Stability Mechanism of Low Temperature C(2)H(4)–SCR with Activated-Carbon-Supported MnO(x)-Based Catalyst

[Image: see text] 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 CeO(2) as a promoter and catalyst stability agent for activated carbon supported MnO(x) was investigated during low temperature deNO(x) based on a C(2)H(4) 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 C(2)H(4) is adsorbed on the Mn(3)Ce(3)/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 Ce(3+)/Ce(4+) redox couplets that prevented the reduction of MnO(2) to crystalline Mn(2)O(3) 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.