Transesterification of Camelina Sativa Oil using Supercritical and Subcritical Methanol with Cosolvents

Transesterification of camelina oil using supercritical methanol with hexane as a cosolvent and subcritical methanol along with potassium hydroxide as a cosolvent/catalyst was investigated to study the methyl ester conversion process. It was found that cosolvents play a vital role in reducing the severity of critical operational parameters and maximize the biodiesel yield. The experimental results from the process parametric evaluation studies show that supercritical methanol with hexane as a cosolvent could produce maximum methyl esters using the following conditions: reaction temperature of 290 °C, methanol to oil ratio of 45, and reaction time of 40 min. For subcritical methanol condition with 0.3 wt % potassium hydroxide as a cosolvent, methyl ester yields of +90% are obtained using the following conditions: reaction temperature of 180 °C, methanol to oil molar ratio of 30, and a reaction time of 20 min. Process variables critical to the methyl ester conversion are determined to be cosolvent ratio, molar ratio of alcohol to oil, and reaction time. Fuel properties of the biodiesel produced are comparable to those of regular diesel and conform to the ASTM standards.