Synergistic binding sites in a hybrid ultramicroporous material for one-step ethylene purification from ternary C2hydrocarbon mixtures

Abstract

One-step separation of C2H4from ternary C2H2/C2H4/C2H6hydrocarbon mixtures is of great significance in the industry but is challenging due to the similar sizes and physical properties of C2H2, C2H4, and C2H6. Here, we report an anion-pillared hybrid ultramicroporous material, CuTiF6-TPPY, that has the ability of selective recognition of C2H4over C2H2and C2H6. The 4,6-connectedfscframework of CuTiF6-TPPY exhibits semi–cage-like one-dimensional channels sustained by porphyrin rings and TiF62−pillars, which demonstrates the noticeably enhanced adsorption of C2H2and C2H6over C2H4. Dynamic breakthrough experiments confirm the direct and facile high-purity C2H4(>99.9%) production from a ternary gas mixture of C2H2/C2H6/C2H4(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 C2H6; meanwhile, the polar TiF62−pillars form C–H•••F hydrogen bonding with C2H2. In contrast, the recognition sites for C2H4in the framework are less marked.