Synthesis and Properties of Spinel-Type Co–Cu–Mg–Zn–Cr Mixed Oxides

• Published in: Journal of solid state chemistry Vol. 152; no. 2; pp. 526 - 532
• Main Authors: Castiglioni, G.L., Minelli, G., Porta, P., Vaccari, A.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.07.2000; Elsevier
• Subjects: Catalysis; Catalysts: preparations and properties; Chemistry; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; General and physical chemistry; Inorganic compounds; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Water, oxides, hydroxides, peroxides; Inorganic compounds; Mixed-valence compounds; Catalysts; Phase transformations; Transition element compounds; Controlled atmospheres; Calcination; Cobalt oxides; XRD; Experimental study; Heat treatments; Chemical reduction; Zinc oxides; Solid solutions; Temperature effects; Spinels; Chromium oxides; Magnesium oxides; Chemical composition; Copper oxides; Crystal structure
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1006/jssc.2000.8724

Different mixed oxides containing Cu, Zn, Co, Mg, and Cr were obtained by calcining hydroxycarbonate precursors at different temperatures (653 or 873 K). Characterization was performed by X-ray diffraction, thermal analysis, infrared and reflectance spectroscopy, and BET surface area determination. Depending on metal composition the mixed oxides were constituted by CuO, ZnO, CuCrO4 ZnCr2O4, CoCr2O4, and CoxCu1−xCr2O4, MgxCu1−xCr2O4, Co2+Co3+xCr2−xO4 solid solutions. The phase evolution during reduction of the mixed oxides, followed by in situ X-ray diffraction up to 973 K, showed that the reducible species, when present, were CuO, CuCrO4, tetragonal CoxCu1−xCr2O4 and MgxCu1−xCr2O4 spinels, with metallic copper and cubic spinels as final products of reduction.