Pore Engineering for One-Step Ethylene Purification from a Three-Component Hydrocarbon Mixture

Ethylene production from C2 hydrocarbon mixtures through one separation step is desirable but challenging because of the similar size and physical properties of acetylene, ethylene, and ethane. Herein, we report three new isostructural porous coordination networks ( NPU-1 , NPU-2 , NPU-3 ; NPU represents Northwestern Polytechnical University) that are sustained by 9-connected nodes based upon a hexanuclear metal cluster of composition [Mn 6 (μ 3 -O) 2 (CH 3 COO) 3 ] 6+ . NPU-1/2/3 exhibit a dual cage structure that was systematically fine-tuned in terms of cage size to realize selective adsorption of C 2 H 2 and C 2 H 6 over C 2 H 4 . Dynamic breakthrough experiments demonstrated that NPU-1 produces ethylene in >99.9% purity from a three-component gas mixture (1:1:1 C 2 H 2 /C 2 H 4 /C 2 H 6 ). Molecular modeling studies revealed that the dual adsorption preference for C 2 H 2 and C 2 H 6 over C 2 H 4 originates from (a) strong hydrogen-bonding interactions between electronegative carboxylate O atoms and C 2 H 2 molecules in one cage and (b) multiple non-covalent interactions between the organic linkers of the host network and C 2 H 6 molecules in the second cage.