期刊
ENVIRONMENTAL SCIENCE & TECHNOLOGY
卷 47, 期 10, 页码 5294-5301出版社
AMER CHEMICAL SOC
DOI: 10.1021/es304732h
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资金
- Science Fund for Creative Research Groups [21221004]
- National High-Tech Research and Development (863) Program of China [2010AA065001, 2012AA062506]
- Research projects of Guangdong Province [2011A032303002]
The performances of fresh and sulfated MnOx-CeO2 catalysts for selective catalytic reduction of NOx by NH3 (NH3-SCR) in a low-temperature range (T < 300 degrees C) Were investigated. Characterization of these catalysts aimed at elucidating the role of additive and the effect of sulfation. The catalyst having a Sn:Mn:Ce = 1:4:5 molar ratio showed the widest SCR activity improvement with near 100% NOx conversion at 110-230 degrees C. Raman and X-ray photoelectron spectroscopy (XPS) indicated that Sn modification significantly increases the concentration of oxygen vacancies that may facilitate NO oxidation to NO2. NH3-TPD characterization showed that the low-temperature NH3-SCR activity is well correlated with surface acidity for NH3 adsorption, which is also enhanced by Sn modification. Furthermore, as compared to MnOx-CeO2, Sn-modified MnOx-CeO2 showed remarkably improved tolerance to SO2 sulfation and to the :combined effect of SO2 and H2O. In the presence of SO2 and H2O, the Sn-modified MnOx-CeO2.catalyst gave 62% and 94% NOx conversions as compared to 18% and 56% over MnOx-CeO2 at temperatures of 110 and 220 degrees C respectively. Sulfation of SnO2-modified MnOx-CeO2 may form Ce(III) sulfate that could enhance the Lewis acidity and improve NO oxidation to NO2 during NH3-SCR at T > 200 degrees C.
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