Revealing the reaction regularity of Mn-CeO2-x catalyst system in catalytic filter for low-temperature NH3-SCR

Abstract

A series of manganese-cerium-based (MnO2-CeO2-x) polyphenylene sulfide (PPS) catalytic filters were prepared via a redox method to enhance catalytic activity and physico-chemical performances. The oxidation regularity of the cerous ion (Ce3+) was revealed through controlling KMnO4 content, based on which a Mn-Ce catalyst system and its corresponding redox equation were established. Furthermore, the preparation of the optimal catalytic filter achieved satisfactory catalytic performance compared with the previous catalytic filters (NO conversion of 93.5 % at 180 °C under low load conditions). This catalytic filter also exhibits excellent catalyst stability, gas permeability, bonding strength, and mechanical properties, making it suitable for complex operating conditions. Particularly, the coexistence of CeO2 and Ce2O3 in the catalyst system leads to an imbalance in surface charge, oxygen vacancies, and unsaturated chemical bonds on the surface of the catalyst, thereby increasing the amount of chemisorbed oxygen, promoting NO oxidation, and further improving selective catalytic reduction of NOx with NH3 (NH3-SCR).