Converting glycerol into glycerol carbonate by transesterification with different esters: reaction steps and coproducts

Glycerol carbonate was produced by transesterification between glycerol and different esters (dimethyl carbonate, diethyl carbonate, ethylene carbonate and propylene carbonate), using CTA-MCM-41 hybrid silica as basic catalyst. CTA-MCM-41 hybrid silica was synthesized using a non-hydrothermal method and was characterized by X-ray diffraction, thermogravimetric analysis and scanning electron microscopy. The catalyst characterizations showed that it had a hexagonal structure, catalytic sites concentration of 1.822 mmol g −1 and particle size in the range of 1–5 µm. The reactions for formation of glycerol carbonate were performed in a batch reactor, with dimethylformamide as solvent, and the products were analyzed by gas chromatography (GC-FID) and (GC–MS). Experiments were performed to study the effects of ester, temperature, catalyst percentage, and molar ratio of the reactants. The main products of the reactions with these esters were glycerol carbonate, glycidol and small amounts of glycerol monocarbonates, glycerol tricarbonate and glycidol carbonate. Cyclic-chain esters showed greater reactivity than straight-chain esters, forming fewer co-products. The reactions with straight-chain esters presented seven reaction steps, three more than the reactions with cyclic-chain esters. Straight-chain and cyclic-chain esters formed the products and co-products following different reaction mechanisms.