Effects of Ce over TiO₂ supported MnO_x-based Catalyst for NO_x Reduction by Ammonia

State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao 266580, China

^* Corresponding author: liuyq-group@upc.edu.cn

Abstract

Ce modified MnO_x-based catalysts have attracted much attention due to its high activity for selective catalytic reduction of NO_x by NH₃ (NH₃-SCR) at low-temperatures. However, the most important role of Ce on the NH₃-SCR performance of MnO_x-based catalysts has not been confirmed. Herein, the typical Ce-Mn/TiO₂ catalyst was synthesized through incipient-wetness impregnation method, the positive role of Ce on Ce-Mn/TiO₂ catalyst in the NH₃-SCR process was revealed by combining different activity tests (including NO oxidation and NH₃ oxidation) and characterizations (including XRD, XPS and He-TPDMS experiments). It was found that the introduction of Ce can promote the dispersion of MnO_x on TiO₂ support. Meanwhile, the doping of Ce in MnO_x can also increase the content of Mn⁴⁺ species. The Mn⁴⁺ species plays a crucial role in NO oxidation reaction, which can trigger the “Fast SCR” reaction and promote the conversion of NO_x. This work provides insight into the catalyst design for NH₃-SCR process at low-temperature.