(693d) Modified Lignin for CO2 Capture, Release, and High Value Chemical Production

Climate change, largely driven by excessive carbon dioxide (CO₂) emissions, presents a critical threat to ecosystems and human society. CO₂ capture technologies offer a promising solution by enabling the removal of CO₂ from the atmosphere for storage or conversion into useful materials. In this study, we present a novel, low-cost ionic polymer derived from non-food biomass lignin for effective CO₂ capture and utilization. The polymer is synthesized by reacting lignin with glycidyltrimethylammonium chloride under alkaline conditions, introducing quaternary ammonium ionic groups. The resulting hydroxide-form ionic lignin polymer captures CO₂ efficiently from both ambient air and concentrated CO₂ streams under ambient temperature and pressure. Structural analysis is conducted using 1H, 13C, and 2D-HSQC NMR, along with FT-IR spectroscopy. The CO₂ capture mechanism involves the formation of bicarbonate ions. Quantification of the absorbed CO₂ is performed using inverse-gated 13C NMR with trioxane as an internal standard. The polymer captures up to 1.06 mmol/g (47 mg/g) CO₂ from concentrated sources and 0.60 mmol/g (26 mg/g) from ambient air. Captured CO₂ is then released in a controlled manner and utilized in the synthesis of cyclic carbonates, demonstrating its practical application. Furthermore, the ionic lignin polymer exhibits reversible CO₂ capture and release over multiple cycles without performance loss. This work introduces a sustainable and recyclable lignin-based polymer system for CO₂ capture and conversion, representing a significant advancement toward scalable, efficient carbon management technologies.