Synthesis and characterization of Mn-Co co-doped TNU-9 denitration catalyst with high activity

Abstract

A simple ion-exchange method is used to prepare Mn and Co-supported TNU-9 denitration catalyst for NH₃-SCR. The denitration activity and H₂O/SO₂ resistance performance of the catalyst are systematically studied. The denitration activity test exhibits that the NO_x removal rate of Mn-Co/TNU-9 is higher than that of Mn/TNU-9 and Co/TNU-9, the NO_x removal rate is greater than 90% and the N₂ selectivity is greater than 99% in the range of 150 ~ 450 °C. It is because the redox cycle of Mn⁴⁺ + Co²⁺ ↔ Mn³⁺ + Co³⁺ improves the redox performance of the catalyst, which is conducive to the conduction of electrons, and then accelerates the oxidation of NO to NO₂ to produce a "fast SCR" reaction, and finally optimizes the overall SCR performance. Furthermore, the change is not significant for the catalytic activity over Mn-Co/TNU-9 in the presence of water. However, the sulfur resistance is poor at low temperatures due to the presence of ammonium bisulfate. It also has excellent catalytic stability. Therefore, supported TNU-9 catalysts will have a good development prospect in denitrification.

Graphical abstract

Mn-Co co-doped TNU-9 catalyst was successfully synthesized by simple ion exchange method and applied in the NH₃-SCR. The results show that Mn-Co/TNU-9 catalyst has an excellent wide activity window in a wide temperature range of 150-450°C (NO_x conversion over 90%), which is because Mn+Co²⁺↔Mn+Co improves the redox performance and facilitates the electron transfer, which further accelerates the oxidation of NO into NO₂ that could result in the “Fast SCR” reaction. The synergistic effect between Mn and Co bimetallic can also improve activity. Moreover, Mn-Co/TNU-9 has very good catalytic stability.