High performance cyclic olefin copolymer (COC) membranes prepared with melt processing method and using of surface modified graphitic nano-sheets for H2/CH4 and H2/CO2 separation

Abstract In this study, cyclic olefin copolymer (COC) composite membranes were prepared with melt processing method by using of various types of graphite nano-sheets namely graphite oxide (GO), octadecylamine (GO-ODA) and stearic acid (GO-SA) modified graphite oxides. Structural and physical characterization of the modified nano-sheets and membranes were conducted by contact angle measurements, XRD, FTIR, TGA, DMA and SEM analysis. Gas permeability ( P ) and ideal gas selectivity values ( α ) of membranes for the H 2 /CO 2 and H 2 /CH 4 were quantified depending on the structural features and the content of fillers. It was found that increasing amount of filler resulted in reducing of CO 2 and CH 4 permeability for all series of membranes. On the other hand, the H 2 permeability values of membranes decreased with the increasing amount of filler in the sample series prepared with GO and GO-ODA but increased in the samples containing of GO-SA. It was also found that the ideal selectivity values of the membrane included 5 wt% of GO-SA for the H 2 /CH 4 and H 2 /CO 2 were drastically improved to 498 and 38.6, respectively. Consequently, the ideal selectivity of GO-SA base membrane was increased by 57.5% for H 2 /CO 2 and by 280% for H 2 /CH 4 separation compared to the COC film. The superior separation performances of the system surpass the current permeability–selectivity tradeoff limits ( Robeson, 2008 upper bound) for H 2 /CO 2 separation.