V2O5-decorated Mn-Fe/attapulgite catalyst with high SO2 tolerance for SCR of NOx with NH3 at low temperature

Abstract

Fe-based catalysts were widely reported with high N2 selectivity in the NH3-SCR reaction in recent years. Unfortunately, the Fe-based catalysts usually exhibit poor NOx conversion at low temperature. In order to solve this problem, MnO2 was chosen to enhance the low temperature activity of the catalyst. In this work, V2O5-decorated Mn-Fe/attapulgite (V@Mn-Fe/ATP) with high SO2 tolerance were prepared by impregnation and sol-gel methods and used for selective catalytic reduction of NO by NH3 (NH3-SCR). In addition, γ-Fe2O3/ATP and Mn-Fe/ATP were also prepared for comparison with the V@Mn-Fe/ATP. The as-prepared catalysts were characterized by XRD, TEM, BET, H2-TPR, NH3-TPD, and XPS. It could be deduced from TEM, XRD, and BET, the specific surface area was improved due to a uniform V2O5 layer formed on the Mn-Fe/ATP surface. The results of XPS and NH3-TPD illustrated that the coating of V2O5 could also enhance the amount of surface chemisorbed oxygen and acidic sites, which play significant influence on oxidation of NO and NH3 absorption during NH3-SCR and are also beneficial to increase SCR reaction rates. Moreover, the test of SO2 tolerance and stability demonstrated that the V2O5 layer could effectively inhibit SO2 poisoning and improve the stability of catalysts. Therefore, the V@ Mn-Fe/ATP was proved to be an excellent catalyst for NH3-SCR.