| 1. |
- Aiello, R., et al.
(författare)
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Zeolite synthesis in microgravity
- 2005
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Ingår i: Topical teams in life & physical sciences. - Noordwijk, Netherlands : ESTEC. - 929092974X ; , s. 78-85
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The results of activities performed by the members of the Topical Team on 'Zeolites synthesis in microgravity' are discussed. A method was developed using a two-temperature synthesis procedure to distinguish between the nucleation and growth phase of the crystallization. The experiments have investigated the possibility of suppressing secondary nucleation by imposing a temperature gradient. Optical thickness of the solution has been monitored by interferometry. The Team, on the basis of findings, has elaborated a research program on zeolite film deposition that includes microgravity experimentation.
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| 2. |
- Andersson, Charlotte, et al.
(författare)
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Silicalite-1 membranes with small crystal size
- 2004
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Ingår i: Recent advances in the science and technology of zeolites and related materials. Part A. - Amsterdam : Elsevier. - 0444518274 ; , s. 626-631
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Konferensbidrag (refereegranskat)abstract
- Silicalite-1 membranes with small crystal size were prepared using a multiseeding method, where the support was repeatedly seeded and exposed to a short hydrothermal treatment up to five times. The film were characterized using SEM, single gas permeation, porosimetry and mixture separation experiment Films with three or four layers were of high quality i.e with minor defects according to the porosimetry experiments but showed poor separation of binary mixtures. This result may be attributed to the small crystal size and/or large amount of grain boundaries in the films.
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| 3. |
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| 4. |
- Bjorklund, Robert B., et al.
(författare)
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Vapor adsorption in thin silicalite-1 films studied by spectroscopic ellipsometry
- 1998
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 102:12, s. 2245-2250
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Tidskriftsartikel (refereegranskat)abstract
- Thin films of silicalite-1 grown on silicon substrates were studied by spectroscopic ellipsometry. Analysis of spectra using an optical model consisting of a single porous layer on silicon yielded average film thicknesses of 84 and 223 nm for films synthesized for 10 and 30 h. Void fraction for the films was 0.32-0.33. Vapor adsorption from a nitrogen carrier gas at room temperature was monitored by ellipsometry. Isotherms for different adsorbates were obtained by analysis of spectra taken at different vapor concentrations using an optical model where the void volume was filled with both nitrogen and condensed vapors. Quantification of the condensed vapor amount was based on the changes in refractive index when adsorbates replaced nitrogen in the pores. Adsorbate volumes for water, toluene, 1-propanol, and hexane were 0.12, 0.12, 0.15, and 0.17 cm3 liquid g-1 film, respectively.
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| 5. |
- Dyhr, Kurt, et al.
(författare)
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Effects of zeolite addition on the manganese catalyzed decomposition of hydrogen peroxide
- 1999
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Ingår i: Journal of porous materials. - 1380-2224 .- 1573-4854. ; 6:4, s. 275-282
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Tidskriftsartikel (refereegranskat)abstract
- Manganese catalyzed decomposition of hydrogen peroxide in the presence of various zeolites was investigated at different pH values, Mn concentrations and zeolite: Mn ratios. Depending upon the level of these parameters the zeolites studied displayed both catalytic and inhibitive effects on the rate of decomposition. At a high pH (10.8) Mordenite 10A in a twofold excess on an ion-exchange capacity basis acted as an inhibitor whereas the other zeolites had little or no effect on the reaction rate. At a lower pH (9.0) zeolite A when added in large excess resulted in a remarkable inhibitive effect whereas the same zeolite resulted in a promotion of the catalytic action of manganese at an intermediate pH (9.9). The complex catalytic nature of zeolite-peroxide-Mn systems is discussed.
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| 6. |
- Dyhr, Kurt, et al.
(författare)
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Use of zeolites in hydrogen peroxide bleaching of pulp
- 1998
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 13:4, s. 257-262
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Tidskriftsartikel (refereegranskat)abstract
- The use of zeolites for inhibition of transition metal catalyzed decomposition of hydrogen peroxide was evaluated. A number of zeolite types (A, P, Y, and mordenite 10A), with different crystal structures and ion-exchange characteristics, were tested as additives in bleaching experiments using a mechanical (TMP) pulp and a chemical (kraft) pulp. For the mechanical pulp, addition of zeolites A and P at a moderate alkali charge resulted in a significant improvement of the bleaching performance as signified by an increase in both brightness and residual peroxide content of the bleaching liquor. The other zeolite types studied did not give any positive effects at the bleaching conditions used. For the chemical pulp, no significant improvements were obtained at any alkali charge using zeolite A as an additive. At high alkali charges, addition of zeolite A resulted in a substantially lower brightness than that reached in a zeolite free reference experiment. The effects of zeolite addition upon the bleaching of pulp are complex and dependent upon a number of factors. Parameters of great importance are the bleaching pH, consistency and the zeolite type and charge
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| 7. |
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| 8. |
- Edin, M., et al.
(författare)
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Hot melt adhesion of liner sized with alkylketene dimer
- 2002
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 17:4, s. 395-400
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Tidskriftsartikel (refereegranskat)abstract
- The effect of the sizing agent alkylketene dimer (AKD) on hot melt adhesive joint strength was studied. By varying the amount of AKD added, and varying the degrees of beating and calendering, sheets with different surface energies, surface structures, and strength properties, were obtained. The sheets were adhesively bonded using a commercial packaging machine, and the adhesive joints were tested in T-peel and creep tests. Contact angles, water absorptivity, delamination strength, density, and surface roughness were measured to study the way in which the addition of AKD, beating, and calendering influence these paper properties. The results indicate that neither sizing with AKD nor calendering or beating have any pronounced effect on the adhesive joint strength, at least not under the conditions used. Most of the differences observed are within the limits of the experimental error. The greatest influence on the joint strength was observed when samples had been stored at low temperature.
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| 9. |
- Elvin, F.J., et al.
(författare)
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Processes for demetalization of fluid cracking catalysts
- 1988
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Ingår i: Fluid catalytic cracking. - Washington, DC : American Chemical Society (ACS). - 0841215340 ; , s. 229-236
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Konferensbidrag (refereegranskat)abstract
- Three processes, Demet III, Demet X and New Demet, for demetallization of metal poisoned octacat fluid cracking catalysts were investigated. These processes removed a significant part of the V (30-40%) from the catalyst. The New Demet and Demet III were very effective in removing Ni (88% and 80%, respectively) while practically no Ni could be removed by Demet X. The Demet procedures also proved effective in removing other contaminants like Fe and Cu. All Demet methods resulted in increased cracking activities as determined by the micro-activity test. The conversions increased from 65% for the untreated catalyst to 76-78% for samples treated according to the different Demet procedures. The increase in activity was accompanied by a corresponding increase in gasoline yield of 5.0-6.5%.
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| 10. |
- Engström, V., et al.
(författare)
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The effect of seed size on the growth of silicalite-1 films on gold surfaces
- 2000
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Ingår i: Microporous and Mesoporous Materials. - 1387-1811 .- 1873-3093. ; 38:1, s. 51-60
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Tidskriftsartikel (refereegranskat)abstract
- Silicalite-1 films grown on gold surfaces seeded with colloidal crystals with a size of 60, 165 and 320 nm were investigated by reflection–absorption infrared spectroscopy, scanning electron microscopy and X-ray diffraction in order to follow up the formation of nano-scale defects and to determine the optimal synthesis conditions for preparation of silicalite-1 films with a low concentration of defects. Using 60-nm-sized colloidal crystals, the seeding method was capable of producing silicalite-1 films with low concentrations of defects and with thicknesses ranging from 100 to 300 nm, which are predominantly oriented with the a-axis perpendicular to the surface. Hydrothermal treatment times of the 60-nm-seeded surfaces longer than 36 h as well as the seeding with 165 or 320 nm colloidal crystals substantially enhanced the formation of defects in the films.
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