Synthesis and characterization of high permeable PEBA membranes for CO2/CH4 separation

•Dimethylformamide (DMF) was utilized as the PEBAX-1074 polymer solvent.•DMF reduced the time required for preparation the PEBAX-1074 polymer solution.•CO2/CH4 separation performance of PEBAX-1074 was improved by use of DMF as solvent.•CO2/CH4 separation performance of PEBAX-1074 surpassed the Robeson upper bound.•Use of DMF led to a membrane with high permeability for CO2.

As the casting solvent affects the domain structure and hence, the permeability and diffusivity of molecules through the membrane, it is found that Dimethylformamide (DMF) changes the gas separation properties of PEBAX-1074. Membranes were prepared by solvent-evaporation method. The solvent reduced the time required for preparation the polymer solution in comparison with other solvents. In order to determine the influence of the evaporation temperature on the performance and morphology of the final membrane, three different evaporation temperatures 60, 80 and 100 °C were utilized. The membranes which were dried at 80 °C, were more selective towards CO2. Non-defective microstructure of fabricated membrane was confirmed by N2 permeation measurement.Membrane performances were investigated by single gas permeability measurements of CO2 and CH4 at different operating temperatures (30-55 °C) and feed pressures (3-7 bar). The results indicated that CO2 permeability and CO2/CH4 ideal selectivity increased with feed pressure and decreased with temperature. The highest selectivity was about 24.4 at 7 bar and 30 °C. In this condition, CO2 permeability was 591 Barrer. Obtained result implied that utilization of DMF as a polymer solvent, considerably improves the CO2 permeability with a slight change in the ideal selectivity.

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