Recent progress towards fuels and value-added chemicals through lignin depolymerization

Abstract

Biomass fuels and chemicals through lignin depolymerization has great potential on replacing fossil oil, in which conform the international topic of green and sustainability. Orbiting the Lignin unstable transition intermediates (such as lignin C-centered radical intermediates and lignin non-radical intermediates) and exogenous radicals, many strategies have been developed to effectively depolymerize lignin into chemicals and fuels. However, lignin depolymerization utilization has bottleneck on large-scale industrial process. Industrialize products still cannot content the quality requirement. For breaking the status quo, summarizing a lignin depolymerization methods and strategies systematically is strong demand. The cleavage sites of C-C/C-O bonds and side chain which induce different radical reaction routes determine different products can be oxidized by photocatalytic, electroncatalytic and preoxidation at mild conditions. With further analysis the possibility of biomass resource on economy and technology, we hope that a controllable lignin depolymerization process, converting lignin to fuels or added-value chemicals, can be applied on large-scale industry. This paper reviews all the lignin depolymerization methods and emphasize the prospective of oxidative lignin depolymerization. Finally, we propose that the lignin oxidation depolymerization to fuels and value-added chemicals will be the most potential route for lignin utilization.