Determination of the Kinetics of Biodiesel Production Using Proton Nuclear Magnetic Resonance Spectroscopy (¹H NMR)

Methyl esters were produced at several temperatures (10, 35, and 45 °C) by transesterification batch reactions of soybean oil with methanol utilizing KOH and NaOH catalysts. The reactions were monitored by aliquot removal and subsequent proton nuclear magnetic resonance spectroscopy (1H NMR) analysis. 1H NMR analysis allowed for the calculation of the average degree of fatty acid unsaturation (DU = 1.52) in oil and methyl ester. 1H NMR analysis also provided initial rates of methyl ester formation and an activation energy of 27.2 kJ/mol. The time-dependent concentration data revealed substantial reaction progress toward equilibrium after only 120 s at a reduced temperature of 10 °C. Understanding the resonance shifts in the 1H NMR spectra of starting materials and products allows for quantitation of reaction progress that is in good agreement with results obtained using other analytical methods.