Enhanced catalytic oxidation of VOCs over porous Mn-based mullite synthesized by in-situ dismutation
2021
Liu, James J. Y. | Zhou, Bing | Liu, Lizhong | Zhang, Yan | Chen, Yu | Zhang, Qiaoling | Yang, Mingliang | Hu, Lanping | Wang, Miao | Tang, Yanfeng
Porous Mn-based mullite SmMn₂O₅ was synthesized by the in-situ dismutation of solid state Mn³⁺ in bulk SmMnO₃ perovskite to catalytic oxidation of benzene and chrolobenznen. The physicochemical property of catalyst was acquired by XRD, SEM, N₂ adsorption–desorption, XPS, O₂-TPD and H₂-TPR. Compared with that of bulk SmMnO₃ and bulk SmMn₂O₅, the porous SmMn₂O₅ mullite (SmMn₂O₅-ID) displayed higher molar ratios of Mn⁴⁺/Mn³⁺ and Oₗₐₜₜ/Oₐdₛ, and better active oxygen desorption capacity, reducibility and larger specific surface, which promoted the preferable low-temperature catalytic oxidation of VOC. The increase in the content of Mn⁴⁺ on the surface of the Sm-Mn mullite reduced the surface defects and increased the proportion of its surface lattice oxygen, thereby promoting the attack of VOC molecules by more lattice oxygen. Combined with the analysis of reactant intermediate for benzene oxidation by in situ diffuse reflectance infrared Fourier transform spectroscopy, the catalytic mechanism of the catalyst was also explored. Moreover, SmMn₂O₅-ID also showed the excellent stability and the superior removal of mixed VOCs with different concentration ratios. This finding provides an efficient and practical method for exploiting highly active Mn-based mullite with a high efficiency and stability for the purification of air pollution.
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