Engineering biomass-derived porous carbons for CO2 capture

Climate change has intensified the demand for sustainable CO 2 capture materials. Moreover, biomass-derived porous carbons appear attractive because of their abundant precursors, tunable pore structures, and versatile surface chemistry. This review examines how synthesis routes, structural properties, and operating conditions could shape CO 2 adsorption. Thermochemical treatment, physical and chemical activation, heteroatom doping, and heterostructure construction are compared alongside metrics that affect capacity. Selectivity, kinetics, mass-transfer resistance, particle shaping, regeneration, and cyclic stability receive attention throughout. However, multiscale simulations and machine-learning methods may be useful tools for clarifying adsorption mechanisms and linking material descriptors to process performance. Quantitative data suggest that nitrogen doping can increase CO 2 uptake by 30-60%, and high-performing biomass-derived carbons commonly exhibit micropore volumes of 0.5-0.8 cm 3 ·g −1 . Nevertheless, for carbons containing strongly basic sites, the optimal pore width may concentrate around 0.7 nm. In contrast, surfaces dominated by weaker physisorption interactions could shift the optimum to approximately 0.8-1.0 nm because doped sites occupy part of the pore space. Water vapour and flue-gas impurities reduce capacity by over 30%. BET surface area alone is therefore a poor guide to performance. More useful information comes from the amount of accessible ultramicropores, the chemical form and location of surface groups, surface wettability, and the conditions under which adsorption takes place. Further progress will require in situ studies of adsorption mechanisms, better control of co-doping, scalable preparation routes, tests using shaped sorbents, and closer integration of material design with process optimization under realistic post-combustion conditions.