Synergistic Modulation of MOF-Derived Cu-Doped Mn ₃ O ₄ over Porous Al ₂ O ₃ Ceramics: Toward High-Performance Toluene Catalytic Oxidation

Advancing the efficient and comprehensive control of volatile organic compounds (VOCs) is a critical cornerstone for establishing global atmospheric pollution prevention systems and achieving long-term improvements in air quality. Although catalytic oxidation is an effective technology for VOCs removal, its practical application is often limited by catalyst sintering and poor low-temperature activity. This study investigates the grain refinement and surface defect engineering of Cu-doped Mn 3 O 4 spinel catalysts derived from metal–organic frameworks (MOFs) for low-temperature toluene oxidation. By controllably introducing Cu, crystal growth is effectively suppressed, and lattice distortion is induced, thereby increasing the density of surface defects. The optimized Cu 0.03 Mn 2.97 O 4 sample exhibits enhanced surface oxygen mobility and modified cation distribution, promoting efficient oxygen activation and redox cycling, which significantly improves low-temperature catalytic activity, achieving a T 90 value of 215 °C. Simultaneously, when the Cu 0.03 Mn 2.97 O 4 catalyst was loaded onto porous Al 2 O 3 ceramic, the gas diffusion efficiency was improved, and the agglomeration of the powder catalyst was effectively inhibited. The obtained Cu 0.03 Mn 2.97 O 4 /C catalyst reached T 90 at 210 °C and maintained excellent stability during the toluene degradation test under 3 vol.% water vapor conditions for 50 consecutive hours. By integrating defect engineering with macroscopic structural design, this work elucidates the intrinsic structure–activity relationship, offering a practical strategy for doping engineering of transition metal oxide catalysts and their integration onto porous ceramic supports.