Supercritical CO2 as solvent for fatty acids esterification with ethanol catalyzed by Amberlyst-15

This work reports on the esterification of fatty acids with ethanol using Amberlyst-15 in a scCO(2)-assisted system. A factorial design was carried out for the following process variables: temperature (70 degrees C-110 degrees C), ethanol to acid molar ratio (3:1 to 9:1) and catalyst to acid concentration (5-20 wt%), with a fixed amount of CO2 added to the reactor (28.62 g). The best reaction condition led to an 87 % conversion at 110 degrees C, 9:1, and 20 wt% in 15 min of reaction time. An exploratory kinetic study illustrates the effect of catalyst amount and molar ratio in isothermal kinetic curves. Also, a catalyst reuse study was performed. Additionally, different carboxylic acids and methanol, instead of ethanol, were evaluated as reagents. At all proposed systems, the addition of scCO(2) increased the reaction conversion. (C) 2020 Elsevier B.V. All rights reserved.