Fabrication of a wide temperature Mn–Ce/TNU-9 catalyst with superior NH3-SCR activity and strong SO2 and H2O tolerance

Abstract

A Mn–Ce co-doped TNU-9 (Mn–Ce/TNU-9) catalyst was synthesized via a simple ion exchange method and then its catalytic activity, water resistance and sulfur resistance were studied in the selective catalytic reduction of NO_x with NH₃ as the reducing agent (NH₃-SCR). The results show that the NO_x conversion of Mn–Ce/TNU-9 is higher than those of Mn/TNU-9 and Ce/TNU-9 at a wide temperature window (150–450 °C), corresponding to >94.0% conversion of NO_x and >99% selectivity of N₂. The redox cycle of Mn⁴⁺ + Ce³⁺ ↔ Mn³⁺ + Ce⁴⁺ improves the redox performance for the Mn–Ce/TNU-9 catalyst and facilitates electron transfer, which further accelerates the oxidation of NO to NO₂ that could lead to the “Fast SCR” reaction, therefore increasing the SCR performance. Furthermore, the synergistic effect between TNU-9 and bimetals can also enhance the activity. In addition, the Mn–Ce/TNU-9 catalyst demonstrates excellent sulfur and water resistance due to the hydrophobicity of TNU-9 and the easy sulfation of Ce protected from the active site Mn. Moreover, Mn–Ce/TNU-9 has a very good catalytic stability. These results prove that the bimetallic catalyst prepared by TNU-9 as the carrier will have a broad application prospect in the field of environmental catalysis.