Process Intensification for the Green Solvent Ethyl Lactate Production Based on Simulated Moving Bed and Pervaporation Membrane Reactors
Total Page：16
File Type：pdf, Size：1020Kb
Process Intensification for the Green Solvent Ethyl Lactate Production based on Simulated Moving Bed and Pervaporation Membrane Reactors A Dissertation Presented to the Faculdade de Engenharia da Universidade do Porto for the degree of PhD in Chemical and Biological Engineering by Carla Sofia Marques Pereira Supervised by Professor Alírio Egídio Rodrigues and Dr. Viviana Manuela Tenedório Matos da Silva Laboratory of Separation and Reaction Engineering, Associate Laboratory LSRE/LCM Department of Chemical Engineering, Faculty of Engineering, University of Porto October 2009 FEUP-LSRE/LCM - Universidade do Porto © Carla Sofia Marques Pereira, 2009 All rights reserved Acknowledgements First of all, I want to thank my supervisors, Professor Alírio Rodrigues and Dr Viviana Silva. Professor Alírio, thank you for all the friendship, constant support and for always challenging me to reach higher goals within my work. Dr. Viviana, I want to thank you for all the encouragement, motivation, constant support, for all the long discussions and great ideas that make me go further and further within my work, and, also, for being a truly and special friend. I am very grateful to Professor Simão Pinho, for the friendship and all the support in the framework of the project “POCI/EQU/61580/2004” and to Professor Madalena Dias for the support whenever needed. To all my LSRE colleagues, especially Israel Pedruzzi, Pedro Sá Gomes, Michael Zabka, João Santos, Miguel Granato, João Pedro Lopes, Alexandre Ferreira and Nuno Lourenço for the friendship, collaboration, and support whenever I needed. To my primary school teacher, Professor João Aveiro, for always believing in me and keeping me motivated along the years. To Fundação para a Ciência e Tecnologia, for the financial support (Research Fellowship: SFRH / BD / 23724 / 2005). To Sofia Rodrigues, Marta Abrantes, Fátima Mota, Miguel Teixeira and Nuno Garrido for all the great moments spent after work!!! Last, but not least, I would deeply like to thank my family and friends, for all giving love, support and trust, especially to my grandmother, Dulcelina, that will always stay in my heart. To my parents and sisters “Green chemistry represents the pillars that hold up our sustainable future. It is imperative to teach the value of green chemistry to tomorrow’s chemists.” Daryle Busch, President of the American Chemical Society (June 26, 2000) Resumo O principal objectivo deste trabalho foi o desenvolvimento de um novo processo eficiente para a produção do solvente verde, lactato de etilo, através da reacção de esterificação entre etanol e ácido láctico, utilizando tecnologias híbridas de reacção/separação baseadas em reactores de leito móvel simulado e processos de membranas por pervaporação. De forma a atingir a meta proposta, foram abordados os seguintes temas: Aquisição de dados fundamentais: A resina de permuta iónica, Amberlyst 15-wet, foi avaliada tanto como catalisador para a reacção de esterificação, como adsorvente selectivo para a água. Os dados cinéticos e de equilíbrio da reacção foram medidos, na gama de temperaturas 50ºC-90ºC, e usados para a determinação da constante de equilíbrio e da lei cinética da reacção como função da temperatura, baseadas em actividades descritas pelo modelo UNIQUAC. Os dados de adsorção foram também medidos, a 20ºC e a 50ºC, e ajustados a uma isotérmica de Langmuir multicomponente, tendo-se assumido uma capacidade volumétrica da monocamada igual para todas as espécies, reduzindo o número de parâmetros de ajuste de 8 para 5, para cada temperatura. Membranas comerciais hidrófilas da Pervatech foram avaliadas para a desidratação do etanol, ácido láctico e lactato de etilo, por pervaporação. As permeâncias de todas as espécies foram determinadas em função da composição e temperatura na gama 48ºC-72ºC. Intensificação de processo: Modelos matemáticos, considerando resistências internas e externas à transferência de massa e velocidade variável devido à mudança das propriedades da mistura multicomponente, foram desenvolvidos para reactores cromatográficos — reactores de leito fixo e de leito móvel simulado, SMBR — e validados pelos dados experimentais. O modelo matemático do reactor de membranas por pervaporação, PVMR, considera, adicionalmente, a permeação através da membrana, os efeitos de polarização por concentração e temperatura e operação não isotérmica. A avaliação teórica do comportamento da unidade SMBR foi realizada para analisar o efeito da configuração, da composição da alimentação e tempo de comutação nas regiões de separação/reacção e/ou no desempenho do processo nos pontos operacionais óptimos. O desempenho do PVMR foi avaliado para operação isotérmica e não isotérmica, e foram determinadas condições apropriadas para a maximização quer da conversão do ácido láctico quer da pureza do lactato de etilo. Finalmente, uma nova tecnologia foi desenvolvida e submetida a registo de patente, o reactor de membranas de leito móvel simulado, PermSMBR, o qual integra membranas selectivas dentro das colunas do SMBR. Abstract The main objective of this work was the development of a new efficient process to produce the green solvent ethyl lactate from the esterification reaction between ethanol and lactic acid by using hybrid reaction/separation technologies based on simulated moving bed reactors and pervaporation membrane processes. To accomplish this target, the following topics were addressed: Basic data acquisition: The acidic ion exchange resin Amberlyst 15-wet was evaluated as both catalyst for esterification and selective adsorbent for water. Equilibrium and kinetic data were measured in the temperature range 50-90ºC, and used to obtain the equilibrium constant and kinetic law as function of temperature, which are based on liquid activities described by the UNIQUAC model. Adsorption data was also obtained and fitted to a multi-component Langmuir isotherm assuming a constant monolayer capacity in terms of volume for all species, reducing the adjustable parameters from 8 to 5, for each temperature. Pervatech hydrophilic commercial membranes were evaluated for the dehydration of ethanol, lactic acid and ethyl lactate, by pervaporation. The permeances of all species were determined as function of composition and temperature in the range 48-72ºC. Process intensification: Mathematical models, considering external and internal mass-transfer resistances and velocity variations due to the change of multi-component mixture properties, were developed for chromatographic reactors — fixed bed and simulated moving bed reactor, SMBR — and validated by experimental data. The pervaporation membrane reactor, PVMR, model also takes into account, the permeation through the membrane, concentration and temperature polarization effects, and non-isothermal operation. The theoretical assessment of the SMBR unit behaviour was performed to analyse the effect of SMBR configuration, feed composition and switching time on the reactive/separation regions and/or on the process performance at the optimal operating points. The performance of the PVMR was evaluated for isothermal and non- isothermal operation, and suitable conditions for maximization of both lactic acid conversions and ethyl lactate purity were examined. Finally, a new technology was developed and submitted to patent registration, the simulated moving bed membrane reactor, PermSMBR, which integrates perm-selective membranes inside the SMBR columns. Zusammenfassung Ziel dieser Arbeit war es einen völlig neuartigen und effizienten Prozess für die Produktion von “Grünem Lösungsmittel” und Ethyl-Lakton, mittels der Verästerung aus Ethanol und Milchsäure über die Hybrid-Technologie, zu entwickeln. Die Reaktion/Trennung basiert auf simulierten Fliessbettreaktoren und Membranprozessen mittels Pervaporization. Um diese Zielsetzung zu erreichen, wurden folgende Themen diskutiert: Folgende wichtige Daten wurden gesammelt: Für den Ionen-Austausch wurde das Harz, Amberlyst 15-wet, genutzt. Es wurde sowohl als Katalysator für die Reaktivverästherung, wie auch als selektiver Adsorbent für Wasser ausgewertet. Die Kinetischen- und chemischen Gleichgewichtsdaten wurden zwischen 50ºC und 90ºC gemessen. Als Vorlage für die Bestimmung der chemischen Gleichgewichtskonstante wie auch der Kinetik als Funktion der Temperatur, wurde das UNIQUAC Model genutzt. Die Adsorptionsdaten wurden zwischen 20ºC und 50ºC gemessen, und entsprechend einer Langmuir-Isotherme für Multikomponenten angeglichen, wobei eine gleich grosse Volumenkapazität der Monoschicht für alle Spezies angenommen wurde. Die Anzahl der zu justierenden Parameter wurde hierbei für jede Temperatur von 8 auf 5 reduziert. Kommerzielle hydrophile Membranen der Firma Pervatech wurden für die Dehydratisierung von Ethanol, Milchsäure und Ethyllakton mittels Permeation ausgewertet. Die Permeation aller Spezies wurde als Funktion der Zusammensetzung und Temperatur, zwischen 48ºC und 72ºC ermittelt. Intensivierung des Prozesses: Es wurden mathematische Modelle für chromatographische Reaktoren entwickelt (Modelierte Festbett- und Fliessbettreaktoren SMBR) und experimentell ausgewärtet, unter Berücksichtigung des internen und externen Massenaustausches, sowie der variablen Geschwindigkeiten. Es herrschen unterschiedlichen Vermischungseigenschaften der Multikomponenten. Das mathematische Modell der Pervaporationsmembrane (PVMR) berücksichtigt gleichfalls die folgenden Effekte: Polarization aufgrund von Temperatur- und Konzentrationsgradienten sowie nicht-isotherme Reaktionsführung. Das theoretische Verhalten