Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract only
Publication Acceptance Date: 4/28/2000
Publication Date: 4/28/2000
Citation: DUNN, R.O. OXIDATION KINETICS OF SOYBEAN OIL FATTY ACID METHYL ESTERS (BIODIESEL). ANNUAL MEETING AND EXPO OF THE AMERICAN OIL CHEMISTS' SOCIETY. 2000. Interpretive Summary:
Technical Abstract: Resistance to oxidative degradation during storage is an increasingly important issue to the successful development of alternative fuels for combustion in compression ignition (diesel) engines. Traditional methods such as the American Society for Testing and Materials (ASTM) method D2274 (Oxidation Stability of Distillate Fuel) for liquid petroleum products or the American Oil Chemists' Society (AOCS) method Cd 12b-92 (Oil Stability Index-OSI) generally require accelerated conditions such as elevated temperatures. It is known that elevated temperatures may modify reaction pathways during oxidation of fatty derivatives. These modifications can compromise or prevent realistic prediction of oxidative stabilities under "real world" (lower) storage temperatures. This work examines the effects of temperature on the oxidation reaction kinetics by measurement of activation energies (Ea) for biodiesel (methyl soyate). Results from pressurized-differential scanning calorimetry (P-DSC) scans at 2000 kPa and under non-isothermal conditions were analyzed by varying ramp rate (1.0-20.0C/min). Methyl soyate samples from four independent sources were used to determine effects of increasing temperature on oxidative stabilities predicted by P-DSC relative to those from modified-OSI analyses. Finally, maximum temperature limits for predicting oxidative stabilities that adequately reflect real world storage conditions are established for methods that employ accelerated conditions.