Efficient synthesis of ethylene carbonate via transesterification of ethylene glycol with dimethyl carbonate over Mg3Al1−xCexO composite oxide

Abstract

A series of Mg3Al1−xCexO composite oxide catalysts were prepared by co-precipitation for the transesterification of ethylene glycol to ethylene carbonate. The characterization results revealed that the addition of cerium changed the acid-base properties of the catalyst and that the strong basic sites on the catalyst surface played an important role in the reaction. The Mg3Al0.9Ce0.1O catalyst showed the highest catalytic activity (ethylene carbonate yield 98.1%). Compared with pure Mg-Al oxide, the appropriate addition of Ce was conducive to improving the surface basicity and adsorbed oxygen content of the catalyst. Additionally, the reaction process of the formation of ethylene glycol hydroxyl group with the alkoxy anion formed by the catalyst attacking the carbonyl carbon of nucleophilic dimethyl carbonate to form an adsorption intermediate (HEMC) on the catalyst surface for further intramolecular rearrangement to form ethylene carbonate was confirmed by operando infrared spectroscopy. The reaction kinetics shows that the reaction conforms to the second-order kinetic equation, and the activation energy is 53.71 kJ·mol−1. Catalytic stability in a fixed-bed reactor was studied. After a long cycle of use (150 h), the yield of ethylene carbonate was stabilized at about 89.0%.