| Summary: | 碩士 === 國立中興大學 === 環境工程學系所 === 100 === In recent years, membrane technology has been widely used in a wide variety of large-scale industrial application for gas separation. Organic membranes are considered to be one of the promising materials for membrane-based gas separation because of its easy preparation, operation and maintenance. However, the tradeoff between permeability and selectivity is one of the biggest problems faced by pure polymer membranes. In contrast, inorganic membrane, such as carbon molecular sieving membrane, shows excellent permeation and separation properties even under high pressure. Therefore, recent research efforts have focused on multi-layer composite membranes to overcome the tradeoff problem through using porous substrate to support polymer membrane.
In this research, polymer/carbon/ceramic multilayer composite membrane with competitively separation performance to symmetric polymeric membrane was synthesized on the top of α-Al2O3 substrate. In order to improve the permselectivity of composite membrane, two kind of polymer/carbon composite membrane were prepared. First, the polymer and carbon film were acing as the selective and intermediate layer, respectively, in which the surface roughness and pore structure of Al2O3 substrate was modified with different carbon texture. Second, the polymer and carbon film were acing as skin and selective layer, respectively, in which the pore size of carbon layer was altered with different viscosity of polymer dope.
The results indicate that in the first kind composite membrane, the roughness of Al2O3 substrate was decreased slightly with modification of carbon layer, especially which derived from PPO polymer. After coating with PPO selectivity layer, the resulting PPO/C/Al2O3 composite membranes presents a high CO2 gas permeability (147.5 Barrer), and the selectivity of CO2/N2 and CO2/CH4 is 20.4 and 19.3, respectively. In the second composite membrane, after modification with PPO polymer the composite membrane show a dense structure. The permeability of CO2 through the PPO/CMS/Al2O3 composite membrane decreased (77.8 Barrer), but the selectivity of CO2/N2 and CO2/CH4 increased significantly, with values at 26.2 and 46.2, respectively.
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