| Abstract |
| The effect of added WO₃ on the catalytic activity and surface characteristics of the MnOx-TiO₂ system was investigated for the low-temperature selective catalytic reduction of NOx with NH₃. Based on physio-chemical characterizations, the specific surface areas of the WO₃-MnOx-TiO₂ catalysts increased from 76.12m²/g to 90.29m²/g as the WO₃ content increased, and crystallinity of the anatase TiO₂ phase decreased. The NOx conversion efficiency of the WO₃-MnOx-TiO₂ catalysts with WO₃ contents was over 70% at 200 °C, and their efficiency was over 90% at 300 °C. The results of Fourier transform infrared spectroscopy indicated that the 1438 and 1632 cm-1 values, which were assigned to Lewis and Brønsted acid sites, increased with the increase in WO₃ content. The enhanced catalytic acidity originated from changes to the physical and chemical structures on the surface. MmOx formed on the TiO₂ surface of the 15 wt% WO₃-doped MnOx-TiO₂, and amorphous state Mn2O3 (Mn3+) and WO3 (W6+) existed on the surface, which led to the improved Lewis and Brønsted acid sites, respectively. |
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| Key Words |
| nanostructured materials, sol-gel, surface, raman spectroscopy, catalytic acidity |
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