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- Separation of nadolol racemates by high pH reversed-phase simulated moving bed chromatographyPublication . Arafah, Rami; Ribeiro, António E.; Rodrigues, Alírio; Pais, Luís S.Nadolol is a pharmaceutical drug marketed as a mixture of four stereoisomers, used to treat cardiovascular diseases. This drug is a mixture of two pairs of racemates, therefore, its complete separation represents a challenging task. Recently, our research group reported the pseudo-binary separation of nadolol by SMB chromatography using both coated Chiralpak AD and Chiralpak IA immobilized chiral stationary phases. In this work, we present an alternative strategy, implementing a first achiral separation step, by using C18 columns to perform the separation of the two pairs of nadolol racemates under reversed-phase mode. Extensive experimental and simulation results will be presented including solvent screening, measurement of equilibrium and kinetic data, and both fixed-bed and SMB preparative separations. Extensive experimental and simulation results will be presented, including solvent screening, measurement of equilibrium adsorption isotherms, breakthrough measurements, and SMB (FlexSMB-LSRE unit) experimental preparative separation using C18 columns.
- Separation of profens by chiral liquid chromatography: preliminary studiesPublication . Ribeiro, António E.; Pais, Luís S.; Rodrigues, Alírio
- Preparative separation of nadolol racemates using reversed-phase liquid chromatographyPublication . Arafah, Rami; Ribeiro, António E.; Rodrigues, Alírio; Pais, Luís S.Nadolol is a nonselective beta-adrenergic receptor antagonist ( -blocker) pharmaceutical drug, widely used in the treatment of cardiovascular diseases, such as hypertension, ischemic heart disease (angina pectoris), congestive heart failure, and certain arrhythmias. Its chemical structure has three stereogenic centers which allows for eight possible stereoisomers. However, the two hydroxyl substituents on the cyclohexane ring are fixed in the cis-configuration, which precludes four stereoisomers; in fact, two pairs of enantiomers. Nadolol is presently marketed as an equal mixture of the four stereoisomers, designated as the diastereoisomers, There are still few published works concerning the separation of nadolol stereoisomers. Most of these works refer the resolution at analytical scale and few refer the separation at preparative scale using the simulated moving bed (SMB) technology [2-4]. This technology is generally based on the use of chiral adsorbents which must have enough recognition for all the chiral species.
- Optimization of simulated moving bed processes for multicomponent chiral separationsPublication . Ribeiro, António E.; Rodrigues, Alírio; Pais, Luís S.This work will present and discuss the experimental and simulation results obtained for the analytical and preparative separation of the four stereoisomers of nadolol, an important example of a non-selective beta-adrenergic receptor antagonist (beta-blocker) pharmaceutical drug, widely used in the treatment of cardiovascular system diseases, such as hypertension, ischemic heart disease (angina pectoris), congestive heart failure and certain arrhythmias. The main focus will be placed in the selection of the proper CSP/solvent combination for SMB operation. Experimental results will be presented using Chiralpak AD and Chiralpak IA CSP (Daicel, Europe) and different mixtures of alkanes, alcohols and acetonitrile as solvent.
- ValorNatural®: a project and a platformPublication . Ferreira, Isabel C.F.R.; Barreiro, M.F.; Pais, Luís S.The use of synthetic additives (preservatives and colourants), in the food and cosmetic industries, is a current major concern, from both the human health and environmental points of view. Although considered a promising safer alternative, the use of natural additives still faces some drawbacks and limitations. A specific problem is the difficulty to find abundant natural sources, preferably based on sustainable cultivation, and adequate green and environmental friendly extraction technologies. Additionally, huge volumes of residues from the forestry and food industries, currently considered as lowvalue by‐products, are underexploited in applications such as energy production and/or as compost. This context is emphasized also by an increasing consumer’ awareness and interest in “chemopreventive nutrition”, being highly receptive to functional foods with specific health‐promoting components (nutraceuticals). The challenge to full exploit the potential of these high added value ingredients derived from natural sources, including mountain matrices, requires the development of integrated multidisciplinary solutions that will consider issues from cultivation to extraction, separation and stabilization processes. All the implemented strategies must be supported by reliable and expedite chemical and biological analysis and methodologies for final products validation. Furthermore, the economy of mountain regions, typically with high levels of diversity in natural matrices (e.g., mushrooms and plants), will strongly benefit from the development of new products based on natural ingredients. Herein, it will be presented ValorNaturalÒ, which is a project aiming at developing and demonstrating extraction and separation methodologies, suitable to be scalable for industrial use, for the production of functional ingredients (preserving, flavouring, colouring and bio‐active agents) for the food and cosmetic industries, from sustainable natural sources. Case studies developed by the research group will be discussed. Furthermore, a platform to support companies working in this field, under development in the Brigantia EcoPark (The Science and Technology Park of Bragança), will be also presented.
- Simulated moving bed technology: principles, design and process applicationsPublication . Rodrigues, Alírio; Pereira, Carla S.M.; Minceva, Mirjana; Pais, Luís S.; Ribeiro, Ana Mafalda; Ribeiro, António E.; Silva, Marta S.P.; Graça, Nuno S.; Santos, João CarlosThis book is a result of more than 20 years research on Simulated Moving Bed (SMB) processes at the Laboratory of Separation and Reaction Engineering (LSRE) and teaching at undergraduate level at the Department of Chemical Engineering (ChE), Faculty of Engineering of University of Porto (FEUP), graduate courses at Technical University (TU) Eindhoven and TU Delft, and an in-house course for Companhia Petroquímica do Nordeste (COPENE) (now Brazchem) and Petrogal. I graduated in ChE at University of Porto (U. Porto) in 1968, having never heard about SMB during those years. I heard about PAREX (and other Sorbex processes) in Nancy during my thesis work (1970e1973) with P. Le Goff and D. Tondeur. I found the idea of SMBdturning fixed-bed operation into continuous processesda bright one. After my African endeavors (teaching at the University of Luanda in Angola and military service there), I landed again at FEUP in August 1976 as an Assistant Professor. An optional course on Petroleum Refining for Chemical Engineering (ChE) was offered to undergraduate students given by Lopes Vaz from Petrogal. He was working in Lisbon but coming to Porto every Saturday morning to teach that course. I asked permission to attend. Lopes Vaz was a very good lecturer. It was an opportunity to learn details of the PAREX unit existing in the aromatics plant in the Refinery of Petrogal in Matosinhos. After the Revolution of April 1974, FEUP began offering evening courses allowing people with a “technical engineer” degree to get a diploma of Chemical Engineering (ChE) from U. Porto by following an additional two-year program. One of my students at that time was Soares Mota working for Petrogal and taking care of the PAREX unit. In 1978, I organized my first NATO Advanced Study Institute (ASI) on “Percolation Processes: Theory and Applications.” One of the lecturers I invited was D. Broughton from UOP (one of the inventors of SMB). He could not come, but instead A. De Rosset lectured in that ASI. I had the opportunity to travel to Des Plaines (Illinois) to visit Universal Oil Products (UOP) and meet D. Broughton at lunch. It was a business trip that I remember because I met some leaders in the Adsorption area (Vermeulen and Klein from University of California (UC) Berkeley, Wankat from Purdue, etc.). In 1984, an opportunity arose for funding to work on PAREX and ISOMAR processes when Veiga Sim~ao was Minister of Industry and Energy (MIE). He launched some Contracts for Industrial Development (CDIs) and I took the initiative of encouraging several engineers from Petrogal to join that initiative. The funding was supposed to be equivalent to 100,000 euro, but when the MIE came to Porto for the signing ceremony it seems he decided not to sign that CDI. I just found those documents while cleaning my office.
- Separation of enantiomers of a chiral epoxide by simulated moving bed chromatographyPublication . Pais, Luís S.; Loureiro, José M.; Rodrigues, Alírio
- Thermal effects on the synthesis of 1,1-dibutoxyethane in a fixed-bed adsorptive reactorPublication . Graça, Nuno S.; Pais, Luís S.; Silva, Viviana M.T.M.; Rodrigues, AlírioThe effects of temperature on the synthesis of 1,1-dibutoxyethane (DBE) in a fixedbed adsorptive reactor were studied by performing both adsorption/desorption and reaction/regeneration experiments at 15 and 35 °C. The Langmuir-type isotherm parameters at 15 and 35 °C were obtained from the adsorption/desorption experiments. The reaction/regeneration experiments showed an increase in both conversion and productivity with increasing temperature. Isothermal and nonisothermal mathematical models were used to simulate the reactor operation with different Damköhler numbers. The simulated results suggest that the reactor productivity can be improved by using the adiabatic operation mode on the fixedbed adsorptive reactor, obtaining a productivity for DBE of 71.8 mol kg–1h–1.
- Simulated moving bed adsorptive reactor: modeling, simulation and operation of a SMBR pilot plantPublication . Pais, Luís S.; Leão, C.P.; Loureiro, José M.; Santos, M.; Rodrigues, AlírioAdsorptive separations are becoming increasingly important in chemical industry. The simulated moving bed technology (SMB) developed by UOP has been used for various separations, namely the recovery of p-xylene from a mixture of C8 isomers (PAREX) or the separation Glucose/Fructose in the SAREX process. More recently flue technology has been introduced in the area of tine chemicals and pharmaceuticals by leading companies SEPAREX and UOP
- Teaching Crossroads: 15th and 16th IPB Erasmus WeeksPublication . Silva, Elisabete Mendes (Ed.); Pais, Clarisse (Ed.); Pais, Luís S. (Ed.)Education has undergone many changes and adaptations due to the uncanny times we live in caused by the pandemic that spread to the world in the first months of 2020. Speaking and writing about the effects of Covid-19 in all areas of life has become a common practice if one thinks of the numerous reports and news put forth by the media about the impact of the virus on people, on the economy, on work and school. No one knows for sure the consequences of Coronavirus. We can only focus and reflect on its short-term effects. Apart from realising that Covid-19 has taken its toll on people, it has forced us to readjust our lives in an unforeseeable way. Working and studying from home became a common practice of life put on hold. Lockdowns, enforced differently by the governments, have tried to bring the pandemic under control to drop transmission rates. In addition, they have dictated (the temporary) course of education and business. Online classes, online meetings, via Zoom or the Microsoft platform Teams, for instance, have given way to a virtual environment to which schools and universities had to adhere. To avoid letting ourselves to be under the sway of Covid-19, we have to carry on with our so-called normal lives, under all accepted constraints, and try to deal with this new situation the best we can. That means that one has to continue teaching, learning and doing research in the search for knowledge, new challenges to unravel less explored fields, and, ultimately, to find a balance between life and work. Starting this preface with the mention of the pandemic was neither innocent nor purposeless. As teachers and researchers, we felt we had to convey a message to all the people involved in the field of education and research. We must resolutely not fear the virus and fight it by doing what we know best. Despite the need to abide by safety rules, we have to continue working. Regarding education, we can already draw some conclusions about the effects of the pandemic throughout these last ten months. Schools and universities have made all the efforts to overcome the constraints caused by Covid-19, facilitating the work of teachers/lecturers, educators, and researchers by fostering collaborative work and technology-enhanced learning. If, on the one hand, many complained about a myriad of negative aspects, namely the reduction of class interaction, technological devices and network problems, on the other, some bravely embraced the idea of going online, despite all the obstacles they would encounter. Overall, everyone adapted and continued working, upholding their beliefs in democratic education. Conferences have also been postponed, cancelled, or transferred to an online context. The Erasmus Week, which was to be held at the IPB in May this year, was regretfully cancelled. Teaching Crossroads was not put off by the virus. It hasn’t stopped the publication process since May last year. As such, we are pleased to have this year’s edition ready, comprising some of the works presented during the 15th and 16th IPB Erasmus Weeks. Finally, we would like to thank the authors who kindly sent us their works to be published, undergoing a thorough review process. Consequently, our last word of appraisal goes to the reviewers who helped us to keep the quality level we aim to maintain. We do hope that both students and teachers enjoy reading the texts published in this number, in the sense they find common teaching intersections that will benefit them throughout the teaching-learning process.