Performance of Supported Keggin-Type Heteropolyacid Catalyst in Liquid Phase Oxidation of Furfural to Maleic Anhydride
Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China
Abstract Four different Keggin-type heteropolyacids were synthesized using different proportions of ammonium molybdate tetrahydrate, ammonium metavanadate, tungstic acid, oxalic acid and phosphoric acid. These Keggin-type heteropolyacid catalysts were obtained using SiO2 as the support by impregnation method. The catalysts were characterized by infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope(SEM) and NH3 temperature programmed desorption(NH3-TPD). The performance of the SiO2-supported Keggin-type heteropolyacid catalyst in liquid phaseoxidation of furfural to maleic anhydride were investigated using H2O2 as oxidant, and dichloroethane as solvent. The effects of catalyst type and dosage, dosage of hydrogen peroxide and solvent, reaction time and reaction temperature on conversion of furfural and yield of maleic anhydride were investigated. The results showed that the catalytic performance was excellent using MoWP/SiO2 as the catalyst, and the optimal reaction conditions were as follows: the reaction temperature 60 ℃, the reaction time 3 h, the mass ratio of catalyst to furfural 0.09, the molar ratio of dichloroethane to furfural 3, and the molar ratio of H2O2 to furfural 2.5. Under these optimal reaction conditions, the conversion of furfural was 82.33%, the yield and the selectivity of maleic anhydride were 78.51% and 95.36%, respectively. The yield of maleic anhydride remained 64.18% over the catalyst reused 5 times.
