Genesis of the active-component precursor in the synthesis of Pt/Al2O3 catalysts: III. Transformations of adsorbed platinum complexes during drying

The transformations of platinum(IV) complexes subsequent to their sorption on the support are considered. As the Pt(IV)/Al2O3 systems are dried at 25°C in daylight, their dehydration is accompanied by the replacement of inner sphere ligands of Pt(IV) by OH groups and the Coulombic bonding between the adsorbed metal complexes and the support turns into coordination bonding. Drying at a higher temperature of 120°C does not increase the extent of hydrolysis of the bound complexes in the predried samples. The observed increase in the proportion of unreadily reducible platinum species is likely due to the multisite adsorption of platinum complexes taking place.