Effective conversion of biomass into bromomethylfurfural, furfural, and depolymerized lignin in lithium bromide molten salt hydrate of a biphasic system

Abstract

A novel approach using a biphasic system consisting of a molten lithium bromide hydrate solution (LiBr·3H₂O) and an organic solvent was developed to efficiently produce furan-based chemicals from cellulose and lignocellulosic biomass. At 125 °C for 2 h, the yield of bromomethylfurfural (BMF) from cellulose reached >90% (molar yield), and the yields of furfural (FF) and BMF from real biomass (herbage, hardwood, and softwood) were ∼70% and ∼85%, respectively. The reaction mechanisms of the polysaccharides and lignin and the role of the molten salt hydrate were investigated and elucidated. In the biphasic system, hemicelluloses and cellulose of the biomass were dissolved, hydrolyzed, dehydrated and brominated to FF and BMF, respectively, in the aqueous phase, and the furan products were simultaneously extracted into and cumulated in the organic phase. Meanwhile, lignin in the biomass was significantly depolymerized through the cleavage of β-aryl ether linkages and separated with high purity for potential coproducts.