Lignin-based hyper-crosslinked polymers with abundant ionic sites for effective conversion of CO₂ in simulated flue...

To achieve the dual goals of utilizing renewable biomass resources and mitigating greenhouse gas emissions, we report a previously unexplored lignin-based hypercrosslinked ionic polymer platform constructed via Friedel-Crafts alkylation of lignin, α,α'-dichloro-p-xylene (DCX), and an ionic monomer bearing multiple ionic sites. Distinct from conventional lignin-derived catalysts, this strategy enables the simultaneous integration of abundant ionic sites and intrinsic lignin hydroxyl groups within a porous framework, creating a multifunctional catalytic microenvironment for CO₂ conversion. Benefiting from the synergistic cooperation among dense ionic sites, lignin-derived hydroxyl groups acting as hydrogen-bond donors, and nucleophilic species, HIP[IL-6-DCX-Lignin-OH]Br exhibited the highest catalytic efficiency. Notably, HIP[IL-6-DCX-Lignin-OH]Br maintained excellent activity for CO₂ cycloaddition under simulated flue gas conditions (85% N₂/15% CO₂), achieving up to 93% yield of styrene carbonate at 110 °C and 1 bar over 24 h. Furthermore, the presence of trace SO₂ and H₂O exerted negligible influence on the catalytic performance, highlighting the unusual tolerance of lignin-based porous catalysts toward realistic flue gas components. Multigram-scale reactions (10-50 mmol) further confirmed the robustness and scalability of this catalytic system. In situ DRIFTS investigations provided mechanistic insights into the cooperative activation of CO₂ and epibromohydrin. This study establishes a previously unexplored lignin-based porous catalytic platform in which abundant ionic sites and intrinsic hydrogen-bond donors are synergistically integrated, enabling efficient CO₂ conversion under simulated flue gas conditions.