Enhancing low-temperature NH3-SCR performance of Fe-Mn/CeO2 catalyst by Al2O3 modification

Abstract In the work, supported catalysts of FeOx and MnOx co-supported on aluminum-modified CeO2 was synthesized for low-temperature NH3-selective catalytic reduction (NH3-SCR) of NO. Impressively, the SCR activity of the obtained catalyst is markedly influenced by the adding amount of Al and the appropriate Ce/Al molar ratio is 1/2. The activity tests demonstrate that Fe-Mn/Ce1Al2 catalyst shows over 90% NO conversion at 75–250 oC and exhibits better SO2 resistance compared to Fe-Mn/CeO2. The Fe-Mn/Ce1Al2 shows the expected physicochemical characters of the ideal catalyst including the larger surface and increased active reaction active sites by controlling the amount of Al doping. Also, the better catalytic activity is well correlated with the present advantaged surface adsorption oxygen species, Mn4+ species, Ce3+ species and the enhanced reducibility of Fe-Mn/Ce1Al2, which is superior to the Fe-Mn/CeO2 catalyst. More importantly, we further demonstrate that the amount and strength of surface acid sites are improved by Al-doping and more active intermediates (monodentate nitrate) is generated during NH3-SCR reaction. This work provides certain insight into the rational creation of simple and practical denitration catalyst environmental purification.