The sediment layer forming in B20 and B5 blends after long term storage is caused by the oxidation and degradation of biodiesel components. Testing found the sediment contains oxidation products of biodiesel fatty acid methyl esters (FAMEs) such as acids, aldehydes and high molecular weight compounds. While biodiesel alone may oxidize, the sediment only forms when blended with petroleum diesel, likely due to polar degradation products aggregating in the non-polar diesel. Adding a small amount of antioxidant to the biodiesel prevents sediment formation. Rancimat testing is not a reliable predictor, as biodiesel with different Rancimat results all formed sediment in blends. Producers

1. Phil Bureman Nalco Company Industry Technical Consultant – BioFuels [email_address] What Is This Stuff on my Fuel Filter? 13 th Latin American Congress on Fats & Oils Rosario, Argentina, November 1, 2009 Tim McGinnis Nalco Company Research Scientist - Research Analytical [email_address] Kim Peyton Nalco Energy Services Research Scientist [email_address]

10. After ASTM D4625, 110 o F (43 o C) , 13 weeks With No Antioxidant Treatment There was no indication of significant sediment formation ULSD Mixed Soy Palm Rancimat Hours Prior to ASTM D4625: >8.0 Hrs 0.6 Hrs 5.1 Hrs 4.8 Hrs

11. A thick, gelatinous sediment layer formed at the bottom of the B20 blend to which no antioxidant has been added. This sediment did not form in inhibited B-20. Untreated Anti-Ox #1 @ 100 ppm in the B100 Anti-Ox #2 @ 100 ppm in the B100 ~ 10.5 vol% A smaller amount of the same sediment formed in the B5 Non-Inhibited SOY B20 (Rancimat before testing >8.0 Hrs), in ULSD without anti-oxidant treatment is unstable after accelerated stability testing

12. A thick, gelatinous sediment layer formed at the bottom of the B20 blend to which no antioxidant has been added. This sediment did not form in inhibited B-20. Untreated Anti-Ox #1 @ 100 ppm in the B100 Anti-Ox #2 @ 100 ppm in the B100 ~ 7.0vol% A smaller amount of the same sediment formed in the B5 Non-Inhibited Mixed Source B20 (Rancimat @ start 3.7 Hrs), in ULSD showed similar instability when subjected to ASTM D4625

15. Gas Chromatography with Mass Spectrometry (GCMS) was used to determine the identity many of the compounds in the separated layer Thermo Electron Trace DSQ GCMS was operated in two distinct ionization modes to give the utmost information regarding the identities of degradation products of FAME Electron Impact Ionization - Gives a “fingerprint” that can be searched against standard spectral databases Methane Chemical Ionization - Gives less fragmented ion patterns which are directly related to the components’ molecular weights Also used were Purge and Trap techniques to look at low molecular weight volatiles, and Gas Chromatography with Flame Ionization Detection GCFID to examine higher molecular weight species.

17. High Temperature GCFID Chromatogram of Sediment High capacity, thin filmed column, along with on-column injection, allows for loading and elution of higher MW species |--------------------------------------------------------| Broadly Eluting Compounds with Molecular Weights Ranging from ~ 500 to 1000 (or greater) “ SIM DIST” Column

18. GC Profile of Sediment vs. Analytical Standards Analyzed Under Identical Conditions (MAG) (DAG) (TAG) Comparing the sediment against standards reveals that the high MW species in the sediment are at least as large as these known high MW contaminants encountered in biofuel. Detailed analyses suggest, though, that these high MW compounds are not merely MAG, DAG, TAG, etc., and are likely more complex reaction products.

19. The Sediment Layer is Very Complex ! We want to identify as many chemical species as possible, but how? - There is a great deal of coelution of multiple components, meaning that some “peaks” contain several species. - The mass spectral “fingerprints” obtained from examining these peaks are often combinations, and therefore do not always provide useful information. A Useful Approach . . . . . - We can separate the sediment into fractions based on solubility in solvents with different degrees of polarity. - We can then analyze each fraction separately to obtain more detailed information about the components present.

20. Solid Phase Extraction (SPE) First, sediment is injected, or “loaded” into a silica containing SPE cartridge Non-polar Cyclohexane is passed through Cyclohexane solubles collected and analyzed Next, slightly polar Cyclohexane:MTBE mix is passed through Cyclohexane:MTBE s olubles are collected and analyzed Next, moderately polar MTBE is passed through MTBE solubles are collected and analyzed Finally, polar Methanol is passed through Methanol solubles are collected and analyzed Note: MTBE is Methyl-t-Butyl Ether

21. Gas Chromatographic Profile of Non-Polar Fraction from Solid Phase Extraction Primary Biodiesel Components The bulk of the components are broad spectrum diesel fuel.

22. Gas Chromatographic Profile of Slightly Polar Fraction from Solid Phase Extraction There are no diesel fuel components in this fraction. All of the peaks seen are polar substances which are not soluble in cyclohexane alone. |------------------------| Mostly degradation products from the oxidation of biodiesel

23. Gas Chromatographic Profile of Moderately Polar Fraction From Solid Phase Extraction Thought to be oxidized biodiesel without cleavage |---------------------------------------| Higher MW Species

24. Gas Chromatographic Profile of Highly Polar Fraction from Solid Phase Extraction There are significant amounts of high molecular weight species that are soluble primarily in the more polar solvents. These are not MAG, DAG, TAG, etc. They appear to be addition products (oligomers) of some of the oxidation products, which must have substantial amounts of polar functionality in their molecular structure. |--------------------------------|

25. Organic Acids Detected in the B20 sediment

26. More examples of some species detected in the B20 sediment

27. Reaction Byproducts and Natural Components Detected in the B20 sediment How were these compounds formed?

28. The High Degree of Un-saturation in some FAME BioFuels, make them Particularly Susceptible to Oxidative Degradation Note that Tallow & Rape based biodiesel contains > 50% unsaturated compounds. Oxidative degradation of animal based biodiesel can and does occur. This is an important fact that is often overlooked! FAME Compound by GC/MS FAME Type, Area % Soy-D Soy-W Mixed Veg. Tallow Palm RME 16:0 Methylpalmate 8.9 11.5 15.3 23.5 44.7 9.9 16:1 Methylpalmitoleate - - - 1.6 - - 18:1 Methyloleate 38.1 34.7 34.2 43.8 37.5 59.2 18:2 Methylinoleate 43.6 47.9 22.9 12.8 5.3 26.2 18:0 Methylstearate 6.2 5.3 10.0 13.6 11.7 3.3 Other Unsaturated Compounds 3.2 0.6 17.6 4.7 0.8 1.4

30. Oxygen Attack at Point of Unsaturation

31. Secondary Oxygen Attack of the Reaction Product

32. Hydrolysis of Esters to Produce Acids

40. A fully detailed report of this work is expected to be published this year in the Journal of ASTM International – Special Issue on BioFuels Thank you for your time! Questions?