Improved low-temperature SCR activity for Fe-BEA catalysts by H2-pretreatment

Abstract

A series of iron-exchanged zeolite beta catalysts (0.5–4wt.% Fe) have been prepared by incipient wetness impregnation and tested for selective catalytic reduction (SCR) of NOX with ammonia as reductant. The catalysts were characterized using BET, NH3-TPD and XPS before and after H2-pretreatment at 650°C for 5h. The NH3-SCR activity tests show that the samples pretreated by hydrogen exhibit higher low-temperature SCR activity compared to the fresh samples, while the high-temperature activity remains almost constant. The results clearly show that the high-temperature H2-treatment has a significant influence on the extent of different iron species formed in the zeolite. Furthermore, H2-treatment of hydrothermally aged samples can recover some of the initial activity, although not completely due irreversible dealumination during the ageing. By H2-pretreatment SCR catalysts with high iron loading and high activity can be prepared.