Evaluation of Partially Hydrogenated Methyl Esters of Soybean Oil as Biodiesel

Authors: Moser, Bryan; Haas, Michael; Moser, Jill; Jackson, Michael - Mike; Erhan, Sevim; List, Gary

Submitted to: European Journal of Lipid Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/8/2006
Publication Date: 1/10/2007
Citation: Moser, B.R., Haas, M.J., Winkler, J.K., Jackson, M.A., Erhan, S.Z., List, G.R. 2007. Evaluation of partially hydrogenated methyl esters of soybean oil as biodiesel. European Journal of Lipid Science and Technology. 109:17-24.

Interpretive Summary: Biodiesel is an alternative fuel derived from vegetable oils or animal fats that can be used in diesel engines. Both the USA and European Union have enacted standards to control the quality of biodiesel to be used in the marketplace. However, the European standard is written to exclude soybean oil as a potential feedstock for biodiesel production. In contrast, soybean oil is acceptable as a feedstock for biodiesel fuel in the USA. Since soybeans are a major oilseed crop in the United States, it would be advantageous for American farmers if soybean oil could be chemically modified to allow its use in the large European biodiesel market. Therefore, we set out to perform a chemical reaction (catalytic partial hydrogenation) on soybean oil before its conversion to biodiesel in an effort to meet the European biodiesel standards. Once this newly modified biodiesel from soybean oil was in hand, we tested a number of important fuel properties (viscosity, lubricity, oxidative stability, specific gravity, and low temperature performance) to verify that it met all U.S. and European standards. Therefore, this work benefits the American soybean oil industry by helping to open the lucrative European biodiesel market for soybean oil use.

Technical Abstract: Biodiesel, an alternative diesel fuel derived from transesterified vegetable oils or animal fats, continues to undergo rapid worldwide growth. Specifications mandating biodiesel quality, most notably in Europe (EN 14214) and the USA (ASTM D6751), have emerged, which in effect limit feedstock choice in the production of biodiesel fuel. For instance, EN 14214 contains a specification for iodine value [IV, 120 g I2/100 g maximum] that eliminates soybean oil as a potential feedstock, as it generally has an IV >120. Therefore, we set out to evaluate partially hydrogenated soy oil methyl esters (PHSME, IV = 116) as biodiesel by measuring a number of important fuel parameters, such as oxidative stability, low temperature properties, lubricity, kinematic viscosity, and specific gravity. Compared to soy oil methyl esters (SME), PHSME was found to possess superior oxidative stability, similar specific gravity, but inferior low temperature properties, kinematic viscosity, and lubricity. The kinematic viscosity and lubricity of PHSME however were within prescribed U.S. and European limits. There is no set value for low temperature properties in biodiesel specifications, but PHSME has superior cold flow behavior when compared to other alternative feedstock fuels, such as palm oil, tallow and grease methyl esters. The production of PHSME from refined soybean oil would increase biodiesel production costs by U.S.$0.04/L (U.S.$0.15/gal) in comparison to SME. In summary, PHSME is within both the European and American standards for all properties measured in this study and deserves consideration as a potential biodiesel fuel.