Catalytic mechanism study on manganese oxide in the catalytic supercritical water oxidation of nitrobenzene

Abstract

Among all the transition metal oxides, MnO₂, which exhibits stable performance in supercritical water oxidation (SCWO), has a relatively high catalytic activity in the catalytic decomposition of organic compounds by oxidation. Hence, for some organics that are difficult to degrade, MnO₂ is a commonly used catalyst. However, the mechanism of the catalytic oxidation of organic compounds by a manganese oxide catalyst is not very clear. In this study, the catalytic mechanism of manganese oxide in the supercritical water oxidation of nitrobenzene was discussed via TG-MS, XRD, activity tests and product analysis. In the process of supercritical water oxidation, the catalyst exists in a mixed MnO₂–Mn₂O₃ state, in the role of an electron relay that promotes the generation of strong oxidizing agents (˙OH, O*) and the catalytic oxidation of nitrobenzene.