Recent Advances in Lignin Depolymerization Techniques: A Comparative Overview of Traditional and Greener Approaches

Due to the increased and excessive consumption of fossil fuels, sustainable alternative energy sources are badly needed replace fuels. The conversion biomass into value-added chemicals is one most promising potential pathways solve this problem. Millions tons lignin, major components biomass, produced annually as a byproduct various industries, where it treated low-value material. However, since has an aromatic polymer nature, lignin proven source for different products. Studies suggest that selective cleavage specific bond complex structure challenges converting targeted product. In study, eight depolymerization methods, both traditional green, reviewed. Acid base catalytic methods straightforward, but due their low selectivity comparatively severe reaction conditions, they expensive not eco-friendly. Pyrolysis-based comes with similar problems higher conversion. contrast, greener approaches, such oxidative, microwave-assisted, super/sub-critical fluids (SCF), ionic liquid (IL), deep eutectic solvent (DES)-based techniques, have shown efficiency in terms phenolic compounds even under milder conditions. SCF, IL, DES-based approaches will likely become more popular future nature. Overall, technologies could make process economically viable sustainable.