An Evaluation of Glycerol Acetalization with Benzaldehyde over a Ferromagnetic Heteropolyacid Catalyst

Tungstophosphoric acid (H3PW12O40) supported on silica-coated magnetite nanoparticles has been prepared and used as a heterogeneous acid catalyst (Fe3O4@SiO2@HPW) in the condensation of benzaldehyde (B) with glycerol (Gly) for the production of cyclic acetals. Physicochemical techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectrometry (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and N2 physisorption were used to characterize the prepared catalyst. The effect of glycerol/benzaldehyde molar ratio (1/1 to 1/1.2), temperature (80-120 degrees C), and catalyst amount (1-5%) on glycerol conversion and the selectivity in main reaction products: benzoic acid, 2-phenyl-1,3-dioxolan-4-yl)methanol, 2-Phenyl-1,3-dioxan-5-ol, 2-phenyl-1,3-dioxolane, and methyl 2-hydroxy-3-phenylpropanoate was studied to evaluate the catalytic activity of the prepared Fe3O4@SiO2@HPW catalyst. The optimization of these process parameters was conducted using Box-Behnken design (BBD). Using the BBD methodology, the optimal parameters (120 degrees C, 1:1.15 glycerol: benzaldehyde, 5% catalyst) were determined, for a glycerol conversion of and cyclic acetals yield of 85.95% and 78.36%, respectively. The catalyst also exhibits excellent activity for glycerol acetalization with other aromatic aldehydes such as cinnamaldehyde, p-methyl-benzaldehyde, p-hydroxy-benzaldehyde, and vanillin.

Automated summary

Researchers prepared a tungstophosphoric acid catalyst supported on silica-coated magnetite nanoparticles for the condensation reaction of benzaldehyde and glycerol to produce cyclic acetals. The catalyst was characterized using various physicochemical techniques. The effect of process parameters such as glycerol/benzaldehyde molar ratio, temperature, and catalyst amount on glycerol conversion and product selectivity was studied. Using the Box-Behnken design methodology, the optimal conditions for the reaction were determined. The catalyst also exhibited excellent activity for glycerol acetalization with other aromatic aldehydes.