Mesoporous nanocrystalline sulfated zirconia synthesis and its application for FFA esterification in oils Original Research Article

Mesoporous nanocrystalline sulfated zirconia catalyst has been prepared from zirconium hydroxide synthesized at different digestion/hydrothermal treatment times. Sulfuric acid and chlorosulfonic acid were used as two different sulfonating agents. The effect of digestion time, sulfonating agent and the calcination temperature on structural, textural and catalytic properties of the prepared catalyst were investigated in details using nitrogen adsorption–desorption (BET), ammonia temperature programmed desorption (NH3-TPD), X-ray diffraction (XRD), thermogravimetry and differential scanning calorimetry (TGA–DSC), and Fourier transform infrared spectroscopy (FTIR). The sulfated zirconia prepared at various digestion times and two different sulfonating agents were tested for the esterification of free fatty acid (FFAs) in soybean oil (prepared by mixing oleic acid in soybean oil) as model reaction. Sulfated zirconia catalyst prepared with 3 h digestion time and 600 °C calcination temperature using chlorosulfonic acid showed the highest catalytic activity with about 85% conversion in just 80 min of esterification time at 60 °C reaction temperature.