PREPARATION AND CHARACTERIZATION OF ALUMINA-SUPPORTED TRIMANGANESE TETROXIDE CATALYSTS

A series of alumina-supported Mn3O4 catalysts were prepared by wet and 'dry' impregnation using manganous acetate as precursor. The state of manganese species on the alumina as a function of manganese loading w as determined by using X-ray photoelectron spectroscopy, Temperature-p rogrammed techniques and X-ray diffraction. The supported crystalline phase with small particle size was evidenced to be the same as the uns upported crystalline Mn3O4. A monolayer dispersion of Mn3O4 onto the s urface of alumina could be obtained only by incipient wetness impregna tion. Some interesting effects of milling were found, namely a lattice contraction of Mn3O4 and encapsulation by Degussa alumina.