Kinetic study on lipase catalyzed trans-esterification of palm oil and dimethyl carbonate for biodiesel production

Kinetics of the trans-esterification of palm oil and dimethyl carbonate (DMC) for biodiesel production has been studied at the catalysis of immobilized lipase Novozyme 435. The relationship between initial reaction rate and temperature was established and the activation energy (Ea) was obtained first, based on the Arrhenius law. The value of Ea was 26.0 kJ/mol. The external diffusion limitation was neglected by raising the agitation speed to 200 rpm. And the influence of internal mass transfer limitations could also be neglected due to the linear relationship between the initial reaction rate and enzyme concentration. The effect of the concentration of palm oil was studied over the range of 30-700 mmol/l by keeping the catalyst amount constant. No substrate inhibition was observed under above experiment conditions. Therefore, the model based on a Ping-Pong bi-bi mechanism without substrate inhibition was proposed to describe the trans-esterification kinetics. The simulated values calculated by MATLAB could fit the experimental values quite well, indicating the trans-esterification kinetics of palm oil and DMC agrees with the ordered bi-bi mechanism. (C) 2013 AIP Publishing LLC.