| 1. |
- Lindmark, Jonas, et al.
(författare)
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Carbon dioxide removal from synthesis gas using MFI membranes
- 2010
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 360:1-2, s. 284-291
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Tidskriftsartikel (refereegranskat)abstract
- A membrane processes may represent a more effective alternative compared to current technology for separation of CO2 from synthesis gas. In the present work, MFI membranes were prepared and the separation performance was evaluated. The Si/Al ratio and the counter ions in the membrane had a significant effect on both single gas permeation and mixture separation by modifying both the effective pore size and the adsorption properties of the membranes. The membranes were relatively unselective for binary mixtures of carbon dioxide and hydrogen, but when the feed also contained water, a CO2/H2 separation factor of 6.2 was achieved for a BaZSM-5 membrane at room temperature. The CO2 permeance for this membrane was as high as 13·10-7 mol · m-2 · s-1 · Pa-1. A suitable terminology for this effect, that a third component, in this case water, enhanced the separation of two other components, in this case CO2 and H2, is sorption enhanced separation. Due to the reduced adsorption of both CO2 and water at higher temperature, the CO2/H2 separation factor was always reduced as the temperature was increased. This work clearly shows that MFI membranes are promising candidates for CO2 separation from synthesis gas.
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| 2. |
- Lindmark, Jonas, et al.
(författare)
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Impregnation of zeolite membranes for enhanced selectivity
- 2010
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 365:1-2, s. 188-197
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Tidskriftsartikel (refereegranskat)abstract
- A new method to enhance the selectivity of zeolite membranes for alternative separation tasks has been developed. Calcined MFI membranes were impregnated with a solution of Ca(NO3)2 in methanol and calcined at 600 °C to thermally decompose the nitrate. SEM and EDS data indicated that calcium compounds were evenly distributed in the entire MFI film and in addition, a few crystals of a calcium compound were observed on top of the film in some locations. A HR-TEM investigation showed that calcium compounds were present in low concentration in the sample and that the interiors of the MFI crystals remained fully crystalline after impregnation and calcination. However, the HR-TEM investigation could neither confirm nor rule out the occurrence of calcium compounds in the pores in the interiors of the crystals. In accordance with the SEM and TEM observations, XRD data showed that calcium compounds on top of the film were relatively large CaCO3 crystals and that the zeolite film remained crystalline after impregnation. However, eventual calcium compounds in the pores of the zeolite could not be studied by XRD since these would probably generate a very weak signal of amorphous material. FTIR data indicated that impregnation increased the amount of both physisorbed and chemisorbed CO2, the latter resulting in carbonate species in the film. n-Hexane/helium adsorption branch permporometry showed that the high quality of the membranes remained after modification. The single component permeance ratio CO2/H2 increased from 0.6 to 1.5 after impregnation. Calculations indicated that the increased CO2/H2 single component permeance ratios were both an effect of increased adsorption of CO2 in the film and reduced pressure drop in the support. The dual component separation factor α CO2/H2 at room temperature increased drastically from 0.7 (H2 selective) to 3.4 (CO2 selective) after impregnation. This work shows for the first time that impregnation procedures can be used to tailor the diffusion properties of zeolite membranes in a similar way as impregnation procedures are used to tailor the catalytic performance of catalysts.
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| 3. |
- Lindmark, Jonas, et al.
(författare)
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Modification of MFI membranes with amine groups for enhanced CO2 selectivity
- 2010
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Ingår i: Journal of Materials Chemistry. - 0959-9428 .- 1364-5501. ; 20:11, s. 2219-2225
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Tidskriftsartikel (refereegranskat)abstract
- Much research on zeolite membranes has been devoted to MFI type zeolite and these membranes can be prepared reproducibly with high quality by our group. However, the MFI pores are too large for separation of small molecules such as CO2, H-2 CH4, and H2O by molecular sieving and the CO2 affinity is not sufficiently strong in our current membranes with quite high Si/Al ratio to achieve CO2 selective membranes. In the present work, existing MFI membranes with high Si/Al ratio are modified with methylamine to increase the CO2 affinity and thus increase the CO2 selectivity. To the best of our knowledge, this is the first time this type of modification is reported for zeolite membranes. These membranes were then evaluated for separation of CO2 from various mixtures of CO2, H-2, CH4 and H2O. The modification had significant effects on both permeances and separation factors and the selectivity towards CO2 was increased considerably for all the feed mixtures tested. The highest separation factor was observed for a CO2/CH4/H2O mixture and alpha-CO2/CH4 was 12 at about 40 degrees C. At the same time, the CO2 permeance was as high as 9 x 10(-7) mol m(-2) s(-1) Pa-1. The separation factor for the amine-modified silicalite-1 membranes was comparable to the highest reported separation factors for MFI membranes, while the CO2 permeance was higher than reported for other selective MFI membranes.
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| 4. |
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| 5. |
- Perdana, Indra, 1973, et al.
(författare)
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Influence of NOx adsorbed species on component permeation through ZSM-5 membranes
- 2010
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 1873-3123 .- 0376-7388. ; 349:1-2, s. 83-89
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Tidskriftsartikel (refereegranskat)abstract
- A thin ZSM-5 film was grown on an alpha-alumina support, resulting in a composite membrane. The membraneswere characterized by SEM and adsorption branch n-hexane/helium permporometry. In addition,the permeation of gas mixtures containing NO2, NO, N2 and argon was evaluated. The effect of temperatureand gas mixture composition on the component permeation and selectivity was investigated.It was found that NOx permeation through the ZSM-5 membrane was partially surface concentrationdependent and was thermally activated. However, transport by gas translational diffusion seemed todominate at the conditions studied. The presence of various NOx adsorbed species appeared to influencediffusion of NO2 in ZSM-5 and reduced transport of other inert and weakly adsorbed components overa wide temperature range (20–400◦C). Strongly adsorbed surface nitrate species formed in the presenceof gas phase NOx should be responsible for the reduced transport of these components at the elevatedtemperature. The findings are of interest for possible applications of ZSM-5 membranes for componentseparation at high temperature.
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| 6. |
- Sandström, Linda, et al.
(författare)
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Separation of methanol and ethanol from synthesis gas using MFI membranes
- 2010
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 360:2, s. 265-275
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Tidskriftsartikel (refereegranskat)abstract
- Methanol or ethanol production from synthesis gas is limited by thermodynamic equilibrium and separation of the alcohol product in or near the reactor at reaction conditions (about 250° C and 50 bar) could improve the process. Separation of methanol and ethanol from synthesis gas by MFI membranes with two different Si/Al ratios has therefore been evaluated in the present work. The synthesis gas was represented by hydrogen, carbon dioxide and water, and membrane separation performance was evaluated at atmospheric pressure and varying temperatures.The highest measured methanol/hydrogen separation factor, 32, was observed for the more polar membrane type with the lowest Si/Al ratio, while the highest ethanol/hydrogen separation factor, 46, was observed for the less polar membrane type with the highest Si/Al ratio, both at room temperature. The separation was controlled by adsorption, and consequently, the separation factors were reduced as the temperature increased, since the feed composition was kept constant.The methanol and ethanol permeances were about 10x10-7 mol m-2 s-1 Pa-1 independent of feed composition, membrane type or temperature, which is more than three times higher than previously reported for gas phase separation using zeolite membranes.A simple mathematical model was successfully fitted to the experimental data. The model suggests that membrane selectivity is temperature dependent, as also observed experimentally, but independent of feed pressure. Experimental data and mathematical modelling thus suggest that the membranes would be alcohol selective at reaction pressure (50 bar) and room temperature, but not at reaction temperature (250°C).
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| 7. |
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| 8. |
- Wirawan, Sang, 1973, et al.
(författare)
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H2/CO2 permeation through a silicalite-1 composite membrane
- 2011
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 1873-3123 .- 0376-7388. ; 375, s. 313-322
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Tidskriftsartikel (refereegranskat)abstract
- Single and binary H2/CO2 gas permeation was studied through a silicalite-1 composite membrane consisting of a thin zeolite film (
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| 9. |
- Aguilar, Wilson, et al.
(författare)
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Comparison between leached metakaolin and leached diatomaceous earth as raw materials for the synthesis of ZSM-5
- 2014
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Ingår i: SpringerPlus. - : Springer. - 2193-1801. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Inexpensive raw materials have been used to prepare ZSM-5 zeolites with SiO2/Al2O3 molar ratios in the range 20 - 40. Kaolin or Bolivian diatomaceous earth was used as aluminosilicate raw materials and sodium hydroxide and n-butylamine were used as mineralizing agents and template. Dealumination of the raw materials by acid leaching made it possible to reach appropriate SiO2/Al2O3 ratios and to reduce the amount of iron and other impurities. After mixing the components and aging, hydrothermal treatment was carried out and the products were recovered The results clearly show for the first time that well-crystallized ZSM-5 can be directly prepared from leached metakaolin or leached diatomaceous earth using sodium hydroxide and n-butylamine as mineralizing agents and template under appropriate synthesis conditions. A longer induction time prior to crystallization was observed for reaction mixtures prepared from leached diatomaceous earth, probably due to slower digestion of the fossilized diatom skeletons as compared with that for microporous leached metakaolin. The use of leached diatomaceous earth allowed higher yield of ZSM-5 crystals within comparable synthesis times. However, low amounts of Mordenite formed, which was related to the high calcium content of diatomaceous earth. Another considerable advantage of diatomaceous earth over kaolin is that diatomaceous earth does not require heat treatment at high temperature for metakaolinization.
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| 10. |
- Ahlberg, Sofia, 1984, et al.
(författare)
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Archipelago from file to factory
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Material and Detail is a course that spans from designing a project to producing and building it. Its basis is parametric design, where a shape is changed by changing some of its variables. Being able to control a design parametrically opens possibilities of trying different solutions quickly, allowing the architect to calibrate one that fits the task precisely.The purpose of the course is to investigate new ways of producing architecture and to familiarize the students with the entire file-to-factory process. The starting point of a single material is a way of making the process more easy to focus. What are the specific characteristics for steel, what can only steel do? At the same time, the idea of taking pieces of a material and forming them into a global shape is at the basis of all craft traditions. This makes the pavilion an apt match for the courtyard of Röhsska – museum of design, arts and crafts.
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