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.