Ideal Molecular Splitter with Object Adaptive for Benchmark n-Butylene/iso-Butylene Separation

The design of an ecologically friendly and low-energy adsorption separator for acquiring high-purity n-butene (n-C₄H₈) and iso-butene (i-C₄H₈) has been anticipated but has not yet materialized. Here, we proposed a physical adsorbent (CALF-20) of a super cage with four-way through and window-specific shrinkage for high-efficiency molecular sieving n-C₄H₈ and i-C₄H₈. Compared with other molecular sieving materials, the adsorption capacity of n-C₄H₈ created a new benchmark (64.27, 54.82, and 0.01 bar). In situ single-crystal X-ray diffraction (SCXRD) and computational simulation validated the vital role of window-specific shrinkage and object adaptation of CALF-20 for high-efficiency molecular sieving and enhancing the n-C₄H₈ binding interaction. Breakthrough experiments under dry and humid circumstances proved that CALF-20 can achieve efficiently purified i-C₄H₈ (≥99.999%) with a benchmark productivity of 105 L/kg by one-step adsorption from a n-C₄H₈/i-C₄H₈ (50/50, v/v) mixture. The excellent separation performance of CALF-20 provides a perfect platform for industrial separation applications.