Reduction effect on cerium oxide catalysts doped with copper(II) ions. An electron paramagnetic resonance study

Abstract

The reduction effect on CuCe oxide catalysts with an atomic ratio Cu : Ce = 0.01 has been studied mainly by EPR techniques. The surface species of copper(II) ion pairs and their precursors (Cu²⁺ ion monomers) were easily reducible by H₂, C₂H₄ and CO. A bronze-like complex (H_xCuCeO₂) has been obtained before the beginning of the effective reduction of Cu²⁺ by heating the solid in the presence of hydrogen or ethene. Ce³⁺ ions have been evidenced near the solid surface during the reduction. By adsorption of CO molecules, CO^–₂ radicals have been formed on the catalyst surface.