Microwave assisted glycerol esterification using CeO2, ZrO2, mixed metal oxide catalyst

Abstract

Present study focuses on the up-cycling of glycerol by esterification reaction using acetic acid to produce acetins. Heterogeneous catalysts such as CeO2, ZrO2 (commercially procured) and CeO2-ZrO2 mixed metal oxide catalysts synthesized using solution combustion method were used to synthesize acetins. The reactions were performed in a microwave reactor at a power level of 900 W, which rendered the reactions faster and simpler compared to the conventional heating method. The effect of temperature (80 °C, 90 °C, 100 °C), the initial molar ratio of glycerol: acetic acid (1:5, 1:10, 1:15) and the amount of catalyst (3 wt%,5 wt%,7 wt%) were studied for all the three catalysts. The study showed a rapid phase of reaction for up to 30 min and then the reaction proceeded at a constant rate. The conversion was higher at 100˚C. Rate constants determined from kinetic model was increasing with temperature. The kinetic data was observed to best fit the pseudo-first-order kinetic model. The study has demonstrated an efficient way of synthesizing acetins in presence of metal oxides by the application of microwave heating as process intensification technology.