SURFACE AND STRUCTURE CHARACTERIZATION OF SOME PEROVSKITE-TYPE POWDERS TO BE USED AS COMBUSTION CATALYSTS

Some perovskite-type transition-metal mixed oxide powders active in th e combustion catalysis, with formulas LaMO(3) (M = Fe, Cr, Co, and Mn) , have been prepared by different methods. Similarly, potential suppor ts for combustion catalysts nearly isostructural with the above ones h ave been prepared, with compositions SrZrO3 and LaAlO3. Mixed phases w ith formulas Sr1-xLaxZr1-xMnxO3 have also been investigated. The bulk properties have been studied by XRD, far-IR spectroscopy, and DTA-TG a nalyses. Morphological properties have been determined by XRD, SEM, an d surface area measurements. These phases crystallize after heating at 970 K (except LaFeO3, which is already crystalline after calcination at 770 K) with surface area ranging 10-20 m(2)/g. The solubility of La MnO3 into SrZrO3 is limited to near 10%. Their surface properties have been investigated by IR spectroscopy that showed a predominantly basi c surface character of all these solids.