NEW NI-AL-CR AND NI-AL-FE CARBONATE HYDROTALCITE-LIKE COMPOUNDS - SYNTHESIS AND CHARACTERIZATION

A series of Ni-AI-M (M = Cr or Fe) double-hydroxide phases with carbonate anions were prepared by coprecipitation, at 60 degrees C, of the corresponding chloride and nitrate solutions with sodium carbonate aqueous solution at pH 10, followed by hydrothermal treatment at 150 degrees C. The characterization and the thermal stability properies of the products were also investigated. Pure hydrotalcite-like materials are obtained, unless an excess of Al or Fe is used, in such a case, an additional phase of pseudoboemite or iron oxide, respectively, is also obtained. Incorporation of aluminum ions in the host layer depends on the nature of the coexistent trivalent cation (chromium or iron), and the thermal stability at high temperatures also depends on the nature of the trivalent cation. (C) 1995 Academic Press, Inc.