Selective catalytic reduction of N2O with C3H6 over Fe-ZSM5 catalyst in the presence of excess O2:: The correlation between the induction period and the surface species produced

The catalytic activity of N2O reduction over Fe-ZSM5 prepared by an ion exchange method was significantly increased by adding C3H6, even in the presence 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 was also observed for the decrease in activity after removing C3H6 or O-2-C3H6 from the N2O-O-2-C3H6 mixture. The length of the induction period was influenced by the partial pressure of C3H6, the composition of the reaction gases 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, H2O and N-2. In situ DRIFT studies showed the formation of CxHy(a) and/or CxHyOz(a) species during the N2O-O-2-C3H6 reaction, the behavior of which (formation and reactivity) correlated well with the induction period phenomenon.