Biodiesel produced from vegetable (soybean) oil through a base catalyzed transesterification with methanol is an inefficient process. Our research group is applying green chemistry principles to improve the efficiency of small-scale (bench top) biodiesel production, but this work has been hindered by the lack of detailed information about the mechanism behind the transesterification reaction. Our goal was to develop a detailed kinetic model that would identify whether rate limiting transesterification occurs at C1/3 or C2 as the glyceryl triester is converted into the di- and mono- ester, and finally free glycerol. Transesterification reactions were conducted on a 25mL scale at 60 degrees Celsius to test our methodology for quenching (stopping) the reaction with acetone d-6, and at room temperature to acquire a Time 0 data point. Reaction time points were analyzed using quantitative NMR, employing an internal reference standard of maleic acid for concentration calculations, and integration data was used to analyze and obtain time course data. All controls and standards gave unambiguous NMR spectra with under 5% error. 2D spectroscopy was also investigated and will be assessed for future usefulness in determining C1/3 or C2 ester branches leaving as the limiting step. The results of this research will help narrow the options for improvements to the reaction efficiency, for example in catalyst design.  This research was supported by a Norris-Richards Summer Scholarship from the Northeastern Section of the ACS, the BSU Adrian Tinsley Program, and a grant from the EPA P3 program (SU835696).

Applying 1H NMR spectroscopy to develop a kinetic model for the transesterification of glycerol fatty acid triesters

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.