Isolated iron sites embedded in graphitic carbon nitride (g-C3N4) for efficient oxidative desulfurization

Abstract

Iron-based catalysts are promising for the catalytic oxidation of H2S owing to their non-toxicity, abundance, and high conversion efficiency. However, their industrial applications are hampered by the low selectivity and poor durability. Herein, we reported a simple one-step pyrolysis approach to synthesize isolated Fe–Nχ sites confined in graphitic carbon nitride (Fe-CN-NHχ). The creation of isolated Fe–Nχ sites was evidenced by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray absorption spectroscopy (XAS), UV–vis-NIR diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS). The well dispersed Fe–Nχ sites offer additional active centers for the reaction, and such form of Fe presence effectively resists the deep oxidation of H2S. As a result, the obtained Fe-CN-NH5 catalyst exhibited outstanding catalytic performance with high sulfur selectivity. Significantly, the Fe–Nχ sites are resistance to sulfur poisoning, leading to excellent durability in the reaction. No obvious decrease of catalytic activity was observed in a reaction period of 180 h, which is better than those of reported iron-based catalysts.