Kinetics of lipase-catalyzed synthesis of soybean fatty acid ethyl esters in pressurized propane.

This work reports new experimental data and mathematical modeling of lipase-catalyzed biodiesel production using soybean oil and ethanol as substrates and pressurized n-propane as solvent. The experiments were carried out in a batch reactor, recording the reaction kinetics and evaluating the effects of temperature in the range of 45-70 degrees C, enzyme content from 1 to 20 wt% and oil to ethanol molar ratios of 1:3, 1:6, 1:9 and 1:15. The solvent to substrates mass ratio and pressure were set at 2:1 and 50 bar, respectively. Results showed that lipase-catalyzed alcoholysis in propane medium might be a potential alternative to conventional techniques for biodiesel production, since good conversions were obtained at mild temperature and pressure conditions. The semi-empirical mathematical model based on balance equations, adopted to describe the transesterification kinetics in pressurized n-propane, yielded relative deviations between experimental and calculated values lower than 10%, thus allowing a satisfactory representation of experimental results and a better understanding of the transesterification reaction.