| Summary: | BaFe<sub>1-x</sub>Cu<sub>x</sub>O<sub>3</sub> perovskites (<i>x</i> = 0, 0.1, 0.3 and 0.4) have been synthetized, characterized and tested for soot oxidation in both Diesel and Gasoline Direct Injection (GDI) exhaust conditions. The catalysts have been characterized by BET, ICP-OES, SEM-EDX, XRD, XPS, H<sub>2</sub>-TPR and O<sub>2</sub>-TPD and the results indicate the incorporation of copper in the perovskite lattice which leads to: i) the deformation of the initial hexagonal perovskite structure for the catalyst with the lowest copper content (BFC1), ii) the modification to cubic from hexagonal structure for the high copper content catalysts (BFC3 and BFC4), iii) the creation of a minority segregated phase, BaO<sub>x</sub>-CuO<sub>x</sub>, in the highest copper content catalyst (BFC4), iv) the rise in the quantity of oxygen vacancies/defects for the catalysts BFC3 and BFC4, and v) the reduction in the amount of O<sub>2 </sub>released in the course of the O<sub>2</sub>-TPD tests as the copper content increases. The BaFe<sub>1-x</sub>Cu<sub>x</sub>O<sub>3</sub> perovskites catalyze both the NO<sub>2</sub>-assisted diesel soot oxidation (500 ppm NO, 5% O<sub>2</sub>) and, to a lesser extent, the soot oxidation under fuel cuts GDI operation conditions (1% O<sub>2</sub>). BFC0 is the most active catalysts as the activity seems to be mainly related with the amount of O<sub>2</sub> evolved during an. O<sub>2</sub>-TPD, which decreases with copper content.
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