Nanosheets of a Layered Metal-Organic Framework for Separation of CO₂/CH₄ using Mixed Matrix Membranes

Mixed matrix membranes represent an important technology for gas separations. Nanosheets of metal-organic framework (MOF) materials of high aspect ratio and size-selective gas transport properties have potential in promoting the efficient mixing of components to form membranes for gas separation. Herein, we report a bottom-up synthesis of extended sheets of kagomé (kgm) topology, kgm^t-Bu, via the linkage of [Cu₂(O₂CR)₄] paddlewheels with 5-tert­-butylisophthalic acid. The growth of the layered structure can be controlled by choice of solvent and modulator. Nanosheets of kgm^t-Bu of average thickness of 20 nm and aspect ratio of 40 to 50 can be obtained, and the sieving effect of the channels in kgm^t-Bu boost the efficient separation of CO₂ over CH₄. A mixed matrix membrane comprising kgm^t-Bu nanosheets with Matrimid shows a 32% enhancement in CO₂/CH₄ selectivity compared with the membrane incorporating the MOF in particulate form.