Esterification of free fatty acids in a rotor-stator spinning disc reactor

Fatty acid methyl esters (FAMEs) were produced by the esterification of free fatty acids (FFA) with methanol, and sulfuric acid as the catalyst in a rotor-stator spinning disc reactor (RSSDR). The RSSDR, which shows excellent mixing efficiency and fast phase separation, was used as a novel continuous-flow esterification reactor. The influence of the variables (e.g., rotational speed, volume flow rate, rotor-stator distance, methanol-FFA molar ratio, catalyst dosage, and temperature) on esterification conversion (η) and productivity of FAMEs (PFAME) were investigated. It was found that the experimental parameters have a great impact on the η and PFAME in the RSSDR system, due to the effect of micromixing intensity and residence time distribution. Furthermore, to compare with other traditional esterification reactors, the values of η, PFAME, and PFAME per unit reactor volume (PFAME/VR) in the RSSDR were also employed to assess the performance for the production of FAMEs. It shows that the maximum values of PFAME, and PFAME/VR attained were 0.14 mol/min and 3.06×10−2 mol/(mL min), respectively. Therefore, the RSSDR is proven to be an effective esterification reactor with high esterification conversion in comparison to conventional esterification reactors.