Ce0.9Fe0.1O1.97/Ag: a cheaper inverse catalyst with excellent oxygen storage capacity and improved activity towards CO oxidation

Abstract

Noble-metal-supported metal oxides (e.g., Au/CeO2, Pd/Al2O3, etc.) are popular as efficient catalysts for many important catalytic reactions, while their high price and easy deactivation restrict their broad application. Herein, we initiate a double substitution methodology to acquire catalysts with merits of excellent catalytic activity, high stability, and relatively low cost. For this purpose, a Au/CeO2 catalyst was used as reference, and the noble metal Au was completely replaced by the cheaper Ag, meanwhile the rare earth ion, Ce4+ of the CeO2 support was partially substituted by the transition metal ion, Fe3+. This inversely supported catalyst, Ce0.9Fe0.1O1.97/Ag, was prepared by a two-step method based on co-precipitation and a subsequent liquid-phase reduction. Systematic characterizations demonstrate that Ag nanoparticles with a diameter of around 50 nm were wrapped by Ce0.9Fe0.1O1.97 layers. Between the Ag nanoparticles and Ce0.9Fe0.1O1.97 layer, there existed a strong interaction. When this sample was tested as a catalyst for CO oxidation, a full conversion temperature of 150 °C was achieved at a space velocity of 24 000 ml h−1 g−1cat, showing a catalytic activity comparable to that previously reported in the literature on the known catalyst Au@CeO2 measured at a lower space velocity of 15 000 ml h−1 g−1cat. More strikingly, this catalyst showed a superb catalytic stability and enhanced oxygen storage capacity. The introduction of smaller Fe3+ into the CeO2 lattice and the strong interactions between Ag and Ce0.9Fe0.1O1.97 strongly improved the stability and catalytic performance.