Microwave-assisted valorization of glycerol to solketal using biomass-derived heterogeneous catalyst

The increase in biodiesel production worldwide makes valorisation of the by-product of this process (glycerol) essential for economic sustainability. Hence, conversion of bioglycerol to platform chemicals such as (2,2-dimethyl-1,3-dioxolan-4-yl)methanol (solketal), a fuel additive, is highly desirable. In this study, glycerol is converted to solketal using a sulfonic acid-functionalized aromatic carbonaceous material (SAFACAM) bearing ancillary hydrophilic groups and acting as a heterogeneous catalyst under microwave irradiation. For the pro-duction of solketal by acetalization, an optimal glycerol:acetone molar ratio of 1:5 was recorded. Using a catalyst dosage of 8 wt% at 70 degrees C for just 10 mins under microwave irradiation (50 W, 100 psi) returned a 98.1 +/- 0.4 % conversion of bioglycerol with 100 % selectivity to solketal. The activation energy of the acetalization reaction was determined to be 35.8 kJ mol 1. Catalyst recovery was probed over six cycles, with a modest loss in activity (82.3 +/- 0.2 % conversion in the sixth cycle) resulting from limited active site leaching, as confirmed by EDS data.

Automated summary

The conversion of glycerol to solketal, a fuel additive, was successfully achieved using a sulfonic acid-functionalized aromatic carbonaceous material as a heterogeneous catalyst under microwave irradiation. The optimal glycerol:acetone molar ratio for the acetalization reaction was found to be 1:5, and a catalyst dosage of 8 wt% at 70 degrees C for 10 minutes resulted in a high conversion of bioglycerol with 100% selectivity to solketal. The acetalization reaction had an activation energy of 35.8 kJ mol 1, and the catalyst showed modest loss in activity over six cycles.