Kinetics of transesterification of palm oil and dimethyl carbonate for biodiesel production at the catalysis of heterogeneous base catalyst

Abstract

The transesterification of palm oil with dimethyl carbonate (DMC) for preparing biodiesel has been studied in solvent-free system at the catalysis of potassium hydroxide (KOH) as heterogeneous catalyst. Fatty acid methyl esters (FAMEs) were analyzed by GC with internal standard method. The effects of reaction conditions (molar ratio of DMC and palm oil, catalyst amount and time) on FAMEs yield were investigated. The highest FAMEs yield could reach 96.2% at refluxing temperature for 8 h with molar ratio of DMC and oil 9:1 and 8.5% KOH (based on oil weight). Kinetics of the KOH-catalyzed transesterification of palm oil and DMC was researched over a temperature range of 65–75 °C. A pseudo first-order model was proposed. The activation energy ( E a) was 79.1 kJ mo1 −1 and the pre-exponential factor ( k o) was 1.26 × 10 9 min −1 from Arrhenius equation. Further, a plausible reaction mechanism for the catalytic process with DMC as acyl acceptor was proposed.