Efficient synthesis of 5-hydroxymethylfurfural by MCM-41 modified with multiple acid sites

As an important platform compound, HMF plays a role in renewable biomass utilization. In this study, an autoclave batch reactor was used to explore the effects of a solid acid catalyst on conversion of glucose to HMF in a biphasic reaction system. Using ordered mesoporous MCM-41 as a carrier, solid acid catalyst x%Al-MCM-41/S with Bronsted acid sites and Lewis acid sites was prepared through a simple method of sulfuric acid modification and cheap metal impregnation. BET, XRD, FTIR, SEM, TEM, EDS mapping, Py-IR and NH3-TPD were used to characterize the porosity, crystal structure, composition, morphology, acid sites and total acid strength of the catalyst. The effects of different stirring rates, catalysts, solvents, temperatures, times, acid properties and other factors on glucose dehydration were researched. With a moderate number of acid sites, glucose can be efficiently converted into HMF at 170 degrees C for 1.5 h, 600 rpm, in 20 wt% NaCl aqueous solution and methyl isobutyl ketone (MIBK). The yield of HMF was 64.83% and the conversion of glucose was 99.12%. Moreover, this system could efficiently convert other carbohydrates into furfural and HMF, such as xylose, fructose, mannose, galactose, sucrose and microcrystalline cellulose. This research found that the solvent and catalyst have good recyclability and the purity of the obtained HMF was as high as 99% by easy operation of rotary evaporation.

Automated summary

This study investigated the effects of a solid acid catalyst with both acid and base sites (x%Al-MCM-41/S) on the conversion of glucose to HMF in a biphasic reaction system. The results showed that glucose can be efficiently converted into HMF under suitable conditions, and the system can also effectively convert other carbohydrates into furfural and HMF. The solvent and catalyst demonstrated good recyclability, and the obtained HMF had a high purity of 99%.