Ceria-Promoted and stabilized copper and iron oxides cooperatively catalyze NO efficient degradation by CO

Abstract

The copper and iron oxides highly dispersed on CeO2 composite system was successfully synthesized by solid-state based methods for NO reduction by CO with a certain sulfur and water resistance. The conversion of NO at 100, 150 and 220 °C can reach ∼40 %, ∼80 % and ∼100 % respectively, at space velocity = 65,000 mL·g−1·h−1. Here, some ex/in-situ characterization techniques are used to explore the active species and catalytic mechanism in the reaction process. The results show that the catalyst system has a large number of defects and contains highly reactive oxygen species. During the reaction, the dominant Ce species can promote the formation of Cu+ active species and enhance its relative stability. Also, under higher temperature reaction atmosphere, Ce species can stabilize Fe3+ and maintain the catalytic performance. The stabilization effect of Ce species on copper and iron makes the catalyst have a quite wider active window. To understand the selective catalytic reduction process of NO by CO, a possible reaction mechanism was proposed by in-situ DRIFTS. Overall, this work provides a possible foundation for understanding the structure, catalytic stability, and activity.