Lignin-derived N–Mg-functionalized porous carbons: Toward efficient CO2 capture and utilization

The rising concentration of atmospheric CO 2 calls for efficient and sustainable carbon capture technologies. Biomass-derived porous carbons have emerged as eco-friendly alternatives to traditional CO 2 adsorbents. In this study, a novel N-Mg-functionalized lignin-derived porous carbon (N-Mg-Lignin) was developed using amine functionalization and MgCl 2 -assisted activation, utilizing lignin as a sustainable carbon source. MgCl 2 played a dual role as both activation agent and metal precursor, promoting the formation of a microporous structure with high surface area (818 m 2 /g) and excellent CO 2 adsorption capacity (3.02 mmol/g at 25 °C, 1 bar). Characterization by BET, XRD, Raman, and XPS confirmed the presence of Mg-based species (MgO and MgCO 3 ), which contributed to Lewis acid-base interactions and additional CO 2 binding sites. Compared to aminated lignin (N-Lignin), the N-Mg-Lignin demonstrated superior performance, attributed to enhanced porosity and the catalytic role of Mg species. Nitrogen doping combined with magnesium incorporation synergistically improved the CO 2 adsorption capacity of the material. This work underscores the viability of converting lignin waste into high-performance CO 2 adsorbents, aligning with goals of climate change mitigation and circular economy strategies.