Facile Preparation of Biomass-Derived Mesoporous Carbons for Highly Efficient and Selective SO₂ Capture

The efficient elimination of SO₂ from flue gases and natural gases is critical for energy utilization and environmental protection. However, selecting or preparing an efficient adsorbent with a high SO₂ capacity, good selectivity, and excellent recyclability is very challenging, and the adsorption mechanism at an atomic level is still controversial. We report a facile one-step method for the synthesis of biomass-derived porous carbons with high specific surface areas (1195-1449 m² g^-1), mesoporous pore size (4-6 nm), and good SO₂ adsorption properties. Our carbon adsorbents exhibited an outstanding SO₂ adsorption capacity of 10.7 mmol g^-1 at 298 K and 1.0 bar, which is more than twice the SO₂ capacity of benchmark carbon material cs1000a (approximately 5.0 mmol g^-1) and commercial ordered mesoporous carbon CKM-3 (5.1 mmol g^-1). The new carbon adsorbents also showed unprecedented SO₂/CO₂, SO₂/CH₄, and SO₂/N₂ separation selectivities of 32, 127, and 2349, respectively, which are comparable with the best performance MOF adsorbents. Dynamic breakthrough experiments confirmed the feasibility of efficient removal of SO₂ from flue gas in an adsorbent column. Even with the presence of water vapor, clear and efficient separation of SO₂ could also be achieved with excellent recycling stability. In addition, a density function theory simulation further illustrates that-NO_x and-OH groups in the carbon frameworks provide strong interactions with SO₂ molecules. The carbon adsorbents synthesized in this work are promising for flue gas desulfurization and natural gas purification applications.