Ru-doped MOF-templated CeMnOx catalysts for efficient oxidation of chlorobenzene: synergistic effects of active oxygen species and acid sites

Abstract

In this study, CeMnO_x was synthesized via a metal–organic framework (MOF)-templated method. Ru doping was subsequently employed to prepare a series of RuCeMnO_x catalysts. The RuCeMnO_x catalyst with 0.8 wt% Ru (RuCeMnO_x-0.8 wt%) demonstrated optimal catalytic activity for chlorobenzene oxidation, achieving 99% chlorobenzene conversion at 268 °C and 97% CO₂ selectivity at 300 °C (reaction conditions: 500 ppm chlorobenzene, 30 000 h⁻¹ gas hourly space velocity, and 10 vol% O₂). The temperature required for 90% chlorobenzene conversion decreased by 80 °C compared to that for the CeMnO_x catalyst. XRD, Raman, XPS, and O₂-TPD analyses were conducted to investigate the relationship between the oxidative activity of the RuCeMnO_x-0.8 wt% catalyst and its physicochemical properties. The results revealed that the electronic interactions and synergistic effects among Ru, Mn, and Ce promoted the formation of oxygen vacancies and improved oxygen migration capacity, thereby elevating the concentration of active oxygen species in the catalyst. Notably, Py-IR and GC-MS analyses demonstrated that these synergistic effects simultaneously increased surface acid sites and improved HCl selectivity, effectively suppressing the formation of polychlorinated by-products such as trichloroethylene and dichlorobenzene. In situ DRIFTS analysis further elucidated the reaction mechanism of chlorobenzene oxidation over the RuCeMnO_x catalyst. This work provides an efficient and stable strategy for the catalytic oxidation of CVOCs.