PREPARATION AND CHARACTERIZATION 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 coprecipit ation method, Some of them are constituted by very pure perovskite-typ e solid solution phases, with tetravalent Zr and Mn substituting for T i in the B site. The addition of Zr to SrTiO3 tends to increase the su rface areas, while the insertion of Mn tends to decrease it, Mn-contai ning materials are active in the catalytic combustion of 1% methane in air at temperatures higher than 700 K and can be competitive with pur e manganite perovskites Like LaMnO3 in spite of the lower Mn content. Pyridine adsorption experiments show that medium strength Lewis acid s ites are located at the surface of these materials, and could be invol ved in the hydrocarbon C-H bond activation.