NH₃-SCR of NO over one-pot Cu-SAPO-34 catalyst: Performance enhancement by doping Fe and MnCe and insight into N₂O formation

One-pot synthesized Cu-SAPO-34 was prepared. Fe and MnCe (at Mn/Ce = 3/7) species were doped on the Cu-SPAO-34 samples by incipient wetness impregnation. The introduction of Fe and MnCe using incipient wetness impregnation enhanced the ammonia selective catalytic reduction (SCR) activity and resulted in the best SCR performance for meeting diesel engine emission control requirement. The 1%Fe/1%MnCe/3.86%Cu-SAPO-34 catalyst showed higher hydrothermal stability than 1%Fe/1%MnCe/Cu-SSZ-13. It also exhibited higher SO₂ resistance and wider temperature window, and yielded less N₂O product. N₂O formation was systematically investigated to study the mechanism. The catalysts were characterized by XRD, XPS, H₂-TPR and NH₃-TPD. The addition of Fe and MnCe increased Lewis acidity, which was beneficial to SCR activity. The lower oxidation state Fe species (Fe²⁺) was also responsible for the enhanced SCR activities.