Improvement of Activity and SO2 Tolerance of Sn-Modified MnOx-CeO2 Catalysts for NH3-SCR at Low Temperatures

被引：495

作者：

Chang, Huazhen ^{[1
]}

Chen, Xiaoyin ^{[2
]}

Li, Junhua ^{[1
,3
]}

Ma, Lei ^{[1
]}

Wang, Chizhong ^{[1
]}

Liu, Caixia ^{[1
]}

Schwank, Johannes W. ^{[2
]}

Hao, Jiming ^{[1
]}

机构：

[1] Tsinghua Univ, Sch Environm, State Key Joint Lab Environm Simulat & Pollut Con, Beijing 100084, Peoples R China

[2] Univ Michigan, Dept Chem Engn, Ann Arbor, MI 48109 USA

[3] Tsinghua Univ, State Environm Protect Key Lab Sources & Control, Beijing 100084, Peoples R China

来源：

ENVIRONMENTAL SCIENCE & TECHNOLOGY | 2013年 / 47卷 / 10期

关键词：

NITRIC-OXIDE; X-RAY; MANGANESE OXIDES; MIXED OXIDES; REDUCTION; NO; NH3; MECHANISM; RAMAN; MNOX/AL2O3;

D O I：

10.1021/es304732h

中图分类号：

X [环境科学、安全科学];

学科分类号：

083001 [环境科学];

摘要：

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.

引用

页码：5294 / 5301

页数：8

共 38 条

[1]

Structural characterization of nanocrystalline SnO2 by X-ray and Raman spectroscopy [J].