Enhancement of Esterification of Ethanol and Propionic Acid by Fixed-Bed Reactor Coupled with Pervaporation Separation

A new efficient coupled process to produce green solvent ethyl propionate was developed, which involved a fixed-bed reactor and pervaporation membrane separation. Firstly, the esterification reaction alone was investigated to explore reaction conditions and kinetics. Secondly, the pervaporation alone was investigated to explore separation conditions and the separation performance of pervaporation membranes. Then, the esterification reaction, coupled with pervaporation to enhance the reaction process, was investigated. Finally, the mathematical model of the esterification reaction, coupled with the pervaporation process, was established. The results showed that the conversion of ethanol reached 78.4% within 5 h. The reaction kinetics were obtained based on the pseudo-homogeneous (PH) model. Under the condition of a circulation flow rate of 100 L/h, the influence of concentration polarization could be well overcome, and a high level of pervaporation could be achieved. The pervaporation coefficients of the four-component system were obtained based on Fick’s law. The dehydration rate increased significantly with the increase in pervaporation temperature, which could effectively enhance the esterification reaction. The model could well predict the experimental results, and the experimental results were in good agreement with the theoretical calculations.