Preparation of biodiesel using supercritical fluid techniques

New methods are explored for producing fatty acid methyl ester via the reaction of vegetable oils or fats with supercritical methanol. The supercritical reaction techniques are summarized and compared with the traditional chemical methods. The supercritical method requires shorter reaction time (from 1-8 h to 3-4 min) and simpler purification procedure because of no catalyst existing in the reaction at all.