Selective catalytic reduction of N2O with C3H6 over Fe-ZSM5 catalyst in the presence of excess O-2: The correlation between the induction period and the surface species produced

The catalytic activity of N2O reduction over Fe-ZSM5 prepared by an ion exc hange method was significantly increased by adding C3H6, even in the presen ce of excess O-2, i.e., selective catalytic reduction (SCR) of N2O occurred with C3H6. We found that there was an induction period for the increase in activity after adding C3H6 to the N2O-O-2 flow. Another induction period w as also observed for the decrease in activity after removing C3H6 or O-2-C3 H6 from the N2O-O-2-C3H6 mixture. The length of the induction period was in fluenced by the partial pressure of C3H6, the composition of the reaction g ases and the reaction temperature. During the latter induction period, CO2, H2O and N-2 were detected as products. These results suggest that adsorbed surface species such as CxHy(a) and/or CxHyOz(a), produced by the reaction in the N2O-O-2-C3H6 mixture, reacted with N2O or N2O-O-2 to produce CO2, H 2O and N-2. In situ DRIFT studies showed the formation of CxHy(a) and/or Cx HyOz(a) species during the N2O-O-2-C3H6 reaction, the behavior of which (fo rmation and reactivity) correlated well with the induction period phenomeno n.