Submitted to: Lipid Technology
Publication Type: Trade Journal
Publication Acceptance Date: 8/20/2006
Publication Date: 12/1/2006
Citation: Knothe, G.H. 2006. Biodiesel and the issue of diesel fuel lubricity. Lipid Technology. 18(5):105-108.
Technical Abstract: The advent of (ultra-)low sulfur diesel fuels based on petroleum has caused changes in the properties of these fuels. One of the major changes is the loss of previously inherent lubricity. Biodiesel, a diesel fuel derived from vegetable oils, animal fats, or used frying oils, is miscible with petrodiesel in all ratios and possesses inherent lubricity. Neat fatty compounds generally exhibit excellent inherent lubricity. Lubricity is to a great extent affected by the presence, nature and number of oxygen moieties, although unsaturation and chain length also play a role. However, biodiesel is required at blend levels of about 2% or higher to impart lubricity in blends with petrodiesel, with lower levels not sufficiently restoring lubricity. Recent investigations have shown that minor components of biodiesel, usually considered contaminants, such as free fatty acids and monoacylglycerols, are to a large part responsible for the lubricity of low-level blends. Neat methyl esters have reduced lubricity compared to these "contaminants".