Review on Synthesis and Catalytic Properties of Cobalt Manganese Oxide Spinels (CoxMn3−xO4, 0 < x < 3)

The cobalt manganese oxides, especially the spinels and related (multiphase) materials described with the formula CoxMn3−xO4 (0 < x < 3), are widely used catalysts in a range of processes in significant industrial and environmental areas. The great diversity in the phase relations, composition, and metal ion valences, together with ion and vacancy site distribution variations, results in great variety and activity as catalysts in various industrially important redox processes such as the removal of CO or volatile organic substances (VOCs) from the air and oxidative destruction of pollutants such as dyes and pharmaceuticals from wastewater using peroxides. These mixed oxides can gain application in the selective oxidation of organic molecules like 5-hydroxyfurfural or aromatic alcohols such as vanillyl alcohol or in the production of fuels and other valuable chemicals (alcohols, esters) with the Fischer–Tropsch method. In this review, we summarize these redox-based reactions in light of the chemical and phase composition of the catalysts with the formula CoxMn3−xO4 with 0 < x < 3.