Browsing by Subject "Transesterification"

Now showing 1 - 3 of 3
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    Advances on kinetics and thermodynamics of non-catalytic supercritical methanol transesterification of some vegetable oils to biodiesel
    (Elsevier, 2018-07-29) Andreo Martínez, Pedro; García Martínez, Nuria; Durán del Amor, María del Mar; Quesada Medina, Joaquín; Ingeniería Química
    Kinetic and thermodynamic parameters of the non-catalytic supercritical methanol transesterification reaction of castor, jatropha, pongamia, tobacco, soybean and jojoba oils to biodiesel production were evaluated in the present study. The experiments were conducted in an 83 ml closed batch reactor at different temperatures (250–350 °C) and reaction times (15–90 min), and at optimal methanol-to-oil molar ratios (15:1 in the case of jojoba wax-oil and 43:1 for the rest of the oils). The pressure reached in the reactor ranged from 10 to 43 MPa. Integral method was used to determine appropriated reaction orders by an adjustment of experimental data to pseudo-zero, pseudo-first and pseudo-second order kinetic equations using Levenberg-Marquardt algorithm. Pseudo-first-order kinetic equation was found to be the most appropriate to describe the supercritical transesterification reaction of the vegetable oils studied. Rate constants and Arrhenius parameters were calculated, the activation energy followed the sequence: castor oil < jatropha oil < tobacco oil < pongamia oil < soybean oil < jojoba wax-oil. It is difficult to explain the behavior of jojoba and castor oils in relation to that of the rest of vegetable oils because they have a very different structure and fatty acid composition, respectively. However, the aforementioned sequence observed for the rest of vegetable oils (jatropha, tobacco, pongamia and soybean oils), which have a similar structure and fatty acid composition, can be attributed to the content of linolenic acid in the oil: the higher the content of linolenic acid, the higher the activation energy and the lower the reaction rate. Finally, thermodynamic study showed that the non-catalytic supercritical methanol transesterification reaction is non-spontaneous (endergonic) and endothermic in nature.
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    Approach to biodiesel production from microalgae under supercritical conditions by the PRISMA method
    (Elsevier, 2019) Ortiz Martínez, Víctor Manuel; Andreo Martínez, Pedro; García Martínez, Nuria; Pérez de los Ríos, Antonia; Hernández Fernández, Francisco José; Quesada Medina, Joaquín; Química Agrícola, Geología y Edafología
    Increasing energy demands lead to the search for sustainable biofuels such as biodiesel from renewable sources such as algal biomass. Specially, microalgae have become increasingly popular as biodiesel feedstock due to their fast-growing rates and relatively high level of lipids. The non-catalytic transesterification reaction of microalgae oil under supercritical conditions in the presence of alcohols is an efficient process for biodiesel production and can overcome some of the limitations posed by subcritical catalytic transesterification. Two-step and one-step processes have been reported for this purpose, in the last case with extraction and transesterification stages being performed simultaneously. This works offer a systematic review using the PRISMA methodology analyzing the status of this research topic and identifying future research strategies. With this work, PRISMA methodology is applied for the first time within technological engineering fields. Moreover, this is the first specific overview on the production of biodiesel from microalgae under supercritical conditions. Several key factors such as microalgae type and operation variables including extraction oil, temperature and reaction time, pressure, water content in biomass, alcohol excess and final biodiesel properties are discussed. Further efforts need to be done in order to study the continuous biodiesel production by the development of integrated processes that involve both microalgae cultivation and biodiesel production.
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    Biocatalytic transesterification of salmon oil in ionic liquid media to obtain concentrates of omega-3 polyunsaturated fatty acids
    (Springer, 2024-06) Fuster, M.G.; Moulefera, I.; García Montalbán, Mercedes; Víllora, Gloria; Ingeniería Química
    In this study, a biphasic system combining oil and ionic liquid was utilized for lipase-catalyzed transesterifcation of salmon oil and alcohol to concentrate n-3 PUFAs, notably EPA and DHA. Various process variables, such as enzyme type, quantity, alcohol chain length, temperature, reactant proportions, and ionic liquid selection, were systematically assessed to optimize the process and enhance the yield of these valuable fatty acids. It was found that the Novozym 435 and Lipolase 100L Type EX emerged as the most efective enzymes. The impact of varying alcohol chain lengths (C1–C8) was examined, revealing that the Novozym 435 enzyme displayed its peak synthetic activity with 2-propanol. The results revealed a substantial increase in the overall activity during the transesterifcation reaction when employing ILs featuring hydrophobic cations and anions with low nucleophilicity. Specifcally, the [omim+][NTf2 −] ionic liquid exhibited the highest level of activity. This research holds promise for more efciently and sustainably obtaining concentrated n-3 PUFAs from fsh oil while reducing environmental impact relative to other existing concentration processes.