Shape- and Size-Dependent Kinetic Ethylene Sieving from a Ternary Mixture by a Trap-and-Flow Channel Crystal

Ethylene (C₂H₄) purification from multicomponent mixtures by physical adsorption presents a great challenge in the chemical industry. This work successfully uses the postsynthetic method of crystal transformation in boiling alkaline solution to synthesize a trap-and-flow channel crystal (namely NTU-67), the flow channel of which provides an effective shape- and size-dependent sieving path for linear molecules such as acetylene (C₂H₂) and carbon dioxide (CO₂), while the adjacent channel possesses customized space for efficient molecular trapping. The three-bladed array of the nanospace enables the crystal to afford a record productivity of C₂H₄ (121.5 mL g⁻¹, >99.95%) from C₂H₂/CO₂/C₂H₄ (1/9/90, v/v/v) mixtures in a single adsorption–desorption cycle under humid and dynamic conditions, even at a high temperature of 343 K and wide gas ratio. The molecular-level insight and mechanism of the cooperative role of the trap-and-flow channel, found computationally and observed experimentally, demonstrates a new design philosophy toward extending the application boundaries of porous coordination polymers to further challenging tasks.