Plasma-assisted catalytic route for transesterification reactions at room temperature

Abstract Biodiesel has been currently obtained from the transesterification reaction of vegetable oils, including residual oil as waste cooking oil (WCO), and usually in the presence of a catalyst. Advanced methods, such as plasma, have been studied to produce biodiesel since it allows for a milder conditions, mainly by decreasing both reaction temperature and time of production. The objective of this work is to investigate the plasma-assisted catalytic route for the monoesters transesterification reactions. H 3 PMo and NaOCH 3 were used as acid and basic catalysts, respectively. The batch plasma reactor used in this work was composed by a borosilicate glass tube with concentric electrodes, in which ethyl acetate and methanol were feed. The effects of the plasma associated with both acid and basic catalysts were investigated in the ambient temperature and atmospheric pressure. In general, plasma-assisted catalytic routes showed higher ethyl acetate conversions, when compared to the routes with no plasma under the same experimental conditions. For example, the ethyl acetate conversion increased from 38% to 77% when plasma is assisting the acid catalytic reaction during 90 min. This level of conversion is comparable with values achieved for the reaction in the presence of basic catalyst without plasma, although in a shorter time of reaction. The synergistic effect between the plasma and the catalysts provided an increase in the reaction rate constants, and high ethyl acetate conversions in shorter reaction times. These findings indicate the plasma-assisted catalyst routes as promising for the production of biodiesel under room temperature, especially for the production from waste oils, which requires the use of acid catalysts and usually under extreme conditions.