Equilibrium and thermodynamic parameters for heterogeneous esterification of butyric acid with methanol under microwave irradiation

Abstract

Synthesis of methyl butyrate was investigated in a microwave irradiated batch reactor in presence of acid ion-exchange resin catalyst, amberlyst-15. Methyl ester was heterogeneously produced by the reaction between butyric acid and methanol. Effect of reaction parameters of temperature (323-343 K), catalyst loading (0-10.5% w/w), alcohol to acid ratio, M (1-5), and amount of molecular sieves added (0-13.5% w/w) on conversion were studied. Equilibrium conversion of 92.6% was achieved in 60 minutes under microwave irradiation. Equilibrium constants at varied temperatures and dependency of equilibrium constant on temperature were studied. Equilibrium constant and equilibrium conversion showed increase with the increase in temperature as expected as per le-Chatelier principle. Van't Hoff plot for esterification of butyric acid was linear with negative slope indicating that reaction was endothermic. Comparative study showed that microwave irradiated method for methyl butyrate synthesis to be very efficient and fast compared with conventional and ultrasound assisted routes under optimized reaction conditions.