Fabrication of nitrogen-dotted lignin-based hypercrosslinked porous polymer and its pyrolytic carbonized materials for capturing CO2

Lignin, with its complex aromatic structure and numerous oxygen-containing functional groups, has potential as a precursor for gas capture applications. However, enhancing the porosity and adsorption sites in lignin-based adsorbent materials remains a challenge. In this study, we developed nitrogen-dotted lignin-based hypercrosslinked porous organic polymers (QL-HCP-II) and activated carbon (HCP-AC) through a two-step chemical synthesis process and subsequent pyrolytic carbonization, respectively, for CO 2 uptake. Initially, lignin’s phenolic hydroxyl groups were quaternized to introduce nitrogen at a concentration of 2.60 %. This nitrogen-dotted lignin was further crosslinked via Friedel-Crafts alkylation and etherification, increasing QL-HCP-II’s specific surface area from 24.98 m²/g to 75.27 m²/g and raising its maximum thermal degradation temperature from 317.6°C to 481.4°C. The nitrogen and oxygen functionalities in QL-HCP-II facilitated stronger interactions with CO₂, improving CO₂ uptake by 120 %. To enhance its performance, the lignin-based polymer was pyrolyzed and carbonized to produce HCP-AC, an activated carbon with a hierarchical pore structure and both oxygen- and nitrogen-containing functional groups. HCP-AC achieved a specific surface area of 419.21 m²/g, and its CO₂ uptake increased significantly to 97.71 mg/g. This study presents an efficient approach for synthesizing lignin-based materials, offering a promising pathway for sustainable CO₂ capture solution. • A nitrogen-dotted lignin-based hypercrosslinked polymer (QL-HCP-II) was prepared. • The specific surface area of QL-HCP-II increased by 3 times. • CO 2 uptake of QL-HCP-II increased by 120 %. • QL-HCP-II was pyrolyzed and carbonized to prepare activated carbon (HCP-AC). • The specific surface area of HCP-AC was 419.21 m²/g, and its CO 2 uptake was 97.71 mg/g.