Theoretical analysis of selective catalytic oxidation of H2S on Fe-N3 co-doped graphene

H2S selective oxidation to produce elemental sulfur is an efficient and essential reaction for recycling the sulfur resource. To uncover the reaction mechanism of H2S selective oxidation, density functional theory (DFT) methods were performed on Fe-N3 co-doped graphene in detail. Compared to pure Fe doped graphene, N doping could enhance the adsorption towards H2S and O2, and H2S acts as an electron donor while O2 acts as an electron acceptor. The H2S adsorption could be enhanced in the co-adsorption with atomic O*, and the HS* adsorption could be enhanced by OH* and OOH*, while S* adsorption could be weakened by oxygenated species. Three possible paths for elemental sulfur formation were investigated thoroughly. The H2S oxidation by atomic O* was considered to be the optimal route in our present calculation. The reaction could be accelerated by pretreating the catalyst with oxygen. Our calculations enable us to understand the mechanism of H2S selective oxidation and rule out Fe-N3 co-doped graphene as a candidate catalyst for desulfuration.