Esterification of oleic acid in a semi-batch bubble reactor for biodiesel production

Abstract

A semi-batch bubble reactor has been developed to produce fatty acid ethyl ester (biodiesel) by acid-catalyzed esterifcation of oleic acid with superheated ethanol vapor. In this paper, the effects of reaction temperature (110, 130 and 150°C), ethanol volumetric flow rate (1.35, 2.50 and 3.65 mL/min) and vapor bubble size on the reactor performance were evaluated. The results demonstrated that temperature and volumetric flow rate have signifcant effects on the chemical reaction, gas phase solubility and mass transfer limitations. In addition, the free fatty acid conversion velocity was increased by approximately 56% when a microporous stainless-steel tube was employed to generate and distribute the vapor bubbles inside the reactor, which allowed the process to reach 95% conversion in approximately 40 minutes for the operating temperature of 150°C and volumetric flow rate of 2.5 mL/min.