Structure and catalytic properties of a Cu2+-containing hydrogel of zirconium dioxide

The distribution of Cu2+ ions in ZrO2 and sulfated ZrO2 hydrogel phases was studied by EPR spectroscopy and voltammetry. The formation of the following three types of copper structures was observed: mononuclear Cu2+ complexes (A), magnetic associates (B), and Cu2+ compounds (C) that gave no EPR signals under the conditions used in the spectroscopic measurements. The specific catalytic activity of various Cu2+ compounds in the liquid-phase reaction of 2,3,5-trimethyl-1,4-hydroquinone oxidation was determined. The copper complexes C were found to exhibit the highest catalytic activity.