Organosolv processing of vine shoots: fractionation and conversion of hemicellulosic sugars into platform chemicals by microwave irradiation

Abstract

Vine shoots were subjected to a mild aqueous extraction (to remove water-soluble extractives), and the extracted solids were reacted in catalyzed media (containing water and 1-butanol) to achieve the one-stage solubilization of lignin and hemicelluloses, yielding a cellulose-rich solid. Operating in a microwave-heated reactor under optimized conditions (190 °C in media containing 2% of catalyst and 52% 1-butanol), 67.8% lignin was dissolved, and solids containing 75% cellulose were obtained. Lignin was recovered from the reaction medium and characterized, whereas the hemicellulose-derived products present in the aqueous phase (obtained under conditions leading to maximum concentrations of 17.7 g pentoses/L) were converted into furfural at 64.6% molar yield by acidic processing in the presence of recycled 1-butanol.