Molecular sieving of iso-butene from C 4 olefins with simultaneous high 1,3-butadiene and n-butene uptakes.

Iso-butene (iso-C 4 H 8 ) is an important raw material in chemical industry, whereas its efficient separation remains challenging due to similar molecular properties of C 4 olefins. The ideal adsorbent should possess simultaneous high uptakes for 1,3-butadiene (C 4 H 6 ) and n-butene (n-C 4 H 8 ) counterparts, endowing high efficiency for iso-C 4 H 8 separation in adsorption columns. Herein, a sulfate-pillared adsorbent, SOFOUR-DPDS-Ni (DPDS = 4,4'-dipyridyldisulfide), is reported for the efficient iso-C 4 H 8 separation from binary and ternary C 4 olefin mixtures. The rigidity in pore sizes and shapes of SOFOUR-DPDS-Ni exerts the molecular sieving of iso-C 4 H 8 , while exhibiting high C 4 H 6 and n-C 4 H 8 uptakes. The benchmark Henry's selectivity for C 4 H 6 /iso-C 4 H 8 (2321.8) and n-C 4 H 8 /iso-C 4 H 8 (233.5) outperforms most reported adsorbents. Computational simulations reveal the strong interactions for C 4 H 6 and n-C 4 H 8 . Furthermore, dynamic breakthrough experiments demonstrate the direct production of high-purity iso-C 4 H 8 (>99.9%) from C 4 H 6 /iso-C 4 H 8 (50/50, v/v), n-C 4 H 8 /iso-C 4 H 8 (50/50, v/v), and C 4 H 6 /n-C 4 H 8 /iso-C 4 H 8 (50/15/35, v/v/v) gas-mixtures.