An investigation on reaction principles of Mn-Fe-CeOx catalyst system: Guide the synthesis of low-temperature NH3-SCR catalytic filter

Abstract

A series of catalytic filters (Mn-Fe-CeO_x/PPS) with satisfactory NO conversion and physical properties were synthesized by the redox method. The Mn-Fe-Ce ternary catalyst system and corresponding oxidation-reduction equation were established by using the low-valent oxidation characteristics of cerium and iron to react with high-valent manganese capable of reduction. Furthermore, the optimal catalytic filter synthesized under the guidance of reaction principles has excellent physicochemical properties such as high NO conversion (100 % at 180 °C), high stability, low loading capacity (66.8 g/m²), and strong binding ability, making it suitable for complex operating conditions. Particularly, in the Mn-Fe-Ce ternary catalyst system, the coexistence of Ce⁴⁺ and Ce³⁺ causes the formation of surface oxygen vacancies, uneven local charge distribution and additional chemisorbed oxygen, which are conducive to the low-temperature selective catalytic reduction (L-T SCR) reaction. Meanwhile, there are also high valence Mn⁴⁺ and Fe³⁺ in catalyst system, which can promote the oxidation of NO and further improve the L-T SCR reaction.