Iron-exchanged zeolites are often deployed industrially to remediate nitric oxide (NO) and nitrous oxide (N₂O) emissions. The nature of the active site and the reaction mechanism involved in the simultaneous removal of NO and N₂O remain largely unknown, primarily because of the heterogeneity of Fe species. Here we combined catalytic experiments with transient operando X-ray absorption spectroscopy, electron paramagnetic resonance and diffuse reflectance infrared Fourier transform spectroscopy to disentangle the nature of Fe species and elementary reaction steps. We identified spectroscopically the square-planar Fe²⁺ sites in the β-cationic position responsible for N₂O activation and the related redox cycle. These sites communicate with tetrahedrally coordinated Fe²⁺ sites in the adjacent γ-cationic position, accounting for adsorption and redox-mediated oxidation of NO. The availability of NH₃ adsorbed on neighbouring Brønsted acid sites regulates the overall reaction rate of this dual-site mechanism by intercepting the NO oxidation sequence. The cooperation between these redox processes ensures enhanced conversion of both NO and N₂O.

换铁沸石通常在工业上部署以修复一氧化氮 （NO） 和一氧化二氮 （N₂O） 排放。活性位点的性质和同时去除 NO 和 N₂O 所涉及的反应机制在很大程度上仍然未知，主要是因为 Fe 物种的异质性。在这里，我们将催化实验与瞬态原位 X 射线吸收光谱、电子顺磁共振和漫反射红外傅里叶变换光谱相结合，以解开 Fe 物质的性质和基本反应步骤。我们在光谱学上确定了β阳离子位置的方形平面 Fe²⁺ 位点，负责 N₂O 活化和相关的氧化还原循环。这些位点与相邻 γ-阳离子位置的四面体配位的 Fe²⁺ 位点相通，负责 NO 的吸附和氧化还原介导的氧化。NH₃ 吸附在邻近的 Brønsted 酸位点上的可用性通过拦截 NO 氧化序列来调节这种双位点机制的总体反应速率。这些氧化还原工艺之间的合作确保了 NO 和 N₂O 的增强转化率。