Reductive catalytic fractionation as a novel pretreatment/lignin-first approach for lignocellulosic biomass valorization: A review

Presently, the use of lignocellulosic biomass is mainly focused on creating pulp/paper, energy, sugars and bioethanol from the holocellulose component, leaving behind lignin to be discarded or burned as waste despite of its highest aromatic carbon and energy content (22-29 KJ/g). During the pulping process, lignin undergoes significant structural changes to yield technical lignin. For a circular bioeconomy, there is an urgent need to enhance the use of native lignin for generating more valuable products. Over the last few years, a new method called 'lignin-first', or 'reductive catalytic fractionation' (RCF), has been devised to achieve selective phenolic monomers under mild reaction conditions. This involves deconstructing lignin before capitalizing on carbohydrates. The objective of this study is to record the recent developments of the 'lignin-first' process. This review also underlines the contribution of RCF biorefinery towards achieving sustainable development goals (SDGs) and concludes with an overview of challenges and upcoming opportunities.

Automated summary

Currently, the main focus of using lignocellulosic biomass is to produce pulp/paper, energy, sugars, and bioethanol, disregarding the high content of aromatic carbon and energy in lignin. The 'lignin-first' or 'reductive catalytic fractionation' (RCF) process has been developed in recent years to selectively produce phenolic monomers from lignin under mild reaction conditions. This study aims to review the recent developments of the 'lignin-first' process and highlights the contribution of RCF biorefinery towards achieving sustainable development goals (SDGs), concluding with an overview of challenges and upcoming opportunities.