| Summary: | 碩士 === 國立中興大學 === 化學工程學系所 === 103 === In this study, various bi-layer membranes were prepared from rubbery polymer (poly dimethyl siloxane and polyether block amide), glassy polymer (polyether sulfones, polystyrene, and cellulose acetate), and ionic liquid ([bmim][BF4]) for the separation of CO2/CH4. The results are as follows: (1) Pure polymer membrane has the increased resistance and decreased permeance with the increased thickness. When the membrane thickness is greater than 20 μm, the gas permeability and CO2/CH4 selectivity of glassy polymer membrane are not changed with the increasing membrane thickness. On the other hand, the gas permeance for the 10 μm glassy polymer membrane has been enhanced greatly due to a big decrease in transport resistance. 20 μm is thus the critical thickness. (2) The results for the bi-layer membranes formed by PDMS/glassy polymer and PDMS/ionic liquid indicate that the gas permeance is dominated by the layer of glassy polymer or ionic liquid. Accordingly, the gas performance of bi-layer PDMS/glassy polymer membrane with a 20 μm glassy polymer layer is not influenced by the addition of various thickness of PDMS layer. When the thickness of glassy polymer layer is decreased to 10 μm, the gas permeance is reduced but the CO2/CH4 selectivity is enhanced for the addition of a thin PDMS layer. By further increasing the PDMS layer thickness, the gas permeance and CO2/CH4 selectivity of bi-layer membrane are not altered anymore. As for bi-layer glassy polymer/glassy polymer membranes, their gas permeance has been influenced by a change in the thickness of either layer. (3) The results calculated based on the resistance-in-series theory are compared with the experimental data for bi-layer membranes. It is found that the deviation errors are less than 40 %, except for the bi-layer membranes with a 10 μm glassy polymer layer.
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