The nitrogen-doped porous carbons/PIM mixed-matrix membranes for CO2 separation

Nitrogen-doped porous carbons (NDPC)/polymer of intrinsic microporosity (PIM) mixed-matrix membranes (MMMs) were fabricated via a thermal treatment of the ionic liquids (ILs)/PIM blending membranes, in which the nitrile-containing ILs reacted and formed the NDPC with three-dimensional-connected frame-works after the thermal post-treatment. The chemical characterization was performed by Fourier transform infrared spectroscopy. The thermal property was investigated by thermo-gravimetric analysis. The average inter-chain distance of the MMMs was evaluated by wide-angle X-ray diffraction. The porous structure was evaluated by low-temperature N2 adsorption-desorption analysis. The membrane morphology was investigated by field-emission scanning electron microscopy. The gas transport property of the NDPC/PIM MMMs was reported. The relationship between gas transport property and physical properties was also discussed. Compared with the original PIM-1 membrane, the NDPC/PIM MMMs displayed much higher CO2 permeability at the cost of an acceptable, slight reduction in CO2/N2 selectivity. The outstanding permeation-separation performance for CO2/N2 exceeds the Robeson upper bound line.