A highly stable MOF with F and N accessible sites for efficient capture and separation of acetylene from ternary mixtures

Abstract

Considering the important applications and purification requirement of C₂ hydrocarbons in the industry, the separation of C₂ in mixtures is a vital task. To achieve this goal, herein a new Ni²⁺-based metal–organic framework (MOF) has been solvothermally prepared by utilizing a tetrazolyl-carboxyl ligand and 4,4′-bipyridine coligands as well as incorporating F⁻ ions. The MOF shows a unique pillared-layer framework based on the novel metal–tetrazolate–carboxylate–fluorine chains, and possesses high chemical stability. Owing to the exposed adsorption sites of uncoordinated N atoms and F⁻ ions in the channels, the MOF had high loadings for C₂H₂ and selectivity for C₂H₂ over C₂H₄, C₂H₆, CO₂ and CH₄. Under ambient conditions, dynamic breakthrough experiments revealed that the MOF performs effective separation of C₂H₂ from binary (C₂H₂–CH₄, C₂H₂–C₂H₆, C₂H₂–C₂H₄, and C₂H₂–CO₂) and ternary (C₂H₂–CO₂–CH₄, C₂H₂–C₂H₆–CH₄, C₂H₂–C₂H₄–CH₄, and C₂H₂–C₂H₄–C₂H₆) mixtures. The comparison based on the GCMC calculation revealed the crucial role of the accessible N and F sites for the selective capture of C₂H₂.