Ternary catalyst Mn-Fe-Ce/Al₂O₃ for the ozonation of phenol pollutant: performance and mechanism

In this study, a novel ternary catalyst Mn-Fe-Ce/Al₂O₃ was synthesized by co-impregnation method, and was characterized by XRD, SEM, XPS, and FTIR. The catalytic performance of this ternary catalyst was evaluated in the heterogeneous catalytic ozonation of phenol pollutants and it improved the removal rate and mineralization degree of phenol pollutants. The changes of dissolved ozone in water and the TBA experiment proved that the ternary catalyst could accelerate the decomposition of ozone into hydroxyl radicals, thus accelerating the oxidation of phenol. Phosphate experiments and surface hydroxyl density measurements proved that surface hydroxyl was the active site of the catalyst. XPS analysis showed that the ternary catalysts accelerated electron transfer through the redox cycles of Mn²⁺-Mn³⁺-Mn⁴⁺, Fe²⁺-Fe³⁺, and Ce³⁺-Ce⁴⁺, which also contributed to the high catalytic activity. Moreover, the catalyst maintained high catalytic activity after five cycles of use. Therefore, the ternary catalyst was considered an efficient and promising catalyst for catalytic ozonation system.