Optimization of the esterification of oleic acid and ethanol in a fixed bed membrane reactor by response surface method

Abstract

In this study, the kinetics of the esterification reaction of oleic acid (OA) and ethanol enhanced by dehydration using a fixed bed coupled pervaporation (PV) technology was studied, as well as the effects of the various factors’ interactions on the conversion rate of OA. The influences of ethanol/OA molar ratio, catalytic bed height, feed speed and reaction temperature on the conversion rate of OA were respectively investigated. The response surface method (RSM) and Box-Behnken design (BBD) are combined to optimize the experimental scheme. The results showed that the conversion rate of OA reached peak of 99.32 % when the molar ratio of ethanol/OA was 9:1, the catalytic bed height was 150 mm, the feed speed was 0.2 ml/min, and the reaction temperature was 80℃. Compared with the esterification reaction without PV, the conversion rate of OA was increased by 12.69 %. Through the kinetic model, the esterification reaction rate constant k1 (30.447), the reaction activation energy Ea1 (36.665 kJ/mol), the preexponential factor A1 (7.889), the pervaporation process activation energy Ea2 (15.788 kJ/mol), and the preexponential factor A2 (3.548) could be counted. To our surprises, the H-type cation exchange resin (H-CER) still showed high catalytic activity after six cycles.