Response Surface Modeling of the Interesterification of Crude and Refined Com Oil with Methanol

摘要

In this study, modeling of the interesterification of crude and refined corn oils with methanol was attempted via the response surface methodology (RSM). For both oils, a central composite rotatable design was used to investigate the effect of the amount of alkali catalyst (sodium methoxide: 0.12 to 2.48%, w/w), temperature (26 to 94°C) and molar ratio methanol/oil (0.96 to 11.0) used, on the production of fatty acid methyl esters (FAME). These esters may be used for biodiesel purposes. Under some of the conditions tested, the equilibrium was attained after a 30-min reaction for both oils. When crude corn oil was used, the production of FAME varied from 0% (corresponding to the lowest amount of catalyst used) to 95%. With respect to the alcoholysis of refined corn oil, the conversion to esters was from 27 to 95%. The production of FAME was significantly affected by the amount of catalyst and the temperature used. A less significant effect of the molar ratio of methanol/oil on the reaction was found. Both for crude and refined oils, the yield of FAME was fitted to second-order models represented by convex surfaces with stationary points (optima) inside the experimental domain. According to the models, the predicted maximum FAME production (95%) is attained after 30 min at 50°C when 1.7 or 2.0% (w/w) of sodium methoxide is used, respectively, on the interesterification of crude or refined oils.