Submitted to: ASAE Annual International Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 22, 1999
Publication Date: N/A
Technical Abstract: Biodiesel, an alternative diesel fuel that may be derived from soybean oil, is composed of long-chain saturated and unsaturated fatty acid alkyl esters. When exposed to air and other prooxidizing conditions, biodiesel undergoes degradation. Although ASTM biodiesel guidelines do not specify a minimum induction period for oxidative resistance, extensive oxidation during storage will affect viscosity, acid value, peroxide value, and other parameters included within these guidelines. This work examines the use of pressurized-differential scanning calorimetry (P-DSC) in analyzing the oxidative stability of biodiesel. Methods were developed for determining onset temperature of oxidation for pressures from 2000-5000 kPa and in static (closed system) mode. Methyl soyate samples from five fuel producers were tested. Increasing pressure decreased onset temperature; therefore, 2000 kPa was selected as the optimum pressure for P-DSC analysis of methyl soyate in static mode. Application of this technique indicated significant increases in onset temperature for samples treated with TBHQ and tocopherol antioxidants. P-DSC results were consistent with those from OSI analysis in accordance with AOCS recommended method Cd 12b-92. This work demonstrates that P-DSC is capable of delivering quantitative measurements of oxidation stability of biodiesel in a very short time frame (min) compared to OSI (h).