Ce-Fe/ZSM-5催化剂NH3选择性催化还原NO性能研究

通过浸渍法将Ce和Fe负载在ZSM-5载体上,制备了1.40%Fe/ZSM-5（数字为金属组分的质量分数,下同）、0.25%Ce/ZSM-5、0.25%Ce-1.40%Fe/ZSM-5和0.50%Ce-1.40%Fe/ZSM-5催化剂。对催化剂进行了表征并研究了其NH₃选择性催化还原（NH₃-SCR）NO的性能。实验结果表明,双金属改性的0.25%Ce-1.40%Fe/ZSM-5催化剂的活性温度窗口范围最广,在350~450 ℃范围内NO转化率超过98%。Ce和Fe以无定型氧化物的形态良好分散在ZSM-5载体表面,没有改变ZSM-5分子筛的微孔结构。0.25%Ce-1.40%Fe/ZSM-5催化剂的有效还原峰面积更大,孤立Fe³⁺和Ce⁴⁺物种含量更多,氧化还原性能显著,催化剂表面具有丰富的中等强度酸性位且酸量较大,有利于 NH₃-SCR 反应的进行。

Research on performance of Ce-Fe/ZSM-5 catalyst forselective catalytic reduction of NO with NH3

Ce and Fe were loaded on carrier ZSM-5 prepared by impregnation method to preparea series of catalyst,such as：1.40%Fe/ZSM-5（number stands for mass fractionof metal component,the same below）,0.25%Ce/ZSM-5,0.25%Ce-1.40%Fe/ZSM-5 and 0.50%Ce-1.40Fe/ZSM-5 catalyst. The catalysts were characterized and their activities for selective catalytic reduction of NO with NH₃ were researched.The experimental results show that the bimetal-modified catalyst 0.25%Ce-1.40%Fe/ZSM-5 has the widest activation temperature range with which the NO conversion rate reaches 98% in the temperature range of 350-450 ℃. Ce and Fe are well dispersed on the surface of the ZSM-5 carrier in the form of amorphous oxide,so that the micropore structure of the ZSM-5 is not changed. The 0.25% Ce-1.40% Fe/ZSM-5 catalyst has a larger effective reduction peak area and more isolated Fe³⁺and Ce⁴⁺ species,which indicate its significant redox performance. There are abundant medium-strength acid sites and a large amount of acid on the surface of the catalyst,which is favorable to the NH₃-SCR reaction.