The effect of Fe species distribution and acidity of Fe-ZSM-5 on the hydrothermal stability and SO2 and hydrocarbons durability in NH3-SCR reaction

Fe-exchanged ZSM-5 catalysts prepared from Na+ and H+ forms of ZSM-5 were evaluated for the selective catalytic reduction of NOx by NH3 (NH3-SCR). Fe-H-ZSM-5 showed higher SCR activity than Fe-Na-ZSM-5 both when fresh and after hydrothermal aging at 750 degrees C in 5% H2O/air. The Fe species distribution and acidity of Fe-H-ZSM-5 and Fe-Na-ZSM-5 were found to be different. The dealumination of the zeolite framework of Fe-H-ZSM-5 during hydrothermal aging was found to be more severe compared with that of Fe-Na-ZSM-5. The durability of Fe-H-ZSM-5 and Fe-Na-ZSM-5 in NH3-SCR was compared using SO2 tolerance and hydrocarbon resistance experiments. The effect of water and SO2 on the activity of the two catalysts was similar, such that their activity decreased at low temperatures and increased at high temperatures. Fe-Na-ZSM-5 showed better propene resistance than Fe-H-ZSM-5. The SO2 and propene poisoning of the two Fe-ZSM-5 catalysts were found to be reversible. (C) 2015, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.