Fe-Cu/ZSM-5催化剂的NH_3-SCR脱硝性能

通过浸渍法制备了Fe和Cu含量比不同的系列Fe-Cu/ZSM-5催化剂,利用XRD、H2-TPR、NH3-TPD和原位DRIFTS等技术对催化剂进行了表征,并对其NH3-SCR脱硝性能进行了研究。结果表明,双金属改性的Fe-Cu/ZSM-5催化剂活性温度窗口拓宽,其中,Fe-Cu/ZSM-5 1∶4催化剂脱硝性能优异,250-450℃下脱硝效率均超过90%,335℃时脱硝效率达到最大值96.46%。铜和铁物种能以无定型氧化物良好分散于载体表面,双金属负载改性催化剂保留了ZSM-5的晶体结构。Fe-Cu/ZSM-5 1∶4催化剂具备丰富的酸性位、良好的氧化还原性能,一定温度条件下NH3-SCR反应过程中同时存在E-R机理和L-H机理,且E-R机理反应起始温度低于L-H机理;200℃为催化脱硝反应的起活温度。

Performance of Fe-Cu/ZSM-5 catalyst in the DeNOx process via NH3-SCR

A series of Fe-Cu/ZSM-5 catalysts with different Fe/Cu molar ratios were prepared by impregnation method and characterized by XRD, H₂-TPR, NH₃-TPD and in situ DRIFTS; their performance in the denitrification (de-NO_x) process via NH₃-SCR was investigated. The results showed that the bimetallic modified Fe-Cu/ZSM-5 catalysts have a broad active temperature window. Especially, the Fe-Cu/ZSM-5 1:4 catalyst with a Fe/Cu molar ratio of 1:4 displays the highest activity; over it, the deNO_x efficiency reaches the maximum of 99.46% at 335℃ and keeps above 90% at 250-450℃. Copper and iron species, present as amorphous oxides, are finely dispersed on the catalyst surface and the bimetallic modified catalysts retain the crystal structure of ZSM-5. The Fe-Cu/ZSM-5 1:4 catalyst exhibits abundant acid sites and excellent redox performance. E-R mechanism and L-H mechanism may coexist during the NH₃-SCR reaction under certain temperature; moreover, the onset temperature of E-R mechanism is much lower than that of L-H mechanism and the denitration reaction may be ignited at 200℃.