Fossil fuels dating back to the first coal mine dug from the Earth have been vital to society’s advances, but have come at a significant cost. Rise in pollutants such as CO2 and particulate matter due to combustion byproducts of these fuels (coal, oil, gasoline, diesel) continue to negatively impact the environment, harming various ecosystems by disrupting precarious balances. Attempts have been made to “clean” fossil fuels, but only to temporary degrees of success. Alternative energy sources such as solar, wind, or hydroelectric are increasing in viability, but are often a difficult transition for fossil fuel reliant individuals. Biodiesel (Fatty Acid Methyl Esters, FAME) is an alternative “cleaner” fuel made from renewable vegetable oils that can be used in diesel vehicles with few to no engine modifications, easing consumer transition to alternative energy sources. Biodiesel is a possible replacement for petroleum diesel due to reduced greenhouse gas emissions, unburned hydrocarbons, carbon monoxide, particulate matter and nitrogen oxides. A diesel engine can run on an 80/20 (B20) mix of petroleum diesel to biodiesel, and with adjustments (to avoid possible clogging) can run 100% (B100) biodiesel. Biodiesel produced from vegetable (soybean) oil through a base catalyzed transesterification with methanol is, however, an inefficient and wasteful 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 research 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 60oC to test our methodology for quenching the reaction with acetone d-6, and at 25oC to acquire a time zero data point. Reaction aliquots were analyzed using quantitative NMR, employing an internal reference standard of maleic acid for concentration calculations, and integrated data was used to analyze and obtain time course data. All controls and standards gave unambiguous NMR spectra with <5% error. 2D spectroscopy was also performed 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 theses’ secondary goal is to develop an introduction and guidebook to cleaner fuels research and kinetic experimentation using NMR instrumentation.
Edward Brush (Thesis Director)
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Original document was submitted as an Honors Program requirement. Copyright is held by the author.
Sprague, Leonard W.. (2016). Development of a Kinetic Model for the Transesterification of Glycerol Fatty Acid Triesters Using 1H (1D and 2D) NMR. In BSU Honors Program Theses and Projects. Item 141. Available at: http://vc.bridgew.edu/honors_proj/141
Copyright © 2016 Leonard W. Sprague