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首页> 外文期刊>Energy Conversion & Management >Advances on kinetics and thermodynamics of non-catalytic supercritical methanol transesterification of some vegetable oils to biodiesel
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Advances on kinetics and thermodynamics of non-catalytic supercritical methanol transesterification of some vegetable oils to biodiesel

机译：植物油非催化超临界甲醇酯交换反应动力学及热力学研究进展

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摘要

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 degrees 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.
机译：在本研究中，对蓖麻，麻风树，pongamia，烟草，大豆和霍霍巴油的非催化超临界甲醇酯交换反应对生物柴油生产的动力学和热力学参数进行了评估。实验在83 ml封闭式间歇式反应器中进行，温度不同（250-350摄氏度），反应时间（15-90分钟），并且甲醇/油的最佳摩尔比（荷荷巴油为15：1）蜡油，其余为43：1）。在反应器中达到的压力为10至43MPa。通过使用Levenberg-Marquardt算法将实验数据调整为伪零级，伪第一级和伪第二级动力学方程，使用积分法确定合适的反应顺序。发现伪一阶动力学方程最适合描述所研究植物油的超临界酯交换反应。计算出速率常数和Arrhenius参数，其活化能遵循以下顺序：蓖麻油<麻风树油<烟草油ongamia油<大豆油<霍霍巴蜡油。霍霍巴油和蓖麻油相对于其余植物油的行为很难解释，因为它们分别具有非常不同的结构和脂肪酸组成。但是，对于其余具有相似结构和脂肪酸组成的植物油（麻风树皮，烟草，浮游植物和大豆油）观察到的上述顺序可以归因于油中亚麻酸的含量：含量越高亚麻酸的活化能越高，反应速率越低。最后，热力学研究表明，非催化超临界甲醇酯交换反应本质上是非自发的（负电荷）和吸热的。

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