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Storage Stability of 50% Biodiesel Blends and Neat Biodiesel Produced in North America

Technical Report ·
DOI:https://doi.org/10.2172/3013240· OSTI ID:3013240

This study investigated aging of two petroleum diesel, seven B100, three B20 blends, and 14 B50 blends representing the full range of fuels in the North American market for 12-weeks at 43 degrees Celsius under the ASTM D4625 accelerated aging protocol. Twelve-weeks under D4625 aging represents approximately 12 months of storage time in clean, dry conditions. Samples were taken every two weeks for measurement of Rancimat induction period (IP), peroxide content, and TAN; and total insoluble were measured at the end of the 12-week test. The petroleum diesel samples showed no evidence of oxidation over the 12-week test. B100 samples slowly oxidized over the 12-week test to have reduced IP, below 2 h for the least stable samples. The three mid-range stability samples (initial IP 5-6 h) showed increased levels of peroxide but did not enter exponential growth (remained in Phase 1). One sample with an initial induction period of roughly 3 h, showed levels of insoluble over the method reproducibility at the end of the test. These results show B100 samples with initial IP greater than 6 h do not exhibit significant acid number or insoluble formation under D4625 conditions which represent 12 months in clean, dry storage. B20 made from biodiesel 31980 exhibited some peroxide formation over 12 weeks, as was also the case for this biodiesel when aged as B100. Neither of the other B20 samples evaluated showed peroxide formation and none of the samples showed increased TAN. None of these samples had measurable insoluble at the end of the test (<2 mg/100 mL). Consistent with our previous work, B20 blends with IP greater than 6 h are stable in D4625 storage for more than 12 weeks, indicating that real fuels can be stored in a clean dry environment for at least 12 months. For B50 blends, while initial IP values are slightly higher for blends into one of the petroleum diesel fuels, the results for the two petroleum blendstocks are very similar. IP values decreased slowly over time, but in all cases remained above 2 h. Corresponding roughly to the B100 results, there was some growth in peroxides the B50 samples made with lower IP B100, but no significant change in acid number over time. One B50 sample showed insoluble formation at a value of 5.4 +/- 1 mg/100 mL, slightly above the repeatability of the test method. The B100 used for this B50 sample also produced a similar amount of insoluble when aged as B100. These results show B50 blends with initial IP greater than 6 h and made with an initial B100 IP of over 6 h do not exhibit significant acid number or insoluble formation under D4625 conditions which represent 12 months in clean, dry storage.

Research Organization:
National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Sponsoring Organization:
Clean Fuels Alliance America
DOE Contract Number:
AC36-08GO28308
OSTI ID:
3013240
Report Number(s):
NREL/TP-2A00-96381
Country of Publication:
United States
Language:
English