Oxygen-deficient Fe₂O₃ bearing pyridine n moieties for spatially decoupled selective H₂S oxidation into sulfur at...

Catalytic oxidation of H₂S is crucial for purifying coke oven gas (COG), yet achieving high sulfur selectivity with robust long-term stability remains challenging, particularly at intermediate temperatures (100-150 °C) ideal for thermal integration with upstream COG hydrolysis. Conventional α-Fe₂O₃ catalysts typically require high operating temperatures exceeding 200 °C and exhibit poor sulfur selectivity, often leading to excessive sulfur oxidation and sulfate formation. Herein, we report an oxygen-deficient iron oxide (Fe₂O₃) coated with nitrogen-doped carbon layer (NC@Fe₂O₃-OVs) for stable and continuous H₂S oxidation at 120 °C for over 40 h, delivering a sulfur capacity of 772.2 mg S g_cat^-1 and an impressive sulfur selectivity of 96.2 %, far outperforming pristine Fe₂O₃ (7.88 mg S g_cat^-1 and 82.2 % selectivity). Oxygen vacancies within the Fe₂O₃ core, as electron-rich centers, strengthen the O₂ adsorption and activation, while the coated N-doped carbon, bearing pyridine N moieties, favors moderate H₂S adsorption through hydrogen bonding. This spatial decoupling of O₂ activation and H₂S adsorption on distinct active sites directs the selective H₂S oxidation to sulfur and facilitates its rapid desorption, contributing to enhanced operational stability by mitigating detrimental sulfate formation. This demonstration of a highly selective and stable catalyst architecture offers a promising and scalable approach toward energy-efficient COG purification in industrial settings.