Synergistic binding sites in a hybrid ultramicroporous material for one-step ethylene purification from ternary C(2) hydrocarbon mixtures

One-step separation of C(2)H(4) from ternary C(2)H(2)/C(2)H(4)/C(2)H(6) hydrocarbon mixtures is of great significance in the industry but is challenging due to the similar sizes and physical properties of C(2)H(2), C(2)H(4), and C(2)H(6). Here, we report an anion-pillared hybrid ultramicroporous material, CuTiF(6)-TPPY, that has the ability of selective recognition of C(2)H(4) over C(2)H(2) and C(2)H(6). The 4,6-connected fsc framework of CuTiF(6)-TPPY exhibits semi–cage-like one-dimensional channels sustained by porphyrin rings and TiF(6)(2−) pillars, which demonstrates the noticeably enhanced adsorption of C(2)H(2) and C(2)H(6) over C(2)H(4). Dynamic breakthrough experiments confirm the direct and facile high-purity C(2)H(4) (>99.9%) production from a ternary gas mixture of C(2)H(2)/C(2)H(6)/C(2)H(4) (1/9/90, v/v/v) under ambient conditions. Computational studies and in situ infrared reveal that the porphyrin moieties with large π-surfaces form multiple van der Waals interactions with C(2)H(6); meanwhile, the polar TiF(6)(2−) pillars form C–H•••F hydrogen bonding with C(2)H(2). In contrast, the recognition sites for C(2)H(4) in the framework are less marked.