Formic acid drives lignin valorization: Multiple pathways to value-added products

<p>Lignin represents an abundant, sustainable carbon resource for green chemicals in nature, yet its rigid polymeric structure makes it difficult to be fully utilized. Formic acid (FA) demonstrates significant potential in lignin valorization, enabling fully renewable processing strategies. This review summarizes the multifaceted roles of FA in lignin applications, including its effectiveness in lignocellulosic biomass fractionation, lignin depolymerization, and value-added transformation of lignin derivatives. The intrinsic mechanism underlying FA's function as both H- and C-containing donor is explored, alongside its potential in lignin derivative reprocessing. Through this review, we identify critical factors that require attention in future research and provide strategic insights for advancing the sustainable utilization of these renewable carbon resources.</p>