SYNTHESIS OF BIODIESEL FROM COFFEE GROUNDS BY DIRECT TRANSESTERIFICATION WITH ALCOHOL/CARBON DIOXIDE MIXTURES

THE PRESENT INVENTION RELATES TO A METHOD FOR PRODUCING BIODIESEL (FATTY ACID ALKYL ESTERS) FROM COFFEE GROUNDS BY DIRECT TRANSESTERIFICATION OF THE OIL FROM THE GROUNDS WITH SUPERCRITICAL FLUIDS. IN PARTICULAR, THE INVENTION INVOLVES THE USE OF, INTER ALIA, SUPERCRITICAL METHANOL, PURE OR WITH A CO-SOLVENT, NAMELY CARBON DIOXIDE, AT PRESSURE CONDITIONS UP TO 350 BAR AND TEMPERATURES UP TO 400ºC. THE ALCOHOL AND THE CO-SOLVENT, COMING FROM THE TANKS (1) AND (2), ARE HEATED IN THE HEATING BATHS (3) AND (4), AND PRESSURISED BY THE HIGH PRESSURE PUMPS (5) AND (6). THEY ARE THEN MIXED (7) AND ENTER THE HIGH PRESSURE REACTOR (8), WHICH IS PLACED IN A HIGH TEMPERATURE FURNACE (9). THE PRESSURE IN THE REACTOR (8) IS CONTROLLED BY AN EXPANSION VALVE (10). THE BIODIESEL IS COLLECTED BY PRESSURISATION THROUGH THE OUTLET VALVE (10) INTO COLLECTION VESSELS (11). THE MAIN APPLICATIONS OF BIODIESEL INCLUDE USE AS A FUEL IN COMPRESSION IGNITION ENGINES; LUBRICATING OIL; OR ADDITIVE IN FUEL OIL, BY ITSELF OR BLENDED WITH OTHER COMPONENTS.