Preparation and characterisation of SrTi1-x-yZrxMnyO3 solid solution powders in relation to their use in combustion catalysis

Mixed oxides with compositions SrTi1-x-yZrxMnyO3, with 0 less than or equal to x less than or equal to 1 and 0 less than or equal to y less than or equal to 0.2 have been prepared with a conventional coprecipitation method, Some of them are constituted by very pure perovskite-type solid solution phases, with tetravalent Zr and Mn substituting for Ti in the B site. The addition of Zr to SrTiO3 tends to increase the surface areas, while the insertion of Mn tends to decrease it, Mn-containing materials are active in the catalytic combustion of 1% methane in air at temperatures higher than 700 K and can be competitive with pure manganite perovskites Like LaMnO3 in spite of the lower Mn content. Pyridine adsorption experiments show that medium strength Lewis acid sites are located at the surface of these materials, and could be involved in the hydrocarbon C-H bond activation.