Role of the support nature in chemisorption of Ni(acac)(2) on the surface of silica and alumina

Nickel acetylacetonate surface species which are formed on silica and alumina supports in the result of chemisorption of Ni(acac)(2) from the gas phase were characterized by FTIR, TG/DSC and chemical analysis. Nickel acetylacetonate is found to be covalently bound to the supports since one acetylacetonate ligand in the initial Ni(acac)(2) molecule undergoes substitution with the oxygen atom of surface hydroxyl group. In the case of alumina, acetylacetone which is evolved reacts with coordinatively unsaturated Al3+ ions of the support surface that results in the appearance of the aluminum acetylacetonate surface species. Oxidation of acetylacetonate ligands coordinated to both nickel and aluminum atoms in the surface species was observed at 300-350 degrees C.