Interesterificação supercrítica do óleo de gergelim (Sesamum indicum L.) com acetato de metila e ácido acético

Abstract

Biodiesel has established itself as a promising source of renewable energy and substitute for oil diesel due to its high energy power, because it is biodegradable and for making a "clean burn". The interesterification with methyl acetate is a technique that has the advantage of producing, in addition to the methyl esters (biodiesel), the Triacetin (product of great market value). The supercritical technology enables the production of biodiesel without the presence of catalysts, eliminating the need for further purification processes. Sesame (Sesamum indicum L.) is one of the oldest oleaginous known to mankind. Due to the high oil content in its seeds, the sesame has become a possibility for the production of biodiesel. Thus, this work investigated the production of biodiesel through the interesterification reaction of sesame oil with methyl acetate under supercritical conditions. A continuous tubular reactor was used under conditions of temperature and pressure of 325-375 °C and 15-20 MPa, respectively, in residence time between 15-55 min, with a molar ratio oil/acetate of 1:40. Pareto analysis showed that temperature was most significant parameter for the yield. A maximum yield in methyl esters of 31.91% was been achieved at 375 °C, 20 MPa in 15 min. Moreover, it was possible to perceive that the addition of 20% (in relation to the oil mass) of a solution of acetic acid at a concentration of 26% in mass, provided an increase in yield under mild temperature condition: 49.81% at 325 °C and 15 MPa in 55 min. With Pareto analysis, in this case, it was concluded that residence time was a significant parameter, however, the combined effect between temperature and residence time was the most relevant for the esters yield.