The emerging role of lignin as a platform for carbon materials in gas adsorption and separation.

Lignin, a widely produced but underutilized renewable aromatic byproduct, presents significant potential as a precursor for functional carbon materials in gas adsorption and separation. A critical analysis reveals that lignin-derived porous carbons exhibit tunable hierarchical porosity and surface chemistry, delivering competitive or superior performance in gas adsorption and separation. However, the performance consistency is fundamentally constrained by feedstock heterogeneity. This review provides a comprehensive and critical overview of recent progress in lignin-derived carbon materials for gas adsorption and separation. It examines preparation methods and functionalization strategies governing porosity, surface chemistry, and structural configuration, followed by performance and mechanisms in CO2 capture, VOC adsorption, inorganic toxic gas removal, and energy gas separation/purification. It also points out the main areas of research and development, including dealing with the variety of raw materials, creating green, low-carbon processes, improving selectivity and stability, and making large-scale use possible. These strategies may facilitate the future development of sustainable lignin-derived adsorbents for carbon capture and gas purification technologies.