A Novel MnO<i>_x</i>–MoO<i>_x</i> Codoped Iron-Based Catalyst for NH₃‑SCR with Superior Catalytic Activity over a Wide Temperature Range

Abstract

MnOx and MoOx, as additives, have proved effective in enhancing the NH3 selective catalytic reduction activity of catalysts. In this study, a new Mn–Fe–Mo catalyst was prepared using both the precipitation method and impregnation method. The redox properties, surface acidity, and reaction intermediates of the prepared catalysts were analyzed using various techniques. The test results showed that the MFMo4 catalyst achieved a NOx conversion rate exceeding 90% over the temperature range of 120–390 °C, demonstrating high potential to replace V-based catalysts due to outstanding activity at both high and low temperatures. The addition of MoOx exerted a detrimental impact on the redox property and avoided the production of N2O, thereby enhancing the N2 selectivity. Furthermore, the codoping of MnOx and MoOx inhibited the adsorption of NOx on the catalysts while resulting in an increased number of Lewis acid sites on the catalyst. This promoted its reaction via the Eley–Rideal mechanism, which played a crucial role in ensuring the catalyst had excellent SCR activity over a wide temperature range