Abstract:
The main purpose of this work is to study the effect of co-solvents on biodiesel production from crude palm oil and olein palm oil in supercritical methanol in batch process. The experimental conditions were; molar ratio of vegetable oil to methanol 1:24-1:42, molar ratio of vegetable oil to co-solvent 1:6-1:24, reaction temperature of 280-350 ℃, reaction time of 10-30 minutes and gauge pressure of 19-25 MPa. Optimization of transesterification process was carried out with respect to methyl ester content by 2ᵏ factorial design. It was found that THF had no significant effect on methyl ester content, while hexane improved methyl ester content and CO₂ could not reduce reaction temperature, pressure and molar ratio of vegetable oil to methanol. From the experimental results, the highest methyl ester content was obtained from the following conditions; molar ratio of vegetable oil to methanol 1:42, reaction temperature of 350 ℃, reaction time of 20 minutes and gauge pressure of 25 MPa. Fuel properties of methyl ester produced at optimum condition were found to meet Thailand specification of biodiesel.