Synthesis and characterization of copper-modified zinc chromites by the high temperature aerosol decomposition process for higher alcohol synthesis

Abstract

The copper substitutional series Cu_xZn_1−xCr₂O₄ where x=0.0–1.0 was synthesized for an investigation of their properties as catalysts for higher alcohol synthesis. The catalysts were prepared by the high temperature aerosol decomposition technique. The process resulted in the formation of the series of metal oxides as uniform hollow spheres having surface areas of 21–35 m² g⁻¹. Characterization of the solid state materials by X-ray diffraction, d.c. arc plasma elemental analysis, BET surface area, EDX mapping, and scanning electron microscopy demonstrated that the particles were homogeneous solid solutions up to a copper substitution of 90% having an unusual cubic spinel structure throughout the series. The copper chromite structure was observed only at copper substitutions greater than 90%. Cesium was also added in varying concentration from 1 to 10 mol.% as a promoter, and these materials were shown by EDX mapping to have a homogeneous cesium dispersion. Comparison of these syntheses to classical methods of preparation demonstrated that the aerosol process resulted in a much higher phase purity with direct formation of the metastable, cubic spinel rather than the normal tetragonal structure.