共沉淀法制备的Mn-Ce/TiO2催化剂低温脱硝性能研究

Low Temperature Denitrification of Mn-Ce/TiO_2 Catalyst Prepared by Coprecipitation Method

本文分别以NH_4OH、(NH_4)_2CO_3、NaOH作为沉淀剂,采用共沉淀法制备了一系列Mn-Ce/TiO_2催化剂,并借助XRD、BET、NH_3-TPD及XPS等测试手段对催化剂进行了表征,初步探讨了沉淀剂对Mn-Ce/TiO_2催化剂SCR脱硝性能影响。结果表明:与(NH_4)_2CO_3和NaOH相比,采用NH_4OH作为沉淀剂制备的Mn-Ce/TiO_2催化剂表现出了最佳的低温脱硝活性。当空速为16000 h^(-1),活性组分的负载量为15%时,催化剂在80℃的NO去除率达85%以上。这主要是由于该催化剂中的锰氧化物主要以无定形态存在;其孔结构更加细化、孔径较小及较大的孔容,为活性组分的均匀负载提供了有利条件;表面具有较多的弱酸性位点和中等酸性位点,且具有良好的氧化还原性强能力,有利于NO和NH3的吸附、氧化,有效的促进了催化剂的低温SCR脱硝活性。

Mn-Ce/Ti02 catalysts were prepared by coprecipitation method using NH40H, （NH4）2C03 and NaOH as precipitants, and the catalysts were characterized by XRD, BET, NH3-TPD and XPS. The effect of precipitant on SCR denitrification of Mn-Ce/Ti02 catalyst was discussed. The results show that Mn-Ce/Ti02 catalyst prepared with NH4OH as precipitant exhibits the best low temperature denitrification activity compared with （NH4）2C03 and NaOH. When the space velocity is 16000 h _1 and the loading of the active component is 15% , the NO removal rate of the catalyst is above 85% at 80 Tl. This is mainly due to the fact that the manganese oxide in the catalyst is mainly in the amorphous state; its pore structure is more refined, the pore size is smaller and the larger pore volume provides favorable conditions for the uniform loading of the active component ; The catalyst has more weak acid sites and moderate acid sites, and has good redox resistance, which is favorable for the adsorption and oxidation of NO and NH3, which effectively promotes the low temperature SCR denitrification activity of the catalyst.