Sulfated Iron Oxide: A Proficient Catalyst for Esterification of Butanoic Acid with Glycerol

Sulfated iron oxide catalysts, prepared by a simple and solvent free method, were studied in the esterification of butanoic acid with glycerol. The effect of the series of preparation parameters such as mixing time, sulfate loading, and calcination conditions, i.e., temperature and its duration, were explored. The catalyst containing 6 wt % sulfate loading with 40 min of mixing time, calcined at 500 °C for 7 h, performed optimally for the conversion of butanoic acid. The characterization of catalysts was carried out by using X-ray powder diffraction (XRD), scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC)-thermogravimetric analysis (TGA), zeta potential, acidity measurements, and leaching tests. The performance of the catalyst has revealed that it is a low cost, stable, efficient heterogeneous catalyst for this reaction when compared with ion exchange resins and other heterogeneous catalysts. Furthermore, the catalyst can be easily separated by filtration and found to be reusable and active