A complex study of the formation of nickel-aluminum oxide catalysts

Autor: V. V. Levina, V. Ya. Danyushevskii, V. I. Yakerson, E. A. Koevskaya, Gennady I. Kapustin
Rok vydání: 1975
Předmět:
Zdroj: Bulletin of the Academy of Sciences of the USSR Division of Chemical Science. 24:2533-2538
ISSN: 1573-9171
0568-5230
DOI: 10.1007/bf01152842
Popis: 1. During the preparation of coprecipitated nickel and aluminum hydroxides, a nickel hydroaluminate of composition 2Ni(OH)2·2Al(OH)3·5H2O is formed, giving a specific highly dispersed phase. 2. At least two factors are responsible for the particle size of the mixed nickel-aluminum hydroxides: the capability of all OH groups of the hydroxides of forming hydrogen bonds, and the interaction of water molecules with aluminum ions. Both factors lower the surface tension of the particles and hinder their crystallization. Decomposition of nickel-aluminum hydroxides proceeds in two steps: at ∼250°, solid solutions of NiO in γ-Al2O3 are formed (for K≤0.3, where K=Ni∶Al); in addition, at 300–450° and medium compositions, NiAl2O4 is formed, and, probably a new phase is formed at K≥0.46. During the transition of nickel hydroaluminate to nickel-aluminum spinel, nickel oxide separates. 4. The compositions and particle sizes of phases arising in the mixed nickel aluminum hydroxide stage determine the behavior of specific phases in later stages.
Databáze: OpenAIRE
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