The pros and cons of lignin valorisation in an integrated biorefinery

Abstract

This short critical review outlines possible scenarios for using lignin as a feedstock in a biorefinery environment. We first explain the position of biomass with respect to fossil carbon sources and the possibilities of substituting these in tomorrow's transportation fuels, energy, and chemicals sectors. Of these, the conversion of biomass to chemicals is, in our opinion, the most worthy. Focusing on lignin, we describe the four main processes for its industrial separation (the Sulfite, Soda, Kraft, and Organosolv processes). Then, we detail several short- and long-term perspectives for its valorisation to aromatics, polymers and materials, as well as new products and in-the-pipeline processes. Finally, we examine the limitations in current lignin valorisation and suggest possible ways forward. Combining the chemical aspects with up-to-date data from economic analyses gives a pragmatic and realistic overview of the commercial applications and possibilities for lignin in the coming decades, where biomass will join shale gas and crude oil as a valid and economical carbon source.