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.

Cobalt- and Copper-Based Chemiresistors for Low Concentration Methane Detection, a Comparison Study

“…The sensor with Pt IDE ( S4 ) has a slightly higher working temperature—T w (220 °C, comparing with 210 °C for the other two sensors- S3 and S5 ). Sensor response is comparable when using Pt or Au as IDE ( S4 , S3 ) except in the methane high-concentration range, where cobalt-based sensor-S5 seems to be performing slightly better than the copper-based sensors - S3 , S4 , thus supporting the literature findings regarding cobalt oxide [ 11 ]. In Figure 3 b, a working temperature experiment is depicted for 2000 ppm of CH 4 injected in the sensing cell equipped with S5 .…”

Novel Nanosized Spinel MnCoFeO4 for Low-Temperature Hydrocarbon Oxidation

“…The comparison of the activities of the spinels prepared for this investigation with the data from the literature reveals that the MCF-S catalyst possesses excellent efficiency in the studied oxidation reactions. It shows lower “light-off” temperatures than single Co 3 O 4 oxide [ 42 ], SBA-15-supported binary Co-Mn-oxides [ 43 ], and copper, nickel, or manganese ferrites [ 23 , 44 ].…”

Total Catalytic Oxidation of Ethanol over MnCoAl Mixed Oxides Derived from Layered Double Hydroxides: Effect of the Metal Ratio and the Synthesis Atmosphere Conditions

“…Nevertheless, the role of the porosity cannot be neglected. A higher specific area could enhance VOC oxidation activity in the ternary oxides [41,42].…”