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 the potential to promote 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, via the linkage of [Cu₂(O₂CR)₄] paddlewheels with 5-tert-butylisophthalic acid. The growth of the layered structure can be controlled by the choice of solvent and modulator. Nanosheets of kgm 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 boost the efficient separation of CO₂ over CH₄. A mixed matrix membrane comprising kgm nanosheets with Matrimid shows a 32% enhancement in CO₂/CH₄ selectivity compared with the membrane incorporating the MOF in the particulate form.