Synthesis of glycerol carbonate from glycerol and urea over tin-tungsten mixed oxide catalysts

• W-Sn mixed oxides are efficient catalysts for the synthesis of glycerol carbonate.
• W-Sn catalysts activity depends on their mole ratio and treatment temperature.
• Presence of amorphous WO3 in W-Sn oxides results in generation of strong acidity.
• Glycerol carbonate yield also depends on reaction parameters.

Tin-tungsten mixed oxide catalysts with varying their mole ratio were prepared by co-precipitation method. The catalysts physico-chemical properties were derived from FT-infrared, Laser Raman, X-ray diffraction, UV–Vis DRS, BET surface area and temperature-programmed desorption of NH3. The catalysts activities were evaluated for the synthesis of glycerol carbonate from glycerol and urea. The activity results showed that Sn-W mixed oxide catalysts are highly active for selective formation of glycerol carbonate. Sn-W catalyst with 2:1 molar ratio exhibited about 52% of glycerol conversion with >95% selectivity towards glycerol carbonate. The active catalyst was subjected to calcination at different temperatures and evaluated for their activity in glycerol carbonate synthesis. The activity of the catalysts depends on mole ratio of Sn/W and treatment temperature which are influencing the surface-structural characteristics of the catalysts. Different reaction parameters such as glycerol to urea molar ratio, reaction temperature and catalyst loading were studied and optimum conditions were established. The catalysts showed consistent activity upon repeated use.

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