Recent Advances in Catalytic Oxidative Depolymerization of Lignin to High-Value Platform Chemicals

Lignin is the most abundant renewable source of aromatic compounds and has attracted considerable industrial interest. However, owing to its complex and heterogeneous structure, as well as its recalcitrant nature, lignin has been less extensively valorized than other components of lignocellulosic biomass, such as cellulose and hemicellulose. Oxidative depolymerization has emerged as a promising strategy for converting lignin into value added chemicals. This process involves the oxidation of lignin in acidic or alkaline media using suitable oxidants and catalytic systems to produce high-value platform chemicals traditionally derived from petroleum resources. This review highlights recent advances in the oxidative depolymerization of lignin, with particular emphasis on the conversion of technical lignins into two main categories of valuable products: aromatic and aliphatic monomers. The catalytic systems and operating conditions that influence product selectivity are discussed, along with the potential of these products as renewable alternatives to fossil-derived chemicals in various industrial applications. Finally, opportunities for integrating lignin oxidative depolymerization into lignin biorefineries and pulp and paper mills are explored.