Reusable Salt-template Strategy for Synthesis of Porous Nitrogen-rich Carbon Boosts H2S Selective Oxidation

Abstract

Removing hydrogen sulfide (H₂S) via the selective oxidation has been considered an effective way to further purify the indusial sulfur-containing due to it can completely transform residual H₂S into elemental sulfur. While N-doped porous carbon was applied to H₂S selective oxidation, a sustainable methodology for the synthesis of efficient and stable N-doped carbon catalysts remains a difficulty, limiting its future development in large-scale applications. Herein, we present porous, honeycomb-like N-doped carbon catalysts with large specific surface areas, high pyridinic N content, and numerous structural defects for H₂S selective oxidation prepared using reusable NaCl as the template. The as-prepared NC-10-800 catalyst exhibits excellent catalytic performance (sulfur formation rate of 784 g_sulfur·kg_cat.^-1·h^-1), outstanding stability (> 100 h), and excellent anti-water vapor, anti-CO₂ and anti-oxidation properties, suggesting significant potential for practical industrial application. The characterization results and kinetic study demonstrate that the large surface areas and structural defects created by the molten salt at high temperature enhance the exposure of pyridinic N sites and thus accelerate the catalytic activity. Importantly, the water-soluble NaCl template could be easily washed from the carbon nanomaterials, and thus the downstream salt-containing wastewater could be subsequently reused for the dissolution of carbon precursors. This environment-friendly, low-cost, reusable salt-template strategy has significant implications for the development of N-doped carbon catalysts for practical applications.