One-Pot processing of Eucalyptus globulus wood under microwave heating: simultaneous delignification and polysaccharide conversion into platform chemicals

Abstract

Eucalyptus globulus (E. globulus) wood samples were treated in media containing acidified water and methyl isobutyl ketone (MIBK) in order to achieve the one-pot conversion of the hemicellulosic and cellulosic fractions into furfural and levulinic and formic and acetic acids, respectively. The reactions were performed under diverse operational conditions (180 or 190 °C, reaction times up to 70 min, liquid-to-solid ratios of 10 or 20 g aqueous phase/g wood, sulfuric acid concentrations of 0.5 or 1 g/100 g aqueous phase). Near-quantitative molar conversion of pentosans into furfural was achieved under conditions leading to limited generation of organic acids. In one-pot experiments performed under selected conditions, the overall yield of furfural and organic acids reached 45.2 g/100 g of wood. MIBK-soluble lignin was recovered from the organic phase by water precipitation at a yield of 17.4 g/100 g of wood, defining an effective method for the simultaneous delignification and polysaccharide conversion of E. globulus wood. The recovered lignin was characterized for structure (using pyrolysis–gas chromatography–mass spectrometry and heteronuclear single quantum coherence) and molar mass distribution.