ARS | Publication request: Comparing biofuels obtained from pyrolysis, of soybean oil or soapstock, with traditional soybean biodiesel: Density, kinematic viscosity, and surface tensions

Submitted to: Energy and Fuels
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 10, 2008
Publication Date: May 5, 2008
Citation: Doll, K.M., Sharma, B.K., Suarez, P.A., Erhan, S.Z. 2008. Comparing biofuels obtained from pyrolysis, of soybean oil or soapstock, with traditional soybean biodiesel: density, kinematic viscosity, and surface tensions. Energy and Fuels. 22(3):2061-2066.

Interpretive Summary: We have determined the physical properties of soybean oil based fuels, made using a pyrolysis method. We also analyzed blended fuels made by mixing our fuels with petroleum based diesel fuels, a current practice in the biofuels industry. For comparison, we did a similar set of experiments with traditional biodiesel. The results show that our pyrolysis method is a viable alternative to the traditional methods, capable of producing fuel with physical properties that are similar to those in petroleum based diesel fuels. Our method has two other advantages as well. First, it does not require the large amount of methanol which is used in traditional biodiesel. Second, it does not produce the glycerin byproduct which is produced using traditional methods. This research benefits the vegetable oil industry by giving a new method where soybean oil can be used as a viable fuel. It also shows the potential to add value to lower quality vegetable oil feedstocks, by turning them into green fuel products.

Technical Abstract: A product with diesel like properties was synthesized by a pyrolysis method, from either edible soybean oil, or an inedible soybean soapstock starting material (PD and SD, respectively). Some physical properties of the material were studied, neat, and in blends; with both high sulfur and low sulfur diesel fuels (HSD and LSD), and at a range of different temperatures. The kinematic viscosities at 40 deg C were 4.5 mm2 s-1 for PD and 3.8 mm2 s-1 for SD, which were reduced in a linear fashion by addition of HSD or LSD. The densities of the fuels at 40 deg C were 0.853, and 0.844 g mL-1, very similar to the density of HSD. The surface tensions of the compounds, also at 40 deg C, were 27.1 mN m-1 for PD and 26.2 mN m-1 for SD. Comparison to traditional biodiesel was made, and overall, led to the conclusion that the pyrolysis products are a viable alternative.