Thesis (MScEng (Process Engineering))--Stellenbosch University, 2008. / Developments in the field of liquid detergents and cosmetics have increased the demand for surfactants, processing aids and emollients. Alcohols are often used in liquid products where they serve as solvents for the detergent ingredients, adjust the viscosity and prevent product separation. Industrial scale oxygenation of the alkane to the alcohol is often incomplete, resulting in a significant amount of residual alkane. Application of these alcohols often requires a low residual alkane content and a post-production separation process is thus required. Traditional separation methods such as distillation and crystallisation are not technically viable as crossover melting and boiling points prevent the successful implementation of such processes and it is envisaged to use supercritical extraction to separate a mixture of n-alkanes and 1- alcohols. The project scope revolves around a product stream consisting of detergent range alcohols and corresponding n-alkanes that need to be separated. To model such a system, a typical detergent range alkane – alcohol feed with an average of 13 carbon atoms was selected, although a large number of the molecules have between 12 and 14 carbon atoms each. Generally the presence of the hydroxyl group as well as an increase in the number of carbon atoms decreases the solubility in supercritical solvents [17]-[19]. The most difficult separation will therefore be that of the alcohol with the least number of carbon atoms, that is 1-dodecanol (alcohol with 12 carbon atoms, CH3-(CH2)9-CH2-OH ) and the alkane with the most number of carbon atoms, that is n-tetradecane (alkane with 14 carbon atoms, CH3-(CH2)12-CH3 ). To model the system, it is assumed that the hydrocarbon backbone is linear and the alcohol is primary. Therefore 1-dodecanol and n-tetradecane are used. If it is possible to separate 1-dodecanol and ntetradecane with the use of supercritical fluids, it should be possible to separate an industrial mixture. The deliverables of this study are: a comparison of the high pressure solubility of n-tetradecane and 1-dodecanol with a selection of possible solvents; a selection of potential solvents to be tested on a pilot plant to confirm practical separation. From the literature and measured phase equilibria, all three solvents (carbon dioxide, ethane and propane) have the ability to distinguish (based on a difference in the pressure required for solubility) between 1-dodecanol and n-tetradecane. Both carbon dioxide and ethane have favourable temperature considerations. Propane has superior solubility of n-tetradecane and 1- dodecanol. Carbon dioxide demonstrates the highest selectivity. Pilot plant experiments have shown that both carbon dioxide and ethane have the ability to separate a 50-50% (mass percentage) mixture of 1-dodecanol and n-tetradecane. Both solvents perform at their best at low temperatures. Carbon dioxide shows the best results at low temperature and conditions of reflux. The highlight of pilot plant experiments with supercritical carbon dioxide is achieving a selectivity of 16.4 with the mass percentage of n-tetradecane at 5% and 82% for the bottoms and overheads product respectively. Very good separation is achieved using supercritical ethane as solvent even without reflux. Attention is drawn to pilot plant experiments where the selectivity is as high as 82 with the mass percentage of n-tetradecane in the bottoms and overheads product at 1% and 82% respectively. It is recommended to measure ternary phase equilibria for the system n-tetradecane, 1-dodecanol and carbon dioxide/ethane to establish the interaction between n-tetradecane and 1-dodecanol. The measured binary phase equilibrium data need to be expanded to include the vapour mass fraction composition in the isothermal solubility data.

Submitted in fulfillment of the requirements of the degree of Master of Engineering, Durban University of Technology, Durban, South Africa, 2016. / Separation processes in the chemical process industries is dependent on the science of chemical thermodynamics. In the field of chemical separation process engineering, phase equilibrium is a primary area of interest. This is due to separation processes such as distillation and extraction which involves the contacting of different phases for effective separation. The focal point of this research project is the measurement and modeling of binary vapour-liquid equilibrium (VLE) phase data of systems containing ether-alcohol organic compounds. The VLE data were measured with the use of the modified apparatus of Raal and Mühlbauer, (1998). The systems of interest for this research arose from an industrial demand for VLE data for systems containing ether-alcohol organic compounds. This gave rise to the experimental VLE data isotherms being measured for the following binary systems: a) Methyl tert-butyl ether (1) + 1-pentanol (2) at 317.15 and 327.15 K b) Methyl tert-butyl ether (1) + 2, 2, 4-trimethylpentane (2) at 307.15, 317.15 and 327.15K c) 2, 2, 4-Trimethylpentane (1) + 1-pentanol (2) at 350.15, 360.15 and 370.15K d) Diisopropyl ether (1) + 2,2,4-trimethylpentane (2) at 320.15, 330.15 and 340.15K e) Diisopropyl ether (1) + 1-propanol (2) at 320.15, 330.15 and 340.15K f) Diisopropyl ether (1) + 2-butanol (2) at 320.15, 330.15 and 340.15K The data for all the measured binary systems investigated at these temperatures are currently not available in the open source literature found on the internet and in library text resources. The systems were not measured at the same temperatures because certain system isotherm temperatures correlate to a pressures above 1 bar. This pressure of 1 bar is the maximum operating pressure specification of the VLE apparatus used in this project. The experimental VLE data were correlated for model parameters for both the  and methods. For the method, the fugacity coefficients (vapour-phase non-idealities) were tabulated using the virial equation of state and the Hayden-O’Connell correlation (1975); chemical theory and the Nothnagel et al. (1973) correlation method. The activity coefficients (liquid phase non-idealities) were calculated using three local-composition based activity coefficients models: the Wilson (1964) model, the NRTL model (Renon and Prausnitz, 1968); and the UNIQUAC model (Abrams and Prausnitz, 1975). Regarding the direct method, the Soave-Redlich-Kwong (Redlich and Kwong, 1949) and Peng-Robinson (1976) equations of state ii were used with the temperature dependent alpha-function (α) of Mathias and Copeman (1983) with the Wong-Sandler (1992) mixing rule. Thermodynamic consistency testing, which presents an indication of the quality and reliability of the data, was also performed for all the experimental VLE data. All the systems measured showed good thermodynamic consistency for the point test of Van Ness et al. (1973) - the consistency test of choice for this research. This however, was based on the model chosen for the data regression of a particular system. Therefore, the combined method of VLE reduction produced the most favourable results for the NRTL and Wilson models. / M

School of Chemical and Metallurgical Engineering, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, South Africa 26 February 2016 / Many reports in the open literature have focused on Fischer-Tropsch (FT) kinetics, yet none of them appear to be able to explain FTS completely. Few of the FT models consider the production of olefins and paraffins separately. To study whether the selectivity to olefins and paraffins follows similar trends and if kinetics alone suffices to explain FT phenomena, a series of FT experiments were conducted in a fixed bed reactor loaded with 10% Co/TiO2. FT feeds were periodically switched from syngas to syngas + N2 by adjusting the total reactor pressure so that the reactant partial pressures (PCO and PH2) remained constant. During the initial deactivation (the first 1200 hours), it was found that the formation rates of olefins remained fairly constant (in some cases they increased) while those of paraffins decreased. This indicates the deactivation is mainly caused by the decrease in the paraffin formation rate. Currently, none of the published kinetic models can explain the phenomenon that the decay of the reaction rates of olefins and paraffins were not the same during the deactivation. At steady state (1055 to 2700 hours, overall reaction rate fairly constant), adding extra N2 decreased the selectivity to the light hydrocarbons. These results suggest that by feeding the extra N2 there could be an increase in selectivity and formation rates to long chain hydrocarbons (C5+). Plotting molar ratios of paraffin to olefin (P/O) with carbon number n+1 versus the ratio with carbon number n revealed linear relationships which are independent of feed gases, catalyst activity and reaction temperature. These results imply that product distributions might be determined by some sort of equilibrium. Another plot of normalised mole fractions of CnH2n, Cn+1H2n+2, and CnH2n+2 in ternary diagrams showed that after disturbances these product distributions tended to stable points. It is suggested that this could be due to slow changes in the liquid composition after the disturbances. Although not all the results are explained, the researcher emphasises that normal kinetics alone cannot explain these results completely. There might be factors, iii including vapour-liquid equilibrium or reactive distillation, which are worthy of consideration to explain FTS. / MT2016

O objetivo deste trabalho é estudar e identificar as não idealidades do sistema água, etanol e glicerina, solução resultante do processo de purificação da glicerina bruta obtida do biodiesel. A proposta é avaliar uma relação de equilíbrio líquido-vapor que contemple todas as não idealidades. O coeficiente de atividade foi calculado pelo método de contribuição de grupos UNIFAC, utilizando parâmetros propostos por Marcolli e Peter (2005) para sistemas de polióis e água. O cálculo do fator de Poynting utilizou a equação de Rackett modificada, pois foi considerado que os fluidos do sistema são líquidos incompressíveis. Após pesquisa na literatura, não foram encontrados dados experimentais do coeficiente de fugacidade da glicerina. Admitiu-se que a fase vapor é uma mistura ideal de gases reais. Portanto, o cálculo do coeficiente de fugacidade não considerou o efeito de mistura. Foram avaliados os métodos: equação cúbica de estado de Peng e Robinson e segundo coeficiente da equação de estado Virial, que foi estimado através de um método de contribuição de grupos e métodos baseados no teorema de estados correspondentes. A proposta de Lee e Chen (1998) foi escolhida e aplicada no resultado final deste estudo, uma proposta do equilíbrio líquido-vapor do sistema água, etanol e glicerina. A sua análise apresentou relevância de não idealidades na fase líquida e na fase vapor. / This research aims to investigate the non-ideality of the system water, ethanol and glycerol from the purification process of the waste of biodiesel production, using rigorous relation for vapor-liquid equilibrium. The activity coefficient was calculated with the group contribution method UNIFAC, with new parameters for polyols/water systems proposed by Marcolli and Peter (2005). The Poynting factor was calculated using the Rackett Equation, assuming incompressible fluid for all components of the system. No experimental results for the fugacity coefficient of the vapor phase of glycerol are available in the literature. The calculation of the fugacity coefficient of the vapor phase for all components of the system was made by the Peng-Robinson equation of state and estimation of second Virial coefficient, using the group contribution and corresponding states methods and assuming ideal mixture of real gases. Lee and Chen (1998) method for the fugacity coefficient were applied for a final vapor-liquid equilibrium model for the system water, ethanol e glycerol. This study indicates strong non-idealities on both liquid and vapor phases.

O objetivo deste trabalho é estudar e identificar as não idealidades do sistema água, etanol e glicerina, solução resultante do processo de purificação da glicerina bruta obtida do biodiesel. A proposta é avaliar uma relação de equilíbrio líquido-vapor que contemple todas as não idealidades. O coeficiente de atividade foi calculado pelo método de contribuição de grupos UNIFAC, utilizando parâmetros propostos por Marcolli e Peter (2005) para sistemas de polióis e água. O cálculo do fator de Poynting utilizou a equação de Rackett modificada, pois foi considerado que os fluidos do sistema são líquidos incompressíveis. Após pesquisa na literatura, não foram encontrados dados experimentais do coeficiente de fugacidade da glicerina. Admitiu-se que a fase vapor é uma mistura ideal de gases reais. Portanto, o cálculo do coeficiente de fugacidade não considerou o efeito de mistura. Foram avaliados os métodos: equação cúbica de estado de Peng e Robinson e segundo coeficiente da equação de estado Virial, que foi estimado através de um método de contribuição de grupos e métodos baseados no teorema de estados correspondentes. A proposta de Lee e Chen (1998) foi escolhida e aplicada no resultado final deste estudo, uma proposta do equilíbrio líquido-vapor do sistema água, etanol e glicerina. A sua análise apresentou relevância de não idealidades na fase líquida e na fase vapor. / This research aims to investigate the non-ideality of the system water, ethanol and glycerol from the purification process of the waste of biodiesel production, using rigorous relation for vapor-liquid equilibrium. The activity coefficient was calculated with the group contribution method UNIFAC, with new parameters for polyols/water systems proposed by Marcolli and Peter (2005). The Poynting factor was calculated using the Rackett Equation, assuming incompressible fluid for all components of the system. No experimental results for the fugacity coefficient of the vapor phase of glycerol are available in the literature. The calculation of the fugacity coefficient of the vapor phase for all components of the system was made by the Peng-Robinson equation of state and estimation of second Virial coefficient, using the group contribution and corresponding states methods and assuming ideal mixture of real gases. Lee and Chen (1998) method for the fugacity coefficient were applied for a final vapor-liquid equilibrium model for the system water, ethanol e glycerol. This study indicates strong non-idealities on both liquid and vapor phases.

The work conducted in this thesis is two-fold. First, binary vapor liquid equilibria of several solvent/CO2 systems are measured at 40 ?? The systems analyzed are all gas-expanded liquids (GXLs) characterized with a Jerguson Cell apparatus. A Jerguson cell is a windowed pressure vessel that allows one to measure the height of the condensed liquid. Using this height and the known overall contents in the cell, one can calculate the liquid composition without using any external sampling. Secondly, this same setup is attached to a sampling system, and solid solubility (fractional crystallization) is measured for various GXL systems. The CO2 acts as an antisolvent in what is commonly known as a gaseous antisolvent (GAS) system. Essentially, this work shows that expansion of the tested solvents with CO2 will cause the precipitation of the solid solute. This work also analyzes the affect two solutes have on each other in a quaternary GAS system. Gas-expanded liquids combine desirable gaseous properties and liquid properties to yield a very useful solvent for many applications. An advantage of GXLs is that a relatively small change in pressure or temperature can greatly affect the solvation properties. The tunability of GXLs increases as the amount of the gas (usually CO2) increases in the liquid phase. With the benign chemical nature and environmental impact of CO2 processing, GXLs and supercritical fluids (SCFs) have garnered a lot of attention for industry and academia. Supercritical fluids in this work refer to pure CO2 above its critical temperature and pressure.

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Bibliography: leaves 187-190.

This thesis is an investigation of the anode of a direct methanol fuel cell (DMFC) through numerical modeling and simulation. This model attempts to help better understand the two phase flow phenomena in the anode as well as to explain some of the many problems on the anode side of a DMFC and show how changing some of the anode side properties could alleviate these problems. This type of modeling is important for designing and optimizing the DMFC for specific applications like portable electronics. Understanding the losses within the DMFC like removable of carbon dioxide, conversion losses, and methanol crossover from the anode to the cathode will help the DMFC become more commercially viable. The model is based on two phase flow in porous media combined with equilibrium between phases in a porous media with contributions from a capillary pressure difference. The effect of the physical parameters of the fuel cell like the thickness, permeability, and contact angle as well as the operating conditions like the temperature and methanol feed concentration, have on the performance of the DMFC during operation will be investigated. This will show how to remove the gas phase from the anode while enabling methanol to reach the catalyst layer and minimizing methanol crossover. / text

Orientador: Martín Aznar, Rubens Maciel Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-17T00:28:23Z (GMT). No. of bitstreams: 1 AlvarezAlvarez_VictorHugo_D.pdf: 123512819 bytes, checksum: ab445a730c3a4943154e0b3ab2a37b10 (MD5) Previous issue date: 2018-08-16T21:28:09Z / Resumo: Os líquidos iônicos são uma interessante alternativa para aperfeiçoar processos com objetivos econômicos e ecológicos. Esta pesquisa tem como objetivo estudar propriedades físico-químicas de líquidos iônicos, próticos e apróticos, puros ou em misturas binárias com ésteres e aldeídos, tais como densidade, velocidade do som, viscosidade aparente, índice de refração e temperatura de decomposição térmica. Além disso, é estudado o comportamento termodinâmico de algumas aplicações dos líquidos iônicos, como equilíbrio líquido-vapor, absorção de gases e equilíbrio líquido-líquido. Inicialmente, foram sintetizados onze líquidos iônicos próticos usando moléculas de hidroxiaminas no cátion e moléculas de ácido orgânico com cadeias alquílicas de diferentes tamanhos no ânion. As propriedades físico-químicas dos líquidos iônicos, no estado puro e em misturas, indicam a formação de agregados nos líquidos iônicos próticos com mais de dois carbonos no ânion, e que o líquido iônico prótico contendo o ânion formiato é instável, formando um éster com o passar do tempo. Nos líquidos iônicos puros, a densidade diminui com o crescer da temperatura ou a cadeia alquílica do ânion; além disso, a viscosidade diminui com o crescer da temperatura, mas aumenta com o crescer da cadeia alquílica do ânion. Nos resultados das misturas binárias de líquidos iônicos com aldeídos ou ésteres, mostra-se que os líquidos iônicos baseados no cátion amônio são parcialmente insolúveis em aldeídos, ocorrendo o contrário para o líquido iônico baseado no cátion imidazólio, embora sejam insolúveis em ésteres. No equilíbrio líquido-vapor a baixas pressões de sistemas binários, observa-se o aumento da temperatura de ebulição do aldeído ou éster influenciado pela concentração do líquido iônico, e a mudança do ponto azeotrópico na mistura etanol-água. No equilíbrio líquido-vapor a altas pressões, o CO2 é mais absorvido nos líquidos iônicos próticos do que nos líquidos iônicos apróticos, especialmente naqueles que contêm o ânion acetato, mostrando quimisorção nesse grupo funcional. No equilíbrio líquido-líquido do sistema ternário líquido iônico + dibenzotiofeno + n-dodecano, observa-se que os líquidos iônicos baseados no cátion amônio conseguem extrair dibenzotiofeno do n-dodecano, tanto quanto um líquido iônico baseado no cátion imidazólio de estrutura mais complexa. Nos estudos de absorção desde uma corrente de CO2 em dois líquidos iônicos próticos a pressão ambiente, a temperatura e o fluxo de gás foram as variáveis limitantes da absorção. Os dados do equilíbrio líquido-vapor e densidade das misturas binárias foram correlacionados através da equação de estado de Peng-Robinson acoplada com a regra de mistura Wong-Sandler/GE. Para o cálculo de GE, foram implementados os modelos termodinâmicos de NRTL, UNIQUAC e COSMO-SAC. Para o equilíbrio líquido-vapor, os desvios na predição foram menores que 2,5% e na correlação menores que 1,5%. Para a densidade da solução, os desvios na predição foram menores que 2,7%. Assim, os líquidos iônicos e as aplicações estudadas demonstram que estes novos compostos podem ser usados para produzir novos processos e os modelos termodinâmicos disponíveis na literatura podem representar esses processos com precisão / Abstract: The ionic liquids are an interesting alternative to improve processes with ecological and economic goals. This research aims to study the physicochemical properties of aprotic and aprotic ionic liquids, pure or in binary mixtures with esters and aldehydes, such as density, sound velocity, viscosity, refractive index and thermal decomposition temperature. Furthermore, it is analized the thermodynamic behavior of some applications of ionic liquids as vapor-liquid equilibrium, gas absorption, and liquid-liquid equilibrium. Initially, eleven protic ionic liquids were synthesized using hydroxylethylamine molecules in the cation and organic acid molecules with alkyl chains of different sizes in the anion. The physicochemical properties in pure and in mixtures of ionic liquids indicate the formation of agregates with more than two carbons in the anion. The protic ionic liquid containing the formate anion is unstable, forming an ester over time. In pure ionic liquids, the density decreases with increasing temperature or alkyl chain of the anion, the viscosity decreases with increasing temperature, but increases with increasing alkyl chain anion. In the results of binary mixtures of ionic liquids with aldehydes and esters, it is shown that ionic liquids based on ammonium cation are partly insoluble in aldehydes ans soluble in esteres, but for the ionic liquid based on imidazolium was the opposite. In the vapor-liquid equilibrium at low pressures of binary systems, there is a increase of the boiling point of the aldehyde or ester influenced by the concentration of ionic liquid. It changes the azeotropic point of ethanol-water mixture. In the vapor and liquid at high pressures, more CO2 is absorbed in the protic ionic liquids than in aprotic ionic liquids. This is especially shown in those containing acetate anion, indicating quimisorption with this functional group. In liquid-liquid equilibrium of ternary system ionic liquid + dibenzothiophene + n-dodecane, it is observed that the ionic liquids based on ammonium cation can be extracted dibenzothiophene from n-dodecane. Both as an ionic liquid based on imidazolium cation of more complex structure. In studies of absorption from a CO2 flow in two protic ionic liquids at ambient pressure, the variables limiting the absorption were the temperature and flow rate. Data from the vapor-liquid equilibrium and density of binary mixtures were correlated using the equation of state of Peng-Robinson with the mixing rule of Wong-Sandler/GE. For the calculation of GE, it was implemented thermodynamic models as NRTL, UNIQUAC and COSMO-SAC. For the vapor-liquid equilibrium, the deviations in the prediction and correlation were lower than 2.5% and 1.5%, respectively. For the mixture density, the deviations in the prediction were lower than 2.7%. Therefore, the ionic liquids an the applications studied demonstrate that these new compounds are reliable to yield new processes and the current thermodynamic models can represent these processes with accuracy / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

Orientador: Maria Alvina Krähenbühl / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-17T04:16:54Z (GMT). No. of bitstreams: 1 Silva_LucianaYumiAkisawa_D.pdf: 1464377 bytes, checksum: 8980b0b6666145c777fdc5a801fdf850 (MD5) Previous issue date: 2010 / Resumo: O biodiesel e um combustível biodegradável, renovável e com menor emissão de gases poluentes do que o petrodiesel. Ele e composto por ésteres alquilícos de ácidos graxos obtidos pela transesterificação de óleos ou gorduras com um álcool de cadeia curta como o metanol ou o etanol. Os ésteres etílicos resultantes da transesterificação com o etanol ainda são pouco caracterizados. Dados de suas propriedades termofísicas e de equilíbrio de fases; que são muito importantes para o projeto, modelagem, simulação e otimização do processo de produção do biodiesel, são escassos na literatura. Neste trabalho determinaram-se dados de pressão de vapor dos ésteres laurato de etila, miristato de etila, palmitato de etila, estearato de etila, oleato de etila e linoleato de etila, e dados de equilíbrio líquido-vapor dos sistemas palmitato de etila + estearato de etila a 40 mmHg, palmitato de etila + oleato de etila a 40 e 70 mmHg e palmitato de etila + linoleato de etila a 70 mmHg. Para a determinação experimental propôs-se a utilização de uma técnica não convencional: a calorimetria exploratória diferencial ("Differential Scanning Calorimetry" - DSC). Nas analises foram utilizadas de 2-5 mg de amostra a uma taxa de aquecimento de 25 oC/min. As amostras foram colocadas em cadinhos herméticos de alumínio com um pequeno orifício na tampa ("pinhole") de 0,25 mm de diâmetro, para garantir a pressão interna constante. Para a determinação de dados de pressão de vapor, o DSC revelou-se ser uma técnica adequada e suas principais vantagens em relação as técnicas convencionais são: utilização de pequena quantidade de amostra e menor tempo de analise. Os dados de equilíbrio líquido-vapor medidos pelo DSC foram satisfatórios. Esta técnica mostrou-se restrita, não sendo adequada para a determinação do equilíbrio liquidovapor de sistemas cujos componentes apresentam grande diferença de volatilidade / Abstract: Biodiesel is a biodegradable, renewable fuel with lower greenhouse gas emissions. It consists of the alkyl esters of fatty acids, obtained by the transesterification of fats and oils with a short chain alcohol such as methanol or ethanol. Ethyl esters resulting from transesterification with ethanol are poorly characterized. The thermophysical properties and phase equilibrium data involving the fatty acid ethyl esters are very important in the design, modeling, simulation, and the optimization of the production of biodiesel, are scarce in the literature. In this work was determined vapor pressure data of the esters ethyl laurate, ethyl myristate, ethyl palmitate, ethyl stearate, ethyl oleate and ethyl linoleate; and vapor-liquid equilibrium data of systems ethyl pamitate + ethyl stearate at 40 mmHg, ethyl palmitate + ethyl oleate at 40 and 70 mmHg and ethyl palmitate + ethyl linoleate ant 70 mmHg. For the experimental determination proposed the use of a non-conventional technique: differential scanning calorimetry (DSC). Samples of 2 to 5 mg were used in the analysis, with heating rate of 25 ?C/min. The samples were placed in hermetic aluminum crucibles with a small hole in the lid ("pinhole") of 0.25 mm diameter, which maintain a constant internal pressure. The technique of differential scanning calorimetry was shown to be appropriate to determining the vapor pressure of ethyl esters. This technique showed advantages over conventional techniques: the use of a small sample size and shorter analysis time. The vapor-liquid equilibrium data measured by DSC were satisfactory. This technique proved to be restricted and it is not suitable for determining the vapor-liquid equilibrium data of systems whose components have large difference in volatility / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química