Change search
Refine search result
1234 51 - 100 of 200
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 51.
    Grahn, Mattias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Wang, Zheng
    Luleå tekniska universitet.
    Lidström-Larsson, Margareta
    Holmgren, Allan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hedlund, Jonas
    Sterte, Johan
    Silicalite-1 coated ATR elements as sensitive chemical sensor probes2005In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 81, no 1-3, p. 357-363Article in journal (Refereed)
    Abstract [en]

    A novel sensitive chemical sensor probe has been fabricated. The sensor principle is based on silicalite-1 coated ATR (attenuated total reflection) elements and FTIR spectroscopy. The microporous silicalite-1 film enriches the analyte to the probe surface, thus increasing the sensitivity. At a relative pressure of n-hexane in helium of 6 × 10−5 the sensitivity of the probe is approximately 85 times higher for the silicalite-1 coated element compared to a 10 cm transmission gas cell and ca. 180 times higher compared to an uncoated element. The performance of the probe is illustrated by determination of an adsorption isotherm for n-hexane in silicalite-1.

  • 52.
    Gualtieri, Magdalena Lassinantti
    et al.
    Luleå tekniska universitet.
    Andersson, Charlotte
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Jareman, Fredrik
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Gualtieri, Alessandro F.
    Dipartimento di Scienze della Terra, Universita di Modena e Reggio Emilia.
    Leoni, Matteo
    Dipartimento di Ingegneria dei Materiali, Università di Trento, I-38050 Mesiano.
    Meneghini, Carlo
    Dipartimento di Fisica ‘E. Amaldi’ Università di Roma Tre, Via della Vasca Navale 84, I-00146 Roma.
    Crack formation in α-alumina supported MFI zeolite membranes studied by in situ high temperature synchrotron powder diffraction2007In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 290, no 1-2, p. 95-104Article in journal (Refereed)
    Abstract [en]

    Cracks are frequently formed in α-alumina supported MFI membranes during calcination. To better understand crack formation, in situ powder diffraction data were collected during calcination of a type of MFI membrane (ca. 1800 nm thick) which is known to crack reproducibly. In addition, data for MFI powder and a blank support were also collected. Both a synchrotron radiation facility and an in-house instrument were used. The unit cell parameters were determined with the Rietveld method, and the strain in the direction perpendicular to the film surface was calculated for the film as well as for the support. The microstrain in the support was also estimated. Based on the results obtained here, a model for crack formation in this type of MFI membrane was proposed. The lack of cracks in other types of MFI membranes (ca. 500 nm) prepared in our laboratory is also explained by the model. In thicker MFI films, the crystals are well intergrown. During heating, the MFI crystals contract and the α-alumina support expands. Consequently, a thermal stress develops in the composite which eventually leads to formation of cracks in the film and structural defects in the support. In thinner films, the crystals are less well intergrown and the thermal expansion mismatch leads to opening of grain boundaries rather than cracks.

  • 53.
    Gualtieri, Magdalena Lassinantti
    et al.
    Luleå tekniska universitet.
    Gualtieri, Alessandro
    Università di Modena e Reggio Emilia.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    The influence of heating rate on template removal in silicalite-1: an in situ HT-XRPD study2006In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 89, no 1-3, p. 1-8Article in journal (Refereed)
    Abstract [en]

    The effect of heating rate on thermal behavior of TPA-silicalite-1 during calcination and the reaction kinetics for TPA decomposition were investigated. The cell parameters of the TPA-silicalite-1 during the heating cycles were determined with the aid of high temperature X-ray diffraction data and the Rietveld method. The template decomposition is accompanied by a large contraction of the unit cell. The unit cell dimensions during template removal are not affected significantly by the heating rate. Consequently, the rate of contraction is approximately proportional to the heating rate. The intensity of some diffraction peaks changes during heating, especially the 101/011 and the 200/020 peaks. The intensity change of those peaks shows the same dependence with temperature as the TPA occupancy, indicating that these parameters are related. An analysis of the kinetics for TPA decomposition based on the intensity change of the 101/011 and the 200/020 peaks was performed. The apparent activation energy (Ea) of the template decomposition in silicalite-1 determined with the Kissinger and the Flynn–Wall–Ozawa methods was 138 (±25) and 138 (±29) kJ mol−1, respectively. The reaction order, determined with the method of Kennedy and Clark, was close to 0.5 indicating that the rate-limiting step is mono-dimensional diffusion. Ea was 140 (±30) kJ mol−1, in good agreement with the results obtained with the other methods. With the results presented here, it is possible to discuss possible effects of the heating rate on the crack formation frequently observed in zeolite membranes during calcination

  • 54.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Control of the preferred orientation in MFI films synthesized by seeding2000In: Journal of porous materials, ISSN 1380-2224, E-ISSN 1573-4854, Vol. 7, no 4, p. 455-464Article in journal (Refereed)
    Abstract [en]

    Single crystal silicon and quartz wafers were seeded with colloidal TPA-silicate-1 crystals. Hydrothermal treatment of the seeded substrates was used to grow dense MFI films. The preferred orientation of the crystals constituting the films as a function of the amount and size of seeds, film thickness and hydrothermal treatment conditions was investigated. In thin films, most of the crystalline material was found to be oriented with the b-axes close to perpendicular to the substrate surface. In thick films, the a- or c-axes were close to perpendicular to the substrate surface depending on the conditions used for hydrothermal treatment. The seed size and amount was found to affect the rate of change in preferred orientation as a function of film thickness. A film growth mechanism which is able to explain the experimental results is proposed

  • 55.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Thin films of molecular sieves: synthesis and applications1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The seed film method for synthesis of ultra thin and thin molecular sieve films was developed. The versatility of the method was demonstrated by successful preparation of films of a number of molecular sieves (silicate-1, ZSM-5, NA) on various supports (silicon, alumina, gold, etc.). The preferred orientation of the crystalline material could be controlled. Silicate-1 films on silicon wafers were evaluated as optical gas sensors. Sorption isotherms of water, toluene, 1-propanol and n-hexane were recorded. ZSM-5 films with a thickness of 1.5 um were crystallized on a porous support and the membranes were evaluated in permeation experiments. The flux in single gas experiments decreased in the series H2O, H2, CO2, O2, N2 and CH4. The difference in flux between each molecule was about 1 order of magnitude which indicated the high quality of the membranes. The measured separation factors for binary mixtures of N2/SF6 and H2/i-C4 were 99 and 66.

  • 56.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Ultra thin films of molecular sieves1997Licentiate thesis, comprehensive summary (Other academic)
  • 57.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Babouchkina, E.
    Luleå tekniska universitet.
    Sterte, Johan
    Thin zeolite NA films by the seed film method1999In: Proceedings of the 12th International Zeolite Conference / [ed] M.M.J. Treacy, Warrendale, Pa: Materials Research Society, 1999, Vol. 3, p. 1857-1862Conference paper (Refereed)
  • 58.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Korelskiy, Danil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Rayson, Mark
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, Patrick R.
    School of Electrical, Electronic and Computer Engineering, University of Newcastle upon Tyne.
    Mass transport in porous media from first principles: an experimental and theoretical study2012In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 415-416, p. 271-277Article in journal (Refereed)
    Abstract [en]

    In the present work, the mass transport of helium through zeolite is experimentally determined by measuring the flow of helium through a zeolite membrane. By using a mathematical model, the mass transport through defects was accounted for to arrive at mass transport through zeolite pores. For the first time, we could thereby experimentally show that the mass transport of helium in zeolite pores is strongly controlled by the amount and location of hydrocarbons in the zeolite pores and varies several orders of magnitude. The mass transport of helium in ZSM-5 zeolite pores is first reduced gradually more than one order of magnitude when the loading of n-hexane is increased from 0 to 47% of saturation. As the loading of n-hexane is further increased to 54% of saturation, the mass transport of helium in the zeolite pores is further reduced abruptly by more than two orders of magnitude. This gradual decrease followed by an abrupt decrease of mass transport is caused by adsorption of n-hexane in the zeolite pores. In a similar yet different fashion, the mass transport of helium in the zeolite pores is reduced abruptly by almost two orders of magnitude when the loading of benzene is increased from 0 to 19% of saturation due to adsorption of benzene in the pore intersections. Effective medium approximation percolation models with parameters estimated using density functional theory employing the local density approximation, i.e. models with no adjustable parameters and the most sophisticated theory yet applied to this system, can adequately describe the experimental observations.

  • 59.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Jareman, Fredrik
    Luleå tekniska universitet.
    Texture of MFI films grown from seeds2005In: Current Opinion in Colloid & Interface Science, ISSN 1359-0294, E-ISSN 1879-0399, Vol. 10, no 5-6, p. 226-232Article in journal (Refereed)
    Abstract [en]

    This review describes how the texture of MFI films grown from seed crystal is developed during film preparation. Reports published during the last 5 years are in focus. Relative growth rates in various crystallographic directions, competitive growth, properties of the seed layer, defects, grain boundaries and other parameters influencing the film properties are discussed. Mathematical models describing competitive growth are also discussed. Suitable characterization methods for defects are described. The last part of the review is devoted to diffusion. Diffusion models accounting for texture in MFI films and the influence of texture on diffussion are discussed.

  • 60.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Jareman, Fredrik
    Luleå tekniska universitet.
    Andersson, Charlotte
    Factors affecting the performance of MFI membranes2004In: Recent advances in the science and technology of zeolites and related materials. Part A: proceedings of the 14 th International Zeolite Conference, Amsterdam: Elsevier, 2004, p. 640-646Conference paper (Refereed)
    Abstract [en]

    Thin MFI membranes with varying morphology have been prepared using high flux alumina supports using all advanced synthesis procedure employing support masking and seeding. Evaluation of membrane quality by physical characterization and permeation measurements revealed a number of factors affecting the membrane performance. In the present work, the effects of film thickness, support type, preferred orientation and calcination rate are discussed. Some quality criteria for zeolite membranes are also debated and the porosimetry technique is discussed.

  • 61.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Jareman, Fredrik
    Luleå tekniska universitet.
    Bons, Anton-Jan
    ExxonMobil Chemical Europe Inc..
    Anthonis, Marc
    ExxonMobil Chemical Europe Inc..
    A masking technique for high quality MFI membranes2003In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 222, no 1-2, p. 163-179Article in journal (Refereed)
    Abstract [en]

    A procedure for the preparation of high quality zeolite membranes was developed. This procedure relies on a masking approach that fills all support pores with wax while leaving the top surface free for deposition of the zeolite film, thus, protecting the support from the synthesis mixture. Zeolite films of different thickness were grown on masked and non-masked supports using a seeded growth method. The zeolite-coated supports were calcined in order to remove the wax from the support and the template molecules from the zeolite. The membranes were characterized by SEM, XRD, single gas and multi-component permeation measurements. Support masking reduces the zeolite membrane thickness and the width of the cracks in the zeolite film. Thicker films, especially those prepared without masking, are defective. Masked membranes with a film thickness of 500 nm show no cracks or pinholes. These membranes have a H2 permeance of 220×10−7 mol/(s m2 Pa), an n-butane permeance of 9.8×10−7 mol/(s m2 Pa) and an n-butane/iso-butane separation factor of 9.0 at 25 °C. The separation factor for a mixture of n-hexane/2,2-dimethyl-butane was 227 at 400 °C and the n-hexane permeance was 5.6×10−7 mol/(s m2 Pa). The p-xylene permeance was 2.7×10−7 mol/(s m2 Pa) and the para/ortho separation factor was 17 at 400 °C for a mixture of xylenes.

  • 62.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Korelskiy, Danil
    Sandström, Linda
    Lindmark, Jonas
    Permporometry analysis of zeolite membranes2009In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 345, no 1-2, p. 276-287Article in journal (Refereed)
    Abstract [en]

    In permporometry analysis of zeolite membranes, the permeance of a non-adsorbing gas, such as helium, is measured as a function of pressure of a strongly adsorbing compound, such as n-hexane in the case of silicalite-1 membranes. The adsorbing compound effectively blocks the transport of the non-adsorbing gas already at very low activity of the adsorbing compound. The plot of the permeance of the non-adsorbing gas as a function of relative pressure of the adsorbing compound is denoted a permporometry pattern. The present work is based on experimental data for a number of thin MFI membranes with a film thickness ranging from 300 to 1800 nm. An adsorption-branch permporometry experiment is simple and straightforward and after activation of the membrane by removing adsorbed species at 300 °C in a flow of dry gas, a full permporometry pattern is recorded within about 7 h for such membranes. It is shown how the distribution of flow-through defects can be estimated from the permporometry pattern using a simple model for permeation based on Knudsen diffusion. The estimated defect distribution is supported by SEM observations. In addition, the permeance of the non-adsorbing gas through defects measured in permporometry can be used to predict the permeance of molecules diffusing through defects in the membrane in mixture separation experiments and also indicate the separation factor. For instance, the helium permeance through defects in an MFI membrane measured by helium/n-hexane permporometry at room temperature can be used to estimate the permeance of 2,2-dimethylbutane (DMB) in a mixture separation experiment at a higher temperature with a feed containing both DMB and n-hexane by assuming Knudsen diffusion for both helium and DMB in the defects. Also, the separation factor αn-hexane/DMB in a mixture separation experiment at a certain temperature with an MFI membrane with a given defect distribution can be estimated from n-hexane/helium permporometry data recorded at the same temperature through an empirical correlation. In summary, adsorption-branch permporometry is a very effective tool for analysis of thin zeolite membranes, that in short time gives data that can be used to estimate the distribution of flow-through defects in the membrane and to estimate the transport of large molecules through defects in separation experiments and also estimate separation performance.

  • 63.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Kurpan, E.
    Luleå tekniska universitet.
    Synthetis of nanosized offretite crystals2001In: Zeolites and mesoporous materials at the dawn of the 21st century: proceedings of the 13th International Zeolite Conference, Amsterdam: Elsevier, 2001, p. 187-Conference paper (Refereed)
  • 64.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mintova, Svetlana
    Luleå tekniska universitet.
    Sterte, Johan
    Controlling the preferred orientation in silicalite-1 films synthesized by seeding1999In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 28, no 1, p. 185-194Article in journal (Refereed)
    Abstract [en]

    Single crystal silicon (100) wafers were seeded with colloidal silicalite-1 crystals and hydrothermally treated in a precursor solution to grow thin silicalite-1 films. A total of 28 experiments in eight series were investigated with SEM and XRD to evaluate the preferred orientation of the crystals constituting the films. The investigated parameters in the film formation process were seed crystal size, amount of adsorbed seed crystals and film thickness after hydrothermal treatment of the seeded substrates. In thin films, most of the crystalline material is oriented with the b-axis perpendicular to the substrate surface. In thick films, most of the crystalline material is oriented with the a-axis perpendicular to the substrate surface. The change in preferred orientation with film thickness is faster when small seeds are used. The amount of adsorbed seeds has a larger influence on the preferred orientation when large seeds are used. A mechanism explaining these trends is proposed. The choice of size and coverage of seeds can be used to control the preferred orientation of the crystals in a film of given thickness within certain limitations.

  • 65.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mintova, Svetlana
    Luleå tekniska universitet.
    Sterte, Johan
    Preferred orientation in thin silicalite films synthesized by seeding1999In: Proceedings of the 12th International Zeolite Conference / [ed] M.M.J. Treacy, Warrendale, Pa: Materials Research Society, 1999, Vol. 3, p. 1809-1816Conference paper (Refereed)
  • 66.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Noack, M.
    Institute of Applied Chemistry e.V., Rudower Chaussee 5, D-12489, Berlin.
    Kölsch, P.
    Institute of Applied Chemistry e.V., Rudower Chaussee 5, D-12489, Berlin.
    Creaser, Derek
    Luleå tekniska universitet.
    Sterte, Johan
    Caro, J.
    Institute of Applied Chemistry e.V., Rudower Chaussee 5, D-12489, Berlin.
    ZSM-5 membranes synthesized without organic templates using a seeding technique1999In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 159, no 1-2, p. 263-273Article in journal (Refereed)
    Abstract [en]

    Porous α-alumina supports were seeded with colloidal TPA-silicalite-1 crystals and calcined. The supports were treated in a synthesis solution to grow the seed crystals into ZSM-5 films. The synthesis solution was free from organic template molecules in order to avoid the calcination step which often introduces cracks in the synthesized zeolite film. An SEM investigation indicated that the zeolite films on the supports were defect free and that the film thickness was approximately 1.5 μm. XRD data showed that the film consisted of well-crystallized ZSM-5. The permeance in single gas experiments decreased in the order H2O, H2, CO2, O2, N2 and CH4. The difference in permeance between each molecular species in the series was almost one order of magnitude which indicated that the membranes were of a high quality. Molecules larger than CH4 permeated with similar and low rates, independent of their kinetic diameters, indicating a non-selective permeation path through defects in the zeolite films. However, the permeance of these larger molecules was less than 1/10 000 of that for H2O. The highest measured separation factors for binary mixtures of N2/SF6 and H2/i-C4 were 110 and 99.

  • 67.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Schoeman, B.J.
    Sterte, Johan
    Synthesis of ultra thin films of molecular sieves by the seed film method1997In: Progress in zeolite and microporous materials: Proceedings of the 11th International Zeolite Conference, Seoul, Korea, 12-17 August 1996, Amsterdam: Elsevier, 1997, p. 2203-2210Conference paper (Refereed)
    Abstract [en]

    A novel and flexible technique for synthesizing continuous ultra thin (<100 nm) molecular sieve films on substrates has been developed. The technique consists of two steps. A monolayer of discrete colloidal zeolite seed crystals is adsorbed on the substrate, whereafter the crystals are allowed to grow into a continuous film upon hydrothermal treatment in a molecular sieve precursor solution. The technique is exemplified by the formation of silicalite-1 films on silicon wafers. The final film thickness in the examples presented was in the range 80 and 800 nm. The films are continuous and crystalline as confirmed by SEM, Kr-adsorption data, ellipsometry, XRD and FTIR.

  • 68.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Schoeman, Brian
    Luleå tekniska universitet.
    Sterte, Johan
    Ultrathin oriented zeolite LTA films1997In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 13, p. 1193-1194Article in journal (Refereed)
    Abstract [en]

    Ultrathin oriented films of zeolite LTA are prepared on single-crystal alumina supports by a method including adsorption of LTA seeds on the support followed by hydrothermal film crystallization.

  • 69.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sterte, Johan
    Synthesis of thin molecular sieve films1999In: Nanostructured materials, ISSN 0965-9773, E-ISSN 1872-9150, Vol. 12, no 1-4, p. 413-416Article in journal (Refereed)
    Abstract [en]

    A method to synthesize thin films of various molecular sieves on a number of substrates employing pre-seeding has been developed. The substrate is modified to enable adsorption of seed crystals. Substrates with an originally negative surface charge are charge reversed by adsorption of cationic polymer molecules. Nobel metal substrates are first silanized to obtain a negative surface charge. Nano seed crystals are adsorbed on the modified substrates from a sol and induced to grow in a synthesis solution to form a dense film with controlled thickness. The versatility of the method may be of great value in the development of novel applications. Films have been tested in membrane and sensor applications with successful results.

  • 70.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sterte, Johan
    Anthonis, Marc
    ExxonMobil Chemical Europe Inc..
    Bons, Anton-Jan
    ExxonMobil Chemical Europe Inc..
    Carstensen, Barbara
    ExxonMobil Research & Engineering Co..
    Corcoran, Ned
    ExxonMobil Research & Engineering Co..
    Cox, Don
    ExxonMobil Research & Engineering Co..
    Deckman, Harry
    ExxonMobil Research & Engineering Co..
    Gijnst, Wim De
    ExxonMobil Chemical Europe Inc..
    Moor, Peter-Paul de
    ExxonMobil Chemical Europe Inc..
    Lai, Frank
    ExxonMobil Research & Engineering Co..
    McHenry, Jim
    ExxonMobil Research & Engineering Co..
    Mortier, Wilfried
    ExxonMobil Chemical Europe Inc..
    Reinoso, Juan
    ExxonMobil Chemical Company.
    Peters, Jack
    ECN Energy Efficiency.
    High-flux MFI membranes2002In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 52, no 3, p. 179-189Article in journal (Refereed)
    Abstract [en]

    The synthesis and evaluation of high performance MFI-type membranes is described. These systems exhibit fluxes that are one to two orders of magnitude higher than previous literature reports, with comparable selectivities, when tested for various single component gases and for mixtures of C4, C6 and xylene isomers. These materials are the result of a rational fabrication approach targeting ultra-thin, defect-free MFI films on open supports by using a two-step support masking technique and a monolayer of colloidal nucleation seeds, followed by in situ hydrothermal growth, producing a defect-free film with a thickness of 0.5 μm. Reproducibility of the membrane preparation was excellent

  • 71.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering. Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Yu, Liang
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Nobandegani, Mojtaba
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Diffusion of small molecules in ultra-thin MFI membranes2019Conference paper (Refereed)
  • 72.
    Hedlund, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Öhrman, Olov
    Msimang, Velaphi
    University of Cape Town.
    Steen, Eric van
    University of Cape Town.
    Böhringer, Walter
    University of Cape Town.
    Sibya, Sifiso
    University of Cape Town.
    Möller, Klaus
    University of Cape Town.
    The synthesis and testing of thin film ZSM-5 catalysts2004In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 59, no 13, p. 2647-2657Article in journal (Refereed)
    Abstract [en]

    The synthesis and catalytic testing of thin ZSM-5 films on glass and alumina beads is described. The thickness of the ZSM-5 films was controlled to 150, 350, 800 and 2300 nm. The samples were characterised by SEM, gas adsorption and p-xylene isomerisation and 1,3,5-tri-isopropyl benzene cracking test reactions. A reaction–diffusion model adequately described the p-xylene isomerisation data. Estimates of model parameters were obtained by fitting the model to the experimental data. In both cases, the reaction rate constant increased with increasing film thickness. The xylene reaction data showed that secondary reaction products increased as expected with increasing diffusion limitations, but the increase was less than that predicted by the variation of thickness only. The trends in the reaction data could be explained by more defects in the thicker films and/or partial poisoning of the zeolite by mobile support cations in thinner films and/or orientation effects.

  • 73.
    Holmgren, Allan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Lidström-Larsson, Margareta
    Luleå University of Technology.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Sterte, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Wang, Zheng
    Luleå University of Technology.
    Sensor for spectroscopic analysis of gases or liquids, comprises attenuated total reflection element with molecular sieve layerPatent (Other (popular science, discussion, etc.))
  • 74.
    Häggström, Caroline
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Öhrman, Olov
    Rownaghi, Ali
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Gebart, Rikard
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Catalytic methanol synthesis via black liquor gasification2012In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 94, no 1, p. 10-15Article in journal (Refereed)
    Abstract [en]

    Biofuel production from gasified black liquor is an interesting route to decrease green house gas emissions. The only pressurised black liquor gasifier currently in pilot operation is located in Sweden. In this work, synthesis gas was taken online directly from this gasifier, purified from hydrocarbons and sulphur compounds and for the first time catalytically converted to methanol in a bench scale equipment. Methanol was successfully synthesised during 45 h in total and the space time yield of methanol produced at 25 bar pressure was 0.16–0.19 g methanol/(g catalyst h). The spent catalyst exposed to gas from the gasifier was slightly enriched in calcium and sodium at the inlet of the reactor and in boron and nickel at the outlet of the reactor. Calcium, sodium and boron likely stem from black liquor whereas nickel probably originates from the stainless steel in the equipment. A slight deactivation, reduced surface area and mesoporosity of the catalyst exposed to gas from the gasifier were observed but it was not possible to reveal the origin of the deactivation. In addition to water, the produced methanol contained traces of hydrocarbons up to C4, ethanol and dimethyl ether.

  • 75.
    Jareman, Fredrik
    et al.
    Luleå tekniska universitet.
    Andersson, Charlotte
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    The influence of the calcination rate on silicalite-1 membranes2005In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 79, no 1-3, p. 1-5Article in journal (Refereed)
    Abstract [en]

    Silicalite-1 films with a thickness of 500 nm on asymmetric α-alumina micro filtration filters were calcined at 500 °C with heating and cooling rates varying between 0.2 °C/min and 5.0 °C/min. The membranes were characterized with single gas permeation, porosimetry, and xylene isomer separation experiments. It was found that the quality of the prepared membranes was independent of the heating/cooling rate according to the single gas permeation and porosimetry characterization. Xylene isomer separation data was found to vary between the samples, but none of the variations could be attributed to the heating/cooling rate during calcination since the variations did not follow a trend but occurred randomly. It is thus concluded that the calcination rate does not influence the quality of these membranes.

  • 76.
    Jareman, Fredrik
    et al.
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Permeation of H2, N2, He and SF6 in real MFI membranes2005In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 83, no 1-3, p. 326-332Article in journal (Refereed)
    Abstract [en]

    This work shows that a previously developed model for single gas permeation in real MFI membranes is applicable to an arbitrary MFI membrane with a different film thickness and defect distribution. The model can predict the flow of H2, N2 and He resonably. Deviations in SF6 flux for thick and oriented films were observed and attributed to a lower diffusion coefficient for the narrower pores in the a-direction of the MFI crystals. By guidance from the model, variations in previously reported single gas permeance ratios for selected membranes can now be attributed to variations in feed pressure, film thickness preferred orientation and defect distribution. It was found that high feed pressures and thick oriented films resulted in large single gas permeance ratios with SF6 in the denominator, even though these membranes were more defective than thinner membranes with more randomly oriented crystals. In general, single gas permeance ratios are strongly dependent on material properties and experimental conditions. These ratios can only be used for comparison of membranes with similar morphology and the ratios must be measured under identical conditions.

  • 77.
    Jareman, Fredrik
    et al.
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Single gas permeance ratios in MFI membranes: effects of material properties and experimental conditions2005In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 82, no 1-2, p. 201-207Article in journal (Refereed)
    Abstract [en]

    A previously developed mathematical model with parameters fitted to experimental data was used to study effects of material properties and experimental conditions on single gas permeance ratios of MFI membranes. The model showed that single gas permeance ratios are highly dependent on substrate morphology, feed pressure, crystallographic orientation and defects in the film. It was found that the pore size and the thickness of the substrate affected permeance ratios, due to mass transfer resistance in the substrate. The applied feed pressure also had a significant effect on the permeance ratios. This is due to differences in mass transfer resistance of the substrate and adsorption characteristics with varying feed pressures. The crystallographic orientation of the zeolite film also affected permeance ratios due to changes in diffusivity with varying orientation of the crystals in the film. Finally, the effect of defects was investigated. As expected, it was found that the permeance ratios decreased when more defects were added in the model. However, if the membrane is not very defective, the permeance ratio is much more affected by the substrate and by variation in pressure drop than by defects. The results in the present work show that single gas permeance ratios cannot be used directly as a benchmark of membrane quality unless all other parameters are kept constant.

  • 78.
    Jareman, Fredrik
    et al.
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Creaser, Derek
    Chalmers University of Technology.
    Sterte, Johan
    Modelling of single gas permeation in real MFI membranes2004In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 236, no 1-2, p. 81-89Article in journal (Refereed)
    Abstract [en]

    A novel permeation model for flow through defects and zeolite pores in real MFI membranes, also accounting for substrate effects has been developed. Defect distributions for two types of MFI membranes were determined from porosimetry data using the model, which incorporated the Horvath Kawazoe (micropores) or the Kelvin equation (mesopores). The narrowest (1.08 nm) and also most common defects were found to be separated with a distance of 10–40 μm according to the model. Diffusion coefficients for hydrogen, helium, nitrogen and SF6 in the zeolite were further determined from single gas permeation data using the model using the independently determined defect distribution. The coefficients are consistent with values previously reported in the literature.

  • 79.
    Jareman, Fredrik
    et al.
    Luleå University of Technology.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sterte, Johan
    Effects of aluminum content on the separation properties of MFI membranes2003In: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 32, no 1-3, p. 159-163Article in journal (Refereed)
    Abstract [en]

    MFI membranes with almost identical film thickness and defect distribution but different Si/Al ratio were evaluated by separation of butane and hexane isomers. Film thickness was evaluated by SEM and defect distribution by porosimetry. When the temperature was varied, the membranes showed similar separation trends for butanes, but clear differences were observed for hexane separation. The hexane separation factor varied with temperature for the silicalite-1 membrane but was constant for the ZSM-5 membrane. It is believed that this difference may be a result of differences in adsorption properties.

  • 80.
    Kangas, Jani
    et al.
    University of Oulu.
    Sandström, Linda
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Malinen, Ilkka
    University of Oulu.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tanskanen, Juha
    University of Oulu.
    Maxwell-Stefan modeling of the separation of H2 and CO2 at high pressure in an MFI membrane2013In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 435, p. 186-206Article in journal (Refereed)
    Abstract [en]

    In the present study, a Maxwell-Stefan based model was developed for the separation of CO2 from H2 at high pressure in an MFI membrane. The usage of the Vignes interpolation formula for mixture surface diffusivities together with the IAST (ideal adsorbed solution theory) using bulk gas phase fugacities for mixture adsorption proved to be a feasible combination for this case. Both the effects of defects in the zeolite film and the mass transfer resistance caused by the support layers were studied and included in the model. Only pure component experimental data was used in the model building to predict the gas mixture permeation. The fitted diffusion parameters were in line with the literature values. The occupancy fraction dependence of CO2 surface diffusivity was utilized for the first time in the prediction of binary separation of H2/CO2 at high pressure on a real MFI membrane. Usage of an occupancy fraction dependence for CO2 surface diffusivity improved the model predictions. The adsorption parameter fitting for hydrogen based on the permeation measurements resulted in a feasible adsorption model, but should be used with caution. The model predicts binary separation measurement results relatively well. Both defects and support have a noticeable impact on the overall performance of the membrane.

  • 81.
    Karimi, Somayeh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Korelskiy, Danil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Mortazavi, Yadollah
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Khodadadi, Abbas Ali
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Sardari, Kaymar
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Esmaeili, Mohammad
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    High flux acetate functionalized silica membranes based on in-situ co-condensation for CO2/N2 separation2016In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 520, p. 574-582Article in journal (Refereed)
    Abstract [en]

    Acetate-functionalized silica membranes were prepared via co-condensation. The molar ratio of functional groups in the silica matrix was varied in the range of 0–0.6, denoted by x. The presence of functional groups bonded to the silica network was revealed by FTIR and 29Si and 13C solid-state NMR analysis. The stability of the groups was studied by TG analysis. The membranes were evaluated for CO2/N2 mixture separation in a temperature range of 253–373 K using a feed pressure of 9 bar and a sweep gas kept at atmospheric pressure on the permeate side. The membranes were found to be CO2-selective at all the conditions studied. The highest observed selectivity was 16 for x=0.4, with a CO2 permeance of 5.12×10−7 mol s−1 m−2 Pa−1. For x=0.2, a permeance of as high as 20.74×10−7 mol s−1 m−2 Pa−1 with a CO2/N2 selectivity of 7.5 was obtained. This permeance is the highest reported for CO2/N2 separation using functionalized silica membranes. It is proposed that the separation mechanism between CO2 and N2 was the preferential adsorption of CO2, which inhibited adsorption and permeation of N2 through the silica pore network. Permporometry results revealed that as the loading of functional groups increased, the He permeance decreased. It was also indicated that the quantity of micropores in the functionalized membrane was higher than that in the parent silica membrane.

  • 82.
    Karimi, Somayeh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Korelskiy, Danil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Yu, Liang
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Khodadadi, Abbas Ali
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Mortazavi, Yadollah
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Esmaeili, Mohammad
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    A simple method for blocking defects in zeolite membranes2015In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 489, p. 270-274Article in journal (Refereed)
    Abstract [en]

    The abatement of defects in zeolite membranes is essential for achieving high selectivity. In the present work, a simple and effective method for blocking defects in ultra-thin (ca. 0.5 μm) MFI zeolite membranes has been developed. The method is based on deposition of an ultra-thin (∼15 nm) layer of amorphous silica on the top surface of the membrane. Permporometry data indicated that the amount of defects, especially defects larger than 4 nm, in the membranes was significantly reduced after the modification. In mixture separation experiments, the CO2/H2 separation factor increased dramatically after blocking the defects in a defective membrane that was selected for the experiments. For instance, at 263 K and 9 bar feed pressure, the CO2/H2 separation factor increased from 8.5 to 36 after modification of the membrane, whereas the CO2 flux only decreased by ca. 40%.

  • 83.
    Karimi, Somayeh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran, Tehran, Iran.
    Mortazavi, Yadollah
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran, Tehran, Iran.
    Khodadadi, Abbas Ali
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran, Tehran, Iran.
    Holmgren, Allan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Korelskiy, Danil
    Materials Technology and Chemistry, Alfa Laval Tumba AB, Tumba, Sweden.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Functionalization of silica membranes for CO2 separation2020In: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 235, article id 116207Article in journal (Refereed)
    Abstract [en]

    Five organic CO2-philic functional groups were incorporated in silica matrixes for preparation of functionalized silica membranes to explore the CO2 separation performance. Chemical groups including acetate, trifluoromethyl, methacrylate, urea and vinyl groups were anchored in the silica network using the co-condensation method.

    The information from 29Si solid-state NMR and FTIR analyses indicates the successful formation of a covalent bond between functional groups and the silica network. The thickness of the functionalized silica layers was measured by SEM and the thermal stability of the organic groups was determined by thermogravimetric analysis (TGA).

    The gas permeance and mixed gas selectivity of CO2/N2 was measured in the temperature range of 253–373 K with a feed pressure of 9 bar. A maximum selectivity of as high as 10 was observed for a trifluoromethyl functionalized silica membrane with a CO2 permeance of 5.5 × 10−7 mol s−1 m−2 Pa−1. Permporometry measurements indicated that the contribution of flow through micropores to the total flow for all the functionalized silica membranes varied between 62 and 82%. All membranes were CO2 selective.

     

  • 84.
    Korelskiy, Danil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Characterization of flow-through micropores in MFI membranes by permporometry2012In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 417-418, p. 183-192Article in journal (Refereed)
    Abstract [en]

    Permporometry was used for the first time to characterize flow-through micropore defects down to 0.7 nm in size in MFI zeolite membranes. Helium was used as the non-adsorbing gas and n-hexane or benzene was used as the adsorbate. The helium flow through zeolite pores was estimated using percolation theory and the remaining flow was assigned to flow-through defects. The area distribution of flow-through defects was estimated from the data using a simple model and similar results were obtained using both adsorbates. The total area of defects determined using n-hexane as the adsorbate was as low as about 0.7% of the membrane area and defects with a width below 1 nm constituted 97% of the total defect area for the best membrane. The permporometry results were supported by n-hexane/1,3,5-trimethylbenzene separation experiments. The permporometry data were also consistent with HR-SEM observations indicating the presence of narrow open grain boundaries, and absence of large cracks and pinholes

  • 85.
    Korelskiy, Danil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Ye, Pengcheng
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Zhou, Ming
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    A study of CO2/CO separation by sub-micron b-oriented MFI membranes2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 70, p. 65475-65482Article in journal (Refereed)
    Abstract [en]

    Separation of CO2 and CO is of great importance for many industrial applications. Today, CO2 is removed from CO mainly by adsorption or physical or chemical absorption systems that are energy-intensive and expensive. Membranes are listed among the most promising sustainable and energy-efficient alternatives for CO2 separation. Here, we study CO2/CO separation by novel sub-micron b-oriented MFI zeolite membranes in a temperature range of 258-303 K and at a feed pressure of 9 bar. Under all experimental conditions studied, the membranes were CO2-selective and displayed high CO2 permeance ranging from 17 000 to 23 000 gpu. With decreasing temperature, the CO2/CO selectivity was increasing, reaching a maximum of 26 at 258 K. We also developed a mathematical model to describe the membrane process, and it indicated that the membrane separation performance was a result of selective adsorption of CO2 on the polar zeolite. The heat of adsorption of CO2 on the zeolite is more negative due to the high quadrupole moment and polarisability of the molecule as compared to CO. At the same time, diffusional coupling (correlation effects) at high adsorbed loadings was found to favour the overall CO2/CO selectivity of the membranes by reducing the diffusivity of the lighter CO molecule in the ca. 0.55 nm pores in the zeolite. The model also indicated that the separation performance was limited by the mass transfer resistance in the support and concentration polarisation on the feed side of the membrane.

  • 86.
    Korelskiy, Danil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Leppäjärvi, Tiina
    Department of Process and Environmental Engineering, University of Oulu.
    Zhou, Han
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tanskanen, Juha
    Department of Process and Environmental Engineering, University of Oulu.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    High flux MFI membranes for pervaporation2013In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 427, p. 381-389Article in journal (Refereed)
    Abstract [en]

    MFI membranes with a thickness of 0.5 μm prepared on a graded α-alumina support were evaluated for separation of feed mixtures of 3 wt.% n-butanol/water and 10 wt.% ethanol/water by pervaporation. The membranes were selective to n-butanol and ethanol. The flux observed in the present work was about 100 times higher than that previously reported for n-butanol/water separation by pervaporation and about 5 times higher than that for ethanol/water separation by pervaporation. At 60 °C, the observed n-butanol/water flux was about 4 kg m−2 h−1 and the n-butanol/water separation factor was about 10 for the best membrane. At the same temperature, the membrane displayed an ethanol/water flux of ca. 9 kg m−2 h−1 and an ethanol/water separation factor of ca. 5. A mathematical model indicated significant mass transfer resistance in the support, which reduced the flux and the selectivity of the membranes.

  • 87.
    Korelskiy, Danil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hedlund, Jonas
    Characterization of small defects in MFI membranes by permporometry, separation experiments and XHR-SEM2010Conference paper (Refereed)
  • 88.
    Korelskiy, Danil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Ye, Pengcheng
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Fouladvand, Shahpar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Karimi, Somayeh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Sjöberg, Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Efficient ceramic zeolite membranes for CO2/H2 separation2015In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2015, no 3, p. 12500-12506Article in journal (Refereed)
    Abstract [en]

    Membranes are considered one of the most promising technologies for CO2 separation from industrially important gas mixtures like synthesis gas or natural gas. In order for the membrane separation process to be efficient, membranes, in addition to being cost-effective, should be durable and possess high flux and sufficient selectivity. Current CO2-selective membranes are low flux polymeric membranes with limited chemical and thermal stability. In the present work, robust and high flux ceramic MFI zeolite membranes were prepared and evaluated for separation of CO2 from H2, a process of great importance to synthesis gas processing, in a broad temperature range of 235–310 K and at an industrially relevant feed pressure of 9 bar. The observed membrane separation performance in terms both selectivity and flux was superior to that previously reported for the state-of-the-art CO2-selective zeolite and polymeric membranes. Our initial cost estimate of the membrane modules showed that the present membranes were economically viable. We also showed that the ceramic zeolite membrane separation system would be much more compact than a system relying on polymeric membranes. Our findings therefore suggest that the developed high flux ceramic zeolite membranes have great potential for selective, cost-effective and sustainable removal of CO2 from synthesis gas.

  • 89.
    Korelskiy, Danil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Ye, Pengcheng
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Nabavi, Mohammad Sadegh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Selective blocking of grain boundary defects in high-flux zeolite membranes by cokin2017In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 16, p. 7295-7299Article in journal (Refereed)
    Abstract [en]

    Commercial application of zeolite membranes has been hindered by the challenge of preparing defect-free membranes. Herein, we report a facile method able to selectively plug grain boundary defects in high-flux MFI zeolite membranes by coking of iso-propanol at 350 °C. After modification, the permeance via defects was reduced by 70%, whereas that via zeolite pores was reduced by only 10%.

  • 90.
    Korelskiy, Danil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Ye, Pengcheng
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Zhou, Han
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    An experimental study of micropore defects in MFI membranes2014In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 186, p. 194-200Article in journal (Refereed)
    Abstract [en]

    In the present work, two ultra-thin MFI membranes, prepared using hydroxide and fluoride ions as mineralizing agents, respectively, were carefully examined by permporometry. The amount of micropore defects, as determined by permporometry, differed significantly between the two different membranes. For the first time, it was demonstrated that the micropore defects determined by permporometry were most likely open grain boundaries. The results were verified by direct observation of the open grain boundaries by a state-of-the-art XHR-scanning electron microscopy instrument. In addition, the permporometry data were also consistent with permeation data using 1,3,5-trimethylbenzene (TMB) as a probe molecule, separation data using an equimolar mixture of n-hexane and TMB, and nitrogen adsorption data.

  • 91.
    Korelskiy, Danil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Ye, Pengcheng
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Zhou, Han
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Correction: An experimental study of micropore defects in MFI membranes2014In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 197, p. 358-Article in journal (Refereed)
    Abstract [en]

    In the present work, two ultra-thin MFI membranes, prepared using hydroxide and fluoride ions as mineralizing agents, respectively, were carefully examined by permporometry. The amount of micropore defects, as determined by permporometry, differed significantly between the two different membranes. For the first time, it was demonstrated that the micropore defects determined by permporometry were most likely open grain boundaries. The results were verified by direct observation of the open grain boundaries by a state-of-the-art XHR-scanning electron microscopy instrument. In addition, the permporometry data were also consistent with permeation data using 1,3,5-trimethylbenzene (TMB) as a probe molecule, separation data using an equimolar mixture of n-hexane and TMB, and nitrogen adsorption data

  • 92.
    Korelskiy, Danil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Ye, Pengcheng
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Zhou, Han
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Reprint of: An experimental study of micropore defects in MFI membranes2014In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 192, p. 69-75Article in journal (Refereed)
    Abstract [en]

    In the present work, two ultra-thin MFI membranes, prepared using hydroxide and fluoride ions as mineralizing agents, respectively, were carefully examined by permporometry. The amount of micropore defects, as determined by permporometry, differed significantly between the two different membranes. For the first time, it was demonstrated that the micropore defects determined by permporometry were most likely open grain boundaries. The results were verified by direct observation of the open grain boundaries by a state-of-the-art XHR-scanning electron microscopy instrument. In addition, the permporometry data were also consistent with permeation data using 1,3,5-trimethylbenzene (TMB) as a probe molecule, separation data using an equimolar mixture of n-hexane and TMB, and nitrogen adsorption data

  • 93.
    Korelskiy, Danil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Zhou, Han
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    An experimental study of micropore defects in MFI membranes2013Conference paper (Refereed)
  • 94.
    Lassinantti, Magdalena
    et al.
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sterte, Johan
    Effects of synthetsis parameters on intra-pore zeolite formation in a zeolite A membrane2001In: Zeolites and mesoporous materials at the dawn of the 21st century: proceedings of the 13th Internationa Zeolite Conference, Amsterdam: Elsevier, 2001, p. 292-Conference paper (Refereed)
  • 95.
    Lassinantti, Magdalena
    et al.
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sterte, Johan
    Faujasite-type films synthesized by seeding2000In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 38, no 1, p. 25-34Article in journal (Refereed)
    Abstract [en]

    Thin and continuous Faujasite-type films were synthesized on α-alumina wafers using a seeding technique. Surface modified wafers were seeded with colloidal zeolite Y crystals prior to film growth in a synthesis mixture. The effects of hydrothermal treatment on film thickness, morphology and preferred orientation of the crystals constituting the film were investigated using scanning electron microscopy and X-ray diffraction. During hydrothermal treatment a precipitate formed rapidly, leaving an almost clear solution in the upper part of the reactor. Experiments at 60–100°C were performed with the sample placed in the upper part of the synthesis solution. An increase in the film growth rate with increasing temperature was observed. Adsorbed seeds were shown to be oriented with the {1 1 1} pyramid, parallel to the substrate surface. A change in the orientation with film growth was noted, probably due to the attachment of secondary crystals to the growing film surface. In one experimental series, film growth was effected at the bottom of the tube at 100°C. Faster film growth and multilayered films were obtained. A decrease in the film thickness after prolonged hydrothermal treatment was observed in all experimental series. This is probably due to the dissolution of the film and formation of zeolite P in the synthesis solution. The thicknesses of the films synthesized in this work are in the range of 150–2700 nm. The films are promising candidates for use in membrane applications.

  • 96.
    Lassinantti, Magdalena
    et al.
    Luleå University of Technology.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sterte, Johan
    Synthesis of thin zeolite Y films on polished α-alumina wafers using a seeding technique1999In: Porous materials in environmentally friendly processes: proceedings of the 1st International FEZA Conference / [ed] I. Kiricsi, Amsterdam: Elsevier, 1999, p. 181-187Conference paper (Refereed)
    Abstract [en]

    Zeolite Y films were synthesized on polished α-alumina wafers by using a seeding technique which includes surface modification, seed adsorption and growth of the seed crystals into a dense film. The film thickness was found to be a linear function of synthesis duration up to a certain point. Further treatment reduced the film thickness. Continuous and crack free films with thicknesses in the range 210 to 2670 nm were synthesized in this work.

  • 97.
    Lassinantti, Magdalena
    et al.
    Luleå tekniska universitet.
    Jareman, Fredrik
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Creaser, Derek
    Luleå tekniska universitet.
    Sterte, Johan
    Preparation and evaluation of thin ZSM-5 membranes synthesized in the absence of organic template molecules2001In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 67, no 1-3, p. 109-119Article in journal (Refereed)
    Abstract [en]

    Porous α-alumina supports with a pore size of 100 nm were seeded with colloidal TPA-silicalite-1 crystals with a size of 120 nm. The seeded supports were calcined and treated in a synthesis solution free from organic template molecules to form ZSM-5 films on the supports. According to SEM images, the films were about 2 μm thick and no defects could be found on the as-synthesized membranes. Single gas permeation data was collected and good quality membranes (defined as having a non-detectable permeance of SF6 after drying at 100°C) were further evaluated using binary/ternary gas mixtures. The selectivity for n-butane/i-butane had a maximum value of 17.8 at 220°C. Water was selectively separated from a helium-diluted vaporized water/ethanol azeotrope with a maximum selectivity of 12.4.

  • 98.
    Lassinantti-Gualtieri, Magdalena
    et al.
    Luleå tekniska universitet.
    Alessandro, Gualtieri
    Dipartimento di Scienze della Terra, Universita di Modena e Reggio Emilia.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Jareman, Fredrik
    Luleå tekniska universitet.
    Sterte, Johan
    Dapiaggi, M.
    Dipartimento di Scienze della Terra, Università di Milano.
    Accurate measurement of the thermal expansion of MFI zeolite membranes by in situ HTXRPD2004In: Recent advances in the science and technology of zeolites and related materials. Part A: proceedings of the 14th International Zeolite Conference, Amsterdam: Elsevier, 2004, p. 703-709Conference paper (Refereed)
    Abstract [en]

    Template removal by calcination of MFI type membranes is often accompanied by crack formation. The thermal behavior of MFI type membranes, synthesized with and without masking, was studied to understand the mechanism. Masking prevents growth of zeolite in the interior of the Support during membrane synthesis. Rietveld refinements of powder diffraction data collected in situ at high temperature allowed to accurately determine the change in thermal expansion of the MFI film and the porous alpha-alumina support. During heating, a relatively large contraction of the cell volume during template removal occurred in the zeolite powder and in the film of the membrane prepared with masking. The much smaller decrease in the non-masked sample indicates that this membrane is under stress during heating and as a consequence, cracks are formed. The stress imposed in the membrane prepared without masking may be due to the opposite thermal behavior of the Substrate in combination with strong bonds between the membrane and the support.

  • 99.
    Leppäjärvi, Tiina
    et al.
    Department of Process and Environmental Engineering, University of Oulu.
    Malinen, Ilkka
    Department of Process and Environmental Engineering, University of Oulu.
    Korelskiy, Danil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Tanskanen, Juha
    Oulu University.
    Maxwell-Stefan Modeling of Ethanol and Water Unary Pervaporation Through a High-silica MFI Zeolite Membrane2014In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 53, no 1, p. 323-332Article in journal (Refereed)
    Abstract [en]

    The pervaporative mass transfer of pure ethanol and water through a thin (0.5 mu m) supported high-silica MFI membrane was studied experimentally at 30-70 degrees C, and modeled on the basis of the Maxwell-Stefan formalism. The temperature dependency of adsorption was described with the temperature dependency of pure component saturated vapor pressure. Two scenarios of coverage dependency, i.e., coverage-dependent and coverage-independent Maxwell-Stefan diffusivity, were applied in the modeling of the mass transfer through the zeolite film. In addition, the mass-transfer resistance of the support layers was taken into account. The derived unary models provided good representations of ethanol and water pervaporation flux. The study illustrates that pure component steady-state pervaporation flux measurements at different conditions offer a feasible basis for determining diffusion coefficients. Basically, pure component adsorption isotherms and derived diffusivities can be used in the modeling of pervaporative mass transfer of mixtures using zeolite membranes

  • 100.
    Leppäjärvi, Tiina
    et al.
    Department of Process and Environmental Engineering, University of Oulu.
    Malinen, Ilkka
    Department of Process and Environmental Engineering, University of Oulu, University of Oulu.
    Korelskiy, Danil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Kangas, Jani
    University of Oulu.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Tanskanen, Juha
    Department of Process and Environmental Engineering, University of Oulu.
    Pervaporation of Ethanol/Water Mixtures through a High-silica MFI Membrane: Comparison of Different Semi-empirical Mass Transfer Models2015In: Periodica Polytechnica. Chemical Engineering, ISSN 0324-5853, Vol. 59, no 2, p. 111-123Article in journal (Refereed)
    Abstract [en]

    Pervaporation of binary ethanol/water solutions of 5-10 wt.% ethanol was studied experimentally through a thin supported high-silica MFI zeolite membrane of hydrophobic character in the temperature range of 30-70 degrees C. The fluxes obtained were very high, 2-14 kg m(-2)h(-1) with ethanol/water separation factors of 4-7. The loss of effective driving force was significant in the supporting layers, which limited the membrane performance. The correlation between the experimental data and three different semi-empirical mass-transfer models was examined The correlation was good especially when the driving force for mass-transfer was determined based solely on bulk feed, or the bulk feed and permeate conditions together Somewhat lower correlation was observed when the driving force was corrected with the effect of support resistance. This was most likely due to the inaccuracies of the used mass transfer parameters in the support. The investigated semi-empirical models can be applied for initial stage process design purposes.

1234 51 - 100 of 200
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf