CO2 and H2 selectivity properties of PDMS/PSf membrane prepared at different conditions

• Published in: Frontiers of chemical engineering in China 2011-12, Vol.5 (4), p.500-513
• Main Authors: Mansoori, S. A. A., Pakizeh, M., Jomekian, A.
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Industrial Chemistry/Chemical Engineering; Nanotechnology; Research Article
• ISSN: 2095-0179; 1673-7474; 2095-0187
• DOI: 10.1007/s11705-011-1108-x

The effects of different solvent/water coagulation mediums, different coagulation bath temperatures (CBT) and different coagulants on the performance, morphology and thermal stability of polysulfone membranes were investigated. The CO 2 /CH 4 , H 2 /CH 4 and H 2 /N 2 separation performance of the membranes were studied by gas permeation. Changing the N,N -dimethyl acetamide (DMAc)/water coagulation medium ratio from pure water to 90/10 vol%, resulted in a complete disappearance of the macrovoids throughout the polysulfone (PSf) polymeric matrix. The PSf membrane prepared in a CBT of 25°C showed the best gas separation performance with ideal selectivities of 46.29, 39.81 and 51.02 for H 2 /CH 4 , CO 2 /CH 4 and H 2 /N 2 respectively, and permeances of 25 and 21.5 GPU for H 2 and CO 2 at 25°C and 10 bar respectively. By increasing the amount of solvent in the gelation bath, the selectivities of H 2 /CH 4 , CO 2 /CH 4 and H 2 /N 2 were dramatically reduced from 46.29, 39.81 and 51.02 to 16.08, 20.2 and 18.5 respectively at 25°C and 10 bar. Reducing the CBT from 80°C to 5°C led to a complete elimination of macrovoids. Using methanol as a coagulant resulted in a less selective membrane compared with membranes from ethanol and water coagulants. The H 2 and CO 2 permeances were respectively about 3 and 9 times more than those for ethanol and water coagulants. Coated membranes were heated at different temperatures to investigate the suppression of undesirable CO 2 plasticization. The membranes were stabilized against CO 2 plasticization by a heat-treatment process.