Catalytic dehydration of fructose to 5-hydroxymethylfurfural over mesoporous Nb-W oxide solid acid catalyst

In this study, a mesoporous Nb-W oxide solid acid catalyst was synthesized and characterized in detail by TEM, N2 physisorption, and Py-FTIR. Effects of the calcination temperature on the pore structure and acid properties were investigated. The results showed that increasing calcination temperature from 400 degrees C to 600 degrees C remarkably affected the characteristics of mesoporous Nb-W oxides, with a decrease in specific surface area, pore volume, and acid amount, but an increase in pore size from 5.1 nm to 10.4 nm. Furthermore, a notable decrease was found in both the fructose conversion and HMF yield in the dehydration of fructose to HMF over Nb-W oxides when increasing the calcination temperature, and the catalyst could keep high catalytic activity and selectivity after recycling 4 times. Solvents also played a key role in the fructose dehydration to HMF over the Nb-W oxides, and DMSO was the optimized solvent. 1H NMR and 13C NMR experiments revealed that the key intermediate, 4-hydroxy-5-hydroxymethyl-4,5-dihydrofuran-2-carbaldehyde, could generate in DMSO but not in other solvents including NMP, DMF, DMAC, and EG.

Automated summary

A mesoporous Nb-W oxide solid acid catalyst was synthesized and characterized. The effects of calcination temperature on the pore structure and acid properties were investigated. Increasing calcination temperature led to a decrease in specific surface area, pore volume, and acid amount, but an increase in pore size. Higher calcination temperature also resulted in a decrease in fructose conversion and HMF yield, but the catalyst maintained high activity and selectivity after recycling four times. Additionally, DMSO was found to be the optimal solvent for the dehydration of fructose to HMF over the Nb-W oxides.