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

Abstract

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.