CO oxidation activity of thermally stable Fe–Cu/CeO2 catalysts prepared by dual-mode arc-plasma process

Abstract

Fe–Cu bimetal nanoparticles were deposited on CeO₂ powders at a low loading level (≤0.2 wt%) by the dual-mode arc-plasma (AP) process. The bimetal particles enabled the formation of Fe–Cu oxide after being thermally aged at 900 °C, which was characterised by a highly dispersed Cu⁺ and Fe³⁺ on the surface of CeO₂. The CO oxidation activity was enhanced by thermal aging at 900 °C when prepared by the AP process compared to the conventional wet-impregnation method, despite the significant decrease in surface area from 170 m² g⁻¹ to less than 10 m² g⁻¹. The higher activity can be rationalised by the more efficient formation of Fe–Cu oxide, the Cu⁺ species of which plays the role of CO chemisorption site. The reaction rate of CO oxidation exhibited partial orders of ~0.9 and ~0.0 with respect to CO and O₂, respectively. Pulsed C¹⁶O–¹⁸O₂ reactions revealed that CO adsorbed on Cu⁺ reacted mainly with lattice oxygen, which implies that the reaction proceeds via the Mars–van Krevelen mechanism.