Perturbed hydrogen permeation of mixed gas with palladium membrane
| Autor: | Hsin-Chi, Hsu, 許新圻 |
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| Rok vydání: | 2004 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 92 Hydrogen permeation by Pd membrane is an excellent method for hydrogen purification and obey the Sievert’s Law. The Pd membrane tube is made by electroless plating. When a hydrogen mixtures,H2 + Y was used as a feed for permeation, the hydrogen permeate was found to be perturbed by Y gas. The different Y gas causes different effects of hydrogen permeation. In this thesis, we used Gas chromatographer equipped with Thermal Conductive Detector and Flame Ionization Detector. When H2 + CO2 was used as a feed, the residual CO2 was analyzed by first converting it to CH4 with a on-line-methanizer. By this way, low ppm of CO2(CH4) can be detected. By choosing different Y gas, the effect of Y gas would be evaluated. The hydrogen permeation by Pd membrane tube is perturbed in a mixed gas. The main reason is attributed to the reduction of the hydrogen concentration along the Pd membrane tube resulting in lower hydrogen permeance. At the same hydrogen partial pressure in the feed, hydrogen permeance is larger when Y=CH4 than when Y= CO2. We attributed it to the poison effect of CO and the molecule size difference. CO2 was found to be reduced to CO which has shown chemisorption hindering hydrogen permeation. The molecule side of CH4 is larger than CO2; therefore, CH4 is not easy to pass through the membrane grain boundary and lattice opening. The more Y gas pass through membrane lattice, the more it interfered hydrogen permeation. Therefore, smaller Y gas having greater extent of passing through membrane causes larger perturbation. Additional perturbation by CO2 was probably caused by insitu-production H2O in the membrane structure formed from hydrogenation of CO2. The hydrogen recovery yield is between 50% to 85% which is operated at 3 to 9 ATM and the recovery yield depended on the hydrogen retention time in the purifier. And the recovered permeate flux is increased by the decreased of hydrogen recovery yield. And hydrogen purity in the permeate is also deceased by higher operating pressure. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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