REPEATED USE OF METHANOL AND SULFURIC ACID TO PRETREAT JATROPHA OIL FOR BIODIESEL PRODUCTION

摘要

Large-scale plantation of jatropha will provide low-cost and reliable feedstock for biodiesel production, but jatropha oil has the tendency to degrade so that it often contains excessive free fatty acid (FFA). In this study, an efficient method was developed by repeated use of the mixture of methanol and sulfuric acid for the pretreatment of jatropha oil with an acid value of 10.4 mg KOH/g. A quadratic polynomial model was established by investigating the effect of water content on the conversion of FFA, while the molar ratio of methanol to FFA was 270:1 and the weight ratio of sulfuric acid to jatropha oil was 1.6%. This model was proved to be valid when the mixture of methanol and sulfuric acid had been used for twenty times. Total sulfuric acid and methanol used for these twenty experiments was 0.21% and 21% respectively, based on the weight of pretreated jatropha oil. Average reaction time of them was 26min; acid values of the pretreated jatropha oil were about 0.6 mg KOH/g, water contents of it were no more than 0.07%. Biodiesel with an ester content of 98.6% was produced through the following alkaline catalyzed biodiesel production process.