Abstract
Biodiesel fuel (BDF) is a cleaner-burning diesel replacement fuel made from renewable sources such as natural oils and fats. An alkali-catalyzed alcoholysis process, to form fatty acid methyl esters (FAME) from vegetable oils, is widely used to produce BDF, however this process requires high costs for purification of by-product and recovery of catalysts. In this study, a new reactor was developed to produce FAME by blowing superheated methanol gas continuously into oils without using any catalysts. High-oleic sunflower oil and methanol were fed into a reactor vessel, and reacted under various reaction conditions. Effects of reaction temperature, methanol feed flow rate, operating pressure, stirring rate, and initial oil volume were investigated. The reaction product inside the reactor (liquid phase) and the one flowing out from the reactor with methanol gas (gas phase) were collected and their composition was analyzed by using thin layer chromatography / flame ionization detection (TLC/FID) and high performance liquid chromatography (HPLC). It has been confirmed that FAME was contained in both the liquid and gas phases. The total production rate of FAME increased with the reaction temperature, while the outflow rate of FAME into the gas phase was maximum at 290°C. Both the total production and the outflow rate increased with the methanol feed flow rate. The total production rate of FAME was maximum at 1.0 MPa, while the outflow rate of FAME was maximum at 0.1 MPa. Increase in initial oil volume and decrease in stirring rate increased both the total production and the outflow rate. As a result, a gas-liquid interface between methanol bubble and surrounding liquid phase appeared to have large effect on the reaction.
