Feasibility of enhancing production of 5-hydroxymethylfurfural using deep eutectic solvents as reaction media in a high-pressure reactor

Abstract

5-hydroxymethylfurfural (HMF) is a versatile biomass-derived chemical for synthesizing useful compounds. In this work an attempt is made to produce HMF by developing a low-cost process for doing that using cellulosic waste and deep eutectic solvents (DESs). The most effective DES was choline chloride/citric acid (ChCl/citric acid, 2/1), which provided a greater glucose conversion percentage (around 100 mol%), HMF yield (8 mol%), and HMF selectivity (8 %) than other DESs with 0.1 g of pure glucose. To increase the HMF yield further, the species of catalyst, reaction time and reaction temperature were varied. The highest glucose conversion percentage (91.76 mol%), HMF yield (15.02 g/g) and HMF selectivity (8%) were obtained with a reaction time of five minutes, a reaction temperature of 130 ℃, sulfuric acid as the catalyst, and a ChCl/citric acid ratio of the DES of 2/1. These optimal conditions were used with the enzymatic hydrolysate of pretreated wood dusts as a substrate. The experimental results thus obtained revealed a glucose conversion percentage, HMF yield and HMF selectivity of 34.86 mol%, 16.46 g/g and 67.43 %, respectively, under these conditions. These results reveal that using enzymatic hydrolysate from pretreated wood in the production of HMF can yield approximately as much (16.46 g/g) as the use of pure glucose, indicating that this low-cost process may be commercially feasible.