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- Amandusson, H., et al.
(författare)
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Alcohol dehydrogenation over Pd versus PdAg membranes
- 2001
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Ingår i: Applied Catalysis A. - 0926-860X .- 1873-3875. ; 217:1-2, s. 157-164
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Tidskriftsartikel (refereegranskat)abstract
- The dehydrogenation of methanol and ethanol and the subsequent permeation of hydrogen through Pd and Pd70Ag30 membranes, respectively, have been studied. In order to keep a continuous hydrogen permeation rate, oxygen needs to be added to the alcohol supply. Without oxygen, the decomposition products will form a contaminating layer on the upstream membrane surface. The extraction of hydrogen from ethanol is six times more effective through a Pd70Ag30 membrane than through a pure Pd membrane (at optimum conditions). For methanol, the hydrogen permeation is 30% larger through a Pd70Ag30 membrane than through a membrane of pure Pd. The increased hydrogen permeation yield through Pd70Ag30 compared to Pd can be attributed mainly to a lower upstream consumption of hydrogen due to water formation, but also to an increased conversion of the alcohol in the presence of oxygen. © 2001 Elsevier Science B.V.
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| 2. |
- Amandusson, H., et al.
(författare)
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Hydrogen permeation through surface modified Pd and PdAg membranes
- 2001
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Ingår i: Journal of Membrane Science. - 0376-7388 .- 1873-3123. ; 193:1, s. 35-47
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Tidskriftsartikel (refereegranskat)abstract
- The hydrogen permeation through surface modified Pd and Pd70Ag30 membranes has been studied at temperatures between 100 and 350°C. Silver has been evaporated on Pd and Pd70Ag30 foils with a thickness of 25µm in order to study the role of the surface composition in comparison with the membrane bulk composition. The Pd70Ag30-based membranes display the largest permeation rates at temperatures below 200°C, while Pd membranes with 20Å silver evaporated on the upstream side show the largest permeation rates above 200°C. There are, consequently, different rate limiting processes above and below 200°C: at temperatures below 200°C, the bulk diffusion through the membrane is rate limiting, while at temperatures above 200°C, the influence of the surface composition starts to become significant. It has further been concluded that a sharp silver concentration gradient from the surface to the bulk is important for the hydrogen permeation rate at temperatures above 200°C. Adding oxygen to the hydrogen supply will almost totally inhibit the hydrogen permeation rate when a pure Pd membrane surface is facing the upstream side, while for silver-containing surfaces the presence of oxygen has almost no effect. On a clean Pd surface, oxygen effectively consumes adsorbed hydrogen in a water forming reaction. With Ag on the surface, no water formation is detected. Co-supplied CO inhibits the permeation of hydrogen in a similar manner on all studied membrane surfaces, independent of surface silver content. © 2001 Elsevier Science B.V. All rights reserved.
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| 3. |
- Nielsen, A.T., et al.
(författare)
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Hydrogen production from organic waste
- 2001
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Ingår i: International journal of hydrogen energy. - 0360-3199 .- 1879-3487. ; 26:6, s. 547-550
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Tidskriftsartikel (refereegranskat)abstract
- The extraction of pure hydrogen from the fermentation of household waste by a mixed anaerobic bacterial flora is demonstrated. Simulated household waste (600 g) was fermented in a bioreactor, which was continuously sparged with nitrogen (30 ml/min) fed in from the bottom. The gas stream from the biorector passes through a sulphide trap (ZnO) and then through a heated palladium-silver membrane reactor to separate hydrogen from the gas stream. In this way, waste remediation and biological hydrogen production is combined in a process where a large proportion of the hydrogen produced can be collected, free of other gaseous species from the fermentation. © 2001 International Association for Hydrogen Energy.
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