The interaction of copper-containing spinels CuFe ₂ O ₄ and CuFeCrO ₄ with hydrogen

The interaction of hydrogen with copper-containing spinels CuFe ₂ O ₄ and CuFeCrO ₄ , which are the catalysts for hydrogenation, alkylation and other reactions, was studied. Copper ions of ferrite are reduced in a reductive atmosphere and segregated to the spinel Fe ₃ O ₄ surface with the formation of Cu ⁰ nanoparticles; their interaction with O ₂ -contaning (less than 1 vol.%) helium leads to the oxidation to Cu ₂ O or CuO. In a reductive medium, copper ferrite-chromite CuFeCrO ₄ segregates copper ions from spinel, which are reduced to Cu ⁰ nanoparticles on the surface of CuFeCr-spinel. Charge compensation of spinel structure occurs due to formation of OH groups and by the partial transition Fе ³⁺ – Fe ²⁺ . Upon mild reoxidation, Cu ⁰ atoms partially return into the spinel structure and partially form the Cu ₂ O phase.