Study on the modification effect of TiO2 support on the low temperature denitration activity of Mn-Ce/TiO2 catalysts
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摘要: 以TiO2、TiO2-Al2O3及TiO2-SiO2为载体，选取Mn为活性组分，Ce为活性助剂，采用分布共混法制备低温SCR催化剂，分析了TiO2载体掺杂Al2O3、SiO2改性后对Mn-Ce/TiO2催化剂低温脱硝活性的影响，运用BET、SEM、XRD、H2-TPR以及NH3-TPD等测试手段对催化剂进行了表征。结果表明，TiO2载体经掺杂改性后，Mn-Ce/TiO2催化剂的比表面积、孔结构参数以及表面孔结构形貌均得到改善和提高；Mn-Ce/TiO2-Al2O3和Mn-Ce/TiO2-SiO2催化剂中TiO2的结晶度均有不同程度降低；经TiO2载体掺杂改性后的催化剂表面低温还原峰面积及催化剂表面酸性位种类及酸性大小显著改善，这都有助于提高催化剂的脱硝活性。通过对TiO2载体掺杂SiO2和Al2O3改性后，催化剂的脱硝活性明显提高，反应温度在80-140℃时，催化剂SCR脱硝活性的顺序是：Mn-Ce/TiO2-SiO2 > Mn-Ce/TiO2-Al2O3 > Mn-Ce/TiO2。Abstract: Low-temperature selective catalytic reduction (SCR) catalysts were prepared by step wise blending method with TiO2, TiO2-Al2O3 and TiO2-SiO2 as support and Mn as active component, Ce as promoter. The effects of doping Al2O3 and SiO2 to TiO2 support on NOx removal activity of the catalysts were systematically investigated. The catalysts were characterized by XRD, BET surface area, SEM, H2-TPR and NH3-TPD. It was found that the specific surface area, pore structure parameters and surface pore structure morphology of the catalysts were improved and the TiO2 crystallinity of Mn-Ce/TiO2-Al2O3 and Mn-Ce/TiO2-SiO2 catalysts were reduced to some extent by doping SiO2, Al2O3 on TiO2 support respectively. The low temperature reduction peak area, acid type and acidity of catalysts surface were improved significantlybydoping modification. All of these were beneficial to enhance the denitration activity of the catalysts. The denitration activity of the catalysts was increased to a great extent by doping SiO2 and Al2O3 on TiO2 support respectively, the order of SCR activity of three kinds of catalysts above was:Mn-Ce/TiO2-SiO2 > Mn-Ce/TiO2-Al2O3 > Mn-Ce/TiO2 when the SCR reaction temperature was in the range of 80-140℃.
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Key words:
- titania /
- doped modification /
- low temperature denitration activity
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图 1 TiO2载体及其掺杂改性Mn-Ce/TiO2催化剂活性
Figure 1 Activity curve of Mn-Ce/TiO2 catalysts prepared by TiO2 support and its doping modification
图 2 TiO2载体及其掺杂改性Mn-Ce/TiO2催化剂吸附-脱附曲线及孔径分布
Figure 2 Adsorption-desorption curve and pore size distribution of Mn-Ce/TiO2-M catalyst
(a): Mn-Ce/TiO2; (b): Mn-Ce/TiO2-Al2O3; (c): Mn-Ce/TiO2-SiO2
图 3 TiO2载体及其掺杂改性16%Mn-Ce/TiO2催化剂的XRD谱图
Figure 3 XRD patterns of Mn-Ce/TiO2 catalysts prepared by TiO2 support and its doping modification
a: Mn-Ce/TiO2; b: Mn-Ce/TiO2-Al2O3; c: Mn-Ce/TiO2-SiO2
■: TiO2; ◆: SiO2; ●: Al2O3
图 4 TiO2载体及其掺杂改性Mn-Ce/TiO2催化剂H2-TPR谱图
Figure 4 H2-TPR profiles of Mn-Ce/TiO2 catalysts prepared by TiO2 support and its doping modification
a: Mn-Ce/TiO2; b: Mn-Ce/TiO2-SiO2; c: Mn-Ce/TiO2-Al2O3
图 5 TiO2载体及其掺杂改性Mn-Ce/TiO2催化剂NH3-TPD谱图
Figure 5 NH3-TPD prefiles of Mn-Ce/TiO2 catalysts prepared by TiO2 support and its doping modification
a: Mn-Ce/TiO2; b: Mn-Ce/TiO2-Al2O3; c: Mn-Ce/TiO2-SiO2
表 1 载体TiO2及其掺杂Mn-Ce催化剂比表面积及孔结构
Table 1 Specific surface area and pore structure of Mn-Ce catalyst prepared by TiO2 support and its doping modification
Catalyst Specific surface area
A/(m2·g-1)Pore volume
v/(cm3·g-1)Average aperture
d/nmMn-Ce/TiO2 22.94 0.058 10.06 Mn-Ce/TiO2-Al2O3 24.87 0.074 11.98 Mn-Ce/TiO2-SiO2 24.68 0.072 11.69 
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