Green synthesis of glycerol carbonate using efficient mixed oxide catalysts

Abstract

The transcarbonation reaction of glycerol (Gly) with diethyl carbonate (DEC) was investigated to synthesise glycerol carbonate (GC) using two major types of basic catalysts: conventional carbonates (K₂CO₃ and Na₂CO₃) and, for the first time in this context, metal oxides (CaO, MgO, MgO/CaO and KNO₃/CaO) calcined at 700 or 900 °C. The introduction of metal oxides as catalysts represents a novel approach for this type of transcarbonation reaction. Analyses showed that the mixed CaO based metal oxides have a porous structure suitable for the transcarbonation reaction and higher BET surface areas compared to single CaO oxide. Two different loadings of each catalyst (5 and 10% mass related to Gly) were used with 2 : 1 molar excess of DEC to produce GC during 3 hours at 110 °C under mechanical stirring (500 rpm). The results showed the benefit of using mixed oxides (MgO/CaO or KNO₃/CaO) calcined at the appropriate temperature, to obtain GC yields and selectivity higher than 90% without byproduct formation.