Production of biodiesel by transesterification of Jatropha oil with microwave heating

Biodiesel has attracted attention due to energy crisis and CO₂ issue. Using an efficient processing technology to prepare biodiesel from Jatropha seed oil is a competitive way to produce biodiesel. Biodiesel was obtained by transesterification reaction using KOH catalyst under microwave radiation in this study. Since the side reactions occur when water and free fatty acids (FFA) exist, a pretreatment is needed. The pre-esterification was used to reduce the amount of FFA. The optimum pre-esterification reaction conditions were 70 °C, 12 wt% methanol, 1 wt% sulfuric acid, and 2 h reaction time. To accelerate the reaction rate of transesterification, microwave radiation was used. The optimum reaction conditions in microwave batch reactor were the molar ratio of oil to methanol of 1: 6, 1 wt% KOH, 200 rpm, and 65 °C. The conversion of the oil was 90% after 10 s reaction time. The reaction rate in microwave reactor was much faster than that by the conventional heating method. The penetration length of microwave in Jatropha seed oil was calculated to be 27 cm. A large scale process was developed by using a continuous microwave reactor. This process has high conversion in a very short reaction time under mild reaction conditions.