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.

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.

PMID:35449939 | PMC:PMC9016832 | DOI:10.1021/acsomega.2c00202

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