Synthesis of hollow structured MnCeOx@PrCeOx catalyst for low temperature NH3-SCR with enhanced SO2 resistance

Abstract

To further enhance the catalytic efficiency and sulfur resistance of the catalyst at low temperatures, particularly at or below 150 ℃, MnCeOx@PrCeOx catalyst with hollow-structure was synthesized. The catalyst demonstrated remarkable NH₃-SCR activity, surpassing 90 % NO conversion and 100 % N₂ selectivity at 90 − 270 °C, and exhibited superior SO₂ and H₂O resistance at ultra-low temperature of 120 °C in the presence of 200 ppm SO₂ and 8 vol% H₂O for more than 16 h. The findings suggest that the MnCeOx@PrCeOx catalyst possesses a large specific surface area and well-dispersed active sites, coupled with strong interactions between Ce, Mn, and Pr. In-situ DRIFTs analysis revealed that the hollow structure enhanced gas adsorption and activation, leading to an increased formation of nitrate and adsorbed ammonia species on the MnCeOx@PrCeOx surface compared to nanosphere structure MnCeOx catalyst. Furthermore, the augmented number of Lewis acidic sites in the MnCeOx@PrCeOx catalyst contributed significantly to its improved acidity, inhibiting SO₂ adsorption, preserving active sites, and preventing sulfate deposition. This work provides valuable insights for the development of SO₂-resistant SCR catalysts at ultra-low temperatures, specifically addressing the synthesis and interaction of multi-metal oxides.