超声波浸渍法制备MnO_x/TiO_2催化剂低温选择性催化还原NO

MnO_x/TiO_2 catalysts prepared by ultrasonic impregnation for low temperature selective catalytic reduction of NO

采用超声波浸渍法、传统浸渍法和溶胶凝胶法制备了一系列的MnOx/TiO2催化剂,采用X射线衍射(XRD)、比表面积测定(BET)、原位红外(in situ FT-IR)、高分辨率扫描电镜(HR-TEM)程序升温还原(TPR)等技术进行表征,同时在模拟氨气选择性催化还原NO的反应条件下(NH3-SCR)对催化剂的低温反应活性进行了考察.研究表明:超声波在催化剂制备过程中的应用对MnOx的分散、催化剂的表面酸性和脱硝反应活性产生了重要的影响;超声浸渍法制备的MnOx/TiO2催化剂表现出较好的反应活性,特别在低温窗口(120℃以下),100℃时的脱硝效率达到了90%.对其进行的各项表征结果显示:催化剂比表面积较大,Ti和Mn具有较强的相互作用,催化剂表面具有较多的Lewis酸位和较高的Mn原子浓度,并且出现了SCR中间产物NH2.

A series of MnOx/TiO2 catalysts were prepared by ultrasonic impregnation,traditional impregnation and sol-gel methods.Their properties were studied by using X-ray diffraction（XRD）,Brunauer-Emmett-Teller（BET） surface measurement,high-resolution transmission electron microscope（HRTEM）,in situ Fourier transform infrared spectroscopy（in situ FT-IR） and temperature programmed reduction（TPR） techniques and their catalytic performance for the selective catalytic reduction of NO with NH3（NH3-SCR）was investigated.It is found that the use of ultrasonic in the solution impregnation for preparing MnOx/TiO2 catalysts has significant effect on the dispersion behavior and surface acid property of manganese oxide on TiO2 as well as the catalytic activity.MnOx/TiO2catalysts prepared by UI（ultrasonic impregnation） method exhibits higher catalytic activity;especially at temperature below 120℃.NO conversion rate at 100℃ is about 90%.The characterization results indicate that the catalyst shows larger specific BET surface area;Ti and Mn have strong interaction;there is a significant amount of Lewis acidity and high concentration of Mn atom as well as the formation of abundant NH2 on the surface.