Continuous Process for HMF Production from Cellulose with Ionic Liquid ([BmIm]Cl)-Water Mixtures

Abstract

Hydroxymethylfurfural (HMF) is a platform compound that can be derived from cellulose for coming biomass society. It is known that the formation of HMF from cellulose is a three-step reaction: (1) hydrolysis of cellulose into glucose, (2) glucose isomerization to fructose and (3) fructose dehydration to HMF. Reactions 1 and 3 are acid-catayzed and reaction 2 is base-catalyzed. To increase the yield of HMF, optimization of each reaction step is necessary. To develop a total process for conversion of cellulose into HMF step 2 (glucose isomerization) was optimized in the presence of water and the effect of water on step 3 was investigated. For isomerization of glucose in the presence of 35 wt% of water in [BmIm]Cl, magnesium carbonate was the most effective base additive (23.1 mol% fructose yield with 85.3 mol% selectivity) for reaction conditions of 120 °C for 30 min reaction time. For dehydration of fructose into HMF with Amberlyst 15, the rate of dehydration of fructose was reduced by adding water and the existence of glucose was negligible for the rate of dehydration of fructose. Finally, continuous HMF production process via three-step reaction is proposed and the yield of HMF from cellulose is estimated to be 32 mol%.