Biodiesel Production from Supercritical Ethanolysis of Soybean Oil

Abstract

The study of biodiesel production in supercritical media is of interest because compared with conventional technologies it does not need catalysts and, therefore, no negative effects are noticed due to the presence of water. In this context, the present work studied the conversion of soybean oil into biodiesel through a transesterification reaction without catalyst with supercritical ethanol in a batch reactor. The reaction time was 15 minutes, and the initial alcohol: oil molar ratio was 39:1. The reactions were carried out in the temperature range of 260 to 300 °C and pressure over 100 bar. The conversion was determined with three different analyses: refractive index, density and dynamic viscosity. All three equipments used to analyze the conversion were calibrated with a soybean biodiesel with purity of 98 %. The results show significant conversion of oil into biodiesel in the temperature of 300 °C. The production of biodiesel decreases as the temperature drops and for the temperature of 260 °C the conversion is negligible. As an attempt to improve the conversion at 260 °C CO2 was added as a co-solvent to the system in a mass ratio of 0.05:1, 0.1:1 and 0.22:1 (CO2:alcohol). The results show that the presence of CO2 did not improved conversion at temperature of 260 °C.