Cobalt oxide promoted tin oxide catalysts for highly selective glycerol acetalization reaction

The excessive production of glycerol as a by-product in the biodiesel industry increased environmental problems due to issues related to storage and waste management. Therefore, the catalytic conversion of glycerol into value-added chemicals is of great interest. Using heterogeneous catalysis, we investigated the selective acetalization of glycerol to solketal (C₆H₁₂O₃), an additive used in fuel production, using acetone in the presence of bimetallic oxide catalysts (Co₃O₄/SnO₂). The catalytic materials were fully characterized using physical and chemical techniques such as nitrogen sorption (BET), power X-ray diffraction, (p-XRD), temperature-programmed desorption, (TPD-CO₂ and TPD-NH₃), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). An attempt to correlate the acidic sites to the catalyst activity was not successful. However, it is important to note that, the reaction gave conversions greater than 90% and maximum selectivity to the formation of the solketal. Optimum conditions were investigated and showed the most active catalyst to be Co₃O₄/SnO₂ (75:25) with conversion above 90%. Catalyst stability evaluations showed that Co₃O₄/SnO₂ (50:50) is very stable and can be recycled up to 6 catalytic cycles with minor catalyst loss.