Sulfur modified N-doped carbocatalysts promote the selectivity for H2S selective oxidation

Sulfur element is widely applied as a non-metallic dopant into carbon framework for the modulation of their chemical activities. An interesting question is whether the intrinsic catalytic performances for the H 2 S selective oxidation to sulfur can be manipulated by sulfur element introduction into carbocatalysts. In this study, we employ a simple solvent-free method to introduce S atoms into framework of N-doped carbocatalysts, resulting in a notable enhancement of the product S selectivity with negligible loss of H 2 S selective oxidation. The experimental results show that the as-synthesized N-S-C-2 catalyst exhibits a H 2 S conversion of 97.5 % and sulfur selectivity of >80 % at a high O 2 -to-H 2 S ratio (2.5) under continuous mode (over the dew point temperature of sulfur, c.a. 210 °C), while also demonstrating robust stability (> 100 h), anti-CO 2 (up to 50 vol%) and anti-oxidation properties. Kinetic analysis and H 2 S/O 2 -TPD-MS results reveal that S introduction attenuates the adsorption and dissociation of H 2 S and O 2 by the N-doped carbon catalyst. Furthermore, density functional theory calculations elucidate that S doping elevates the adsorption energies of H 2 S and O 2 at the pyridinic N site, thereby moderately reducing the adsorption of H 2 S and O 2 , consequently preventing the over-oxidation of H 2 S to SO 2 and enhancing S selectivity. The double doping promotion effect of carbon materials reported in this investigation offers an alternative insight for the development of highly selective carbon desulfurization catalysts.