Direct N2O decomposition over iron-substituted small-pore zeolites with different pore topologies

Four cage-based, small-pore zeolites with similar framework Fe contents (0.7-0.9 wt%) but different framework structures (i.e., Fe-PST-7, Fe-LTA, Fe-SSZ-13, and Fe-RTH) have been synthesized and employed as direct N2O decomposition catalysts. When steam -activated, the light-off temperatures (770 K) for Fe-PST-7 and Fe-LTA were found to be about 40 K lower under wet feed conditions than that (810 K) for Fe-ZSM-5, the most widely studied catalyst for this reaction. Furthermore, their light-off temperatures were found to be even lower than the temperature (780 K) for Fe-FER, the best direct N2O decomposition catalyst. The overall characterization results of our study strongly suggest that the presence of strong Brensted acid sites in zeolites, as well as the zeolite framework topology, has a profound effect on the type and distribution of extraframework Fe species, and therefore the N2O decomposition activity of supported Fe catalysts.