Catalytic Oxidation of Toluene over Nanorod Manganese Oxides Catalysts: Phase Change Effects

Four manganese oxide (MnO)(x) catalysts with different phases were prepared via a hydrothermal method, and the toluene oxidation over the four manganese dioxide (MnO) catalysts was studied. Among the catalysts, delta-MnO2 exhibits the best performance, excellent stability, and reusability. Moreover, delta-MnO2 possesses the highest specific surface area, with more exposed active sites compared to the other catalysts with which to make contact with toluene, leading to it exhibiting excellent activity. Furthermore, delta-MnO2 shows more lattice defects, Mn3+/(Mn3+ + Mn4+), oxygen vacancies, and surface adsorbed oxygen than the other catalysts, resulting in its excellent redox properties and catalytic performance. In addition, oxygen molecules adsorb on the oxygen vacancies of delta-MnO2, which are beneficial to the adsorption and oxidation of toluene, with benzyl alcohol, benzaldehyde, benzoic acid, and benzoic acid ester detected as specific intermediate products.