Smooth pore surface in zeolites for krypton capture under humid conditions

Efficient trace radioactive krypton isotopes ( 85 Kr) capture from air under humid conditions is a critical challenge for nuclear safety and environmental protection. Commercial zeolites suffer from low Kr/N 2 selectivity due to cation-induced interactions that strengthen nitrogen (N 2 ) adsorption, while their hydrophilicity triggers severe water competition. Herein, we proposed utilizing the smooth pore surface in pure-silica zeolites to weaken the N 2 adsorption and mitigate water competition. The pure silica ZSM-11 exhibited the record-high Kr/N 2 selectivity (4.8) and Kr uptake of 12.8 cm 3 /g at 298 K and 1 bar, superior to the commercial zeolites. Its intersecting ten-membered ring (10-MR) channels facilitated optimal Kr interactions and distribution, as corroborated by Grand Canonical Monte Carlo (GCMC) simulations, which revealed preferential multisite Kr···O interactions with significantly higher Kr densities than N 2 . Dynamic breakthrough experiments demonstrated that pure silica zeolites, particularly ZSM-11, achieved superior Kr capturing performance and cycling stability under humid conditions (RH = 72.6%), realizing a leap from ppm levels to high purity (> 80%) Kr. This work demonstrated the rational design of pore surface and topologies in zeolite for inert gases capture provided an effective technological route for radioactive krypton isotopes separation under humid conditions. Pure silica zeolites eliminate cation-induced N 2 competition inherent in commercial cationic zeolites. Furthermore, the MEL structure further enhances Kr diffusion and multisite interactions compared to the CHA structure, enabling optimal performance for trace radioactive krypton isotopes separation under humid conditions. • Smooth pore surface strategy in zeolites weakens N 2 adsorption. • ZSM-11 exhibits the highest Kr/N 2 selectivity and uptake ratio at 298 K and 1 bar. • MEL topology enhances Kr diffusion and multisite van der Waals interactions. • Dynamic breakthrough tests confirm superior performance under humid conditions. • One-step adsorption‐desorption purifies ppm‐level Kr to >80% purity.