Low-temperature SCR of NO with NH3 over noble metal promoted Fe-ZSM-5 catalysts.

We have reported previously the excellent performance of Fe-exchanged ZSM-5 for selective catalytic reduction (SCR) of NO with ammonia at high temperatures (300-400 °C). In this work, we found that the reaction temperature could be decreased to 200-300 °C when a small amount of noble metal (Pt, Rh, or Pd) was added to the Fe-ZSM-5. The SCR activity follows the order Pt/Fe-ZSM-5>Rh/Fe-ZSM-5>Pd/Fe-ZSM-5 at 250 °C. On the Pt promoted Fe-ZSM-5, 90% NO conversion was obtained at 250 °C at GHSV = 1.1 × 105 h-1. Moreover, the noble metal improved the resistance to H2O and SO2. The presence of H2O and SO2 decreased the SCR performance only very slightly. [ABSTRACT FROM AUTHOR]