Microscopic functionality of FeN4 sites in polymeric carbon nitride for efficient H2S oxidation

Abstract

The development of the low-cost and efficient catalysts for H2S removal is essential and provides an alternative to the traditional Claus process. However, the microscopic mechanism of thermocatalysis for H2S selective oxidation has rarely been systematically studied. Herein, we report the microscopic mechanism of H2S selective oxidation on the single atom Fe-doped carbon nitride (Fe@CN) by the density functional theory (DFT) calculations. The results indicate that Fe atom prefers to form FeN4-CN with the barrier of 0.48 eV for H2S selective oxidation, which agrees well with the experimental results. Furthermore, a new quasi Mars–van Krevelen (quasi-MvK) mechanism including extracting and refilling the proton on Fe@CN is determined. Overall, this work reports the mechanism for selective oxidation of H2S into elemental S at the atomic scale, which provide theoretical insights into the design and development of highly reactive and selective catalysts for H2S oxidation.