METHANOLYSIS AND ETHANOLYSIS OF ANIMAL FATS: A COMPARATIVE STUDY OF THE INFLUENCE OF ALCOHOLS

Biodiesel from animal fats with methanol and ethanol was produced in the presence of sodium methoxide and sodium ethoxide as catalysts. Two samples of pork fats and one natural beef tallow were directly transesterified with a good final product yield: 87.7 86.7 and 86.3% for methanolysis, and 78.4, 82.6 and 82.7% for ethanolysis, respectively. Methyl ester content was also determined, being higher than 96.5 mass% for all the samples prepared. The presence of natural C17:0 in animal fats makes it necessary to correct the method proposed in the standard EN 14103 (2003). Biodiesel density at 15 degrees C of the samples was between 870 and 876 kg/m(3), within the acceptance range of standard EN 14214, and the dynamic viscosity at 40 degrees C of the produced biodiesels was in the range of 4.5 to 5.16 mm(2)/s, also fulfilling requirements of EN 14214 standard. The iodine value is much lower than the superior limit established by EN 14214 standard but oxidation stability (OSI) is lower than the required limit, 6 h, of the standard, which can be attributed to the lack of natural antioxidants in tallows.