Recent advances of lignin valorization techniques toward sustainable aromatics and potential benchmarks to fossil refinery products

[Display omitted] •Functionalities and potential values of petroleum and biorefinery aromatics were compared.•Important linkages that offer lignin particular characteristics in valorization were overviewed.•Valuable lignin products derived from various techniques were reviewed and evaluated.•State-of-the-art fractionation and depolymerization techniques were discussed with criticism.•Future directions on technology development and economic assessment were summarized. Aromatic compounds are important fuels and key chemical precursors for organic synthesis, however the current aromatics market are mainly relying on fossil resources which will eventually contribute to carbon emissions. Lignin has been recognized as a drop-in substitution to conventional aromatics, with its values gradually realized after tremendous research efforts in the recent five years. To facilitate the development of a possible lignin economics, this study overviewed the recent advances of various biorefinery techniques and the remaining challenging for lignin valorization. Starting with recent discovery of unexplored lignin structures, the potential functions of lignin related chemical structures were emphasized. The important breakthrough of lignin-first pretreatment, catalytic lignin depolymerization, and the high value products with possible benchmark with modern aromatics were reviewed with possible future targets. Possible retrofit of conventional petroleum refinery for lignin products were also introduced and hopefully paving a way to progressively migrate the industry towards carbon neutrality.