Study on CO2 facilitated separation of mixed matrix membranes containing surface modified MWCNTs

Mixed matrix membranes (MMMs) for CO2-facilitated separation were prepared by incorporating different surface-modified multiwalled carbon nanotubes (MWCNTs) in a fixed carrier membrane material. Polymer containing amino groups, poly(vinylalcohol-co-vinylamine) (VA-co-VAm) was synthesized as polymeric matrix. MWCNTs as well as MWCNTs surface-modified with-OH and-NH2 were applied as nanofillers. The physical property, chemical structure, and membrane morphology were characterized by FT-IR, TG, XRD, DSC, CA, XPS, and SEM. The effects of content, functional group, temperature, and pressure on gas permselectivity were studied. Results show that the incorporation of nanofillers can effectively restrict the polymer chain packing and lead to low crystallinity. The MMMs exhibited higher CO2 permselectivity than the pure polymeric membrane. For all the MMMs, the CO2 permeance and selectivity increased with MWCNTs contents to a maximum and then decreased. MWCNT-NH2 can be regarded as the most effective nanofiller. MMMs with 2.0 wt % MWCNT-NH2 displayed the highest CO2 permeance of 132 GPU and CO2/N-2 selectivity of 74. Both CO2 permeance and selectivity were decreased with feed gas pressure and temperature. The membrane exhibited good stability in the testing with the binary gas mixtures of CO2/N-2 for 110 h under 0.54 MPa. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47848.