Effect of preparation parameters on the performance of conductive composite gas separation membranes

Mixed matrix composite membranes of a conducting polymer, polypyrrole (PPy) , and an insulating polymer, polybisphenol-A-carbonate (PC) were prepared b y a combined in-situ polymerization and solvent evaporation. Mixed matrix c omposite membranes were synthesized to combine the good gas transport prope rties of conductive polymer, PPy, with good mechanical properties of PC. The permeation rates of some commercially important gases. Ar, CH4, CO2, H- 2, N-2 and O-2 were measured. Effects of different preparation parameters o n the membrane performance were investigated. The parameters investigated w ere the effect of composition (in terms of PC content), effect of hydrophil icity or hydrophobicity of the surface, annealing, solvent evaporation temp erature and supporting electrolyte type and its concentration on the membra ne performance. The SEM images and TGA graphs have showed that, the most effective paramete r on the membrane performance was the supporting electrolyte type and conce ntration. Best results were obtained for a membrane dried at 100 degreesC w hich is cast from an initial solution of 7% PC, containing 0.01 M para-tolu ene sulfonic acid (PTSX) as support electrolyte. Mixed matrix membranes of PPy with PC showed higher selectivities with respect to dense, homogenous, flat sheet PC membranes. Selectivity values for this membrane are CO2/N-2 = 5.9, O-2/N-2 = 4.2, H-2/CH4 = 5.2 while permeabilities for CO2, O-2, H-2 a re 11.6, 8.2 and 19.5 Barrers, respectively. (C) 2001 Elsevier Science B.V. All rights reserved.