Efficient catalytic removal of COS and H₂S over graphitized 2D micro-meso-macroporous carbons endowed with ample nitrogen sites synthesized via mechanochemical carbonization

Developing a suitable catalyst for the elimination of highly toxic carbonyl sulfide (COS) and hydrogen sulfide (H₂S) is of great significance in terms of industrial safety and environmental protection. We demonstrate here the facile synthesis of graphitized 2D micro-meso-macroporous carbons by one-step carbonization of a mixture of urea and glucose at 700–900 ℃. The as-synthesized graphitized catalysts, designated as 2D-NHPC-x (x = urea/glucose mass ratio), are endowed with an ultra-high concentration (12.9–20.2 wt%) of stable and versatile nitrogen sites (e.g. pyrrole and pyridine) which are anchored on the surface via stable covalent bonding. As a result, the 2D-NHPC-x are active in catalytic hydrolysis of COS on pyrrolic N to H₂S, and the H₂S can be subsequently captured on pyridinic N and converted to elemental sulfur at ambient conditions over the same materials. Among the prepared catalysts, 2D-NHPC-x can catalytically hydrolysize 91% of COS to H₂S at 30 ℃, whereas the conversion ratio over the common catalysts g-C₃N₄ and Fe₂O₃ are below 6.0%. Furthermore, these catalysts also exhibit H₂S conversion and sulfur selectivity of nearly 100% at 180 ℃ with long-time durability, which is higher than those of the most reported carbon-based catalysts. In contrast, the H₂S capacities of activated carbon, ordered mesoporous carbons (OMC) and N-doped OMC are 3.9, 1.5 and 2.39 mmol g^-1, respectively. Both the experimental and theoretical results are disclosed that 2D-NHPC-x are superior to the nitrogen-doped porous materials ever applied in simultaneous catalytic elimination of both COS and H₂S.