Home – Home – Jornals – Chemistry for Sustainable Development 2013 number 1

Results are reported on studying the interaction of Pt (IV) anionic chloride complexes with layered magnesium-aluminum hydroxides in the course of synthesizing Pt/MgAlO_x catalysts. As the oxide precursors there were layered hydroxides used with different nature of interlayer anions (and ОН^–) and with Mg/Al ratio ranging within 2–4. The nature of an interlayer of anion is an important parameter affecting the amount of fixed platinum, the composition of surface species and the sites of location thereof in the structure of layered material. In the case of using a hydroxide carrier with the carbonate counterion the fixation of platinum occurs with the participation of the OH groups of hydroxide layers, via adsorbing the hydrolyzed forms of the complexes on the surface. The reduction thereof leads to the formation of isometric platinum particles of 2–4 nm in size. When attaching the platinum complexes to aluminum-magnesium hydroxide with interlayer anions ОН^–, the precursor of the active component is mainly located in the interlayer space, with further forming the particles of flat morphology 50 nm long and the thickness close to the interlayer distance in the layered carrier (0.75 nm). In the case of varying the Mg/Al ratio, an increase of triply charged aluminum cation causes changing the structural characteristics and adsorption properties of aluminum-magnesium hydroxide to result in the formation of an oxide phase with a more developed surface area and higher pore volume. Increasing the positive charge density and enhancing the electrostatic interaction promote the adsorption of a greater amount of platinum (IV) anionic complexes and a stronger interaction thereof with the hydroxide layers. In the case of changing the Mg/Al ratio from 4 to 2, one can observe increasing the dispersity level of the supported platinum particles and increasing the activity of Pt/MgAlO_x catalysts in the propane dehydrogenation reaction.