A comparison of carbon/nanotube molecular sieve membranes with polymer blend carbon molecular sieve membranes for the gas permeation application

A novel polyetherimide (PEI)/multi-wall carbon nanotubes (MWCNTs) composite carbon membrane was prepared by spin coating method using PEI as a precursor. The PEI precursor was also modified by blending with polyvinylpyrolidone (PVP) and its effect on the gas transport property of the resulting carbon membrane was examined. The characteristics of the carbon structures and the gas permeation properties of the carbon molecular sieve (CMS) membranes pyrolyzed at 500 °C were investigated. The best performance was obtained using the PEI/nanotube CMS membrane, where CO2 permeability 1463 Barrer and O2/N2 permselectivity was 24.16 at 26 °C. Further the membranes were extensively characterized by field emission scanning electron microscopy (FE-SEM) for surface morphology studies and thermal gravimetric analysis (TGA) for thermal properties. X-ray diffraction was employed to characterize the structures. The results indicated that the MWCNTs improve gas diffusivity by increasing the micropore volume, even the MWCNTs were not well dispersed in CMS membrane.