A confined MoN2@N-rich carbon catalyst derived from β-cyclodextrin encapsulating phosphomolybdic acid for oxidative removal of H2S

Abstract

The efficient removal of H2S is significant to the chemical industry and environmental protection. In this study, a macrocycle-confinement pyrolysis strategy was explored to synthesize a confined MoN2@N-rich porous carbon (MoN2@NPC) catalyst using β-cyclodextrin encapsulating phosphomolybdic acid (PMo12 ⊂ β-CD) as a Mo precursor to improve the desulfurization activity of carbonaceous catalysts for the efficient conversion of H2S to sulfur. The decomposition of PMo12 ⊂ β-CD not only generated well distributed MoN2 sites, but also enriched pore structures due to the pore-forming ability of β-CD. MoN2@NPC possessed a high breakthrough capacity of 173.9 mg/g at room temperature and excellent durability (>100 h) at 200 °C toward continuous H2S selective oxidation. Furthermore, MoN2@NPC showed a remarkable superiority to common catalysts (PC, NPC, and MoN2-NPC), revealing the effectiveness of the macrocycle-confinement pyrolysis strategy for strengthening desulfurization activity. The excellent desulfurization ability of MoN2@NPC was attributed to the synergetic effect of uniform MoN2 sites and N species (pyridinic N and pyrrolic N). Additionally, the formed water film and activated O2 on MoN2@NPC further induced H2S dissociation and oxidation. This work provides a key insight into the behavior of H2S oxidative removal over NPC-based catalysts and offers a promising route to construct non-precious catalysts with high desulfurization activity.