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United States Department of Agriculture

Agricultural Research Service

Research Project: VEGETABLE OIL-BASED FUELS, ADDITIVES AND COPRODUCTS

Location: Bio-oils Research Unit

Title: Synthesis of biodiesel fuel additives from glycerol using green chemistry and supercritical fluids

Authors
item Artz, William -
item Self, Ethan -
item Hurst-Thomas, Cory -
item Kraft, Mary -
item DUNN, ROBERT

Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2011
Publication Date: May 1, 2011
Citation: Artz, W.E., Self, E.C., Hurst-Thomas, C.C., Kraft, M.L., Dunn, R.O. 2011. Synthesis of biodiesel fuel additives from glycerol using green chemistry and supercritical fluids [abstract]. Annual Meeting and Expo of the American Oil Chemists' Society. p. 70.

Technical Abstract: For every 3 moles of fatty acid esters produced, 1 mole of glycerol remains, ~11% of the biodiesel volume. One new method of glycerol use could be as a biodiesel fuel additive/extender using eco-friendly heterogeneous catalysts and supercritical fluids (SFs). SFs have advantages such as greater diffusivities, lower viscosities, better catalyst surface “wetting”, and more rapid transfer to/from catalyst surfaces. Samples were analyzed using GC/MS. Experiments were completed at SF and non-SF conditions with Amberlyst® catalysts. Glycerol ethyl ethers and cyclic compounds (dioxanes and dioxolanes) were formed. For the reactions in glass vials at low pressures (100ºC), the yields were ~0.26% to 0.48% (ethers) and ~0.16% to 0.78% (cyclics). At SF conditions (100ºC and 205 atm) the yields ranged from ~0.28% to 3.84% ethers and ~0.21% to 1.26% cyclics. For the SF experiments at 120ºC and 205 atm, the glycerol conversion was ~9% to 19% with 94% to 98% ethers and ~2% to 6% cyclics. For experiments completed at 180ºC and 314 atm, the glycerol conversion rate was ~25.5%, with 55.4% mono-ethyl-, 13.8% di-ethyl-, 0.2% tri-ethyl ether of glycerol, and 30.6% combined cyclic compounds. One investigator used non-SF conditions and non-green methods with better glycerol conversion (32%) (160-200ºC), but the primary product (90+%) was the mono-ethyl ether, which is not very soluble in biodiesel.

Last Modified: 8/19/2014