TiO_2载体掺杂对Mn-Ce/TiO_2催化剂低温脱硝性能影响研究

以TiO_2、TiO_2-Al_2O_3及TiO_2-SiO_2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TiO_2载体掺杂Al_2O_3、SiO_2改性后对Mn-Ce/TiO_2催化剂低温脱硝活性的影响,运用BET、SEM、XRD、H2-TPR以及NH_3-TPD等测试手段对催化剂进行了表征。结果表明,TiO_2载体经掺杂改性后,Mn-Ce/TiO_2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/TiO_2-Al_2O_3和Mn-Ce/TiO_2-SiO_2催化剂中TiO_2的结晶度均有不同程度降低;经TiO_2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TiO_2载体掺杂SiO_2和Al_2O_3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/TiO_2-SiO_2M n-Ce/TiO_2-Al_2O_3M n-Ce/TiO_2。

Study on the modification effect of TiO2 support on the low temperature denitration activity of Mn-Ce/TiO2 catalysts

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 NO_x 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℃.