An entirely renewable biofuel production from used palm oil with supercritical ethanol at low molar ratio

Abstract

The biofuel production from used palm oil (UPO) using supercritical ethanol (SCE) at low molar ratio was investigated in order to produce an entirely renewable fuel. The effects of the reaction time and ethanol to oil molar ratio were considered from 0.5 to 10 min and 6:1 to 18:1, respectively. The optimal parameters were 10 min and a 12:1 molar ratio, representing a remarkable reduction from 42:1 for the conventional SCE process. Because of the high operating temperature, the triglycerides conversion rate reached 99%, and the glycerides content met the international specification for biodiesel. However, an ester content of 70% was obtained at optimal conditions. The side reaction between glycerol and ethanol demonstrated a positive effect in increasing fuel yield by 8.15%. The product can be considered an alternative biofuel instead of biodiesel.