Insights into the Redox and Structural Properties of CoOx and MnOx: Fundamental Factors Affecting the Catalytic Performance in the Oxidation Process of VOCs

Abstract

Volatile organic compound (VOC) abatement has become imperative nowadays due to their harmful effect on human health and on the environment. Catalytic oxidation has appeared as an innovative and promising approach, as the pollutants can be totally oxidized at moderate operating temperatures under 500 °C. The most active single oxides in the total oxidation of hydrocarbons have been shown to be manganese and cobalt oxides. The main factors affecting the catalytic performances of several metal-oxide catalysts, including CoOx and MnOx, in relation to the total oxidation of hydrocarbons have been reviewed. The influence of these factors is directly related to the Mars–van Krevelen mechanism, which is known to be applied in the case of the oxidation of VOCs in general and hydrocarbons in particular, using transitional metal oxides as catalysts. The catalytic behaviors of the studied oxides could be closely related to their redox properties, their nonstoichiometric, defective structure, and their lattice oxygen mobility. The control of the structural and textural properties of the studied metal oxides, such as specific surface area and specific morphology, plays an important role in catalytic applications. A fundamental challenge in the development of efficient and low-cost catalysts is to choose the criteria for selecting them. Therefore, this research could be useful for tailoring advanced and high-performance catalysts for the total oxidation of VOCs.