Mn-Ce interface engineering boosts low-temperature catalytic oxidation of chlorobenzene: Optimized oxygen vacancies and acid sites

Atomic defects in catalysts (such as vacancies, substituted atoms, or interstitial atoms) are the decisive factors in initiating low-temperature catalytic reactions. The study achieved the selective exposure of Mn-doped CeO 2 (111) crystal planes and facilitated the migration of oxygen species at the interface through the regulation of Mn and Ce precursors, thereby enhancing the low-temperature catalytic performance for chlorobenzene (CB). The Mn: Ce precursor ratio strongly influences activity; Mn 1 Ce 1 shows optimal performance with T 50 ≈ 142 ℃ and T 90 ≈ 192 ℃. Structural analyses confirm Mn incorporation into the CeO 2 lattice across multiple facets, optimizing Mn-O v -Ce interfacial sites, increasing surface acidity, and elevating oxygen‑vacancy (O v ) concentration (3.6 ×10 13 spins/g). CB was nearly completely mineralized to CO 2 at 240 ℃, while chlorine was mainly removed as HCl. Oxygen is crucial for the dynamic generation and cycling of O v , effectively replenishing the consumed adsorbed oxygen (O ads ) during catalysis, whereas the presence of water vapor causes competitive adsorption, reducing catalytic activity. In-situ DRIFTS, in-situ EPR, and DFT calculations demonstrated that surface O ads are the primary active oxygen species. CB trapped by O v is sequentially converted into intermediates (e.g., phenol and benzoquinone) and ring-opening products (e.g., maleic anhydride and formic acid) under the action of O ads , ultimately mineralizing into CO 2 . The Mn-doped CeO 2 (111) crystal facet exhibited the lowest CB adsorption energy (-2.4 eV), O v formation energy (1.1 eV), and HCl formation energy (-1.3 eV). Furthermore, Mn serves as a dechlorination site, effectively promoting C-Cl bond cleavage and inhibiting chlorine poisoning at CeO 2 interface.