MnOx catalysts supported on γ-Al2O3, ZSM-5, and SAPO-34: Effect of support on the activity of Mn supported catalysts in NO abatement by NH3

Abstract

The NH₃–SCR of NO reaction has been studied using three different manganese containing catalysts supported on γ-Al₂O₃, ZSM-5, and SAPO-34. The nanocatalysts were prepared by homogeneous deposition precipitation (HDP) method and characterized via BET, TEM, H₂-TPR, and NH₃-TPD analysis. The activity of the catalysts varied significantly depending on the type of the support. The Mn-ZSM-5 and Mn/γ-Al₂O₃ catalysts were more active for NO conversion than Mn-SAPO-34 catalyst. The no correlation was found between surface area, strength and amount of acid sites, and NO conversion of the catalysts. The results of H₂-TPR revealed lower onset reduction temperatures of MnO_x species in Mn-ZSM-5 and Mn/γ-Al₂O₃ compared with Mn-SAPO-34, indicating easily reducibility of MnO_x species in these catalysts. The redox properties of catalysts are responsible for the SCR activity. The Mn-SAPO-34 catalyst contains low quantitative of access reducible MnO_x species, which is followed by considerable decrease in the activity. The NO conversion ability of Mn-supported catalysts has been correlated with support structure.