Hydrophobic zeolites have been identified as suitable adsorbents for capturing radioactive iodine species from nuclear-power-plant off-gas because of their high stability and strong water resistance. However, only the most common zeolites have been investigated for the capture of molecular iodine to date. Herein, we demonstrate that the composition and pore structure of zeolites considerably affect their iodine adsorption performance. A novel all-silica ExxonMobil material-17 (EMM-17) zeolite having a unique three-dimensional 10(12) × 10(12) × 11-ring channel system exhibits a high adsorption capacity for iodine and methyl iodide in the presence of water. EMM-17 outperforms previously reported zeolites in terms of gravimetric and volumetric adsorption capacity in dynamic adsorption measurements. The excellent iodine/methyl iodide capture properties are attributed to the combination of optimal pore size, high pore volume, strong hydrophobicity, and suitable particle morphology. This study provides useful insights for designing efficient adsorbents for iodine capture.

The separation of hexane isomers is of vital importance to produce high quality gasoline in the petrochemical industry. However, the similar vapor pressure and boiling point of hexane isomers bring great difficulties and challenges in the separation process. Sieving effect, which allowing smaller molecules pass through and preventing others, should be a powerful strategy to solve this problem by making good use of porous materials. Therefore, physical separation by metal-organic framework (MOF) materials appears and becomes a burgeoning separation technique in industry. Due to the weak interaction between hexane isomers with absorbents, it puts forward higher requirements for the accurate design of MOF materials with optimal pore system. To address this issue, a novel MOF [Zn₉(tba)₉(dabco)₃]·12DMA·6MeOH (abbreviation: Zn₉(tba)₉(dabco)₃; H₂tba = 4-(1H-tetrazol-5-yl)-benzoic acid; dabco = 1,4-diazabicyclo[2.2.2]octane; DMA = N,N-dimethylacetamide) with bcu network has been designed and synthesized by reticular chemistry strategy. Benefiting from the pre-designed topology and suitable linear ligand H₂tba and dabco, the structure of Zn₉(tba)₉(dabco)₃ exhibits two types of channels with triangular-like and quadrilateral-like geometry. Zn₉(tba)₉(dabco)₃ with appropriate channel size and shape displays potential selective adsorption capacity of vapor-phase hexane isomers through sieving effect. Moreover, outstanding gas adsorptive separation properties of Zn₉(tba)₉(dabco)₃ could also be speculated by theoretical ideal adsorbed solution theory (IAST), suggesting Zn₉(tba)₉(dabco)₃ can be regarded as a potential adsorbent material for purification natural gas. Breakthrough experiments show that Zn₉(tba)₉(dabco)₃ is capable of discriminating all four hexane isomers at 298 K, and the corresponding research octane number (RON) of the eluted mixture closes to 95, which is higher than the standard for industrially refined hexane blends (about 83). We speculate that sieving effect and diffusion are a synergetic contributory factor in their elution dynamics, which may be ascribed to temperature-dependent interaction between pore aperture and each isomer. This work presents a typical example for design of efficient MOF absorbents by reticular chemistry strategy.