Stability Mechanism of Low Temperature C2H4-SCR with Activated-Carbon-Supported MnO x -Based Catalyst

Fang Liu; Jiangyuan Zhao; Shengbao He; Qing Liu; Guangli Liu; Li Yang

doi:10.1021/acsomega.2c00202

Stability Mechanism of Low Temperature C₂H₄-SCR with Activated-Carbon-Supported MnO _x -Based Catalyst

ACS Omega. 2022 Mar 24;7(14):12004-12014. doi: 10.1021/acsomega.2c00202. eCollection 2022 Apr 12.

Authors

Fang Liu¹, Jiangyuan Zhao¹, Shengbao He², Qing Liu¹, Guangli Liu³, Li Yang¹

Affiliations

¹ School Of Low-Carbon Energy And Power Engineering, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China.
² Petrochemical Research Institute of PetroChina, Beijing 102206, China.
³ Lanzhou Petrochemical Research Center, PetroChina, Lanzhou 730060, Gansu, China.

Abstract

Manganese-based catalysts have shown great potential for use as a hydrocarbon reductant for NO _x reduction (HC-SCR) at low temperatures if their catalytic stability could be further maintained. The effect of CeO₂ as a promoter and catalyst stability agent for activated carbon supported MnO _x was investigated during low temperature deNO _x based on a C₂H₄ reductant. The modern characterization technology could provide a clear understanding of the activity observed during the deNO _x tests. When reaction temperatures were greater than 180 °C and with ceria concentrations more than 5%, the overall NO conversion became stable near 70% during long duration testing. In situ DRIFTS shows that C₂H₄ is adsorbed on the Mn₃Ce₃/NAC catalysts to generate hydrocarbon activated intermediates, R-COOH, and the reaction mechanism followed the E-R mechanism. The stability and the analytical data pointed to the formation of stable oxygen vacancies within Ce³⁺/Ce⁴⁺ redox couplets that prevented the reduction of MnO₂ to crystalline Mn₂O₃ and promoted the chemisorption of oxygen on the surface of MnO _x -CeO _x structures. Based on the data, a synergetic mechanism model of the deNO _x activity is proposed for the MnO _x -CeO _x catalysts.