Gas separation properties of poly(amide-6-b-ethylene oxide)/amino modified multi-walled carbon nanotubes mixed matrix membranes

Abstract Amino modified multi-walled carbon nanotubes (MWNTs-NH 2 ) were incorporated into poly(amide-6- b -ethylene oxide) (Pebax 1657) to prepare mixed matrix membranes (MMMs). The permeation properties of CO 2 , N 2 , CH 4 and H 2 were studied and the physical properties of Pebax/MWNTs-NH 2 MMMs were characterized by X-ray diffractometer (XRD), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The incorporation of MWNTs-NH 2 increased the amorphous region of Pebax phase in Pebax/MWNTs-NH 2 MMMs, which was beneficial for the improvement of gas permeabilities. The apparent activation energy for permeation ( E p ) for CO 2 decreased with the increase of pressure, while those for N 2 , CH 4 and H 2 almost did not change. The E p for CO 2 , N 2 , CH 4 and H 2 slightly decreased with the incorporation of MWNTs-NH 2 . Compared with pristine Pebax membrane, CO 2 permeability increased almost 3 times for Pebax/MWNTs-NH 2 MMMs with 33 wt% MWNTs-NH 2 . With the increase of MWNTs-NH 2 content, the normalized permeabilities of N 2 , CH 4 and CO 2 showed almost the same increment and the selectivities of CO 2 /N 2 , CO 2 /H 2 and CO 2 /CH 4 remained constant, which were consistent with the Maxwell model prediction. Thus, the incorporation of MWNTs-NH 2 significantly improved the gas permeation properties of Pebax/MWNTs-NH 2 MMMs.