Ionic liquids as eco-friendly catalysts for converting glycerol and urea into high value-added glycerol carbonate

Abstract

Acidic, basic and neutral ionic liquids (ILs) have been used as catalysts in the carbonylation of glycerol with urea. The results show that neutral ILs have high catalytic activity in the reaction. The excellent performance of the catalysts can be attributed to the synergistic effect of the cation and anion. We speculated that the cation with positive charge activates urea, and the anion with negative charge activates glycerol. In addition, the well balanced acid-basic properties of the catalysts are necessary for good catalytic performance. The ILs can be reused at least five times without loss of activity. Using ILs, instead of the traditional metal catalysts, reduces the use of non-renewable resources. It is eco-friendly that two inexpensive and bio-based raw materials were used and the catalytic reaction was carried out without solvent.