Mechanochemical-assisted production of 5-hydroxymethylfurfural from high concentration of cellulose

Direct production of the platform chemical 5-hydroxymethylfurfural (5-HMF) from cellulose is challenging due to the rigid structure of cellulose. Herein, 5-HMF was effectively obtained from cellulose with high loading concentrations (> 20 wt.%) via an Al2(SO4)3-assisted mechanochemical method. The Al2(SO4)3 not only acted as catalyst for its Lewis and Bronsted acidity, but also assisted the disruption of the hydrogen bonds among cellulose molecules during ball milling pretreatment. The particle size and crystallinity of the cellulose greatly decreased after Al2(SO4)3-assisted ball milling pretreatment. The effects of various factors, including the organic solvent, reaction temperature and time, catalyst dose, and substrate concentration, on the yield of 5-HMF from cellulose were studied. A yield of 5-HMF up to 43.5% was obtained from cellulose via the developed mechanochemical-assisted method. A 36.1% yield of 5-HMF was retained when the initial cellulose loading concentration was as high as 21.6 wt.%. The green and efficient mechanochemical-assisted method was applicable to the efficient coproduction of 5-HMF and furfural from several waste biomass feedstocks.