Lignin-First Approach to Lignocellulosic Biomass Valorisation

The global surge in energy demand, driven by population growth, rapid industrial expansion and commerce, has triggered the depletion of fossil fuels, environmental pollution, global warming and climate change. Consequently, there is a pressing priority to reduce global carbon emissions through sustainable developmental strategies. Sustainable alternative energy sources such as lignocellulosic biomass (LCB) fulfil the current energy needs while mitigating CO 2 emissions. Nevertheless, devising a practical, economically feasible and sustainable approach for harnessing energy, extracting fuels and producing value-added products from renewable sources is still challenging. The conventional fractionation process aims to produce a cellulose-rich pulp or biofuels from the cellulose fraction of LCB at the expense of lignin, the most abundant aromatic compound in nature. The “lignin-first” approach, which prioritises targeting lignin rather than cellulose, is a suitable technique to effectively depolymerise native lignin to high yields of bio-aromatics that can improve the economic feasibility through high-value product generation and reduced waste generation while leaving behind a cellulose-rich solid residue, which can be further processed for biofuel production. This chapter presents the current state-of-the-art in lignin-first approach to lignocellulosic biomass valorisation, focusing on lignin stabilisation strategies followed by solvent depolymerisation or catalytic hydrodeoxygenation, and summarises the challenges and opportunities in the valorisation of lignin fraction of plant biomass.