Synthesis of layered magnesium-aluminum hydroxide on the γ-Al2O3 surface for modifying the properties of supported platinum catalysts

Abstract

Layered magnesium-aluminum hydroxides of hydrotalcite-like structure were synthesized on the surface of γ-Al2O3. The synthesis was performed via the interaction of aluminum and magnesium hydroxides and carbonate ions in the pores of alumina support. Novelty of the approach was that the synthesis involved the boehmite phase AlO(OH) that formed directly on the surface of γ-Al2O3 under hydrothermal conditions. This approach provides fixation of the forming layered phase on the surface of initial support and retains textural parameters of the support. The formation of a layered structure on the γ-Al2O3 surface was confirmed by XRD analysis and electron microscopy studies. Investigation of the H2[PtCl6] anchoring on γ-Al2O3 with supported magnesium-aluminum hydroxide by UV–vis DRS, 195Pt NMR and HRTEM showed that platinum was adsorbed on the surface as chloride forms of the complexes with a low degree of hydrolysis even at a low metal content. Catalytic properties of the synthesized supported platinum catalysts were examined in a model reaction of propane dehydrogenation. In comparison with the alumina-platinum catalyst, the modified sample showed a better stability at a somewhat higher yield of propylene because the formation of heavy products was suppressed.