Efficiently catalytic glycerol to solketal through acetalization over sulfated UiO-66

Abstract

Herein, a facile synthetic approach was developed to prepare sulfated UiO-66 (named as UiO-SO₃H-X, X represents the molar fraction of the sulfonated ligand). UiO-SO₃H-X were comprehensively characterized using powder X-ray diffraction (pXRD), Fourier Transform Infrared Spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), Thermal Gravimetric Analyzer (TGA), N₂ adsorption–desorption, Transmission Electron Microscope (TEM) analyses. The sulfonic acid groups were uniformly dispersed throughout the crystalline framework. Notably, UiO-SO₃H-30 exhibits superior catalytic activity and durability in the acetalization reaction of solketal from glycerol. Glycerol conversion of 79.6 % with a solketal selectivity of 99.5 % was achieved at 60 °C, while maintaining initial activity for 5 consecutive cycles. Meantime, UiO-SO₃H-30 possesses a maximum turnover frequency (TOF) of 272.3 h⁻¹ for per acid site, which is superior than most heterogeneous acid catalysts. This work supplies a feasible method to synthesize upstream by product of biodiesel, producing significant influence for biomass utilization in chemical industry fields.