Yolk-Shell Zeolite Nanoreactors Enable Multi‑Poison Resistance for NOx Reduction
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The practical application of ammonia selective catalytic reduction (NH 3 -SCR) for stationary NO x abatement is severely restricted by rapid catalyst deactivation in flue gases containing SO 2 and alkali metal. Although coupling zeolites with transition-metal oxides improves poisoning tolerance, most adopted loading or confining strategies cannot simultaneously ensure high redox-site content and effective protection. Herein, we realize a zeolite-confined nanoreactor concept by constructing a yolk-shell catalyst, in which high-content (>10 wt.%) MnFeO x nanoparticles are confined within a hollow ZSM-5 single-crystal shell, with the zeolite framework fully preserved. In situ X-ray absorption fine structure (XAFS) and diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS), together with density functional theory (DFT) calculations, reveal a synergistic dual-shielding mechanism: the ZSM-5 shell physically hinders SO 2 from attacking the active oxide core, while external Brønsted acid sites chemically suppress SO 2 adsorption and intercept alkali metal. Consequently, the catalyst maintains >90% NO x conversion with high N 2 selectivity under co-poisoning by SO 2 and K. This work establishes hollow zeolite-confined nanoreactors as a versatile platform for designing durable emission-control catalysts, enabling stable long-term operation under industrially relevant multi-poisoning conditions.
