ARS | Publication request: Lipase-catalyzed transesterification to remove saturated monoacylglycerols from biodiesel

Submitted to: European Journal of Lipid Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 2, 2012
Publication Date: August 1, 2012
Citation: Padhi, S.K., Haas, M.J., Bornscheuer, U.T. 2011. Lipase-catalyzed transesterification to remove saturated monoacylglycerols from biodiesel. European Journal of Lipid Science and Technology. 113(10):1219-1229.

Interpretive Summary: Biodiesel, a biobased diesel fuel produced from vegetable oils, animal fats, and algal oils, is the only Federally approved biobased diesel fuel in the U.S. at this time. Approximately 1 billion gallons will be produced in this country in 2011. Although the introduction of this fuel into the national fuel infrastructure has been largely seamless, large volume production, distribution and use have resulted in some unanticipated challenges. One of these has been the fact that the products of incomplete conversion of the feedstock to fuel can include a group of molecules, known as saturated monoglycerides (SMG), which can precipitate from solution at low temperatures. The resulting solid particles can plug fuel fiters, reducing fuel flow to an engine and thus causing reduced power or engine failure. Existing industry measures to reduce SMG levels include conducting multiple redundant biodiesel synthesis reactions, and cycles of chilling and filtration. These options can slow production, add expense, and reduce the yield of biodiesel. Here we describe for the first time another option: the use of a specific enzyme to degrade the SMG to readily removed species, and show that this approach is capable of achieving a substantial reduction in the SMG content of a biodiesel. This offers a new, potentially industrially useful, route for the removal of SMG from biodiesel.

Technical Abstract: Saturated monoacylglycerols (SMG) are known to be present in fatty acid methyl esters (FAME) intended to be used as biodiesel. These SMG can strongly affect the properties of biofuels such as the cloud point, and they have been implicated in engine failure due to filter plugging. It is shown here that lipase G from Pencillium camembertii can be efficiently used for the transesterification of SMGs to fatty acid methyl ester and glycerol even in the presence of the bulk biodiesel. Thus, in samples of commercial biodiesel to which glycerol monostearate (GMS) and glycerol monopalmitate (GMP) had been added, their levels were enzymatically reduced from 2 percent (w/v) to 0.22 percent (w/v) for GMP and 0.14 percent (w/v) for GMS as confirmed by GC-MS analysis.