It is very challenging to achieve efficient and deep desulfurization, especially in flue gases with an extremely low SO 2 concentration. Herein, we report a microporous metal−organic framework (ELM-12) with specific polar sites and proper pore size for the highly efficient SO 2 removal from flue gas and other SO 2 -containing gases. A high SO 2 capacity of 61.2 cm 3 •g −1 combined with exceptionally outstanding selectivity of SO 2 /CO 2 (30), SO 2 /CH 4 (871), and SO 2 /N 2 (4064) under ambient conditions (i.e., 10:90 mixture at 298 K and 1 bar) was achieved. Notably, the SO 2 /N 2 selectivity is unprecedented among ever reported values of porous materials. Moreover, the dispersion-corrected density functional theory calculations illustrated the superior SO 2 capture ability and selectivity arise from the high-density SO 2 binding sites of the CF 3 SO 3 − group in the pore cavity (S δ+ •••O δ− interactions) and aromatic linkers in the pore walls (H δ+ •••O δ− interactions). Dynamic breakthrough experiments confirm the regeneration stability and excellent separation performance. Furthermore, ELM-12 is also stable after exposure to SO 2 , water vapor, and organic solvents.

High N-content porous carbons are successfully synthesized from shrimp-shells as an appropriate solid adsorbent for CO 2 capture and CO 2 /N 2 (fuel gas), CO 2 /CH 4 (biogas), and CH 4 /N 2 (coalbed gas) binary mixture separation. The resultant porous carbons exhibited a welldeveloped pore texture (specific surface area up to 1984.7 m 2 g −1 , pore volume up to 1.00 cm 3 g −1 ) and a high N-content up to 5.06 wt %. These favorable properties of carbon led to excellent CO 2 adsorption capacities of 6.82 and 4.20 mmol g −1 at 1 bar, 273 and 298 K, respectively. The different pore sizes govern the CO 2 adsorption at low/high temperatures. Furthermore, superior separation selectivities for binary gas mixture pairs (CO 2 /N 2 = 47, CO 2 /CH 4 = 8, and CH 4 /N 2 = 5, at 298 K and 1 bar) were predicted by the IAST model. The N functionality and pore volume affect the gas-mixture selectivity. The outstanding adsorption and separation performances coupled with effective transient breakthrough behavior make these porous carbons potent adsorbents for commercial applications. This work has developed a promising solution for converting biowastes into a high-value product for environmental and energy applications.

It is very challenging to prepare biomass-derived porous carbons with well-confined ultramicropores. Traditionally, biomass-derived carbons, via a chemical activation process, possess wide pore size distributions from micropores to macropores. Outstanding BET surface area of 2676 ± 107 m2 g–1 was obtained with excellent CO2 uptake of 6.15 and 2.26 mmol g–1 under 1 and 0.15 bar at 273 K. Furthermore, the outstanding CO2/N2, CO2/CH4, and CH4/N2 selectivities of 43.5, 7.4, and 5.9 were obtained on an OTS-1-550 at 298 K and 1 bar. The pore size effect on CO2 capture and gas-separation performance was carefully investigated, indicating that the ultramicropores (<1 nm) governed the CO2 adsorption capacity at 1 bar. Also, the vacuum swing adsorption (VSA) processes and breakthrough experiments have confirmed their practical application potential.

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