Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7157801 | Energy Conversion and Management | 2018 | 10 Pages |
Abstract
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 83â¯ml closed batch reactor at different temperatures (250-350â¯Â°C) and reaction times (15-90â¯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 43â¯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 oilâ¯<â¯jatropha oilâ¯<â¯tobacco oilâ¯<â¯pongamia oilâ¯<â¯soybean oilâ¯<â¯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.
Related Topics
Physical Sciences and Engineering
Energy
Energy (General)
Authors
Pedro Andreo-MartÃnez, Nuria GarcÃa-MartÃnez, MarÃa del Mar Durán-del-Amor, JoaquÃn Quesada-Medina,