Synergy effect between copper and manganese oxides in hopcalite catalysts

A hopcalite-type catalyst was prepared by coprecipitation of copper and manganese nitrates and calcination at 550°C. Its catalytic activity in the oxidation of hydrogen and carbon monoxide was compared with the activity of single phase CuO, Mn 2 O 3 and CuMn 2 O 4 and of the mechanical mixture CuO·Mn 2 O 3 . It was found that the high catalytic activity of hopcalite does not arise from the interaction of copper and manganese cations within the spinel lattice of copper manganite, but from a synergistic cooperation of CuO and Mn 2 O 3 phases in physical mixture. To account for this synergy, a model based on oxygen spillover was proposed.