC-PC-SAFT can be used to predict vapor-liquid equilibria for binary systems among the different studied components with satisfactory accuracy with no binary interaction parameter.

A modelagem termodinâmica do equilíbrio de fases e a determinação de propriedades termodinâmicas de sistemas em que as moléculas apresentam associação é um problema desafiador na indústria química. Embora o uso de equações de estado tenha sido durante muito tempo restrito aos sistemas de fluidos simples, há uma crescente demanda por modelos que também sejam adequados a compostos complexos e macromoleculares. O avanço teórico mais aparente para equações de estado com tais capacidades foi conseguido por aplicação dos princípios da mecânica estatística, o qual considera as forças de associação entre as moléculas em sua teoria molecular. Um exemplo desta categoria é a equação de estado PC-SAFT (Perturbed Chain-Statistical Associating Fluid Theory), cuja formulação requer apenas um pequeno conjunto de parâmetros para cada componente e estas interações são computadas através de regras de mistura. Desta forma, os objetivos deste trabalho foram a implementação do termo de associação desta equação e o desenvolvimento de ferramentas para o cálculo de propriedades termodinâmicas de sistemas contendo fluidos associados e não-associados, bem como para o cálculo do equilíbrio de fases. Todas as funções foram desenvolvidas no software MATLAB e a verificação da implementação foi feita através de comparação entre os resultados obtidos com estas ferramentas e dados experimentais e/ou outras equações de estado presentes na literatura. Através da comparação com dados de equilíbrio de fases disponíveis na literatura, foi analisado o desempenho da equação PC-SAFT com associação para diferentes sistemas multicomponentes e múltiplas fases envolvendo substâncias polares e apolares. Os resultados obtidos foram satisfatórios quando comparados a dados experimentais e aqueles obtidos através de outras equações de estado. / Modeling the phase equilibrium and thermodynamic properties of systems in which molecules exhibit associating interactions remains a challenging problem in chemical industry. Although the use of equations of state has for a long time been restricted to systems of simple fluids, there is an increasing demand for models that are also suitable for complex and macromolecular compounds. Progress toward this goal has been achieved by applying principles of statistical mechanics, which takes molecular theories into account. One example of such approach is the PC-SAFT (Perturbed Chain-Statistical Associating Fluid Theory) equation of state, which requires only a small set of parameters for each component and whose interactions are obtained by mixing rules. The goals of this work have been the implementation of the PC-SAFT association term and the development of tools for thermodynamic properties calculation of associating and non-associating systems, as well as for phase equilibria calculation. All the functions have been developed using MATLAB software and their implementation analysis has been made by comparing obtained results to experimental data and those obtained by other equations of state available in literature. Through these comparisons, PC-SAFT performance has been analyzed for different multicomponent and multiphase systems involving polar and non-polar substances. The obtained results have shown good correlation to both experimental data and those obtained by other equations of state.