A Sulfur-Tolerant MOF-Based Single-Atom Fe Catalyst for Efficient Oxidation of NO and Hg0

Catalytic oxidation of NO and Hg-0 is a crucial step to eliminate multiple pollutants from emissions from coal-fired power plants. However, traditional catalysts exhibit low catalytic activity and poor sulfur resistance due to low activation ability and poor adsorption selectivity. Herein, a single-atom Fe decorated N-doped carbon catalyst (Fe-1-N-4-C), with abundant Fe-1-N-4 sites, based on a Fe-doped metal-organic framework is developed to oxidize NO and Hg-0. The results demonstrate that the Fe-1-N-4-C has ultrahigh catalytic activity for oxidizing NO and Hg-0 at low and room temperature. More importantly, Fe-1-N-4-C exhibits robust sulfur resistance as it preferably adsorbs reactants over sulfur oxides, which has never been achieved before with traditional catalysts. Furthermore, SO2 boosts the catalytic oxidation of NO over Fe-1-N-4-C through accelerating the circulation of active sites. Density functional theory calculations reveal that the Fe-1-N-4 active sites result in a low energy barrier and high adsorption selectivity, providing detailed molecular-level understanding for its excellent catalytic performance. This is the first report on NO and Hg-0 oxidation over single-atom catalysts with strong sulfur tolerance. The outcomes demonstrate that single-atom catalysts are promising candidates for catalytic oxidation of NO and Hg-0 enabling cleaner coal-fired power plant operations.