Nitrogen-Decorated, Ordered Mesoporous Carbon Spheres as High-Efficient Catalysts for Selective Capture and Oxidation of H₂S

Hydrogen sulfide (H2S) is highly toxic and corrosive, and its selective removal from fuel and flue gases is of significance. It is a challenge to develop a dual-role material for efficient H2S capture as well as selective H2S oxidation. In the present work, we designed a class of nitrogen-decorated ordered mesoporous carbon spheres (denoted herein as N-OMCS-T, where T stands for carbonization temperature) for such an end. The N-OMCS-T with ordered mesopores are large in BET surface area (1201–1500 m2/g), and enriched with nitrogen sites of pyridinic and pyrrolic nature, and exhibit strong interaction with H2S as verified in DFT calculations. With large BET surface areas, ordered mesopores, and abundant nitrogen sites, the N-OMCS-T materials show extraordinary efficacy for the capture of H2S: H2S capacities are up to 13.4 mmol/g (0 °C, 1 bar), and the Ideal Adsorption Solution Theory selectivity in cases of H2S/​CO2, H2S/​CH4, and H2S/​N2 is 2.1–8.5, 11.0–25.5, and 30.4–81.7, respectively, much higher than those of porous materials such as activated carbon, OMCS, Zeolite A, UiO-66, and SBA-15. Moreover, N-OMCS-T could act as efficient and long-lived metal-free catalysts for selective oxidation of the captured H2S to sulfur under mild conditions