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The separation of isomeric C4 paraffins is an important task in the petrochemical industry, while current adsorbents undergo a trade-off relationship between selectivity and adsorption capacity. In this work, the pore aperture of a cage-like Zn-bzc (bzc=pyrazole-4-carboxylic acid) is tuned by the stepwise installation methyl groups on its narrow aperture to achieve both molecular-sieving separation and high n-C4 H10 uptake. Notably, the resulting Zn-bzc-2CH3 (bzc-2CH3 =3,5-dimethylpyrazole-4-carboxylic acid) can sensitively capture n-C4 H10 and exclude iso-C4 H10 , affording molecular-sieving for n-C4 H10 /iso-C4 H10 separation and high n-C4 H10 adsorption capacity (54.3 cm3 g-1 ). Breakthrough tests prove n-C4 H10 /iso-C4 H10 can be efficiently separated and high-purity iso-C4 H10 (99.99 %) can be collected. Importantly, the hydrophobic microenvironment created by the introduced methyl groups greatly improves the stability of Zn-bzc and significantly eliminates the negative effect of water vapor on gas separation under humid conditions, indicating Zn-bzc-2CH3 is a new benchmark adsorbent for n-C4 H10 /iso-C4 H10 separation.
Wang et al. (Wed,) studied this question.