Upgrading of glycerol from biodiesel synthesis with dimethyl carbonate on reusable Sr-Al mixed oxide catalysts

The high demand for renewable energy has led to the upsurge of methanol-assisted biodiesel synthesis. Therefore, glycerol as a byproduct entered the waste stream given the oversupply of biodiesel to the market. The dimethyl carbonate (DMC)-assisted transesterification of glycerol on a catalyst has been a popular approach for converting glycerol into valuable glycerol carbonate (GLC). The synthesis of GLC from the DMC-assisted transesterification of glycerol on mixed oxide catalysts (Srx-Al) with different Sr/Al ratios was examined in this study. A glycerol conversion of 99.4% and a GLC yield of 100% were achieved in a catalyst with Sr/Al = 0.5 (Sr0.5-Al). Both values are higher than those in catalysts synthesized with Sr/Al = 0.25 and 0.75. The Sr0.5-Al catalyst withstood five transesterification reaction cycles without a serious deactivation induced by the leaching of active SrO. Therefore, the Sr0.5-Al catalyst is suitable for consecutive uses in the DMC-assisted transesterification of glycerol with DMC into GLC.