BaFe_1−xCu_xO₃ Perovskites as Soot Oxidation Catalysts for Gasoline Particulate Filters (GPF): A Preliminary Study

A series of BaFe_1−xCu_xO₃ catalysts (x = 0, 0.1, 0.3 and 0.4) have been synthetized, characterized and used for soot oxidation in gasoline direct injection (GDI) exhaust conditions. The characterization of the catalysts (by BET, ICP-OES, XRD, XPS, H₂-TPR and O₂-TPD) reveals that copper is incorporated into the perovskite lattice leading to: (i) the distortion of the original hexagonal perovskite structure for the lowest copper content catalyst (BFC1) and the modification of the structure, from hexagonal to cubic, for the catalysts with higher copper content (BFC3 and BFC4), (ii) the generation of a BaOx–CuOx oxide as minority segregated phase for BFC4 catalyst, (iii) the increase in the amount of oxygen surface vacancies for BFC3 and BFC4 catalysts, and (iv) the decrease in the total amount of O₂ released during O₂-TPD experiments. All the BaFe_1−xCu_xO₃ perovskites are active for soot oxidation under the highest demanding GDI exhaust conditions (regular stoichiometric GDI operation, i.e., 0% O₂). The catalyst with the highest copper content (BFC4) shows the highest soot conversion, related to its largest amount of β-oxygen evolved, and, to the presence of a high amount of copper species (as BaOx–CuOx oxide) on its surface.