Investigation of structural and catalytic properties of BaLa4Cu5-yRuyO13-delta with 0.0 <= y <= 3.0 and of LaBaCuRuO6

We have investigated the possibility of substituting Ru for Cu in the BaLa4 Cu5O13-delta structure according the formula BaLa4Cu5-yRuyO13-delta with 0 less than or equal to y less than or equal to 3. In the BaLa4Cu5O13-delta s tructure the solubility of Ru was found to be limited to y < 0.5. For y <gr eater than or equal to> 0.5, the samples contained a perovskite-related pha se of the composition BaxLa4-xCu2.5Ru2.5O13-delta. A monophasic sample was obtained for x = 2.5, with the composition LaBaCuRuO6, confirmed by X-ray d iffraction studies and elemental analysis of individual grains by scanning electron microscopy (SEM). Its structure was determined from X-ray powder d iffraction (XRPD) data, using the Rietveld method, and found to be a double -perovskite type with the space group I4/m and the unit-cell parameters a = 5.6328(1) and c = 7.9877(1). The catalytic activity for simultaneous oxida tion of CO and C3H6, and reduction of NO was studied over BaLa4Cu5O13-delta , BaLa4Cu4.75Ru0.25O13-delta, La4BaCu2.5Ru2.5O13-delta, and LaBaCuRuO6, und er both reducing and oxidizing conditions. BaLa4Cu5O13-delta exhibited some catalytic activity for oxidation of CO and C3H6,whereas reduction of NO wa s found only for the Ru containing samples, and under reducing conditions. The best catalytic activity for oxidation of CO and C3H6 and reduction of N O was found for the perovskite-related sample La4BaCu2.5Ru2.5O13-delta. (C) 2000 Elsevier Science Ltd. All rights reserved.