The separation of C2 hydrocarbons is crucial yet energy-intensive in the petrochemical industry. This work reports a novel metal-organic framework (MOF), Zn2(BDPO)0.5(5-atz)3·2.5DMA·2H2O (1) (H4BDPO = N,N'-bis(3,5-dicarboxyphenyl)oxalamide, 5-Hatz = 5-amino-1H-tetrazole), constructed from mixed carboxylate and azolate linker with rich N/O active sites from oxalamide and amine groups in ligands, for efficient one-step purification of C2H4 from C2 hydrocarbons. The MOF has the characteristic of a unique layer-pillar framework based on the metal-azolate layers pillared by BDPO linkers and possesses candy-like cages with polar porous surfaces, leading to the adsorption selectivity, higher uptake, and affinity for C2H2 and C2H6 over C2H4. The MOF reveals significant IAST selectivities for C2H2/C2H4 (3.1) and C2H6/C2H4 (1.8) from equimolar mixtures at 298 K, and efficient one-step dynamic separation from C2H4/C2H6/C2H2 (8:1:1, v/v/v) ternary mixtures to produce high-purity C2H4 (99.9%). Grand canonical Monte Carlo (GCMC) simulations show that the strong host-guest interactions for C2H2 and C2H6 within the cages from the rich N/O active sites contribute to the excellent C2H4 separation ability.
Jing et al. (Tue,) studied this question.