A strategy to improve the performance of MnCe-MOFs/ZSM-5 for formaldehyde degradation at ambient temperature
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Reducing airborne formaldehyde (HCHO) to the indoor environmental standard (0.08 mg/m 3 ) remains challenging when relying solely on physical adsorption. Ambient-temperature catalytic oxidation offers an effective alternative, decomposing HCHO into CO 2 using high performance transition metal oxides. New type metal organic frameworks (MOFs) of monometallic, bimetallic oxides and supported catalysts with different carriers synthesized by the hydrothermal method were investigated in this study. 1.0 g of catalyst powder was dispersed uniformly on the petri dish (Φ=90 mm) and the initial concentration of HCHO was regulated to 1.0±0.5 mg/m 3 . The reaction temperature was set to ambient temperature (25±5°C), and the measurements for HCHO concentration were performed triply every 12 h. Among them, MnCe-MOFs displayed a high degradation rate (96.3%) at 48 h, with notable stability attributed to the synergistic redox cycling of Ce 4+ /Ce 3+ and Mn 3+ /Mn 4+ , which generated abundant reactive oxygen species (ROS, O 2 - and ·OH), along with their excellent hydrophobicity. Electron paramagnetic resonance (EPR) analysis revealed that oxygen-deficient sites facilitate the complete oxidation of HCHO. As for supported catalysts, 20wt%MnCe-MOFs/ZSM-5 also exhibited a high oxidation activity (93.4%) ascribed to abundant active components of MnCe-MOFs, surface week acid sites, high surface areas, and abundant oxygen vacancies, indicating high stability for HCHO oxidation.
