ENHANCING BIODIESEL PRODUCTION VIA HETEROGENEOUS CATALYSIS TRANSESTERIFICATION BY USING PHYSICAL PROCESSES: MICROWAVE AND ULTRASOUND UTILIZATION

In the biodiesel production, via transesterification, physical methods have been tested to improve efficiency. In this research activity, the microwave have been tested to reduce the reaction time in a continuous process. Moreover, ultrasound utilization has been investigated as effective in order to improve biodiesel synthesis via transesterification process. Experiments have been carried out at bench scale by using soybean oil and methanol (molar ratio alcohol/oil 6:1); as catalyst 1% NaOH or 10% triphosphate potassium were used. For microwave tests, reactants have been injected in a 5.0 m pipe that was inserted in a microwave oven; the product has been recovered outside the oven. Obtained results are very promising. Ultrasound experimental tests were carried out in a batch reactor (500 ml flask) with a condenser, hot bath, magnetic stirrer and/or an ultrasound probe system. As matter of fact, experimental tests carried out by using microwave have pointed out that microwaves can be usefully employed to perform the transesterification of vegetable oils and to reduce reaction time. Moreover, ultrasound seems to be more effective than magnetic stirrer.