Hierarchical N-Doped Carbons Endowed with Structural Base Sites toward Highly Selective Adsorption and Catalytic Oxidation of H2S

H2S catalytic elimination via selective oxidation process has received considerable attention because it can transform highly toxic H2S into elemental sulfur under mild condition without thermodynamic limitation. For this purpose, catalysts with high performance in H2S capture and selective oxidation are urgently needed. Herein, we report novel nitrogen-doped carbon-based catalysts (denoted as PPy-KOH-T), which are synthesized by direct carbonization of polypyrrole at 600-800 degrees C using KOH as an activator. The obtained PPy-KOH-T shows large specific surface areas (1116-3157 m(2)/g), hierarchical structure, and abundant nitrogen active sites. As a result, PPy-KOH-T exhibits high performance in H2S selective capture. The H2S adsorption capacity of PPy-KOH-700 is as high as 19.7 mmol/g (0 degrees C, 1 bar), and the ideal adsorption solution theory (IAST) selectivity of H2S/N-2 is up to 117.6, which is much better than that of activated carbon (4.8). It is found that PPy-KOH-T could completely catalyze the oxidation of H2S into elemental sulfur at temperatures as low as 150 degrees C. It can be applied to the purification of high-sulfur natural gas and blast furnace gas and the recovery of elemental sulfur. Significantly, the as-prepared catalyst displays superior long-term stability in the desulfurization reaction compared with g-C3N4 and commercial Fe2O3.