Single-phase and two-phase base-catalyzed transesterification of canola oil to fatty acid methyl esters at ambient conditions

Experiments were performed at ambient temperature to investigate mass transfer during the transesterification reaction of canola oil with methanol (MeOH) to form fatty acid methyl esters by use of a sodium hydroxide (NaOH) base catalyst. Reactions were conducted at two NaOH catalyst concentrations under quiescent conditions, agitated two-phase conditions, and agitated single-phase conditions that were achieved by the addition of a solvent, tetrahydrofuran. A MeOH to oil molar ratio of 6:1 was employed. Small conversions, at ambient conditions, accentuated the effects of mass transfer on the transesterification reaction. For two-phase reactions, it was postulated that the reaction occurred at the interface between the two phases. The influence of mass transfer was indicated by the increased reaction rate resulting from (a) stirring a two-phase reaction mixture and (b) changing a two-phase reaction to a single-phase reaction through the addition of a solvent. In some experiments an induction period was observed. Factors influencing the induction period were identified.