Sustainable valorisation of glycerol via acetalization as well as carboxylation reactions over silicotungstates anchored to zeolite Hβ

• Valorization of glycerol over silicotungstates anchored to zeolite Hβ.
• Effect of creating a lacuna on the parent silicotungstate has been discussed.
• Highly efficient catalytic systems in terms of activity and selectivity.
• Mild reaction conditions make the system environment friendly.
• Catalysts can be recycled up to 4 times without significant loss in the activity.

A simple, green and effective pathway towards valorisation of glycerol to value added products has been demonstrated. In this context, catalysts comprising parent as well as lacunary silicotungstates anchored to large pore zeolite Hβ have been synthesized and characterized by various physicochemical methods. Parent silicotungstic acid based catalyst proved to be better catalyst in terms of conversion of glycerol showing 73% conversion for carboxylation reaction and 97% conversion of glycerol towards acetalization reaction. The better activity of the catalyst was correlated with its strong acidic character. It was observed that by tuning the acidity of parent silicotungstate by formation of lacunary silicotungstate leads to the increase in the selectivity of 5-membered dioxolane from 68% to 78% and selectivity of glycerol carbonate from 72% to 75%. Both the catalysts were reusable up to four cycles under the investigated reaction conditions. The probable mechanisms for both the reactions are also discussed.

Environmentally benign route towards valorisation of glycerol via acetalization as well as carboxylation has been demonstrated over silicotungstates anchored to zeolite Hβ.Figure optionsDownload high-quality image (247 K)Download as PowerPoint slide