Department of Environmental Engineering, Zhejiang University, Hangzhou, China.
Chemosphere. 2010 Feb;78(9):1160-6. doi: 10.1016/j.chemosphere.2009.11.049. Epub 2009 Dec 29.
MnCe oxides were supported on TiO(2) and Al(2)O(3) by an ultrasonic impregnation method and used for selective catalytic reduction (SCR) of NO with NH(3) at low-temperature (80-220 degrees C). MnCe/TiO(2) showed a relatively higher SCR activity than MnCe/Al(2)O(3) at the temperature range of 80-150 degrees C. When the reaction temperature was higher than 150 degrees C, MnCe/Al(2)O(3) exhibited superior SCR activity to MnCe/TiO(2). NH(3) temperature programmed desorption study proved that MnCe/TiO(2) was mainly Lewis acidic, while MnCe/Al(2)O(3) could provide more Brönsted acid sites. These acid sites play an important role in SCR according to in situ diffuse reflectance infrared transform spectroscopy (DRIFT) analysis. The main SCR reaction was a typical Eley-Rideal mechanism on MnCe/TiO(2), which took place between coordinated NH(3)/NH(4)(+) and gas-phase NO. For MnCe/Al(2)O(3), the reaction mainly occurred via another pathway when the temperature exceeded 150 degrees C, which commenced with the adsorption and oxidation of NO and was followed by reaction between NO(2) or NO(2)-containing compounds and NH(3) adspecies. This reaction pathway makes a significant contribution to the improved NO conversion for MnCe/Al(2)O(3) at higher temperature.
采用超声浸渍法将 MnCe 氧化物负载在 TiO2 和 Al2O3 上，用于 NH3 低温（80-220°C）选择性催化还原（SCR）NO。在 80-150°C 的温度范围内，MnCe/TiO2 比 MnCe/Al2O3 具有相对更高的 SCR 活性。当反应温度高于 150°C 时，MnCe/Al2O3 比 MnCe/TiO2 具有更优异的 SCR 活性。NH3 程序升温脱附研究表明，MnCe/TiO2 主要是路易斯酸性的，而 MnCe/Al2O3 可以提供更多的布朗斯台德酸位。这些酸位在原位漫反射红外变换光谱（DRIFT）分析中对 SCR 起着重要作用。主要的 SCR 反应是在 MnCe/TiO2 上发生的典型的 Eley-Rideal 机制，它发生在配位的 NH3/NH4+和气相 NO 之间。对于 MnCe/Al2O3，当温度超过 150°C 时，反应主要通过另一种途径发生，该途径起始于 NO 的吸附和氧化，随后是 NO2 或含 NO2 的化合物与 NH3 吸附物之间的反应。这种反应途径为 MnCe/Al2O3 在较高温度下提高 NO 转化率做出了重要贡献。
