Mixed-Matrix Membranes of the Air-Stable MOF-5 Analogue [Co4(μ4-O)(Me2pzba)3] with a Mixed-Functional Pyrazolate-Carboxylate Linker for CO2/CH4 Separation

Abstract

The synthesis of the isostructural MOF-5 analogue 3D-[Co4(μ4-O)(Me2pzba)3] with the bi- or mixed-functional pyrazolate-carboxylate linker was improved by the use of microwave heating instead of previously described conventional thermal heating, giving a higher yield at drastically shorter reaction time with nearly doubled BET surface area, smaller size, and less aggregation. The significantly increased air/moisture stability of [Co4(μ4-O)(Me2pzba)3] compared to MOF-5 made the Co-MOF amenable for the preparation of moisture-tolerant [Co4(μ4-O)(Me2pzba)3]/Matrimid mixed-matrix membranes (MMMs) without the use of inert conditions. Uniformly embedding of the small metal–organic framework (MOF) particles was achieved in the polymer, without aggregation and with good MOF–polymer compatibility. [Co4(μ4-O)(Me2pzba)3]/Matrimid MMMs exhibited an improved CO2/CH4 separation performance over neat Matrimid membranes with an increase in mixed-gas selectivity from 41 for Matrimid to 60 for the 24 wt % MMM at 3 bar trans...