Dehydration of Mannitol Catalyzed by Oxide Supported Phosphotungstic Acid
CHEN Hanming1,2, MO Xuekun3, ZHENG Yanchun4, XU Bingbing3, HOU Mingxuan1, GE Junxiao1, ZHU Mingqiao1,2
1. College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310058, China;
2. Institute of Zhejiang University-Quzhou, Quzhou 324000, China;
3. Zhejiang Zhenghe Fluid Technology Company Limited, Hangzhou 310014, China;
4. Quzhou Juhua Polyamide Fibre LLC, Quzhou 324000, China
Abstract A series of supported catalysts with different loading amounts were prepared by impregnating Keggin-type phosphotungstic acid onto SiO2, TiO2, ZrO2, and Al2O3 carriers. Characterization methods such as infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and temperature programmed desorption (NH3-TPD) were used to analyze the catalyst. The performance of the prepared catalysts in the dehydration of mannitol was studied under solvent-free and depressurized conditions. The effects of catalyst carrier type, phosphotungstic acid loading, reaction time, reaction temperature, and catalyst dosage on the conversion of mannitol and dehydration products were investigated. The results showed that the 30% PW/SiO2 catalyst exhibited superior catalytic performance. The optimal process conditions were a catalyst to mannitol mass ratio of 0.03, a reaction temperature of 170 ℃, a reaction time of 2 h, and a vacuum degree of 0.09 MPa. Under these conditions, the conversion of mannitol was 100.0%, the yield of 2,5-sorbitan was 55.7%, the yield of 1,4-mannitan was 9.7%, the yield of isomannide was 25.9%, and the yield of other components was 8.5%.
