Abstract
In this paper, non-catalytic high temperature deacidification process of glycerol rich in acid oil was studied. Through orthogonal experiment, the primary and secondary order of influencing factors was temperature, glycerol dosage and reaction time, and the optimal process conditions were further verified: The ratio of fatty acid to glycerol is 1:1.2, the reaction temperature is 240°C, and the acid value can be reduced to 1.66 mg KOH/g for 2 h. In addition, the activation energy of the reaction was 54.93 kJ/mol by kinetic study. Combined with the K1 value of each reaction, it was confirmed that the temperature rise was conducive to the progress of the reaction. Finally, the high temperature ionization theory of glycerol is put forward, and the mechanism of auto-catalyzed deacidification reaction of glycerol is deduced by using this theory. This theory not only explains this study, but also perfectly explains the slow reaction time of low glycerol dosage.
Highlights
Biodiesel is a kind of green liquid energy synthesized from renewable oil [1]
Esterification of fatty acids and fatty alcohols usually needs to be carried out under the condition of catalyst [18], so how can fatty acids and glycerol react quickly without catalysis? This indicates that the high temperature deacidification of glycerol with fatty acids may be due to the autocatalysis of glycerol
Through orthogonal experiment, it is further verified that glycerol can be used to achieve rapid esterification and acid reduction for acid-rich oil without catalysis
Summary
Biodiesel (fatty acid alkyl ester) is a kind of green liquid energy synthesized from renewable oil [1]. In order to reduce the cost, the use of waste oil or acidified oil has become the best choice [12] [13], which reduces the cost of raw materials, and turns waste into treasure, protecting the environment and food safety (reduce the return of gutter oil to tables) Such oils with high acid value cannot directly undergo base-catalyzed transesterification due to the presence of a large number of free fatty acids, so esterification and acid reduction are often required in advance [14]. The optimal process for deacidification of glycerol was obtained through orthogonal analysis, and the activation energy of the reaction was obtained, and the mechanism was detailed It will have high reference value for theoretical research and practical production
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