Research Progress on Catalytic Conversion of Lignin to Chemicals

ZENG Xuezhi; WANG Wenyu; HUO Minxian; QI Yi; QIU Xueqing; LIN Xuliang; QIN Yanlin

doi:10.20078/j.eep.20250211

Abstract：The escalating environmental impact of fossil fuel consumption is driving a global shift towards more sustainable energy sources.In this transition,greener energy production methods are under continuous development,with biomass emerging as a pivotal component in these mitigation strategies.Production of lignocellulosic biofuels has seen significant advancements in recent years.Several biofuel processes leveraging the bioconversion of the cellulosic fraction of pretreated biomass are advancing towards commercial scale-up.However,to enhance the economic viability of these processes,it is crucial to valorize the underutilized lignin fraction.Lignin,as a naturally abundant and renewable aromatic biomass resource,is increasingly seen as a viable alternative to fossil resources and industrial raw materials,garnering widespread attention from both academia and industry.Currently,lignin is primarily used for combustion to generate process heat.However,these traditional routes fail to fully harness its potential value and contribute to environmental issues.Employing lignin as a feedstock for producing aromatic chemicals could lead to greater economic benefits.In the context of carbon peak and carbon neutrality policies,the development and utilization of lignin have become a major research focus.Catalytic conversion of lignin into high-value-added chemicals,such as phenolic compounds and biofuels,presents an effective pathway to enhance its value.However,challenges persist due to lignin's stable structure and complex spatial configuration,resulting in condensation polymerization and the formation of byproducts during its catalytic conversion.These factors result in low reaction conversion rates and selectivity,hindering the large-scale application of lignin depolymerization.Consequently,a significant challenge lies in developing efficient catalytic conversion strategies that can precisely control bond breaking and inhibit the polycondensation of reaction intermediates,enabling the efficient transformation of lignin into fine chemicals.Recently,various lignin depolymerization and upgrading strategies have been proposed,including thermocatalysis,electrocatalysis,photocatalysis,microwave-assisted catalysis,and ultrasonic catalysis.This review comprehensively overviews the latest progress in catalytic conversion technology,focusing on process types,catalyst development,and target products.It also explores the key issues governing reaction pathways and mechanisms,offering valuable insights to researchers.Finally,the review explores the prospects and challenges of lignin depolymerization and upgrading strategies,providing a forward-looking perspective on this important field of study.