Inorganic siloxane-modified nanosheet-assembled MnOx hollow sphere catalyst for VOC removal from coal-fired flue gas: Enhanced water resistance and Activity

T Huang and YY Ge and X Zhang and BX Shen and F Shen, CHEMICAL ENGINEERING JOURNAL, 484, 149638 (2024).

DOI: 10.1016/j.cej.2024.149638

Water poisoning of catalysts presents a significant practical challenge in the removal of pollutants from coal-fired flue gas. Herein, a highly water-resistance Mn catalyst, with a structure of hollow spheres (NS) assembled by nanosheets and modified by inorganic siloxane was developed. The hydrophobic catalyst (Mn-Si0.06/NS) showed a 50% increase in VOC removal efficiency compared to Mn/Al2O3 when exposed to wet flue gas containing 10 vol% water vapor. Strikingly, Mn-Si0.06/NS exhibited robust SO2 resistance, especially under flue gas with high water vapor content. Mechanistic results shows that the enhanced water resistance of catalyst resulted from the synergy between morphological structure and the inorganic siloxane modification. DRIFTS and XPS analyses showed that the catalyst effectively prevented the water poisoning effect, which involves lattice oxygen consumption and transformation. The ability of catalyst to utilize oxygen under wet flue gas was also confirmed by product analysis, which revealed a clear preference for the oxidation reaction path of o-xylene compared with Mn/Al2O3. Molecular dynamics (MD) simulations show the dynamic scenario of VOC and water vapor adsorption on the catalysts and provide an intuitive picture of the catalysts' water resistance.

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