High performance post-modified polymers of intrinsic microporosity (PIM-1) membranes based on multivalent metal ions for gas separation

Abstract

Novel post-modified polymers of intrinsic microporosity (PIM-1) membranes with cross-linkages formed through multivalent metal ions have been prepared. Structural characterization was performed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectrometer (XPS). The cross-linking effect on gel content of the membrane was determined. The thermal property was evaluated by thermo-gravimetric analysis (TGA). The average chain-to-chain distance of the polymer was investigated by wide-angle X-ray diffraction (WAXD). The O2, N2, CH4 and CO2 gas transport properties of post-modified PIM-1 membranes were reported. The relationship between gas transport property and physical properties was also discussed. Compared with original PIM-1 membrane, the post-modified PIM-1 membranes display higher gas selectivity for O2/N2, CO2/N2 and CO2/CH4 with a corresponding decrease in gas permeability. The outstanding permeation-separation performance for CO2/CH4 exceeds the Robeson upper-bound line. The post-modified PIM-1 membranes display a potential application for industrial-scale CO2/CH4 separation. In addition, it is probably that the incorporation of multivalent metal ions can expand the applicable scope of PIM-1 membrane.