Mild fractionation of poplar into reactive lignin via lignin-first strategy and its enhancement on cellulose saccharification

Abstract

The lignin-first biorefinery approach was desirable to produce lignin-derived products by protecting the linkages of lignin and reducing condensation reaction. However, so far lignin-first strategy studies were mainly carried out under harsh conditions, causing serious destruction of lignin structure and reduction of chemically labile linkages, which was not conducive to enhance value of lignin adequately. In this work, mild fractionation of poplar via lignin-first strategy using dioxane/methanol at 80 °C was developed for purposely extracting reactive lignin with a relatively higher yield (>50%), purity (>99%), β-O-4' linkages and p-hydroxybenzoate group as compared with controlled sample. In addition, glucose yield of cellulose-rich residue under lignin-first strategy was significantly enhanced to 98.57% due to the superior cellulase adsorption abilities, which was obviously higher than the controlled group (53.88%). Overall, this mild lignin-first strategy was promising to fractionate lignocellulose into reactive lignin and fermentable glucose, thereby achieving full utilization of lignocellulose biomass.

Keywords: 2D NMR; Enzymatic hydrolysis; Lignin-first strategy; Reactive lignin.