TY  - JOUR
AU  - Xie, Xinlin
AU  - Yuan, Jibin
AU  - Liu, Lei
AU  - Liu, Hanzi
AU  - Sun, Zhiqiang
PY  - 2026
TI  - Dual kinetic effect from confined iron nanoparticles in zeolite modulates high-temperature catalytic NO reduction and NH3 oxidation
JO  - Industrial Chemistry & Materials
SN  - 2755-2608
SP  - 457
EP  - 471
VL  - 4
IS  - 4
AB  - The selective catalytic reduction of ammonia (NH3-SCR) is a promising technology for abating nitrogen oxides (NOx), yet its application at high temperatures is severely hampered by the over-oxidation of ammonia, leading to a trade-off between NOx conversion and N2 selectivity. Herein, we construct a series of Fe-exchanged ZSM-5 catalysts with controlled Fe loadings (0.05–0.5 wt%) to decouple the competing reaction pathways. The optimized 0.1Fe@ZSM-5 catalyst achieves 83.0% NOx conversion at 700 ℃ and maintains exceptional stability for over 120 h under harsh conditions, representing a significant performance enhancement. Mechanistic investigations combining kinetic modeling and in situ spectroscopy reveal a dual kinetic regime, governed by the size of the Fe species. Catalysts with low Fe loadings favor the standard SCR pathway via stable NH4+ and NH2* intermediates, whereas catalysts with higher loadings and larger Fe nanoparticles promote the undesirable oxidation of ammonia to NOx. The result identifies that the optimal catalytic sites for high-temperature SCR rely on a delicate balance, activating ammonia for the desired reaction while suppressing its subsequent over-oxidation. These findings provide new implications for advanced catalyst design by tuning the active site structure to navigate competing reaction kinetics.
UR  - https://doi.org/10.1039/d5im00245a
DO  - 10.1039/d5im00245a