| 초록 |
Composite membranes of cellulose acetate (CA) dense skins on fine paper supports were prepared by spin-coating from cyclohexanone and DMF solution. The morphology of membrane surfaces and cross-sections was examined by scanning electron microscopy, and the thickness of polymer skin layers was observed from several hundred nanometers to several micrometers depending on spin-coating condition. Gas separation performances of the membranes were evaluated from permeation measurements on each pure gas of hydrogen, carbon dioxide, methane, nitrogen and the binary 50:50 mixtures of H2/CH4, CO2/CH4, CO2/N2 under 4 atm, 35 ℃. Permeabilities in CA films of several-micrometer thickness were measured as 11, 7, 0.35, and 0.2 barrer for hydrogen, carbon dioxide, methane, and nitrogen, respectively. For the separation of CO2/CH4 mixture, the selectivity increased from 1.9 to 20 as the CA skin thickness increased from 0.52 to 3.7 micrometer. For H2/CH4 mixture, the ideal perm-selectivity exceeded experimental selectivity determined from permeation experiments of the 50:50 mixture. The experimental selectivity increased from 2.8 to 32 as the skin thickness increased from 0.65 to 3.7 micrometer. |
