Formation of platinum sites on layered double hydroxide type basic supports: II. Effect of the nature of the interlayer anion of the layered aluminum-magnesium hydroxides on platinum binding and Pt/MgAlO x formation

The interaction of aqueous H2PtCl6 solutions with hydrotalcite-type aluminum-magnesium hydroxides differing in the nature of their interlayer anion is reported. In the case of CO 3 2− as the interlayer anion, the introduction of the platinum(IV) chloro complex does exerts no significant effect on the structural properties of the support, on its thermal decomposition dynamics, and on the textural characteristics of the resulting oxide phase. The binding of the platinum complexes to “activated hydrotalcite” with interlayer OH− anions increases the interplanar spacing and enhances the thermal stability of the layered structure. This is accompanied by marked changes in textural characteristics of the material, leading to the formation of a nearly monodisperse mixed oxide phase. In the Pt/MgAlO x samples obtained by reductive treatment, a considerable proportion of platinum is in the form of planar particles, and this corroborates the hypothesis that the metal complex at the sorption stage is mainly localized in the interlayer space of this support. Platinum binds to the support as chloro complexes via rapid anion exchange, and these bound platinum species are characterized by a higher reduction temperature.