TiO_2载体掺杂对Mn-Ce/TiO_2催化剂低温脱硝性能影响研究

Study on the modification effect of TiO_2 support on the low temperature denitration activity of Mn-Ce/TiO_2 catalysts

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_2>M n-Ce/TiO_2-Al_2O_3>M n-Ce/TiO_2。

Low-temperature selective catalytic reduction（SCR）catalysts eere prepared by step eise blending method eith 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 NOxremoval activity of the catalysts eere systematically investigated.The catalysts eere characterized by XRD,BET surface area,SEM,H2-TPR and NH3-TPD.It eas found that the specific surface area,pore structure parameters and surface pore structure morphology of the catalysts eere improved and the TiO2 crystallinity of Mn-Ce/TiO2 -Al2O3 and Mn-Ce/TiO2 -SiO2 catalysts eere reduced to some extent by doping SiO2 ,Al2O3 on TiO2 support respectively.The loetemperature reduction peak area,acid type and acidity of catalysts surface eere improved significantlybydoping modification.All of these eere beneficial to enhance the denitration activity of the catalysts.The denitration activity of the catalysts eas increased to a great extent by doping SiO2 and Al2O3 on TiO2 support respectively,the order 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 ℃.