Sustainable Lignin‐Based LaCl ₃ ‐Hypercrosslinked Polymers as High‐Efficiency Heterogeneous Catalysts for CO ₂ Cycloaddition Under Mild Conditions

ABSTRACT The utilization of CO 2 as a sustainable feedstock for synthesizing high‐value cyclic carbonates via cycloaddition with epoxides is a promising route for carbon resource utilization. However, challenges remain in developing efficient and eco‐friendly catalysts under mild conditions. Herein, we report a novel heterogeneous catalyst (HCPs‐La) fabricated by immobilizing LaCl 3 in lignin‐based hypercrosslinked polymers (HCPs), which were prepared by FeCl 3 ‐catalyzed Friedel–Crafts alkylation reaction. Characterization (FT‐IR, N 2 sorption, XRD, TGA, XPS, SEM, TEM, etc.) confirmed the amorphous porous structure, uniform elemental distribution, and thermal stability of HCPs‐La. The hierarchical porous structure of HCPs‐La, enriched with hydrogen bond donors (–OH, –COOH) and Lewis acid sites (La 3+ ), synergistically enhanced CO 2 activation and epoxide ring‐opening. Under mild conditions (80°C, 1‐MPa CO 2 , 20 h), HCPs‐La(1) achieved a remarkable yield of 99% for cyclic carbonate. The catalyst exhibited broad substrate adaptability, maintaining high efficiency for diverse epoxides, and demonstrated exceptional recyclability over six cycles without significant activity loss. This work pioneers a lignin‐driven catalytic paradigm, where renewable biomass waste is transformed into a high‐performance catalyst for CO 2 ‐to‐carbonate valorization, aligning with circular economy principles.