The Synthesis of 5-Hydroxymethylfurfural from Glucose in Biphasic System by Phosphotungstic Acidified Titanium-Zirconium Dioxide

Phosphotungstic acidified titanium-zirconium dioxide catalysts with different loading of phosphotungstic acid (HPA) were synthesized by a precipitation-impregnation method. The phosphotungstic acidified solid acids were characterized by fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), ammonia temperature programmed desorption (NH3-TPD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM) techniques. And the catalytic performance of HPA/TiO2-ZrO2 was explored for glucose degradation to 5-hydroxymethylfurfural (5-HMF) in biphasic system, such as the loading of HPA, the molar ratio of TiO2 to ZrO2, reaction time, temperature, amount of catalyst, the volume ratio of V-NaCl(aq)/V-THF and magnetic stirring speed. It was found that activity of the catalyst was related to the amount and density of acid site. The optimized yield of 51.3% for 5-HMF and the optimum conversion rate of 95.4% for glucose were achieved by 5% HPA/TiO2-ZrO2. Meanwhile, recycling performance of the catalyst was investigated. And the catalyst had good thermal stability, the yield of 5-HMF was 41.2% and the conversion rate of glucose remained at 85.4% after five cycles.