H2/CH4 separation with PEI membranes

In this study, composite PDMS/ (PEI membrane was synthesized by phase inversion method. The permeation and sorption of hydrogen and methane was measured at different conditions. The obtained results are presented as below: Critical concentration of PEI membrane was determined by viscometric method and it was 24%. Pressure tests indicated that by increasing the trans-membrane pressure from 1 to10 bars, the H2 permeance descended but CH4 permeance was enhanced. This led to selectivity reduction by increasing the pressure. Solubility of H2 declined and solubility of CH4 increased by pressure increasing. Hydrogen sorption mechanism was dual mode whereas methane sorption mechanism was Flurry-Huggins. Temperature tests showed that in the range of 298.15–313.15 K, the H2 and CH4 permeance increased with increasing temperature. The increasing rate of H2 was higher than that of CH4 and led to selectivity enhancement by increasing temperature. The use of higher polymer concentration made membrane denser and increased selectivity. Lower coagulation bath temperature makes dense membrane and increased selectivity.