铜锰复合低温NH_3-SCR整体催化剂的制备及其性能研究

Preparation and characterization of monolith catalysts loaded with copper and manganese for low-temperature NH_3-SCR

以堇青石蜂窝陶瓷为载体,采用溶胶-凝胶法在其表面不同质量比交替负载Mn-Ce-O/TiO2和Cu-Ce-O/TiO2得到多层复合催化剂,用于NH3选择性催化还原NO。活性测试表明,在两种活性层的共同作用下,复合催化剂有很好的低温活性和很宽的活性温度窗口。以氨气为还原剂,NO浓度为1025 mg/m^3,空速12600h^-1时,在250℃下NO的转化率就可以达到95%；200℃-300℃下,NO的转化率高于80%。对比实验表明,在此条件下复合催化剂的催化效果明显优于Mn-Ce-O/TiO2/CC和Cu-Ce-O/TiO2/CC单活性相催化剂。BET、XRD、XPS及TPR测试表明,催化剂的高活性与其较大的比表面积、较高含量的无定形分布活性组分、锐钛矿型TiO2、丰富的表面裂纹及良好的氧化还原性能有关。

Mn-Ce-O/TiO2 and Cu-Ce-O/TiO2 phases were loaded onto the cordierite honeycomb ceramics using sol-gel method. A series of monolith catalysts with multilayer washcoat was prepared with different mass ratio of these two phases. The catalysts exhibit high activity at low temperatures and a wide temperature window for the selective catalytic reduction of NO with ammonia （NH3-SCR）. NO conversion was 95% at 250℃ with the inlet NO concentration of 1025 mg/m^3, and the gas hourly space velocity （GHSV） of 12600 h^-1 ; the conversion of NO was above 80% in the temperature range of 200℃-300℃. The catalysts with multilayer washcoat performed much better in NH3-SCR than the single-phase catalyst. The results from BET, XRD, XPS, TPR, and SEM suggested that the high activity of these catalysts can be attributed to the large surface area, high loading of amorphous active components, TiO2 in the form of anatase, abundant surface cracks, and good redox capability of the muhilayer structures.