Microreactor-assisted synthesis of surface-active oxygen-rich Mn–Ce oxide particles and their catalytic activity in the wet air oxidation process

Abstract

In this study, a central-collision type microreactor was applied to the synthesis of Mn–Ce oxide catalysts by a liquid-phase oxidation method, which suffers from poor homogeneity and therefore has not been widely used in catalyst synthesis. This approach aimed to achieve improved structural homogeneity and oxygen defect formation. As a model reaction, phenol degradation by catalytic wet air oxidation was investigated using synthesized δ-type Mn–Ce oxides as catalysts. Compared with conventional stirring synthesis, microreactor-assisted synthesis afforded catalysts with finer and more uniform particles, larger specific surface areas, higher concentrations of surface oxygen species and bulk oxygen defects, and highly dispersed CeO₂ within the MnO₂ matrix. When applied to phenol degradation, a degradation efficiency of 57% after a reaction time of 1 h was achieved for the catalyst synthesized using the microreactor, in contrast to 43% for the catalyst synthesized by conventional stirring. These findings demonstrate that microreactor-assisted synthesis effectively incorporates unstable oxygen species into the catalyst structure, resulting in the enhancement of the efficiency of oxidative degradation reactions.