Improved redox synthesis of Mn–Co bimetallic oxide catalysts using citric acid and their toluene oxidation activity

Abstract

In this work, high-activity cobalt-doped α-MnO₂ hybrid materials were prepared using the citric acid oxidation reduction (CR) technique and applied to the catalytic oxidation of toluene. Compared to the traditional processes such as sol–gel, co-precipitation and our previous reported self-driving combustion process, the microstructure of Mn–Co bimetallic oxide catalyst is easier to regulated as well as the dispersion of active phase. Moreover, some accurate characterization techniques such as XRD, H₂-TPR, O₂-TPD, SEM, TEM, and XPS have been employed, to further illustrate the intrinsic factors for the efficient catalytic oxidation of toluene. It was ultimately found that the CR-Mn10Co1 prepared by citric acid oxidation reduction method could catalyze the oxidation of 90% of toluene at 232 °C, and its excellent catalytic performance was significantly related to its large specific surface area, excellent oxidation reduction ability, and abundant Mn³⁺ species and oxygen vacancy content. Therefore, citric acid oxidation reduction (CR) provides a convenient and effective route for the efficient and low-cost synthesis of Mn–Co catalysts for removing VOCs.