Details

Autor(en) / Beteiligte

• Chen, George Q.
• Scholes, Colin A.
• Qiao, Greg G.
• Kentish, Sandra E.

Titel

Water vapor permeation in polyimide membranes

Ist Teil von

• Journal of membrane science, 2011-09, Vol.379 (1), p.479-487

Ort / Verlag

Amsterdam: Elsevier B.V

Erscheinungsjahr

2011

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• ► Concentration polarization effects eliminated at elevated feed pressure. ► Permeabilities of water vapor, CO 2 and CH 4 obtained in mixed gas conditions. ► Water permeability increased with water vapor activity and CO 2 pressure. ► CH 4 and CO 2 permeability declined as water vapor was added to the mixed gas feed. The study of the influence of water vapor in the feed stream of a mixed gas membrane separation system is of considerable practical importance. Water vapor may plasticize the membrane, it may undergo competitive sorption with other gas species and it can form clusters as it permeates. In this work, a modified mixed gas permeation system was employed to accurately measure the permeation properties of the polyimides 2,2′-bis(3,4′-dicarboxyphenyl) hexafluoropropane dianhydrid-2,3,5,6-tetramethyl-1,4-phenylenediamine (6FDA-TMPDA) and poly(3,3′-4,4′-benzophenone tetracarboxylic – dianhydride diaminophenylindane) (Matrimid ® 5218) under exposure to humidified methane at 35 °C. This approach was then applied to further evaluate the permeation properties of the polymers in humidified mixtures of carbon dioxide and methane at 35 °C at atmospheric and elevated feed pressures. Water vapor permeabilities obtained at 2 and 7.5 bar total feed pressure, increased from 3200 to 3900 Barrer and from 20000 to 27000 Barrer as the water level increased for Matrimid and 6FDA-TMPDA respectively, reflecting increases in water vapor solubility and possibly plasticization and clustering effects due to the presence of water vapor. Conversely, the permeabilities of CH 4 and CO 2 declined due to competitive sorption of water.