Reaction between methanol and commercial seed oils under microwave irradiation

The transformation of triglycerides, contained in a commercial seed oil int o methyl esters, was studied in the presence of microwave irradiation and t he results were compared with those obtained using traditional methods. Thi s reaction is quite rapid using conventional and microwave heating; shorter reaction times were observed under microwaves in the presence of a variety of catalysts and the reaction was found practically complete in less than 2 minutes in most cases. Longer irradiation times in the absence of catalys ts yielded increasing amounts of free acids, as detected by gas chromatogra phy. The catalytic behavior of sodium methylate, sodium hydroxide, sodium c arbonate, sulfuric acid, benzensulfonic acid and boron carbide was briefly discussed. The carbide provides an effective catalysis of the trans-esterif ication in the presence of microwaves, without leaving traces of acidic or basic by-products. A lab scale plant for a continuous transesterification p rocess was also described.