Metal-Induced Localized Microcrystals Buffer Poisoning in NOx Catalytic Reduction

Abstract

Metal impurities in flue gas severely threaten the service life of NOx abatement catalysts. While traditional acid-base interaction strategies rely on sacrificial sites, such passive defense mechanisms merely mitigate activity loss rather than fundamentally resolving poisoning. This study establishes an active defense mechanism by fabricating amorphous high-entropy metal oxides capable of sequestering metal poisons by inducing localized microcrystallization. These resulting microcrystals are subsequently transformed into extra active centers for NOx reduction. Systematic investigation reveals that the K-migration pathway drives a structural evolution from a disordered metastable state to locally ordered nanocrystalline regions, significantly enhancing lattice oxygen mobility. This transition facilitates the activation of NH3 into O-NH2– intermediates. Furthermore, the coordination of surface-adsorbed nitrates undergoes a transition from stable bidentate to easily decomposable monodentate configurations, ensuring a sufficient supply of NO2 species for the fast-SCR reaction. Consequently, NOx conversion is unexpectedly enhanced following metal poisoning. This strategy increases poisoning resistance by accommodating metal posions and constructing new active sites in situ.