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Chemistry and Industry of Forest Products ›› 2020, Vol. 40 ›› Issue (5): 17-26.doi: 10.3969/j.issn.0253-2417.2020.05.003

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Conversion of Hexose to 5-Hydroxymethylfurfural Catalyzed by Phosphated Binary Ti-Zr Oxide

Yuan ZHAO,Yang QU,Lingjun ZHU,Hao XU,Kaifeng LU,Shurong WANG*()   

  1. State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
  • Received:2020-04-04 Online:2020-10-28 Published:2020-10-31
  • Contact: Shurong WANG E-mail:srwang@zju.edu.cn

Abstract:

5-hydroxymethylfurfural (HMF), an important precursor for biofuel production, can be prepared via dehydration of carbonhydrates such as cellulose. In this study, titanium tetraisopropanolate and zirconium n-butoxide with different molar proportion were used as the precursor to prepare binary oxides (TiZrO). Phosphorus was introduced to enhance the acidity of catalyst and to obtain TiZrPO. TiZrPO-1, TiZrPO-2 and TiZrPO-3 catalysts were prepared, when n(Ti):n(Zr) was 7:3, 1:1 and 3:7, respectively. The structures of these catalysts were characterized by XRF, STEM, FT-IR and NH3-TPD, and the catalytic performance for the conversion of fructose and glucose to HMF was tested. The characterization results suggested that Ti, Zr and P distributed evenly in the catalysts. Moreover, the distribution of Brønsted acid and Lewis acid could be controlled by adjusting the value of n(Ti):n(Zr). When n(Ti):n(Zr) was 1:1, the amount of Brønsted acid reached the maximum (2.55 μmol/g) in TiZrPO-2, and the corresponding Brønsted acid to Lewis acid ratio (0.49) was also the highest. The catalytic performance of TiZrPO on the conversion of fructose and glucose showed that, among the three catalysts, TiZrPO-2 had the best catalytic performance with 98.5% conversion of fructose and 76.5% yield of HMF at 40 min, and 72.2% conversion of glucose and 38.1% yield of HMF at 180 min; when TiZrPO-2 was recycled and reused for 4 times, the conversions of fructose and glucose still reached as high as 92.7% and 65.8%, respectirely. While the corresponding HMF yields were 72.6% and 30.4%, respectively, which indicated that TiZrPO-2 had satisfying reusability. According to the product analysis for fructose, levoglucosan, etc., it was found that Lewis acid could promote the conversion of glucose to fructose, while side reactions involving fructose was also favored. Brønsted acid could accelerate the dehydration of glucose to levoglucosan, and it also catalyzed the direct dehydration of fructose and glucose to HMF.

Key words: fructose, glucose, 5-hydroxymethylfurfural, metal oxide, phosphate

CLC Number: