Studies on the preparation, characterization and catalytic activity test with oleic acid esterification of silicotungstic heteropoly acid

The nitric acid acidification method incorporated with an ether extraction technique is used to prepare a silicotungstic heteropoly acid catalyst in this study. The resulting catalyst is characterized by scanningelectron microscopy (SEM), infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), temperature programmed desorption of ammonia (NH₃-TPD) and thermogravimetric analysis (TG). The catalytic activity of thesilicotungstic heteropoly acid catalyst is studied from the esterification reaction of oleic acid and methanol.The syntheses conditions with respect to catalytic activities have been optimized individually, including themass ratio of methanol to oleic acid, as well as the mass ratio of catalyst to reactants, reaction time and reaction temperature. Results show that when the mass ratio of methanol to oleic acid is 3:2, mass ratio of catalyst toreactants is 1.4 %, reaction time 3.5 h and reaction temperature is 65 ℃, a yield of methyl oleate 96.45 wt% isobtained from this optimal reaction condition.