Structural Modulation and Adsorptive Behavior of CuFe-LDHs-derived Catalysts through Mn Doping: Dual Enhancement of Low-Temperature Catalytic Performance and Sulfur Resistance

Addressing the activity and resistance to toxicity of sintered flue gas at low temperatures is crucial. This study focuses on the design of Mn-doped Cu3Fe1-LDHs as a bifunctional catalyst for synergistic CO oxidation in NH3-SCR. Compared with the Cu3Fe1Ox catalysts, the Mn-doped Cu3Mn0.25Fe0.75Ox catalysts achieved dual enhancement of NOx and CO conversion at low temperature and oxygen-enriched conditions, albeit with lower N-2 selectivity. They also demonstrated good sulfur-resistant performance. Confirming by theoretical calculations and characterization techniques, the chemical bonding configuration of Cu3Fe1Ox was verified. Mn is uniformly distributed in the catalyst and formed a solid solution with Cu2+ and Fe3+ in the crystal lattice. This contributed to the stable growth of the crystals during synthesis, thus improving the size and morphology of the crystals and providing more active sites. Mn introduction also promoted charge transfer between Cu2+ and Fe3+, and enhanced the catalyst's adsorption capacity and reactivity. Chemisorption analysis revealed that the incorporation of Mn significantly improved the catalyst's reduction capacity, oxygen adsorption ability, and acidic sites. Furthermore, in situ DRIFTS and DFT calculations demonstrated that Mn doping improved NH3 and CO adsorption, thereby improving the catalyst's overall performance. The SO2 adsorption results showed that Mn doping enhanced the surface acidity of the catalyst, reducing SO2 adsorption and sulfate formation. The development of this catalyst has important industrial application value for ultralow emission of sintering flue gas.