No abstract

A mathematical model of an isothermal semibatch bubble reactor has been developed to describe the esterification reaction of free fatty acids with superheated alcohol vapor. The proposed model accounts for the effects of mass transfer followed by chemical reaction in the liquid phase. The fluid physical properties are calculated by published correlations, and the partition coefficient of alcohol vapor was estimated based on thermodynamic models of vapor−liquid equilibria. Experimental data of acid-catalyzed esterification of oleic acid with superheated ethanol vapor at different conditions of temperature and gas superficial velocities were used to estimate the liquid side mass transfer coefficients and kinetic parameters. The results obtained showed that the model satisfactorily fits the experimental data for all operating conditions and was also able to simulate and predict experimental results for intermediate conditions with a coefficient of determination R 2 of 0.987. In addition, the estimated values of the mass transfer coefficient agreed with data reported in the literature for gas−liquid reactors.

A semi-batch bubble reactor has been developed to produce fatty acid ethyl ester (biodiesel) by acid-catalyzed esterification 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 significant 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.