Preparation, Characterization and Catalytic Behavior of Perovskites with Nominal Compositions La1-xSrxGa1–2yCuyRuyO3

Catalysts of the compositions La1-xSrxGa1–2yCuyRuyO3 with 0 ≤ x ≤ 0.2 and 0 ≤ y ≤ 0.35 have been prepared ex situ as powders and in situ on a cordierite monolith provided with a Ga2O3 washcoat. The samples were characterized by X-ray diffraction, scanning electron microscopy/energy dispersive spectometry, and analytic transmission electron microscopy/energy dispersive spectometry studies. Selected samples were subjected to catalytic tests with respect to oxidation of CO and C3H6 and reduction of NO under rich and lean conditions, respectively. It was found that Cu and Ru ions could replace Ga in the perovskite structure of LaGaO3, as outlined in the formula above, whereas the solubility of Sr was limited to x ≤ 0.10. The replacement of some Ga by Cu and Ru ions improved the catalytic activity for oxidation of CO and C3H6 and reduction of NO under rich conditions, whereas under lean conditions, no activity for reduction of NO was observed. The light-off temperatures recorded under rich conditions for oxidation of CO and C3H6 and reduction of NO for the La0.8Sr0.2Ga0.8Cu0.1Ru0.1O3 samples prepared in situ, T50 = 374, 357, and 461°C, respectively, were 50–100° lower than for the ex situ prepared sample.