Efficient gas and alcohol uptake and separation driven by two types of channels in a porous MOF: an experimental and theoretical investigation

Abstract

Utilizing the self-assembly strategy between the paddle-wheel Cu₂(COO)₄ cluster and a terephthalic acid ligand modified by a triazolyl group, namely H₂tztp = 2-(1H-1,2,4-triazol-1-yl)terephthalic acid, a porous MOF, [Cu_0.5(tztp)_0.5]·0.5DMA (1), has been successfully designed and built. 1 is a three-dimensional self-interpenerated framework with a (3,6)-connected rtl topology, and contains hydrophilic and hydrophobic channels decorated with rich uncoordinated triazolyl N atoms and benzene rings from tztp ligands, respectively. The unique porous environment leads not only to high gas adsorption amounts of CO₂, C₂H₆, C₂H₄ and C₂H₂ but also to a good separation ability of C₂ hydrocarbons over CH₄, CO₂ over CH₄, and C₂H₂ over CO₂ in the MOF. The specific adsorption sites of CO₂ and C₂ hydrocarbons were explored by a molecular simulation. The breakthrough experiments demonstrated excellent dynamic separations for CO₂ and CH₄, C₂ hydrocarbons and CH₄ as well as C₂H₂ over CO₂. The MOF also revealed excellent adsorption and separation ability for CH₃OH over other bulkier alcohol molecules.