Green synthesis of glycerol carbonate via transesterification of glycerol using mechanochemically prepared sodium aluminate catalysts

Glycerol, an important by-product from biodiesel production, has significant potential as platform chemical with several different pathways of value addition being investigated. Herein, we report the synthesis of glycerol carbonate via the transesterification of glycerol with dimethyl carbonate using supported sodium aluminate catalysts. The effects of catalyst preparation method, and different metal oxide supports were investigated. Mechanochemically prepared catalysts were more stable than the corresponding catalysts prepared using a wet impregnation technique. Alumina as a support was found to provide the highest level of stability, amongst the metal oxide supports tested. The mechanochemically prepared catalyst with a sodium aluminate loading of 20 wt% supported on alumina, was found to be the most effective catalyst achieving 96 % yield of glycerol carbonate after 60 minutes. The catalysts were thoroughly characterized to investigate the effect of the catalyst synthesis method on the catalyst structure, catalytic activity and stability. Mechanochemically prepared 20 wt% sodium aluminate supported on alumina showed facile recovery and good reusability over four times with only a marginal decrease in activity.