Dissertations / Theses on the topic 'Ethanol Dehydration'

As a renewable energy source, bioethanol is widely used for blending in gasoline in an attempt to partly alleviate the energy crisis and reduce the greenhouse gas emissions. To produce fuel grade ethanol, the dehydration process of bioethanol is a critical step for the economic viability of the whole process. With a single distillation column it is not possible to overcome the azeotropic point of the ethanol/water mixture. In addition, the distillation process is a very energy intensive and costly process. In this thesis, two major topics concerning the dehydration process of bioethanol are discussed. First, the multiple objective optimization of the fuel grade bioethanol dehydration is performed along with a parametric analysis of A-type zeolite membrane pervaporation. Three cases were investigated using the ranked Pareto domain that was obtained in each case. The optimal results were identified as attractive compromised solutions considering the four objectives: the total number of stages, the total area, the energy consumed, and the exergy loss. The temperature drop per stage was found to be the dominating factor. The second theme is the exergy loss minimization of the pervaporation/distillation hybrid system at the tangent pinch on the vapor-liquid equilibrium curve. Results show that both the exergy loss and the reflux ratio of the hybrid system are reduced compared to a single distillation column. In addition, the exergy loss of the hybrid system is correlated with the variation of the reflux ratio.

The cost of pretreatment process for saccharification from biomass and the cost of dilute ethanol purification are significant components of the overall cost for fuel grade ethanol production through fermentation or other biological routes. This work focuses on developing optimal designs of dilute ethanol purification process and the new acid hydrolysis technology for the production of fermentable sugars from biomass where the overarching goal is to reduce the cost of ethanol production from biomass. In this thesis, the ethanol separation process with the reverse osmosis membrane pretreatment is developed to reduce separation cost and energy consumption especially when the feed is dilute. In addition, the new solid phase reactive separation system for biomass saccharification via acid hydrolysis is proposed. This new process is applied for both dilute and concentrated acid hydrolysis where the goal is to increase sugar yield and to reduce byproduct formation. The reaction kinetics of the concentrated acid hydrolysis is investigated through batch experiment. All of these use optimization approaches for seeking the best process designs and for parameter estimations.

First generation bioethanol generated from feedstocks is a sustainable alternative to fossil fuels, and the demand for fuel ethanol has promoted studies on the use of the grain as feedstock. This thesis describes various process designs and the economic feasibility for producing the main product ethanol and other by-products such as Biogas and DDGS (Distillers Dried Grains with Solubles) from the grain. The techno-economic analysis was performed by the data provided by Agroetanol industry, located in Norrköping, Sweden. The key target of this simulation work was to evaluate the influence of several process designs and the main production factors on the ethanol production process, in terms of energy efficiency, ethanol production cost and plant profitability. The main aim of this work was to simulate the current industrial process and to develop novel alternative retrofits by integrating new technologies and for investigating the effects on the plant profitability. In the base case, the cost sensitivity analysis was carried out on the grain buying price, ethanol and DDGS selling price. Along with the cost sensitivity analysis, the capacity sensitivity analysis was performed on the base case model to check the influence of different capacities on the plant profitability. While coming to the study of developing alternative retrofits, the three retrofits were developed on the base case process and they are as following: Retrofit 1) modifying the distillation and dehydration section of the base case retrofit (current process in Agroetanol), Retrofit 2) checking the impact of ethanol concentration on technical and economic aspects of the plant and Retrofit 3) installing the biogas digester.The modelling effort resulted in developing the base case model with an ethanol production rate of 41,985 ton/ year. The capital cost of the base case process was calculated to be at 68.85 million USD and the aspen economic analyzer calculated the product value of the ethanol and DDGS as 0.87 USD/litre and 0.37 USD/kg, respectively. Through cost sensitivity analysis results, it is identified that the ethanol selling price and the grain buying price have significant effects on the plant economy and it is confirmed that they are the main factors playing on the plant profitability in the base case model.The results of the alternative retrofits clearly demonstrate the importance of higher ethanol tolerant strains in ethanol production, which showed a less payback period compared to the base case. The payback periods of all the cases are showing the following patterns from the least to the highest: Retrofit 2 (17%) > Base case > Retrofit 3 > Retrofit 2 (4%) > Retrofit 1.Further retrofitting analysis results also suggested that using the stillage for biogas production will help in reducing the energy costs of the plant. The energy consumption of all the retrofits in ascending manner is as follows: Retrofit 3 > Retrofit 2 (17%) > Base case > Retrofit 1 > Retrofit 2 (4%). The energy usage result comparison of all the cases shows that, in third retrofit the overall energy consumption is decreased by 40% than the base case model.

The aim of this thesis is to investigate heterogeneous catalysis for the dehydration of methanol and ethanol at a gas-solid interface over a wide range of solid Brønsted acid catalysts based on Keggin-type heteropoly acids (HPAs), focussing on the formation of dimethyl ether (DME) and diethyl ether (DEE), respectively. The dehydration of methanol to dimethyl ether (DME) was studied over a wide range of bulk and supported HPAs and was compared with the reaction over HZSM-5 zeolites (Si/Al = 10−120). Turnover rates for these catalysts were measured under zero-order reaction conditions. The HPA catalysts were demonstrated to have much higher catalytic activities than the HZSM-5 zeolites. A good correlation between the turnover rates and catalyst acid strengths, represented by the initial enthalpies of ammonia adsorption, was established. This correlation holds for the HPA and HZSM-5 catalysts studied, which indicates that the methanol-to-DME dehydration occurs via the same (or a similar) mechanism with both HPA and HZSM-5 catalysts, and that the turnover rate of methanol dehydration for both catalysts is primarily determined by the strength of catalyst acid sites, regardless of the catalyst pore geometry. Dehydration of ethanol was also studied over a wide range of solid Brønsted acid catalysts based on Keggin-type HPAs in a continuous flow fixed-bed reactor in the temperature range of 90-220 oC. The catalysts included H3PW12O40 (HPW) and H4SiW12O40 (HSiW) supported on SiO2, TiO2, Nb2O5 and ZrO2 with sub-monolayer HPA coverage, as well as bulk acidic Cs salts of HPW (Cs2.5H0.5PW12O40 and Cs2.25H0.75PW12O40) and the corresponding core-shell materials with the same total composition (15%HPW/Cs3PW12O40 and 25%HPW/Cs3PW12O40, respectively) comprising HPW supported on the neutral salt Cs3PW12O40. The ethanol-to-DEE reaction was found to be zero order in ethanol in the range of 1.5-10 kPa ethanol partial pressure. The acid strength of the catalysts was characterised by ammonia adsorption microcalorimetry. A fairly good correlation between the catalyst activity (turnover frequency) and the catalyst acid strength (initial enthalpy of ammonia adsorption) was established, which demonstrates that Brønsted acid sites play an important role in ethanol-to-DEE dehydration over HPA catalysts. The acid strength and the catalytic activity of core-shell catalysts HPW/Cs3PW12O40 did not exceed those of the corresponding bulk Cs salts of HPW with the same total composition, which contradicts the claims in the literature of the superiority of the core-shell HPA catalysts.

Content: Fish collagen has been considered to be an alternative for mammalian collagen, however, physicochemical properties of fish collagen-based materials such as gels are so far not adequate for actual application. In the present study, we prepared two types of fish collagen gels with sufficient elasticity: i) dehydrated fibrillogenesis collagen gels (DFCG), which were fabricated via collagen self-assembly followed by immersion in different concentrations of ethanol solutions, and ii) dehydrated cross-linking collagen gels (DCCG), which were fabricated via collagen self-assembly and simultaneous cross-linking followed by immersion in ethanol solution. Furthermore, the physicochemical properties of DFCG and DCCG were analyzed by atomic force microscopy, differential scanning calorimetry, enzymatic degradation and dynamic viscoelastic measurements. The microstructure of DFCG was consisted of characteristic Dperiodic collagen fibrils and insusceptible of ethanol concentrations (20-100% (v/v)). However, the thermal stability, remaining weight after enzymatic degradation and mechanical properties of DFCG distinctly increased with the increase of ethanol dose, possiblely ascribing that ethanol with higher polarity might dehydrate partial free water of DFCG and strengthen the interactions of hydrogen bond. Especially, for the gel treated by 100% (v/v) enthanol, Td increased by 32.7 °C and G′ was 55-folds than those of undehydrated gel (43.1 °C and 239.2 Pa). In the case of DCCG, the formation of collagen fibrils was depended on the concentrations of N-hydroxysuccinimide adipic acid derivative (NHS-AA), which was converted to [NHS-AA]/[NH2] ratios (calculated by the [active ester group] of NHS-AA and [ε-NH2] of lysine and hydroxylysine residues of collagen). As the ratio= 0.05, the characteristic D-periodic fibrils were still formed and the treatment of 60% (v/v) ethanol increased the Td (52.5 °C) and G′ (7388 Pa) values of the gel compared with those of uncross-linked gel (49 °C and 2064.32 Pa, respectively), majorly resulting from the effects of covalent cross-linking bonds and hydrogen bonds. However, when the ratio= 0.2, the collagen self-assembly was intensively inhibited and the dehydration of free water within gel structure in the absence of thick fibrils led to the shrinkage of the gel and an obvious decrease in Td (42 °C) and G′ (432 Pa). Although the [NHS-AA]/[NH2] ratio further increased to 0.8, the thermal stability and elasticity of the gel enhanced mildly suggesting that the presence of thick fibrils formed via the self-assembly was significantly crucial for reinforcing the gels. Take-Away: The fish collagen gels with excellent elasticity were prepared via the treatment of ethanol. The physicochemical properties of the dehydrated gels were depended on the concentrations of ethanol. The presence of characteristic D-periodic fibrils was significantly crucial for reinforcing the gels.

Orientadores: Reginaldo Guirardello, Maria Regina Wolf Maciel<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química<br>Made available in DSpace on 2018-08-26T21:49:21Z (GMT). No. of bitstreams: 1 Stinguel_Lucas_M.pdf: 1977338 bytes, checksum: 117f124dbe6de9464d8e0ea3c2274878 (MD5) Previous issue date: 2015<br>Resumo: Um dos principais problemas na produção de etanol é o elevado custo energético associado a sua separação por causa do excesso de água e a existência de um azeótropo na mistura etanol-água, levando em conta que através da destilação convencional esta mistura só pode ser separada até um máximo de 95% em peso. Para produzir o etanol anidro é necessário mais um tipo de destilação, chamada de desidratação, onde as mais utilizadas são as destilações azeotrópica e extrativa, mas a produção via adsorção vem crescendo bastante nos últimos anos devido a necessidade de um produto mais puro. No entanto o projeto de adsorção para separar o etanol da água é muito trabalhoso, já que este deve operar em ciclos, isso leva ao uso da simulação como uma saída para o projeto de um processo de adsorção. Entre os simuladores disponíveis no mercado existe o EMSO, que é um simulador de fácil acesso e gratuito, porém o EMSO não possui um modelo de adsorção dentro de sua biblioteca. Com isso o objetivo principal do presente trabalho é a implementação de um modelo de adsorção no software EMSO para a separação da mistura etanol-água. O modelo matemático utilizado neste trabalho foi retirado da literatura, o qual foi utilizado para desidratação de etanol em um ciclo de adsorção completo. As simulações de adsorção foram realizadas com o tempo total de 345s, já que esse é o tempo gasto para que uma coluna fique saturada em um ciclo de adsorção. Foi atingindo o perfil de fração molar de agua satisfatório nas simulações o que leva a concluir que o software EMSO pode muito bem ser utilizado para a simulação de um processo de separação da mistura etanol-água por adsorção<br>Abstract: A major problem in ethanol production is the high energy cost associated with their separation because of excess water and the existence of an azeotrope in ethanol-water mixture, taking into account that through the conventional distillation this mixture can be separated to a maximum of 95% by weight. To produce anhydrous ethanol is required another distillation type, called dehydration, where the most used are the azeotropic and extractive distillation, but the production by adsorption has increased greatly in recent years because of the need for a more pure product. However the adsorption project to separate ethanol from water is very laborious, since it must operate in cycles, this leads to the use of simulation as an outlet for the design of an adsorption process. Among the simulators available in the market there is EMSO, which is an easily accessible and free simulator, but EMSO has no adsorption model in your library. Thus the main objective of this work is the implementation of an adsorption model in EMSO software to separate the ethanol-water mixture. The mathematical model used in this study were taken from the literature, which was used for ethanol dehydration in a complete adsorption cycle. The adsorption simulations were performed with the total time of 345s, since this is the time taken for a column is saturated in an adsorption cycle. The water mole fraction profile satisfactorily in the simulations which leads to the conclusion that the EMSO software may well be used for the simulation of a process of separation of ethanol-water mixture by adsorption has been reached<br>Mestrado<br>Desenvolvimento de Processos Químicos<br>Mestre em Engenharia Química

Orientador: Rubens Maciel Filho<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química<br>Made available in DSpace on 2018-08-18T17:35:35Z (GMT). No. of bitstreams: 1 Fonseca_NatalieAlexandraAmezquita_M.pdf: 1706178 bytes, checksum: 6e4b89c3e1712bb8a16be86c7a7f01bc (MD5) Previous issue date: 2011<br>Resumo: Um dos problemas na produção de etanol é o elevado custo energético associado a sua separação por causa do excesso de água e a existência de um azeótropo na mistura etanol - água, pelo que através da destilação convencional esta mistura só pode ser separada até um máximo de 95% em peso. Existe na atualidade um notável interesse no desenvolvimento de processos tecnológicos com o objetivo de melhorar as técnicas de separação necessárias para isolar o etanol do produto obtido na fermentação. Convencionalmente as técnicas empregadas para a purificação final na etapa posterior à destilação convencional são a destilação azeotrópica e a destilação extrativa, embora a importância relativa da adsorção tenha aumentado nos últimos anos como conseqüência do desenvolvimento dos processos de adsorção, a invenção das peneiras moleculares. Desta forma o processo PSA (Pressure Swing Adsorption) como um processo de maior eficiência térmica tornou se uma alternativa à destilação azeótropica. No entanto, o desenho e a análise de um sistema PSA é uma tarefa difícil devido ao grande número de parâmetros envolvidos na simulação numérica, pelo que é de grande importância a utilização de simuladores comerciais no estúdio deste tipo de processos. No presente trabalho foi estudada a dinâmica do processo PSA para a desidratação de etanol com zeólitas 3A mediante sua simulação no Software comercial Aspen Adsim. Foram estimados a partir de dados experimentais encontrados na literatura os parâmetros da Isoterma de Langmuir e o coeficiente de transferência de massa dado por LDF e estabelecido o ciclo de Adsorção PSA completo. As condições utilizadas foram similares as indústrias e foram estabelecidos ciclos por médio da ferramenta Cycle Organizer do simulador com 4 passos básicos assim: Adsorção, Despressurização, Purga e Pressurização em um tempo total de 11,5 minutos para dois leitos de adsorção. Foi atingido um estado estável CSS ao redor de 383 ciclos com uma pureza de 99,4%, 92,9% de recuperação e 46,83 l/hr/kg de produtividade. Foram pesquisados os efeitos da pressão de adsorção, a concentração da água na alimentação e vazão de alimentação, assim com a influência dos parâmetros da isoterma de Langmuir e do coeficiente de transferência de massa MTC para dois leitos de adsorção sob a Porcentagem de Pureza, Recuperação e Produtividade. Mediante este análise foi possível verificar que todas as variáveis de processo estudadas são significativas nas variáveis de resposta, enquanto constatou se que o parâmetro MTC é um parâmetro sensível que depende do sistema e das resistências que atuam no momento da transferência de massa, pelo que tem que ser estimado a partir de dados experimentais. Os efeitos das variáveis de projeto diâmetro e comprimento da coluna influíram notoriamente na produtividade do processo.Em conclusão o simulador Aspen Adsim tem sido apresentado como uma ferramenta útil para simulação dinâmica de um processo de adsorção<br>Abstract: One of the problems with ethanol production is the high energy cost which is associated with the separation of ethanol due to of excess water and the existence of an azeotrope in the mixture ethanol-water, by conventional distillation the mixture can be separated up to 95% weight. Currently, there is great interest in the development of technological processes to improve the necessary separation techniques in order to isolate the product obtained in ethanol fermentation. Conventionally, the techniques employed for final purification after conventional distillation are azeotropic distillation and extractive distillation. Although the relative importance of adsorption processes has increased in recent years as a result of increased development of adsorption process and the invention of molecular sieves. Thus, the PSA (Pressure Swing Adsorption) technique as a process of improved thermal efficiency has become an alternative in the azeotropic distillation. However, the design and analysis of a PSA system represents a difficult task due to the large number of parameters involved in the numerical simulation. Therefore, it is of great importance the commercial use of simulators in this research process. This study analyzed dynamics of the PSA process for the dehydration of ethanol with zeolite 3A by means of its commercial simulator software Aspen Adsim. It estimated that the parameters of the Langmuir isotherm and mass transfer coefficient given by LDF based on experimental data from the literature, furthermore, it established the complete PSA adsorption cycle. The conditions were similar to those used in the industry and have been established by means of the simulator, Cycle Organizer tool, the following for basics steps: adsorption, depressurization, purge and pressurization in a total time of 11,5 min to two adsorption beds. A steady state was reached - CSS around 383 cycles, with a purity of 99.4%, 92.9% of recuperation and 46.83 l/hr/kg of productivity. A parametric study also was done to investigate the effects of adsorption pressure, the concentration of water in food, feed flow, the of the Langmuir isotherm parameters and mass transfer coefficient - MTC for two adsorption beds under the percentage of purity, recovery and productivity. Through this analysis it was verified that all processes variables are significant in the studies response variables. While the MTC parameter found that is a susceptible parameter and depend on the resistances of transfer and, therefore, has to be estimated from experimental data. The effects of design variables such as diameter and length of bed visibly influenced the productivity of this process. In conclusion the simulator Aspen Adsim has been presented as a useful tool for dynamic simulation of adsorption process<br>Mestrado<br>Desenvolvimento de Processos Químicos<br>Mestre em Engenharia Química

Orientador: Heloise de Oliveira Pastore<br>Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química<br>Made available in DSpace on 2018-08-21T05:07:04Z (GMT). No. of bitstreams: 1 Pietre_MendelssolmKisterde_D.pdf: 10147011 bytes, checksum: bc8b63b205099dec1b50bf41ce37c4ef (MD5) Previous issue date: 2012<br>Resumo: O presente trabalho descreve a síntese e esfoliação dos precursores lamelares [V,Al]-PREFER e [V,Al]-Nu-6(1), onde os elementos Al e V foram inseridos diretamente na síntese. Difração de raios-X, fisissorção de N2 e Si-MAS-RMN confirmaram o sucesso da esfoliação. A manutenção da entidade zeolítica foi observada por FTIR, através da presença dos anéis duplos, enquanto que a presença de Al tetraédrico, responsáveis pelos fortes sítios ácidos de Bronsted, foi confirmado por Al-MAS-RMN. Através das técnicas espectroscópicas, V-MAS-RMN e UV-Vis, observa-se que diferentes tratamentos conduzem a formação de espécies com ambientes distintos de vanádio. Para os catalisadores obtidos a partir do tratamento em meio alcalino, observou-se somente espécies de vanádio tetracoordenado com a estrutura. Por outro lado, os materiais derivados do processo em meio ácido, geram sítios octaédricos de vanádio, localizados fora da rede. A questão do acesso foi confirmada pela reação de desidratação da xilose. Os materiais esfoliados foram mais eficientes do que os respectivos zeólitos Nu-6(2) e ferrierita, evidenciando que os sítios ácidos estão mais facilmente acessíveis a moléculas volumosas. A sondagem da bifuncionalidade dos catalisadores [V,Al]-lTQ-6 e [V,Al]-lTQ-18 foi feita através da reação de oxidação e desidratação da molécula de etanol. Observou-se a formação majoritária de produtos de desidratação (éter etílico + etileno) mostrando a maior atividade dos sítios ácidos. Nos sólidos [V,Al]-lTQ-6(B), o processo que governa a formação do acetaldeído é o tipo de sítio de vanádio presente e não a composição química como se esperava. Por outro lado, na reação do etanol com os sólidos [V,Al]-lTQ-6(B), mesmo apresentando maior teor de vanádio, a seletividade ao acetaldeído é menor do que observado para os catalisadores [V,Al]-lTQ-6(B). Nesse caso, há a provável contribuição das ligações V-O-Si que conduz a reação para a formação de éter etílico, diminuindo a seletividade ao acetaldeído<br>Abstract: This work describes the synthesis and delamination of the [V,Al]-PREFER and [V,Al]-Nu-6(1) layered zeolites, where Al and V were directly inserted into the zeolitic framework. X-ray diffraction, N2 physisorption and Si-MAS-NMR confirmed the delamination success. The maintenance of zeolitic entities was verified by FTIR through double rings presence, whereas the tetrahedral Al sites presence, responsible by strong Bronsted acid sites, was confirmed by Al-MAS-NMR. Such observed by V-MAS-NMR and UV-Vis spectra, different treatments leads to the formation of distinct vanadium sites. Tetrahedral vanadium sites are obtained for the catalysts from alkaline treatment only. In the other hand, extraframework vanadium sites are generated for the samples derivates from acid treatment. As observed by xylose dehydration reaction, delaminated solids were more efficient than Nu-6(2) and ferrierite zeolite, showing that the acid sites are more exposed and, consequently, easily accessible to bulky molecules. The bifunctionality of the [V,Al]-lTQ-6 and [V,Al]-lTQ-18 catalysts were probed by ethanol oxidation and dehydration. It was observed the majority formation of dehydration product (diethyl ether + ethylene) showing the best activity of the acid sites. It was verified, for [V,Al]-lTQ-6(B) catalysts, that specific structural arrangements of the vanadium sites present in the delaminated layers is determining for catalysts activity than just chemical composition, particularly the amount of vanadium, which could be expected as responsible for the generation of redox sites potentially active. In the other hand, for [V,Al]-lTQ-18(B) catalysts, presented lower acetaldehyde selectivity, even with higher amounts of vanadium. One possible explanation can be due the contribution of Si-O-V bonds leading the reaction to the diethyl ether formation, lowering the acetaldehyde selectivity<br>Doutorado<br>Quimica Inorganica<br>Doutor em Ciências

Orientadores: Rubens Maciel Filho, Carlos Eduardo Vaz Rossell<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica<br>Made available in DSpace on 2018-08-11T20:59:18Z (GMT). No. of bitstreams: 1 Dias_MarinaOliveiradeSouza_M.pdf: 13614518 bytes, checksum: 8a7fafce0407822a32d8f9833a1d2d86 (MD5) Previous issue date: 2008<br>Resumo: O objetivo desta dissertação é apresentar a descrição e a simulação de processos de produção de etanol a partir do caldo e do bagaço da cana-de-açúcar, visando o levantamento do consumo de energia destes processos. Foram consideradas melhor ias no processo convencional de produção de etanol a partir do caldo, tais como a realização de eficientes tratamento e esterilização do caldo, a condução da fermentação a temperaturas mais baixas (28°C) do que as utilizadas atuamente, o estudo de configuração de destilação duplo efeito e a otimização de processos de desidratação para produção de etanol anidro. O processo de produção de etanol a partir do bagaço da cana-de-açúcar é baseado em um processo de hidrólise do tipo Organosolv com ácido diluído em três etapas: pré-hidrólise da hemicelulose, deslignificação Organosolv e hidrólise da celulose. Considerando-se a utilização de 70 % do bagaço gerado nas moendas como matéria prima do processo de hidrólise estudado, seria possível aumentar a produção de etanol em cerca de 17 %, considerando somente a fermentação das hexoses obtidas a partir da celulose do bagaço. A realização do processo de hidrólise leva a um aumento do consumo de energia do processo, que pode ser compensado pela otimização do processo convencional de produção .de etanol a partir do caldo da cana-de-açúcar, do aproveitamento da palha e de subprodutos do processo de hidrólise como a lignina, e da integração térmica do processo integrado, que utiliza caldo e bagaço como matéria prima para produção de etanol. O equacionamento do consumo energético da produção integrada de etanol a partir da cana-de-açúcar e do bagaço de cana-de-açúcar constitui um obstáculo à viabilização técnica e econômica do processo de hidrólise. Este trabalho visa apresentar então colaborações no sentido de superar este obstáculo, considerando-se a produção de etanol a partir do bagaço de cana-de-açúcar por meio de um processo de hidrólise do tipo Organosolv com ácido diluído<br>Abstract: The main objective of this dissertation is to present the description and simulation of bioethanol production processes from sugarcane juice and bagasse, considering the evaluation of energy consumption. Some improvements were considered for the conventional bioethanol production process from sugarcane juice, such as efficient juice treatment, sterilization and concentration, lower fermentation temperatures (28°C) than the ones used nowadays in the industry, study of a double effect distillation sys tem and optimization of dehydration processes for anhydrous bioethanol production. The process considered for bioethanol production from sugarcane bagasse is based on an Organosolv process with dilute acid hydrolysis, carried on three non-simultaneous steps: prehydrolysis of hemicellulose, Organosolv delignification and cellulose hydrolysis. The use of 70 % of sugarcane bagasse generated on the mills as raw material for the hydrolysis process allows an increase in bioethanol production of 17 %, considering exclusively the fermentation of the hexose obtained from the cellulose fraction of sugarcane bagasse. An increase on energy consumption is observed when bagasse is used as raw material in the hydrolysis process, but it may become feasible considering the optimization of conventional bioetlJ.anol production process, the use of sugarcane trash and lignin as fuel in boilers and the thermal integration of the integrated process, which uses sugarcane juice and bagasse as raw materiaIs for bioethanol production. Evaluation of the energy consumption of the integrated production of ethanol from sugarcane and sugarcane bagasse constitutes an obstacle for the technical and economical feasibility of the hydrolysis processo This work aims to present contributions to help surpass this obstacle, considering the production of ethanol from sugarcane bagasse using an Organosolv process with dilute acid hydrolysis<br>Mestrado<br>Desenvolvimento de Processos Químicos<br>Mestre em Engenharia Química

Fundação de Amparo a Pesquisa no Estado do Rio Grande do Sul<br>Ethene or ethylene is a hydrocarbon mainly used in plastic manufacture, through the polymerization. The production of ethene in large scale is performed through cracking process of oil light fractions. In the incessant search of clean and renewable sources to reduce the emission of greenhouse gases, it has been studied the ethylene production with alternative routes. Among the alternative ways of production, the dehydration reaction of ethanol with acid catalysts, like alumina, consists in a very interesting route, since ethanol is widely produced in Brazil, mainly by fermentation of sugarcane juice. However, with relation to the reaction mechanism of the catalytic conversion of the ethanol to ethene, there are some questions when aluminas are used. Therefore, the objective of this work is the study of two metastable forms of aluminas with different acid characteristics, γ- e η-alumina, in order to elucidate the mechanism of dehydration reaction of ethanol to ethene and compare the performance of these two aluminas. For that, two aluminum hydroxides, boehmite and bayerite, were treated in three different temperatures, leading to six catalysts with different acid properties. The catalysts were characterized and in situ reactions with DRIFTS were performed to understand the reaction mechanism. Also, it has studied the reaction kinetics with experiments in laboratory scale unit reaction. With literature information and DRIFTS analysis, some kinetic models were proposed in order to obtain a reaction rate model and to estimate the kinetics parameters. The models presented good adjusts to the experimental data and contributed to the comprehension of the reaction mechanism of ethanol catalytic dehydration.<br>O eteno ou etileno é um hidrocarboneto utilizado principalmente na fabricação de plásticos, através de sua polimerização. A produção de eteno em larga escala é realizada através do processo de craqueamento de frações leves do petróleo. Na incessante busca por fontes limpas e renováveis para reduzir a emissão de gases poluentes na atmosfera, tem-se o estudo da produção de eteno por rotas alternativas. Dentre os meios alternativos de produção, a reação de desidratação de etanol com catalisadores ácidos, como a alumina, consiste em uma rota muito interessante, já que o etanol é amplamente produzido no Brasil, principalmente através da fermentação do caldo de cana-de-açúcar. No entanto, com relação ao mecanismo reacional da conversão catalítica de etanol em eteno, ainda existem algumas questões quando aluminas são usadas. Portanto, o objetivo deste trabalho é o estudo de duas formas metaestáveis de aluminas com diferentes características ácidas, γ- e η-alumina, a fim de elucidar o mecanismo da reação de desidratação do etanol a eteno e comparar o desempenho das duas aluminas. Para isso, dois hidróxidos de alumínio, boemita e bayerita, foram tratados em três diferentes temperaturas, obtendo-se seis catalisadores com diferentes propriedades ácidas. Os catalisadores foram caracterizados e reações in situ por meio de DRIFTS foram realizadas para compreensão do mecanismo reacional. Ainda, estudou-se a cinética reacional por meio de experimentos em unidade de reações de escala de laboratório. Com informações da literatura e das análises de DRIFTS, alguns modelos cinéticos foram propostos com a finalidade de se obter um modelo de taxa de reação e estimar os parâmetros cinéticos. Os modelos apresentaram um bom ajuste aos dados experimentais e contribuíram na compreensão do mecanismo da reação de desidratação catalítica de etanol.

Orientadores: Maria Aparecida Silva, Lauro Euclides Soares Barata<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química<br>Made available in DSpace on 2018-08-09T22:19:35Z (GMT). No. of bitstreams: 1 Braga_AliceMurteiraPinheiro_M.pdf: 1481376 bytes, checksum: 51d0064751b63561ff5b78fbb24c1537 (MD5) Previous issue date: 2007<br>Resumo: Modificações da atmosfera ao redor do produto têm sido utilizadas para prolongar o armazenamento de frutas e vegetais frescos. Atualmente, esta técnica tem-se estendido também a processos de secagem, influenciando características sensoriais do produto desidratado. Durante a secagem de frutas, uma fração de compostos volúveis importantes para a composição do aroma é perdida durante a retirada da água. Para muitos produtos alimentícios, a presença de voláteis é um fator fundamental de qualidade. Com o objetivo de verificar a influência da atmosfera modificada na retenção de compostos voláteis, o presente trabalho analisa os experimentos de secagem de abacaxi (Smooth Cayenne) sob composição normal do ar e atmosfera modificada por etanol (0,5% v/v), variando temperatura e velocidade do ar, avaliando a variação da composição volátil durante o processo. Os experimentos de secagem foram conduzidos num túnel, feito com paredes de policarbonato e um sistema de aquisição para controle de dados, onde se pôde acompanhar continuamente o peso da amostra e controlar a temperatura do gás de secagem. Para quantificar a retenção dos voláteis, foi utilizada a metodologia de microextração por fase sólida acoplada a cromatógrafo gasoso com espectrômetro de massa (SPME-GC-MS). A modificação da atmosfera de secagem com vapor de etanol promoveu uma evaporação mais intensa da água, assim como uma maior retenção de compostos voláteis. A composição volátil mudou significativamente durante a secagem, não somente pela perda de alguns componentes, mas também pela produção de outros<br>Abstract: Modifications of the atmosphere surrounding the product have been used to prolong the storage of fresh fruits and vegetables. Currently, this technique has also been extended to drying processes, influencing sensorial characteristics of the dried product. During the drying of fruits, a fraction of the volatile compounds that are important for the aroma composition is lost during water removal. For many food products, the presence of volatile is a basic factor of quality. To verify the influence of the modified atmosphere on volatiles retention, the present work analyzed experiments of pineapple (Smooth Cayenne) drying under normal air composition and in atmosphere modified by ethanol (0.5% v/v), varying temperature and air velocity, evaluating the variation of the volatile composition of the product during the process. The drying experiments were carried out in a tunnel, with walls made of policarbonate and an acquisition system for data control, which could continuously monitor the weight of the sample and also control the temperature of the drying gas. To quantify the volatiles retention, a solid phase microextration methodology coupled to gas chromatography-mass spectrometry (SPME-GC-MS) was used. The modification of the drying atmosphere with ethanol vapour promoted more intense water evaporation as well as higher volatiles retention. The volatile composition was changed significantly during drying, not only due to the loss of some compounds, but also due to the production of others<br>Mestrado<br>Engenharia de Processos<br>Mestre em Engenharia Química

Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>Calcination variables, temperature, time and heating rate, used in obtaining different transition aluminas were simultaneously investigated using statistical experimental design. Empirical models correlating catalyst final properties and calcination conditions were employed. It was found that all calcination variables play fundamental roles on acidity of alumina catalyst. Furthermore, interaction effects among these variables and non-linear effects also are of fundamental importance for the final properties catalyst. Therefore, the use of simultaneous variation of calcination conditions through experimental design is of great importance in detecting such interactions. It was observed that the use of high heating rates favor the formation of pore with larger diameters and with high pore volume and, for short calcination time, high heating rate also contributes to the formation of higher concentration of acid sites. The acid sites characterization of transition aluminas were performed by temperature programmed desorption of ammonia (NH3-DTP), which showed that there are two distinct acid sites on the surface these materials. The desorption dates were adjusted by a model in which the catalyst bed was considered as single continuously stirred tank reactor and the intrinsic kinetic was chosen to be of first order for adsorption and desorption. The ethanol conversion was higher for the alumina with higher acid sites concentration, suggesting a relationship between the activity of the alumina for the ethanol conversion and its acidity. The selectivity for the ethylene formation also was higher for the more acid aluminas, while the selectivity to ether presented opposite behavior. Therefore, a successful control of all calcination conditions can be an effective method to adjust the final physical and chemical properties of transition alumina catalyst, aiming the highest yield of ethylene from ethanol dehydration.<br>Foram preparadas aluminas de transição investigando-se simultaneamente o efeito das variáveis de calcinação: temperatura, tempo e taxa de aquecimento, usando planejamento estatístico de experimentos. Modelos empíricos foram empregados para correlacionar as propriedades finais dos catalisadores às variáveis de calcinação. Foi observado que todas as variáveis de calcinação influenciam a concentração de sítios ácidos das aluminas. Além disso, efeitos de interação entre estas variáveis, bem como efeitos não lineares também são de fundamental importância para as propriedades finais deste catalisador. Estes efeitos só podem ser identificados com a variação simultânea das condições de calcinação através do uso do planejamento de experimentos. Foi observado que o uso de elevada taxa de aquecimento favorece a formação de aluminas com maior volume e tamanho de poros e, para curtos períodos de tempo de calcinação, elevada taxa de aquecimento também contribui para a formação de maior concentração de sítios ácidos. A caracterização dos sítios ácidos das aluminas foi realizada pela técnica de dessorção de amônia à temperatura programada (DTPNH3). Esta caracterização indicou a presença de dois tipos de sítios ácidos na superfície destes materiais. Os dados de dessorção foram ajustados por um modelo que considera a cinética de dessorção e readsorção como reações de primeira ordem em um modelo de reator de mistura perfeita. A conversão de etanol foi maior para as aluminas com maior concentração de sítios ácidos, indicando uma relação entre a atividade das aluminas para a conversão de etanol e sua acidez. A seletividade para a formação de eteno também foi maior para as aluminas mais ácidas, enquanto que a seletividade para éter exibiu comportamento inverso. Portanto, o controle adequado de todas as condições de calcinação pode ser um método eficiente para ajustar as propriedades físicas e químicas finais de aluminas de transição, visando obter maior rendimento na produção de eteno a partir da desidratação de etanol.

碩士<br>國立臺灣科技大學<br>化學工程系<br>97<br>ABSTRACT The design and control of ethanol dehydration process via heterogeneous and homogeneous (extractive distillation) azeotropic distillation will be investigated in this thesis. For heterogeneous azeotropic distillation, proposed design is adapted from Ryan and Doherty (1989) which introduced the used of combine pre-concentrator/ recovery column, Arifin and Chien (2007) also uses the same conceptual design for isopropyl alcohol dehydration process. In the thesis, a short-cut design to screen several alternative entrainers has beed proposed. It is found that cyclohexane is the best entrainer for this entrainer dehydration process since benzene can no longer be used in the industry. Optimal design flowsheet for the two-column system has been obtained bu minimizing the total annual cost. For homogeneous extractive distillation, ethylene glycol (EG) is used as heavy entrainer. The design flowsheet includes pre-concentrator column, an extractive distillation column and an entrainer recovery column. The optimal design flowsheet of this complete process has been established showing that the total annual cost and energy consumption of this design flowsheet is significantly less than the competing design flowsheet via heterogeneous azeotropic distillation. A very simple overall control strategy has also been proposed which requires only one tray temperature control loop in each column to hold the high-purity specifications of the two products. Dynamic simulations reveal that fixing of the reflux ratio is a suitable control strategy.

碩士<br>元智大學<br>化學工程與材料科學學系<br>104<br>In this study, the prepared catalysts for the ethanol dehydration in a fixed bed reactor was obtain more active acidic catalyst under the reaction conditions at lower temperatures. This study explored the experimental conditions, including different type catalysts (ZSM-5 zeolite catalyst by using the impregnation method modified with phosphorous and lanthanum, active aluminum oxide (γ-Al2O3)). With examined the weight hourly space velocity, water content of ethanol, and reaction temperatures. Characterization of the catalyst was carried out with BET, NH3-TPD, SEM, TGA, XPS and XRD. The experimental results show that when the concentration of ethanol is 95%, the yield and selectivity of ethylene can be achieved 98.5% and 100%, respectively, using ZSM-5 zeolite catalyst by dealuminization at 220 °C. When the concentration of ethanol is 20%, the yield and selectivity of ethylene can be achieved 94.3% and 94.4%, respectively, using ZSM-5 zeolite catalyst by phosphorous-modified at 240 °C. Both of these catalysts are the best among all prepared catalysts.

Canola meal was used as an adsorbent in a pressure swing adsorption (PSA) apparatus for ethanol dehydration. The experiments were conducted at different pressures, temperatures, vapor superficial velocities, vapor concentrations and particle sizes. Adsorption experiments were performed at equilibrium and breakthrough points. The results demonstrated that canola meal can break the azeotropic point 95.6 wt% and produce over 99 wt% ethanol. At elevated temperature, feed water concentration, and vapor superficial velocity, it was found that the mass transfer rate increased. In addition, the mass transfer rate decreases when either the total pressure or the size of the adsorbent particles are increased. Breakthrough curves were simulated and the overall mass transfer resistance was evaluated at all experimental runs. The internal mass transfer resistance was identified as the relevant mass transfer mechanism. For canola meal, the equilibrium water/ethanol uptake was achieved at 100, 105, and 110˚C. The Frenkel-Halsey-Hill (FHH) and Guggenheim-Andrson-de-Boer (GAB) models perfectly simulated the water adsorption isotherms. By applying Dubinin-Polanyi model to the experimental data, canola meal was identified as a large pore (non-porous) material. The heat of adsorption on canola meal with particle size of 0.43-1.18 mm was determined to be -32.11 kJ/mol. The result confirms that the adsorption process is an exothermic phenomenon and is of physical type due to the fact that the value obtained as the heat of adsorption is negative and its magnitude is within the range 20–80 kJ/mol. The equilibrium water uptake on canola meal was similar to that reported for other starchy and cellulosic adsorbents, while the ethanol uptake was higher. Water saturated canola meal was successfully regenerated by passing nitrogen at 110˚C which is lower than that for molecular sieves commonly used in industry for bioethanol dehydration. The canola meal bio-adsorbent was re-used for more than 32 cycles and no significant change in adsorption capacity was observed.

The new desilicated forms of the zeolites X, Y and ZSM-5 were prepared by the selective removal of silicon atoms from the parent zeolites in an aqueous solution of base. This treatment, which decreases the Si/Al ratio while keeping the zeolite framework almost unmodified, enhanced the ion exchange capacities of all the zeolites, a property which can be exploited industrially for the X and Y zeolites since the desilicated forms had higher total ion removal rates of calcium and magnesium ions from hard water. Similarly, desilication results in a higher density of acid sites as shown in the following. $\sp1$H MAS NMR studies were done on anhydrous samples of desilicated ZSM-5 and have detected a signal which was not observed for the parent sample and is believed to arise from the interaction of Bronsted acid sites hydrogen bonded to framework Aluminum atoms. This corresponds to the creation of a second generation of Bronsted Acid Sites (BAS II) distinguishable from the normal bridging hydroxyl BAS (BAS I) associated with tetrahedrally coordinated aluminum in the zeolite framework. In catalytic testing studies, the desilicated ZSM-5 zeolite was found to display a higher total conversion in the dehydration of absolute ethanol into ethylene, however the selectivity for ethylene was higher for the parent zeolite at lower reaction temperatures. This was a direct consequence of the higher density of acid sites on the desilicated zeolite, which is comprised of BAS II in the presence of "unusual" Lewis acid sites of type II (LAS II). These Lewis acid sites were also detected by $\sp1$H MAS NMR during the rehydration phase and are believed to be produced by dehydroxylation of BAS II which were generated by the "desilication-healing" phenomena. LAS II are distinguishable from LAS I since the latter are easily rehydrated back to the corresponding BAS I. The nature and strength of these different acidic sites on the parent and those created on the desilicated ZSM-5 were also studied in more detail by the techniques of XPS, FTIR, NH$\sb3$ TPD, nitrogen and argon adsorption and desorption (BET), DTA/TGA and poison testing using pyridine and 2,6-dimethylpyridine. Upon steam treatment of the desilicated zeolite, both the total conversion and selectivity for ethylene improved significantly in the dehydration of absolute ethanol. Steaming was capable of rehydrating the LAS II into BAS II, a reconversion which was previously too demanding to be achieved under the conditions of catalytic testing, hence the low selectivity for ethylene at lower reaction temperatures. Further evidence of this reconversion is provided by catalytic testing with aqueous ethanol for which the desilicated zeolite achieved higher total conversions and selectivities for ethylene than the parent at all reaction temperatures, and the selectivity for ethylene was always significantly higher than was achieved with absolute ethanol. This has important implications for the Bioethanol to Ethylene Process. A cut off temperature was also confirmed for the dehydration of ethanol, at which the reaction mechanism changed from the two step conversion into diethyl ether and ethylene, into the one step, direct conversion to ethylene. These temperature ranges were determined to be 200-225$\sp\circ$C and 225-250$\sp\circ$C for absolute and aqueous ethanol respectively.

碩士<br>中原大學<br>化學工程研究所<br>99<br>In the distillation separation of ethanol vapor and water vapor, it can form an zoetrope at 78.2℃, at which there are 95.6wt% ethanol and 4.4wt% water. Traditional azeotropic distillation and extractive distillation to obtain anhydrous ethanol need more energy than adsorption. Adsorption as a low energy consumption process has attracted attention to apply in ethanol dehydration. Recently, some investigators have tried to use starch to replace Zeolite 3A. However, it has a low efficiency in adsorption selectivity and regeneration and starch powder was become glue after adsorption with water vapor. In the present study, starch was immobilized using sol-gel method to solve these problems. This study obtained adsorption equilibrium data by the BET experiment for water and ethanol on immobilized starch. Then isotherm curve and the parameters by numerical method and expressed by the Langmuir isotherm. The isotherm is applied to analyze the effect of the variables such as feed concentration, velocity, particle size and bed length on the breakthrough performance. Breakthrough curves of ethanol were measured by using a gas-phase FT-IR instead of traditional GC. Application of the gas-phase FT-IR could detect changes of gas concentration more fast than the traditional GC. Results showed that on influence of feed concentration, velocity, particle size and bed length is significant on different on breakthrough time and breakthrough curve shape. The effects of particle size and bed length on outlet concentration (C/Co) is significant, with increase of the velocity the roll-over phenomenon is more obvious. In dynamic absorption, the slope of breakthrough curve and C/Co may represent mass transfer behavior. The optimum experimental parameters were expressed as follows: Inlet concentration: 92%, particle size: 1~2 mm, velocity: 500 sccm and the length of the bed: 7cm.

碩士<br>嘉南藥理科技大學<br>環境工程與科學系暨研究所<br>99<br>The purpose of this study is to prepare polysulfone basde thin film composite membrane for dehydration ethanol of solution by pervaporation. Polysulfone was used as supported membrane. 1,3,5-benzenetricarbonyl chloride (TMC) was as the monomer in oil phase and 1,6-diaminohexane was used as the monomer in water phase in interfacial polymerization method. The effect of polymerization times, monomer concentration, impregnating time of monomer, sequence of monomer immersing, reaction temperature, post heat treatment, and various monomers on the separation performance of composite membranes were investigated. In this investigation, it was found that much more polymerization times induced the layer separation between the polyamide film and support membrane. The significant defect strongly declined the separation factor of composite membrane in pervaporation. The immersing step is an important factor to dominate the thin film formation. This study revealed that the oil phase first is the best choice to prepare a defect free composite membrane. The results indicated that the oil phase first increased much more monomer in the support layer and benefited the polymer growth in the interfacial layer and produced a well structure thin film. It is concluded that considering the optimum monomer concentration, reaction time, post treat treatment could prepare a good performance of TFC composite membranes. The SEM observations confirmed that the thin polyamide film was well coating on the support membrane and it was also showed that conditions of polymerization significantly affected the thin film thickness on the composite membranes. The contact angle measurement indicated the hydrophilic properties of composite membrane can be improved by coating the polyamide layer on the composited membrane by TFC method. The evidence of polyamide on the composite membrane was carried out by ATR-FT-IR analysis. The strong C=O and N-H bands were observed on the surface of composite membrane. The high performance pervaporation of TFC membranes for dehydration of ethanol mixture can be prepared by considering the optimum conditions in this study.

碩士<br>嘉南藥理大學<br>環境工程與科學系<br>105<br>The purpose of this investigation is focused on the hydrophilic modification of polysulfone(PSF), poly ether imide(PEI), and polysulfone/ poly ether imide membranes on the improvement of separation performance of pervaporation process for dehydration of ethanol/water mixtures. The wet phase inversion method was used to prepare the modified membranes and posted coating poly ethylene imine for hydrophilic enhancement. The hydrophilic properties of modified membranes were tested by water contact angle measurement. The influent factors on the separation performance of modified membranes were included casting polymer concentration, poly ethylene imine concentration, ionization, feed ethanol concentration and operation temperature in pervaporation process. It was found that the increase in casting polymer concentration increased the skin layer thickness and improved the separation factors of membrane. The optimum prepared polysulfone membrane presented a 267 g/m2hr permeation flux and 334 separation factor. The best poly ethylene imine coating membrane showed a 200 g/m2hr permeation flux and 636 separation factor on pervaporation test. It is worth to noted that those modified membrane will be further increased the separation factor after using the chloride acid ionization. The permeation flux increased with increasing the operation temperature during the PV test due to the enhancement on polymer chain mobility of in the PV process. On the other hand, the feed ethanol concentration on the membrane swelling properties showed the significantly changed the permeation and separation behavior in the PV process. It is concluded that the modification of polyethylene imine coating and ionization exactly increased the hydrophilic of membranes and also improved the separation performance in this investigation.

碩士<br>國立成功大學<br>化學工程學系碩博士班<br>96<br>The aim of this study is to investigate the dehydration of aqueous ethanol solutions by pervaporation using chitosan membranes which were crosslinked in sulfuric acid and embedded with various types of zeolites(3A, 4A, 5A, NaX and NaY). Effects of crosslinking time, zeolite contents and operation temperature on pervaporation performances were studied. The membranes were characterized by Fourier transform-infrared spectrometry(FT-IR), X-ray diffractometer(XRD), scanning electronic micro- scopy(SEM). In addition, thermal properties of the membranes embedded with different amout of silica were investigated by thermal gravimetric ananlysis(TGA). Furthermore, effects of crosslinking time, contents and types of zeolite on swelling behaviors in ethanol and in water of chitosan membranes were also investigated. Compared to the uncrosslinked chitosan membranes, the swelling ratio of the crosslinked chitosan membranes in water increased slight, whereas it declined quite obviously in ethanol. This can be attributed to the enhancement in polarity of the membranes by crosslinking. With addition of zeolites, the swelling ratio in water increased with increasing zeolite contents while it decreases more significantly in ethanol compared to the data of membranes without zeolite embedded. It is found that the total permeability increased with increasing zeolite contents in the EtOH/water pervaporation experiments. On the other hand, the increase in separation factor was observed only when the contents of zeolite were above 20wt.%.

This PhD work proposes the use of two microbial exopolysaccharides, GalactoPol and FucoPol, for the development of membranes to be applied in relevant dehydration processes in industry. The starting material is obtained from a low cost, abundant carbon source, the glycerol produced as a by-product from the biodiesel industry, which represents a key economic advantage. A special attention was given to the development of membranes with enhanced mechanical and transport properties, and superior water selectivity for application in dehydration processes by pervaporation and vapour permeation. The approaches selected for designing target membrane properties included polymer cross-linking and the development of hybrid membranes using the sol-gel method. Firstly, the membranes were modified using different crosslinking agents: trichloroacetic acid for GalactoPol and genipin for Fucopol. Different crosslinking protocols were studied in order to evaluate their potential use for ethanol dehydration by pervaporation. These membranes were characterised in terms of their morphological structure, resistance to solvents and mechanical properties. They showed high water affinity, good chemical resistance towards organic solvents and adequate mechanical properties. Pervaporation experiments were performed using both types of membranes for different water concentration in the feed stream (5.0 to 10.0 wt.%) at a constant temperature of 30 ºC. In addition, the impact of the exopolysaccharide purification protocol – by dialysis and by-dia-ultrafiltration – on the properties and transport performance of composite FucoPol membranes for pervaporation was also studied. Significant differences were found in the swelling behaviour and transport selectivity depending on the purification method. The shear stress imposed during purification by the dia-ultrafiltration method led to a disintegration of polysaccharide aggregates, and, as consequence, denser membranes were obtained, affecting the transport selectivity. The membranes developed, in particular, the composite GalactoPol-PES and dia-ultrafiltrated FucoPol-PES membrane, exhibited a high potential for ethanol dehydration, since a water/ethanol selectivity of 134 and 143, respectively, at 10.0 wt.% water in ethanol was achieved. Although they showed excellent affinity for water, they become progressively unstable in aqueous solutions. Thus, novel hybrid FucoPol membranes were developed combining the best properties of the inorganic network with the selectivity of the microbial polysaccharides, to be applied in pervaporation processes for ethanol dehydration, as well as, in gas dehydration. The hybrid membranes were prepared by incorporation of a SiO2 network homogeneously dispersed by a sol-gel method using (3-Glycidyloxypropyl) trimethoxysilane (GPTMS) as a crosslinker silica precursor. These membranes were structurally, mechanically and thermally characterised. They presented a dense and homogeneous structure, resistant to deformation, a glass transition temperature (Tg) of 43 ºC and a thermal decomposition between 240-251 ºC. Hybrid FucoPol membranes were successfully applied in ethanol dehydration, with higher selectivity values than commercial membranes PERVAP® 4101. However, they lost their stability in contact with solutions of 10.0 wt.% water in ethanol after three days of operation. In contrast, when these membranes were applied for N2 dehydration, they were stable, showed reproducible results and extremely high water selectivities. Permeation of water vapour and pure gases (CO2, CH4 and N2), at different conditions of gas humidity content was monitored by mass spectrometry. Gas mixtures containing 20 vol.% CO2 + 80 vol.% N2 and 70 vol.% CH4 + 30 vol.% CO2 were also studied to mimic industrial applications, namely flue gas and biogas dehydration. The hybrid membranes developed showed barrier properties to all gases studied, with a gas permeability below 1 barrer. On the other hand, they exhibited high water permeabilities and selectivities. When processing the biogas mixture, the water permeability was found to be three times higher than water permeability in the flue gas mixture, leading to a H2O/CH4 selectivity much higher than H2O/N2 selectivity (4042 and 294, respectively). The hybrid FucoPol membranes showed that, in real situations, have the capacity to dehydrate mixtures, with the advantage of not losing N2 or CH4, due to the low permeability values of these gases. This work shows that microbial polysaccharides obtained from a renewable source and purified without using solvents can be a sustainable alternative to other materials used in industrial dehydration processes. Strategies for further improvement should include optimization of polymer cross-linking conditions and optimization of the thickness of the active layer of the composite membranes in order to improve the long term stability of the membranes and promote higher fluxes, without compromising selectivity.

碩士<br>嘉南藥理大學<br>環境工程與科學系<br>103<br>The purpose of this investigation is to develop a new method to prepare thin film composite polypyrrole membrane with porous polysulfone support and applied for pervaporation dehydration of ethanol solution. Polypyrrole polymerization was appeared on the interphase of phase inversion region and it was initiated by the ferric ion in the coagulatant water phase. The polysulfone support was also formed in the wet phase inversion process with NMP/polysulfone system with suitable amount of pyrrole in the casting solution. In this investigation, the thin film composite polypyrrole membrane was successful prepared by the wet phase invesion peocess. It was found that the ionization of polypyrrole effective icreased the hydrophilicity and enhanced the separation factor of pervaporation. It was worthed to note that too much pyrrole monomer in the casting solution did not benefit the defect free thin film formation but the defects increased with too much pyrrole monomer in the castion solution. Based on the results of this study, the separation performance hollow fiber composite membranes were prepared with 28.4wt% polypyrrole/polysulfone in NMP solution with 0.05M ferric aqueous solution as the coagulant and initiator of redox polymerization. It was found that the permeation flux can be achieved 147.61g/m2h and separation factor is 1198 with 90wt% ethanol solution in feed at 25oC. On the other hand, the conductivity of composite membrane significantly improves high than 106 times than the polysulfone membrane. The thin film composite polypyrrole membranes own the highly hydrophilic properties, suitable permeability, and good separation factor. It is expected that this composite membrane can be well applied for separation process and polymer conductive application.

In this study, polyelectrolyte membranes were prepared by layer-by-layer self-assembly on top of an interfacially polymerized polyamide substrate, and these thin-film-composite membranes were studied for pervaporative dehydration of ethylene glycol, ethanol and isopropanol. The performance of composite membranes based on polyethylenimine/poly(acrylic acid) (PEI/PAA) multilayers on a polyamide substrate showed good selectivity and stability for ethylene glycol dehydration. In order to understand the formation process of the polyelectrolyte multilayers, the growth of polyelectrolyte multilayers fabricated on the inner surface of cuvette was investiagted. The membrane surface became increasingly hydrophilic with an increase in the number of polyelectrolyte double layers, which favored water permeation for pervaporative dehydration of organic solvents. Water contact angle on the membrane surface decreased from 68?? to 20?? when 7 polyelectrolyte bilayers were deposited on the polyamide substrate. Although the (PEI/PAA) based polyelectrolyte membranes showed good performance for dehydration of ethylene glycol, these membranes did not perform well for the dehydration of ethanol and isopropanol at relatively high feed alcohol concentrations. This was found to be caused by insufficient stability of PEI/PAA bilayers and the polyamide substrate in the ethanol and isopropanol. To improve the performance of the composite membranes for dehydration of ethanol and isopropanol, the outermost surface layer was deposited with PEI, followed by crosslinking. A further improvement in the membrane selectivity was accomplished by substituting the PEI with partially protonated chitosan in the last few polyelectrolyte bilayers during membrane fabrication. It was demonstrated that using interfacially polymerized polyamide membrane as a substrate, polyelectrolyte membranes with less than 8 bilayers could be fabricated for the dehydration of alcohol and diol. This represents a siginificant advancement as a large number of polyelectrolyte bilayers (as many as 60) are often needed. Glutaraldehyde crosslinked polyelectrolyte self-assembled membranes comprising of chitosan and PAA were also prepared for isopropanol/water separation. The resulting membrane showed stable performance with good permeation flux and separation factor. The effects of crosslinking conditions (e.g., concentration and temperature of crosslinking agent, and crosslinking time) on the membrane performance were studied. Alternatively, using PEI as polycation, when anionic PAA was substituted with alginate in the last few polyelectrolyte bilayers during membrane fabrication, stable membranes with a good performance were obtained without the need of chemical crosslinking. The polyethylenimine/alginate self-assembly membranes showed good selectivity and stability for dehydration of ethanol. For instance, a permeation flux of 0.24 kg/(??? h) and a separation factor of 206 were obtained at room temperature at 10 wt% feed water concentration with a membrane comprising of 10 double layers of polyelectrolytes.

碩士<br>嘉南藥理科技大學<br>環境工程與科學系暨研究所<br>98<br>ABSTRACT The purpose of this investigation is to prepare a semi-IPN poly glycidyl methacrylate/polysulfone composite membrane for dehydration of water/ethanol solution by pervaporation. Utilizing semi-IPN technology with suitable dosage of cross linking agent, monomer concentration, radiated dosage, and initiator, the composite membranes were prepared and characterized the physical and chemical properties and their influences on the performance of pervaporation. In the first part of this investigation, the dry method was used to prepare the semi-IPN poly glycidyl methacrylate/polysulfone composite membrane. The effect of the PGMA content in the membranes on the morphology and hydrophilicity were investigated and the influences of the properties changes on the dehydration performance were also concerned by characteristics analysis. It was found that the radiated dosage and monomer concentration significantly dominated the content of PGMA in semi-IPN membranes and the increase in PGMA content also enhanced the water selectivity and swelling properties of composited membranes. Due to the IPN structure in polymer matrix, the selectivity of membranes increased and declined the permeation rate of permeate with increasing the degree of IPN. Thought the increase in monomer concentration enhanced the degree of IPN in the membrane, but the excessive monomer induced a homo-polymerization and lead to a decrease in the PGMA content in composite membranes. This homo-polymer induced the phase separation in the casting solution and further formed the micro-phase separation in the membrane formation. It is concluded that the optimum radiated dosage and monomer concentration in the semi-IPN solution are the key factors to prepare the homogeneous composite membranes. The second part of this investigation is to utilize the ring opening reaction with sulfuric acid to grafting the sulfuric group on the semi-IPN polymer. The sulfuric acid opened the epoxy group of PGMA to form the sulfonated PGMA. It was expected that the sulfuric group significantly enhanced the hydrophilic properties. The increase in the sulfuric group content in the composited membranes preferred the water selective property during the pervaporation and declined the water contact angle on the membrane surface. It is indicated that the hydrophilic properties of the polymer further increased by the sulfonation. The separation performance of pervaporation also showed the significantly improvement for dehydration by the semi-IPN modification on the polysulfone membranes. The third part of this study is to prepare the asymmetric membranes. It was found that the micro phase separation in the casting solution strongly declined the selectivity of IPN membranes. Base on the morphology observations and separation performance analysis, they were indicated that the polymer phase separation could not form a defect free skin layer and this factor dominated the decline of selectivity of composited membranes in the separation process.

碩士<br>嘉南藥理科技大學<br>環境工程與科學系<br>101<br>The purpose of this study is to develop an in-situ interfacial polymerization technology to prepare a high separation performance hollow fiber Thin film composite (TFC) membrane and applied for dehydration of ethanol mixtures by pervaporation. With in-situ interfacial polymerization technology, 1,6-Diaminohexane and m-Phenylenediamine diamine were used as the monomer in water phase and 1,3,5-benzenetricarbonyl chloride was used as the monomer of oil phase to process the interfacial polymerization in phase inverse region of wet membrane formation method. The morphology and skin layer structure of Thin film composite membrane were observed by the E-SEM. FTIR-ATR spectra was used to identify the polyamide structure on the skin layer of hollow fiber. In this investigation, the composition of phase inverse regents and the preparing conditions of hollow fiber, e.g. flow rate of bore liquid, monomer concentration, and structure variation of monomer, were discussed and the effect of above parameters on the dehydration performance were also investigated in this study. It was found that the bore liquid regent composition, n-hexane/ butanol ratio was a key factor to dominate the skin layer structure. The optimum monomer concentration for TFC reaction is necessary for defect free TFC membrane preparation. An over-dosage of monomer concentration in TFC preparation declined the dehydration performance due to the TFC layer separated from the skin layer. IT was also found that the 1.5wt% 1,6-Diaminohexane or 2.0wt% m-Phenylenediamine and 0.5wt% 1,3,5-benzenetricarbonyl chloride were the optimum concentration in the 30/70 (butanol/n-hexane) core liquid in TFC membrane preparation. The high separation performance and stability of TFC composite membranes can be prepared with a dense TFC polyaimde layer on the skin of hollow fiber. The permeation rate is 145.6 g/m2h and separation factor achieved 2835 under an optimum preparation condition with 90% ethanol in feed at 25℃.