Wood biorefinery based on γ-valerolactone/water fractionation†
A novel biorefinery concept based on the fractionation of woody biomass in a γ-valerolactone (GVL)/water binary mixture is introduced. Under optimal GVL/water ratio, Eucalyptus globulus wood was effectively fractionated in a single step into its principal components. The pulp fraction, characterized by high yield, high cellulose purity and high bleachability, was directly spun to produce regenerated cellulosic fibers with mechanical properties comparable to the best man-made fibers currently available in the market. Most of the hemicelluloses and lignin in wood were extracted and dissolved into the spent liquor. The dissolved hemicellulose-based fraction may be upgraded to furanic platform chemicals in subsequent catalytic conversion processes. About 50–60% of the extracted lignin was precipitated by the addition of water, an anti-solvent. The precipitated lignin was characterized by low carbohydrate and ash contamination, high phenolic content, relatively low polydispersity and low molecular mass. The lignin extracted by GVL/water fractionation may thus be suitable for a wide range of energy, material or chemical applications.