Efficiently Selective Oxidation of H₂S to Elemental Sulfur over Covalent Triazine Framework Catalysts

As a highly toxic and corrosive waste gas in the industry, hydrogen sulfide (H₂S) usually originates from the utilization of coal, petroleum, and natural gas. The selective catalytic elimination of H₂S shows great significance to ensure the safety of industrial processes and health of human beings. Herein, we report efficiently selective oxidation of H₂S to elemental sulfur over covalent triazine framework (CTF-1-x, x = 400, 500, 600, 400-600 °C) catalysts. CTF-1-x samples were prepared from polymerization of 1,4-dicyanobenzene to form polyaryl triazine networks under ion solidothermal conditions in the presence of ZnCl₂, which acts as both an initiator and a porogen. The resultant CTF-1-x samples possess abundant micro-mesoporosity, large Brunauer-Emmett-Teller (BET) surface areas, and tunable structural base sites with edge amine and graphitic nitrogen characteristics, which were homogeneously decorated onto their frameworks. As a result, CTF-1-x samples act as efficient and long-lived catalysts in selective oxidation of H₂S to sulfur under ambient conditions (100% H₂S conversion, 100% sulfur selectivity at 180 °C, 12 000 mL/(g·h)), and their activities were superior to those of commercial Fe₂O₃ and g-C₃N₄ desulfurization catalysts. Abundant nitrogen structural base sites of CTF-1-x effectively activate the reactants, and abundant micro-mesoporosity facilitates mass transfer in and out of CTF-1-x. The improved design of the nitrogen-doped carbon material for H₂S activation and conversion could enhance the development of more active and robust nitrogen-doped carbon catalysts.