Influence of the addition of transition metals (Cr, Zr, Mo) on the properties of MnOx-FeOx catalysts for low-temperature selective catalytic reduction of NOx by Ammonia

► The co-precipitation and citric acid methods were used to prepare MnOx-FeOx catalysts. ► Mn-Fe (CP) exhibited better activity due to low crystallinity and large surface area. ► Cr doping reduced the take-off temperature remarkably but Zr and Mo raised that. ► Active components had better dispersion with less agglomeration for Cr-doped sample. ► The Cr-doped sample had larger amount of Lewis acidity and active intermediate.