Investigation of structural and catalytic properties of BaLa 4Cu 5−yRu yO 13−δ with 0.0 ≤ y ≤ 3.0 and of LaBaCuRuO 6

Abstract

We have investigated the possibility of substituting Ru for Cu in the BaLa 4Cu 5O 13−δ structure according the formula BaLa 4Cu 5−yRu yO 13−δ with 0 ≤ y ≤ 3. In the BaLa 4Cu 5O 13−δ structure the solubility of Ru was found to be limited to y < 0.5. For y ≥ 0.5, the samples contained a perovskite-related phase of the composition Ba xLa 4−xCu 2.5Ru 2.5O 13−δ. A monophasic sample was obtained for x = 2.5, with the composition LaBaCuRuO 6, confirmed by X-ray diffraction studies and elemental analysis of individual grains by scanning electron microscopy (SEM). Its structure was determined from X-ray powder diffraction (XRPD) data, using the Rietveld method, and found to be a double-perovskite type with the space group I4/ mand the unit-cell parameters a = 5.6328(1) and c = 7.9877(1). The catalytic activity for simultaneous oxidation of CO and C 3H 6, and reduction of NO was studied over BaLa 4Cu 5O 13−δ, BaLa 4Cu 4.75Ru 0.25O 13−δ, La 4BaCu 2.5Ru 2.5O 13−δ, and LaBaCuRuO 6, under both reducing and oxidizing conditions. BaLa 4Cu 5O 13−δ exhibited some catalytic activity for oxidation of CO and C 3H 6, whereas reduction of NO was found only for the Ru containing samples, and under reducing conditions. The best catalytic activity for oxidation of CO and C 3H 6 and reduction of NO was found for the perovskite-related sample La 4BaCu 2.5Ru 2.5O 13−δ.