Kinetics of the production of glycerol carbonate by transesterification of glycerol with dimethyl and ethylene carbonate using potassium methoxide, a highly active catalyst

The biodiesel industry has been dealing with the issue of glycerol oversupply for some time, leading to blossoming research regarding its valorisation to yield value-added derivatives. This work presents the production of glycerol carbonate through the transesterification of glycerol with dimethyl carbonate (DMC) and ethylene carbonate (EC), also obtaining valuable methanol and ethylene glycol, respectively. CH3OK was used as catalyst, with kinetic runs being conducted under mild operation conditions: temperature (50-70 degrees C using DMC; 40-60 degrees C using EC), molar excess of organic carbonate to glycerol (1.5-3) and low catalyst loads (1000-2500 ppm for DMC; 50-150 ppm for EC). Kinetic models were proposed, fitted and verified considering the transition from a biphasic to a single phase liquid system and a first order deactivation of the catalyst. In the reaction with DMC, the model contemplates an irreversible reaction with activation energy of 28.4 +/- 1.5 kJ.mol(-1) and deactivation constant of 0.03 +/- 0.01 min(-1). Using EC, the activation energies were 83.0 +/- 1.6 kJ.mol(-1) and 58.7 +/- 11.4 kJ.mol(-1) for the direct and reverse reactions, respectively, and the deactivation constant was 0.11 +/- 0.02 min(-1). This catalyst demonstrates a much higher activity for these reactions than K2CO3. (C) 2015 Elsevier B.V. All rights reserved.