Mixed Dimensional Nanostructure (UiO‐66‐Decorated MWCNT) as a Nanofiller in Mixed‐Matrix Membranes for Enhanced CO 2 /CH 4 Separation

Mixed‐matrix membranes (MMMs) with combination of two distinct dimensional nanofillers (such as 1D‐3D, 2D‐3D, or 3D‐3D, etc.) have drawn special attention for gas separation applications due to their concerted effects on gas permeation and mechanical properties. An amine‐functionalized 1D multiwalled carbon nanotube (NH 2 ‐MWCNT) with exceptional mechanical strength and rapid gas transport was crosslinked with an amine‐functionalized 3D metal‐organic framework (UiO‐66‐NH 2 ) with high CO 2 affinity in a Schiff base reaction. The resultant crosslinked mixed‐dimensional nanostructure was used as a nanofiller in a polysulfone (PSf) polymer matrix to explore the underlying synergy between 1D and 3D nanostructures on the gas separation performance of MMMs. Cross‐sectional scanning electron microscopy and mapping revealed the homogenous dispersion of UiO‐66@MWCNT in the polymer matrix. The MMM containing 5.0 wt. % UiO‐66@MWCNT demonstrated a superior permeability 8.3 Barrer as compared to the 4.2 Barrer of pure PSf membrane for CO 2 . Moreover, the selectivity (CO 2 /CH 4 ) of this MMM was enhanced to 39.5 from the 28.0 observed for pure PSf under similar conditions of pressure and temperature.