Efficient continuous dehydration of fructose to 5-hydroxymethylfurfural in ternary solvent system

• HMF was continuously synthesized by Amberlyst-catalyzed dehydration of fructose. • The composition and proportion of organic solvents in the system were essential. • Adding dioxane in aqueous phase increased the hydrogen bonding affinity with fructose. • The extraction of HMF to organic phase inhibits the unfavorable side reactions. • 93% selectivity and 84% yield of HMF was obtained in biphasic ternary solution. Biomass-derived 5-hydroxymethylfurfural (HMF) has been identified as a versatile precursor for clean fuels and degradable polymers. Here, we developed an efficient flow-through system to continuously produce HMF in high selectivity from fructose dehydration. Effects of solvent, the relative ratio of aqueous to organic phase, the proportion of different cosolvents in the organic phase as well as the reaction variables on reactivity of fructose dehydration to HMF were comprehensively investigated to obtain the optimal results. The conduction of a H 2 O/dioxane/methyl isobutyl ketone (MIBK) ternary solvent system in combination with Amberlyst 70 as catalyst contributed to 93 % selectivity and 84 % yield of HMF in residence time as short as 1.6 min. The strengthened hydrogen bonding interactions by the addition of dioxane accounted for an increase in the interactions of fructose with water and cosolvent molecules, accelerating the dehydration rate. Meanwhile, the in-situ extraction of HMF from active aqueous phase to organic phase by MIBK protected it from unfavorable side reactions. The reaction system exhibited good stability without significant change on the catalytic performance over 10 h reaction. Additionally, fructose was selectively dehydrated from fructose-glucose mixtures, holding great promises for the integration with the industrial operations producing mixture of sugars (such as fructose corn syrup).