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United States Department of Agriculture

Agricultural Research Service

Title: Oxidative Stability of Alternative Diesel Fuels and Extenders from Vegetable Oils and Animal Fats (Biodiesel)

item Dunn, Robert

Submitted to: American Institute of Chemical Engineers
Publication Type: Abstract Only
Publication Acceptance Date: November 21, 1997
Publication Date: N/A

Technical Abstract: Mono-alkyl esters from vegetable oils and animal fats are attractive as alternative fuels and extenders for combustion in direct injection compression ignition (diesel) engines. These alkyl esters, referred to as biodiesel, can easily be converted from transesterification of vegetable oils or animal fats with alcohols such as methanol or ethanol. During periods of extended storage, oxidation degradation of fatty derivatives such as biodiesel can occur at a significantly more accelerated pace than petroleum middle distillates under similar conditions. This work examines the effects of oxidation under accelerated conditions (such as elevated temperatures) on biodiesel and biodiesel-distillate blends. Differential scanning calorimetry (DSC) and conductivity-based analytical techniques are employed to determine oxidation induction periods of fuel formulations. Results show that although winterization significantly reduces the oxidative stability of neat methyl soyate, this reduction is greatly diminished when winterized biodiesel is blended at 20 vol% in petroleum middle distillates. Effects of oxidation on viscosity, density, cloud point, pour point, acid value and other fuel properties are also evaluated for biodiesel derived from several oil and alcohol feedstocks. Finally, recommendations are made relating to oxidative stability in the context of fuel specifications and product quality.

Last Modified: 4/19/2015
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