Preparation of 5-(hydroxymethyl)furfural by the catalytic degradation of cellulose in an ionic liquid/organic biphasic system

Abstract

This work has established the optimum reaction conditions in a biphasic system using microcrystalline cellulose as the raw material, an ionic liquid as the solvent, metal chloride as a catalyst, and an organic solvent as the extraction reagent. The optimum reaction conditions were microcrystalline cellulose:ionic liquid - 1:10 (mass ratio), chromium(III) chloride (CrCl3) - 6.8 mol% (based on the glucose unit of cellulose molecule), reaction time - 3 h, temperature - 130 °C, and mass ratio of 1-butyl-3-methyl-imidazolium chloride ([BMIM]Cl) to methylbenzene - 1:4.4]. Under these conditions, the yields of glucose and 5-(hydroxymethyl)furfural (5-HMF) were 27% and 55%, respectively. The solvent [BMIM]Cl could be reused twice. The first recovery rate of [BMIM]Cl was approximately 70.9%. The product 5-HMF was obtained in 64.7% yield, which decreased after the first [BMIM]Cl recycling. The second recovery rate of [BMIM]Cl was 45%. The yield of 5-HMF was 39.6%, which decreased after the second recycling of [BMIM]Cl. In this paper, the energy consumption, operation, reutilization of [BMIM]Cl, and product yields of a one-phase system and a biphasic system were compared. Experimental results demonstrated that the biphasic solvent system was suitable for the degradation of cellulose to glucose and 5-HMF.