In the present work, membranes from block copolymer poly(ether-b-amide-6) (Pebax® MH 1657) and its blends with poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-block-PPG-block-PEG) and poly(ethylene glycol)-ran-poly(propylene glycol) (PEG-ran-PPG) copolymers were prepared by a solution casting and solvent evaporation method. In fact, the beneficial properties of PEG (high selectivity) with those of PPG (high permeability, amorphous) have been combined. The fabricated membranes were characterized by DSC, FTIR-ATR, AFM and SEM. According to DSC analysis, T m for both soft and hard segments, T g and crystallinity of blended membranes were decreased which was beneficial for the gas transport through the membranes. Effects of additive mass content (10 to 50 wt%), operating temperature (À10 to 30 C) and feed pressure (3 to 15 bar) on gas transport properties were studied for CO 2 and CH 4 gases. The use of PPG randomly distributed in the PEG, was more effective to enhance the membrane separation properties. CO 2 permeability was increased eight-fold (from 84 to 677 Barrer), while the CO 2 /CH 4 selectivity nearly remained constant. The mixed gas results of the blended membrane showed that the plasticizing effect of CO 2 increased the permeability of CH 4 with no significant change in the CO 2 permeability which resulted in lower mixed gas selectivity. Also, it was found that the CO 2 permeability remained high at sub-ambient conditions (down to À10 C) as soft phase crystallization did not occur.

CuBTC and NH2‐CuBTC metal organic frameworks (MOF) were used to produce mixed matrix membranes (MMM) with a block copolymer of poly(ether‐b‐amide‐6) (Pebax® MH 1657) as the polymer matrix to investigate the effect of amine functionalized group (–NH2) on the CO2/CH4 gas separation performance of the MMM. The MOF were fully characterized by XRD, FTIR‐ATR, TGA, N2, CO2, and CH4 adsorption, while the MMM were characterized using FTIR‐ATR, TGA, DSC, and SEM. Permeability and selectivity of the MMM were studied at different MOF mass contents (5 to 20 g/g) and feed pressures (0.3 to 1.5 MPa) for pure and mixed gases. The CO2 permeability for 20 g/g of both Pebax/CuBTC and Pebax/NH2‐CuBTC MMMs was nearly twice that of the neat polymeric membrane, while the presence of amine functionalized group in NH2‐CuBTC produced an increasing trend of CO2/CH4 ideal selectivity at high NH2‐CuBTC loading and about a 60 % increase was observed at 20 g/g of NH2‐CuBTC.

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