Characteristics of Cr2O3–CuO/MgF2 catalysts and a comparison with Cr2O3/MgF2 and CuO/MgF2 systems

Abstract

A characterization of binary preparations containing Cr₂O₃ and CuO supported on magnesium fluoride has been carried out. The IR study enabled characterization of complexes formed on the surface of the samples, namely, the [CrO₆], [CrO₄] structures and Cu²⁺ ions in the neighbourhood of oxygen or fluorine-containing ligands. Some of these species were also detected by EPR spectroscopy. The results proved that electron transfer from Cr³⁺ to Cu²⁺ takes place. Cr₂O₃–CuO/MgF₂ preparations were also tested in model catalytic reactions such as: propan-2-ol decomposition, the dehydrogenation of cyclohexane, cumene cracking and hydrogenation of nitrobenzene. A distinct increase in the activity of the binary preparations over those of the Cr₂O₃/MgF₂ and CuO/MgF₂ systems was observed. In every case the rise in activity was attributed to the Cr–Cu interaction.