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  • 301.
    Kasedde, Hillary
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi. Makerere University, Kampala, Uganda.
    Lwanyaga, Joseph
    Kirabira, John Baptist
    Bäbler, Matthäus
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Optimization of Solar Energy for Salt Extraction from Lake Katwe, Uganda2014Inngår i: Global NEST. International Journal, ISSN 1108-4006, Vol. 16, nr 6, s. 1152-1168Artikkel i tidsskrift (Fagfellevurdert)
  • 302. Khan, Z.
    et al.
    Yusup, S.
    Kamble, P.
    Naqvi, Muhammad
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Watson, I.
    Assessment of energy flows and energy efficiencies in integrated catalytic adsorption steam gasification for hydrogen production2018Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 225, s. 346-355Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study addresses the energy flows and energy efficiency of integrated catalytic adsorption biomass steam gasification for hydrogen production in a pilot scale bubbling fluidized bed system utilizing palm kernel shell as feedstock. The integrated catalytic adsorption utilizes catalyst and CO2 adsorbent together in the single fluidized bed gasifier. Various variables such as effect of temperature (600–750 °C), steam to biomass ratio (1.5–2.5 w/w), adsorbent to biomass ratio (0.5–1.5 w/w), fluidization velocity (0.15–0.26 m/s) and biomass particle size (0.355–0.500 to 1.0–2.0 mm) are investigated. The results imply that the overall requirement of gasification energy increases with increasing gasification temperature, steam to biomass ratio, fluidization velocity, and decreases with adsorbent to biomass ratio whilst no significant increase is observed by varying the biomass particle size. However, a slight reduction in required energy is observed from 600 °C to 675 °C which might be due to strong CO2 adsorption, an exothermic reaction, and contributes to the energy requirements of the process. Besides, hydrogen-based energy efficiencies increase with increasing temperature while first increases to a medium value of steam to biomass ratio (2.0), adsorbent to biomass ratio (1.0) and fluidization velocity (0.21 m/s) followed by a slight decrease (or remains unchanged). The integrated catalytic adsorption steam gasification is found to be a high energy consuming process and thus, waste heat integration needs to be implemented for feasible hydrogen production

  • 303. Khattab, Ibrahim A.
    et al.
    Ghaly, Montaser Y.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ali, Mohamed E. M.
    Farah, Joseph Y.
    Zaher, Fatama M.
    Badawy, Mohamed I.
    Photocatalytic degradation of azo dye Reactive Red 15 over synthesized titanium and zinc oxides photocatalysts: a comparative study2012Inngår i: Desalination and Water Treatment, ISSN 1944-3994, E-ISSN 1944-3986, Vol. 48, nr 1-3, s. 120-129Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanoparticle TiO2 and ZnO were prepared by facile method. The XRD pattern study shows that there is no obvious difference in crystal composition of various shapes of TiO2 and ZnO. The photocatalytic degradation of Reactive Red 15, commonly used as a textile dye, using synthesized titanium and zinc oxides was investigated. The effects of influential parameters such as initial pH, catalyst loading, initial dye concentration and addition of hydrogen peroxide were studied. The degradation efficiency was expressed by the removal of color and chemical oxygen demand (COD). The study reveals that: (1) Both catalysts, under corresponding optimal conditions, can be employed as an effective photocatalyst for the elimination of color and COD from dye wastewater. Also, ZnO is more efficient catalyst than TiO2; (2) Addition of proper amount of hydrogen peroxide improves both the decolorization and the degradation of the dye; (3) The photocatalytic degradation of Reactive Red 15, in the presence of both photocatalysts, obeyed pseudo-first order kinetics. The biodegradability ratio BOD5/COD increases from original zero up to 0.52 and 0.6 within 90 minutes irradiation time using 1 and 0.75 g/L TiO2 and ZnO, respectively.

  • 304.
    Kirabira, John Baptist
    et al.
    Makerere University.
    Kasedde, Hillary
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mekanisk metallografi. Makerere University.
    Ssemukuuttu, Dominic
    Makerere University.
    Towards the improvement of salt extraction at Lake Katwe, Uganda2013Inngår i: International Journal of Scientific and Technology Research, ISSN 2277-8616, Vol. 2, nr 1, s. 76-81Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The occurrence of Lake Katwe salt deposit in Western Uganda is well-known through the East African region. Production of salt from this saline lake has been practiced for decades following traditional methods; however the quality and yield of the products are poor. There are also risks of burns, as the workers get into direct contact with the brine. Detail assessment and evaluation of the mine has been done through field studies, raw sample materials analysis. Results indicate that the raw brine from the lake is rich in sodium, chloride, potassium, carbonates, sulphate ions with traces of calcium, magnesium, and bicarbonate ions. This motivates the aspiration to properly extract salts from such a rich source. The lake brines contain impurities such as organic matter and suspended solids. With increasing demand for usage of sustainable technologies for saltextraction, the present study calls for the improvement of salt extraction at Lake Katwe through optimizing the use of the current solar evaporation technique while integrating it with a mechanized chemical separation process. This would ensure better recovery and process efficiencies, low costs and simple brine pre-treatment procedures.

  • 305.
    Kirm, Ilham
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Sanati, Mehri
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Shift catalysts in biomass generated synthesis gas2006Inngår i: 12th Nordic Symposium in Catalysis-May 28-30-Trondheim-Norway, NTNU , 2006, s. 144-145Konferansepaper (Annet vitenskapelig)
  • 306.
    Ko, Jordan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Zahrai, Said
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Vomhoff, Hannes
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Literature review of the numerical studies on transport phenomena in hydrocyclones.Manuskript (preprint) (Annet vitenskapelig)
  • 307. Kocík, Jaroslav
    et al.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bourajoini, Hasna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Pham, Tung Ngoc
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Faculty of Science and Engineering, Industrial Chemistry & Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Hájek, Martin
    Čapek, Libor
    Screening of active solid catalysts for esterification of tall oil fatty acids with methanol2017Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 155, nr 1, s. 34-38Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The paper is focused on the description of the activity/selectivity of mesoporous silica based materials loaded with various types of active species in the esterification of tall oil free fatty acids. The metals such as aluminium, molybdenum, gallium and zinc, including their combinations were impregnated on the mesoporous silica, which was tested in esterification reaction. All these catalysts preserved its tall oil free fatty conversion in the first and the second catalytic cycles. However, while only insignificant amount of gallium or molybdenum was lost from the solid catalyst into the liquid phases, zinc leached from every studied solid catalyst. In contrast to impregnated gallium on mesoporous silica, which exhibited higher acidity and higher tall oil free fatty acids conversion in the first catalytic cycle, but its value was not preserved in the second catalytic test.

  • 308.
    KOLAKOWSKI, MARCIN JANUSZ
    KTH, Skolan för kemivetenskap (CHE).
    CFD simulation of fluid flow in milliliter vials used for crystal nucleation experiments2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This work investigates the fluid flow in a cylindrical millilitre vial stirred by a magnetic stirred bar using Computational Fluid Dynamic (CFD). Stirred millilitre vials are used to study nucleation phenomena and crystallization as an outline of literature study of nucleation and crystallization phenomena and the role of stirring in this process. The baffle free vial was meshed with around 500,000 cells. To simulate the stirring a rotary frame and moving walls were used. Stirring speeds were between 100 and 1000 rpm where considered, correspondently to a stirrer Reynolds number between 260 and 2600. For stirring speeds bellow 500 rpm, simulations by both the both laminar flow model and the k-ε model where run, while above 500 rpm only k-ε was used. Results of the two models were very similar indicative the adequacy of k-ε to simulate the flow even at low Reynolds. The flow shows expected circulation pattern with upwards pumping close to side walls and downwards pumping in the centre of cylindrical vial. At 1000 rpm circulation patterns expands up to the top of the vial while at 300 rpm and lower the upper half of the vial is poorly mixed. The average turbulent energy of the flow is very low comparing with the squared stirrer tip speed and the power number decrees with Reynolds number, indicating that the flow is not fully turbulent.

  • 309.
    Korelskiy, Danil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Development of permporometry for analysis of MFI membranes2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Zeolite membranes exhibiting high flux and high selectivity are of major interest for potential future applications. In order to achieve high flux and high selectivity, the zeolite film must be thin (< 1 µm) and free from flow-through defects. The development of thin defect free zeolite membranes requires powerful tools for characterization of flow-through defects in the membranes. Permporometry is one of the most straightforward and powerful techniques for characterization of flow-through pores in ceramic membranes. In permporometry, the flow of a non-condensable gas, e.g., helium, through the membrane is monitored as a function of the activity of a strongly adsorbing compound, e.g., hydrocarbon.In the present work, MFI membranes prepared by a seeding method were characterized by permporometry using helium as the non-condensable gas and n-hexane or benzene as the adsorbing compound. In order to appreciate permporometry data, the membranes were also characterized by scanning electron microscopy (SEM), single gas permeation and separation experiments. The permporometry data were then compared to the SEM morphology of the membranes, permeances of different probe molecules and membrane separation performance.In order to determine the conditions of the permporometry experiment leading to blocking of zeolite pores, a model describing helium transport in the zeolite pores in the presence of n-hexane or benzene was developed. The model is based on percolation theory and knowledge of the adsorption isotherms and adsorption sites for n-hexane and benzene in the zeolite pores. Parameters needed in the model were estimated by Density Functional Theory (DFT) using a Local-Density Approximation (LDA), the most sophisticated theory yet applied to this system. Based on the permporometry data, it was demonstrated that the model could adequately describe helium transport in zeolite pores in the presence of the hydrocarbons.The sensitivity of the permporometry technique towards the defect size has been improved considerably. It was revealed that high quality MFI membranes prepared in the present work contained mainly micropore defects which are most like the defects in the zeolite crystal lattice (intracrystalline defects).The work has shown how permporometry data could be used to estimate the area distribution of the flow-through defects in the membranes. The results on the defect distribution were corroborated by the SEM observations and the separation experiments. The width of cracks, including support cracks, and open grain boundaries observed by SEM was in excellent agreement with the defect width estimated from permporometry data. A straightforward correlation was observed between separation data and permporometry data, i.e. membranes of higher quality according to permporometry analysis exhibited greater separation performance. Also, the permeance of molecules diffusing through defects in the membrane in the separation experiment was found to scale with the permeance of helium through the defects measured in the permporometry experiment. In addition, this work showed that single gas permeance ratios could not detect slight variations in the membrane quality. For membranes with similar however slightly different amount of defects, the ratios are mainly affected by the membrane thickness and support morphology.To summarise, the present work demonstrates that permporometry data adequately reflect membrane quality and that permporometry is a very powerful technique for MFI membrane characterization.

  • 310.
    Korelskiy, Danil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Quality and performance of zeolite membranes2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Zeolite membranes displaying high flux and high selectivity are of major interest for potential industrial applications, such as gas and liquid separations. In order to achieve high flux and high selectivity, the zeolite membrane must be thin (< 1 µm) and free from flow-through defects. The development of thin defect-free zeolite membranes requires powerful tools for characterisation of the defects in the membranes. Permporometry is one of the most straightforward, non-destructive and powerful techniques for characterisation of flow-through pores in inorganic membranes. In permporometry, the flow of a non-adsorbing gas, e.g., helium, through the membrane is monitored as a function of the activity of a strongly adsorbing compound, e.g., hydrocarbon.The work showed how permporometry can be used to quantify defects in the mesopore range in MFI membranes. The results were in excellent agreement with SEM observations and separation experiments. For the first time, it was also shown that flow-through defects down to 0.7 nm in size in MFI membranes could be detected by permporometry and quantified using the permporometry data. The total amount of defects in high quality MFI membranes was found to be small accounting for less than 1% of the total membrane area. In turn, defects with a width below 1 nm constituted as much as 97% of the total area of defects for the best membranes. The permporometry results were consistent with SEM observations and separation experiments, demonstrating that permporometry data adequately reflect membrane quality and that the technique is a very powerful and reliable characterisation tool.This work also illustrated that single gas permeance ratios could not detect slight variations in the membrane quality. For membranes with similar however slightly different amount of defects, the ratios are mainly affected by the membrane thickness and support morphology.The MFI membranes were also evaluated for separation of dilute aqueous solutions of n-butanol and ethanol, and 1 µm zeolite X membranes were evaluated for separation of water from ethanol using pervaporation. The MFI membranes were selective to n-butanol and ethanol, whereas zeolite X membranes were selective to water. The flux observed for the MFI membranes was about 100 times higher than those previously reported for n-butanol/water and about 5 times higher than the highest reported for ethanol/water separation by pervaporation. The zeolite X membranes showed good pervaporation performance in terms of both flux and selectivity. However, both flux and selectivity were found to be reduced by a significant mass transfer resistance in the support in all the pervaporation experiments. At the same time, heat transfer limitations were found to be negligible.

  • 311.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Characterization of flow-through micropores in MFI membranes by permporometry2012Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 417-418, s. 183-192Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 312.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ye, Pengcheng
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Zhou, Ming
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    A study of CO2/CO separation by sub-micron b-oriented MFI membranes2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 70, s. 65475-65482Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 313.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Leppäjärvi, Tiina
    Department of Process and Environmental Engineering, University of Oulu.
    Zhou, Han
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Tanskanen, Juha
    Department of Process and Environmental Engineering, University of Oulu.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    High flux MFI membranes for pervaporation2013Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 427, s. 381-389Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 314.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Hedlund, Jonas
    Characterization of small defects in MFI membranes by permporometry, separation experiments and XHR-SEM2010Konferansepaper (Fagfellevurdert)
  • 315.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ye, Pengcheng
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Fouladvand, Shahpar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Karimi, Somayeh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Sjöberg, Erik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Efficient ceramic zeolite membranes for CO2/H2 separation2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2015, nr 3, s. 12500-12506Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 316.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ye, Pengcheng
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Nabavi, Mohammad Sadegh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Selective blocking of grain boundary defects in high-flux zeolite membranes by cokin2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 16, s. 7295-7299Artikkel i tidsskrift (Fagfellevurdert)
    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%.

  • 317.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ye, Pengcheng
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Zhou, Han
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    An experimental study of micropore defects in MFI membranes2014Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 186, s. 194-200Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 318.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ye, Pengcheng
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Zhou, Han
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Correction: An experimental study of micropore defects in MFI membranes2014Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 197, s. 358-Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 319.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ye, Pengcheng
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Zhou, Han
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Reprint of: An experimental study of micropore defects in MFI membranes2014Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 192, s. 69-75Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 320.
    Korelskiy, Danil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Zhou, Han
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    An experimental study of micropore defects in MFI membranes2013Konferansepaper (Fagfellevurdert)
  • 321.
    Kornmann, Xavier
    et al.
    Luleå tekniska universitet.
    Berglund, Lars A.
    Luleå tekniska universitet.
    Sterte, Johan
    Giannelis, E.P.
    Department of Materials Science and Engineering, Cornell University Ithaca.
    Nanocomposites based on montmorillonite and unsaturated polyester1998Inngår i: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 38, nr 8, s. 1351-1358Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The concept of nanoscale reinforcement provides opportunity for synthesis of new polymer materials with unique properties. Montmorilonite (MMT) was derived from bentonite, purified, activated by sodium ions and mixed with reacting unsaturated polyester (UP). X-ray and transmission electron microscopy data were in support of the formation of a partially delaminated nanocomposite material. At an MMT content of only 1.5 vol%, the fracture energy, GQ of the nanocomposite was doubled, 138 J/m2 as compared with 70 J/m2 for the pure UP.

  • 322.
    Koroidov, Sergey
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Anderlund, Magnus F
    Styring, Stenbjörn
    Thapper, Anders
    Messinger, Johannes
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    First turnover analysis of water-oxidation catalyzed by Co-oxide nanoparticles2015Inngår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 8, nr 8, s. 2492-2503Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Co-oxides are promising water oxidation catalysts for artificial photosynthesis devices. Presently, several different proposals exist for how they catalyze O-2 formation from water. Knowledge about this process at molecular detail will be required for their further improvement. Here we present time-resolved O-18-labelling isotope-ratio membrane-inlet mass spectrometry (MIMS) experiments to study the mechanism of water oxidation in Co/methylenediphosphonate (Co/M2P) oxide nanoparticles using [Ru(bpy)(3)](3+) (bpy = 2,2'-bipyridine) as chemical oxidant. We show that O-16-Co/M2P-oxide nanoparticles produce O-16(2) during their first turnover after simultaneous addition of (H2O)-O-18 and [Ru(bpy)(3)](3+), while sequential addition with a delay of 3 s yields oxygen reflecting bulk water O-18-enrichment. This result is interpreted to show that the O-O bond formation in Co/M2P-oxide nanoparticles occurs via intramolecular oxygen coupling between two terminal Co-OHn ligands that are readily exchangeable with bulk water in the resting state of the catalyst. Importantly, our data allow the determination of the number of catalytic sites within this amorphous nanoparticular material, to calculate the TOF per catalytic site and to derive the number of holes needed for the production of the first O-2 molecule per catalytic site. We propose that the mechanism of O-O bond formation during bulk catalysis in amorphous Co-oxides may differ from that taking place at the surface of crystalline materials.

  • 323. Kumar, N.
    et al.
    Shojaee, Maryam
    KTH, Skolan för kemivetenskap (CHE).
    Spivey, J.J.
    Catalytic bi-reforming of methane: From greenhouse gases to syngas2015Inngår i: Current Opinion in Chemical Engineering, ISSN 2211-3398, Vol. 9, s. 8-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The bi-reforming reaction to produce syngas from CH<inf>4</inf> and CO<inf>2</inf> offers significant advantages over dry reforming and oxy-CO<inf>2</inf> with respect to catalyst deactivation by carbonization. This approach has potential for powerful new alternatives and is entering the stage of increasing advanced research toward commercialization of the technology. Research is ongoing to develop catalysts that are resistant to high temperatures and the presence of a more oxidative environment due to steam. All current research on bi-reforming catalysis is focused on Ni-based catalysts, a logical extension based on commercial materials on steam/methane reforming and dry reforming. However, recent work on thermally stable crystalline oxides has promise, particularly in resisting carbon deposition while remaining stable at the demanding conditions of bi-reforming.

  • 324.
    Kyprianidis, Konstantinos
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Skvaril, JanMälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Developments in Near-Infrared Spectroscopy2017Collection/Antologi (Fagfellevurdert)
    Abstract [en]

    Over the past few decades, exciting developments have taken place in the field of near-infrared spectroscopy (NIRS). This has been enabled by the advent of robust Fourier transform interferometers and diode array solutions, coupled with complex chemometric methods that can easily be executed using modern microprocessors. The present edited volume intends to cover recent developments in NIRS and provide a broad perspective of some of the challenges that characterize the field. The volume comprises six chapters overall and covers several sectors. The target audience for this book includes engineers, practitioners, and researchers involved in NIRS system design and utilization in different applications. We believe that they will greatly benefit from the timely and accurate information provided in this work.

  • 325.
    Lai, Kwok Kei
    et al.
    Hong Kong University of Science and Technology, Clear Water Bay, P. R. China .
    Renneberg, Reinhard
    Hong Kong University of Science and Technology, Clear Water Bay, P. R. China .
    Mak, Wing Cheung
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biosensorer och bioelektronik. Linköpings universitet, Tekniska fakulteten.
    High efficiency single-step biomaterial-based microparticle fabrication via template-directed supramolecular coordination chemistry2016Inngår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 18, nr 6, s. 1715-1723Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biomaterial-based microparticles have attracted much attention for medical and biological applications such as pharmaceutics, bioseparation and cosmetics. Emerging technologies enable versatile and facile fabrication of microparticles, with key features being purity, precise size control, mild preparation conditions and minimal processing. Here, an innovative approach combining template synthesis, biomolecule assembly and partial-purification within a single step for high efficiency fabrication of pure biomaterial-based microparticles is reported. This concept is based on facile co-precipitation of biomolecules within CaCO3 templates and simultaneous crosslinking of entrapped biomolecules via Ca2+ driven supramolecular coordination chemistry, followed by template removal. Carbohydrate (alginate) and proteins (casein and fresh milk) are used as models of biomolecules. The process driven by selective crosslinking automatically excludes non-specific materials from the template and thus provides the additional function of partial-purification, as demonstrated using highly complexed fresh milk. This green approach to fabrication of biomaterial-based microparticles offers three critical advantages (i) mild conditions to preserve the chemical and secondary structures of biomolecules; (ii) single processing step to facilitate scale-up production; and (iii) partial-purification without the need for upstream raw material purification. This innovative approach not only addresses fundamental issues in fabrication techniques, but also marks progress in energy and environmental conservation during manufacturing processes.

  • 326.
    Lantto, Jonas
    KTH, Skolan för kemivetenskap (CHE).
    Analytical model of mass transfer through supported liquid membranes2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This report details the development and validation of a model for the simulation of supported liquid membrane processes, as applied to the extraction of lanthanides. Supported liquid membranes are systems where two phases, usually aqueous, are separated by a third phase, typically organic, which acts as a membrane, in order to separate solutes from one phase to the other. The model employs an analytical solution to the diffusion equation for the organic phase and linear approximations of the resistances to mass transfer in the aqueous phase boundary layers. The goal of this model is to underline the importance of taking these boundary layer resistances into account.

     

  • 327.
    Lanza, Roberto
    et al.
    Università di Padova.
    Canu, Paolo
    Universita` di Padova, Dipartimento di Principi e Impianti di Ingegneria Chimica.
    Dalle Nogare, Daniela
    Universita` di Padova, Dipartimento di Principi e Impianti di Ingegneria Chimica.
    Gas Phase Chemistry in Cellulose Fast Pyrolysis2009Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 48, nr 3, s. 1391-1399Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We experimentally and theoretically studied cellulose pyrolysis at high temperature and short residence time. We investigated the gas phase chemistry with dedicated experiments and feeding intermediates. Results have been also compared with equilibrium calculations, both single (gas) phase and allowing for solid C formation. Our aim was to understand the cellulose degradation mechanism and particularly the role of gas phase chemistry. We provided evidence of a simplified mechanism, where CO formation is a first, fast step that can be related to levoglucosan ring opening, while H(2) comes from a totally different route, based on hydrocarbon reforming reactions, which also provide further CO. In addition, butadiene was identified as a key intermediate in the decomposition sequence. The different paths and rates of CO formation and H2 formation explain why the ratio of CO to H(2) is not constant, particularly at short residence time. A two-stage process or longer contact time is required, if aiming at syngas production.

  • 328.
    Lanza, Roberto
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Velasco, Jorge
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Recent developments and achievements in partial oxidation of methane with and without addition of steam2011Inngår i: Catalysis / [ed] James J. Spivey, Royal Society of Chemistry, 2011, 23, s. 50-95Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The latest works on catalytic partial oxidation of methane (CPO) have beenconsidered and reviewed to give an updated frame of the state of the art inthis topic. Papers published since 2008 have been considered, dealing withthe process both without and with addition of steam. Particular attentionwas dedicated to Ni and Rh, that are the most used metals. The mechanismfollowed by the reaction was also considered as well as new and promisingtechnologies such as SOFCs, membrane reactors and plasma systems.

  • 329.
    Larsson, Ann-Charlotte
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Einvall, Jessica
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Andersson, Arne
    Lund University.
    Sanati, Mehri
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Physical and chemical characterisation of potassium deactivation of a SCR catalyst for biomass combustion2007Inngår i: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 45, nr 1-4, s. 149-152Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The deactivation of a commercial Selective Catalytic Reduction (SCR) catalyst, of V2O5-WO3/TiO2 type, has been studied through comparisons with results from a full-scale biomass combustion plant to that with laboratory experiments. In the latter, the catalyst was exposed to KCl and K2SO4 by both wet impregnation with diluted salt solutions and deposition of generated submicrometer aerosol particles by means of an electrostatic field. The reactivity of fresh and deactivated samples was examined in the SCR reaction. Chemical and physical characterizations were focusing on internal structures and chemical composition. Deposition of submicrometer sized particles on the monolithic SCR catalyst was shown to induce deactivation with characteristics resembling those obtained in a commercial biomass combustion plant.

  • 330.
    Larsson, Ann-Charlotte
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Einvall, Jessica
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Andersson, Arne
    Lund University.
    Sanati, Mehri
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Targeting by Comparison with Laboratory Experiments the SCR Catalyst Deactivation Process by Potassium and Zinc Salts in a Large-Scale Biomass Combustion Boiler2006Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 20, nr 4, s. 1398-1405Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The deactivation of a commercial selective catalytic reduction (SCR) catalyst of type V2O5−WO3/TiO2 has been studied in this work through comparisons of results from a full-scale biomass combustion plant with those from laboratory experiments. In the latter, the catalyst was exposed to KCl, K2SO4, and ZnCl2 by both wet impregnation with diluted salt solutions and deposition of generated submicrometer aerosol particles by means of an electrostatic field. The reactivity of freshly prepared and deactivated catalyst samples was examined in the SCR reaction, for which the influence of the different salts and the method of exposure were explored. Chemical and physical characterizations of the catalyst samples were carried out focusing on surface area, pore volume, pore size, chemical composition, and the penetration profiles of potassium and zinc. Particle-deposition deactivation as well as commercially exposed catalyst samples were shown to impact surface area and catalyst activity similarly and to have penetration profiles with pronounced peaks. Salt impregnation influenced pore sizes and catalyst activity more strongly and showed flat penetration profiles. Deposition of submicrometer-sized particles on the monolithic SCR catalyst has been shown to induce deactivation of the catalyst with characteristics resembling those obtained in a commercial biomass combustion plant; the laboratory process can be used to further assess the deactivation mechanism by biomass combustion.

  • 331.
    Larsson, Ann-Charlotte
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Einvall, Jessica
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Sanati, Mehri
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Physical and Chemical Characterisation of Potassium Deactivation of an SCR Catalyst for Biomass Combustion2006Inngår i: 12th Nordic Symposium in Catalysis-May 28-30-Trondheim-Norway, 2006, s. 198-199Konferansepaper (Annet vitenskapelig)
  • 332.
    Larsson, Mårten
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Görling, Martin
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Alvfors, Per
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Bio-methane upgrading of pyrolysis gas from charcoal production2013Inngår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 3, s. 66-73Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article presents a novel route for bio-methane synthesis utilizing pyrolysis gas from charcoal production. It is a retrofit option that may increase overall process efficiency in charcoal production while adding a valuable product. The pyrolysis gas from charcoal production can be used for bio-methane production instead of burning, while the required heat for the charcoal production is supplied by additional biomass. The aim is to evaluate the energy efficiency of bio-methane upgrading from two types of charcoal plants, with and without recovery of liquid by-products (bio-oil). Aspen simulations and calculations of the energy and mass balances are used to analyse the system. The yield of bio-methane compared to the import of additional biomass is estimated to be 81% and 85% (biomass to bio-methane yield) for the syngas case and the pyrolysis vapour case, respectively. When the biomass necessary to produce the needed electricity (assuming ηel = 33%) is included, the yields amount to 65% and 73%. The results show that the suggested process is a competitive production route for methane from lignocellulosic biomass.

  • 333.
    Lassebro, Joakim
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Förstudie till rengöringsvalidering av produktionssystem för handdesinfektionsmedlet AHD 20002017Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [sv]

    Vid tillverkning av produkter avsedda för medicinalt bruk är det viktigt att minska mängden av korskontaminering som kan överföras från tillverkningen av en produkt till en annan. Genom att utföra en rengöringsvalidering utvärderar man rengöringsprocessens effektivitet och fastställer vad som behöver göras för att hålla sig inom de nivåer som krävs.

    I detta examensarbete planeras och genomförs en förstudie till en rengöringsvalidering av det produktionssystem där handdesinfektionsmedlet AHD 2000 tillverkas.

    Inledningsvis genomfördes en genomgång av produktionssystemet och ett antal så kallade kritiska punkter valdes ut. Dessa punkter är områden där rengöringsprocessens effektivitet bedöms kunna variera. För att mäta effektiviteten genomfördes tre olika tester: svabbtest, sköljtest och en visuell kontroll. För svabb- och sköljtestet analyserades provernas totala organiska innehåll (TOC) och dess förbrukning av kemiskt bundet syre (COD). Erhållna analysresultat jämfördes med beräknade gränsnivåer, dvs. nivåer som kan accepteras för de två testerna. Dessa gränsnivåer är beräknade baserat på en generell nivå som vanligtvis ligger på mellan 10-500 ppm av tillverkad batch. För den visuella kontrollen gjordes en fysisk inspektion för att bedöma synliga spår av produktrester.

    Resultatet för svabbtestet visade att alla provsvar vid respektive kritiska punkt låg under den beräknade gränsnivån vilket betyder att kriteriet för svabbtestet är uppnått. För sköljtestet hamnade provresultaten något över den beräknade gränsnivån men har trots det bedömts vara inom rimliga gränser. Vid den visuella kontrollen noterades inga synliga spår och detta kriterium var alltså uppfyllt.

    Slutsatsen är alltså att alla tre kriterier för validering av rengöringsprocessen är uppfyllda vilket betyder att rengöringsprocessen är tillräckligt effektiv för att avlägsna spår av tidigare tillverkad produkt.

  • 334.
    Lassinantti, Magdalena
    Luleå tekniska universitet.
    Synthesis, characterization and properties of zeolite films and membranes2001Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The work presented in this thesis was aimed to synthesize zeolite films in the absence of organic additives to avoid the potentially detrimental calcination procedure. Furthermore, the support surface was seeded with colloidal seed crystals prior to film growth. This technique has previously been used to prepare thin zeolite films. The films were characterized by Scanning electron microscopy (SEM), X-ray diffraction (XRD) and gas permeation experiments. Films of three different types of zeolites were synthesized in this work; FAU-type zeolite, ZSM-5 and zeolite NaA. The thickness of the FAU-type zeolite films could be controlled by varying the synthesis temperature and duration. However, a maximum film thickness was found. Prolonged hydrothermal treatment caused the film thickness to decrease due to the transformation of FAU into zeolite P. The adsorbed seeds were oriented with the <111> pyramid parallel to the surface of the support. During growth, the crystals constituting the films became randomly oriented. The ZSM-5 films were tested as membranes for the separation of butane isomers. The selectivity for n-butane/i-butane had a maximum value of 17.8 at 220°C. Furthermore, the ZSM-5 membranes were found to be catalytically active, converting ethanol into diethylether and ethylene. The growth of silicious species into the porous support during zeolite NaA membrane synthesis was examined. Higher temperatures of synthesis resulted in relatively more growth into the porous support compared to the film growth on top of the support. By using a multi-step synthesis procedure at low temperature, thicker films with less growth into the support could be prepared.

  • 335.
    Lassinantti, Magdalena
    et al.
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Sterte, Johan
    Effects of synthetsis parameters on intra-pore zeolite formation in a zeolite A membrane2001Inngår i: Zeolites and mesoporous materials at the dawn of the 21st century: proceedings of the 13th Internationa Zeolite Conference, Amsterdam: Elsevier, 2001, s. 292-Konferansepaper (Fagfellevurdert)
  • 336.
    Lassinantti, Magdalena
    et al.
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Sterte, Johan
    Faujasite-type films synthesized by seeding2000Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 38, nr 1, s. 25-34Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 337.
    Lassinantti, Magdalena
    et al.
    Luleå University of Technology.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Sterte, Johan
    Synthesis of thin zeolite Y films on polished α-alumina wafers using a seeding technique1999Inngår i: Porous materials in environmentally friendly processes: proceedings of the 1st International FEZA Conference / [ed] I. Kiricsi, Amsterdam: Elsevier, 1999, s. 181-187Konferansepaper (Fagfellevurdert)
    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.

  • 338.
    Lassinantti, Magdalena
    et al.
    Luleå tekniska universitet.
    Jareman, Fredrik
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Creaser, Derek
    Luleå tekniska universitet.
    Sterte, Johan
    Preparation and evaluation of thin ZSM-5 membranes synthesized in the absence of organic template molecules2001Inngår i: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 67, nr 1-3, s. 109-119Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 339.
    Lassinantti-Gualtieri, Magdalena
    et al.
    Luleå tekniska universitet.
    Alessandro, Gualtieri
    Dipartimento di Scienze della Terra, Universita di Modena e Reggio Emilia.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    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 HTXRPD2004Inngår i: Recent advances in the science and technology of zeolites and related materials. Part A: proceedings of the 14th International Zeolite Conference, Amsterdam: Elsevier, 2004, s. 703-709Konferansepaper (Fagfellevurdert)
    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.

  • 340.
    Lefevr, Avlina
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Methods of Chemical and Physical Modification Used in Increasing Poor Solubility of Orally Administered Medications: -2014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Poor-water solubility of chemical compounds accounts for 40% and more of new medicalentities become discarded. Low solubility results in chemical substances cannot be deliveredto the target organ or cells, for that reasons there is a need to increase low water-solubilitywith various physical and chemical methods. In this paper we have examined various physicaland chemical methods of increasing poor solubility suggested in the pharmacological booksand journals and looked at how these methods can be practically used in increasing poorwater-solubility of four medications from the WHO Essential List of Medications. Thefindings of the paper are that several methods have shown good results for dissolution invivo: complexation with cyclodextrins and use of surfactants (physical methods), developmentprodrug (chemical methods). Improved medications provide a good solution for chronically illpatients who take high doses over a long period of time. Another benefit of improvedsolubility is lower cost of treatment, which is an important issue in poor regions of the world.

  • 341.
    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 tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Tanskanen, Juha
    Oulu University.
    Maxwell-Stefan Modeling of Ethanol and Water Unary Pervaporation Through a High-silica MFI Zeolite Membrane2014Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 53, nr 1, s. 323-332Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 342.
    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 tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Kangas, Jani
    University of Oulu.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    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 Models2015Inngår i: Periodica Polytechnica. Chemical Engineering, ISSN 0324-5853, Vol. 59, nr 2, s. 111-123Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 343. Li, Debing
    et al.
    Hu, Wei
    KTH, Skolan för bioteknologi (BIO).
    Zhang, Junqiao
    Shi, Hui
    Chen, Qu
    Sun, Tianyang
    Liang, Lijun
    Wang, Qian
    Separation of Hydrogen Gas from Coal Gas by Graphene Nanopores2015Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, nr 45, s. 25559-25565Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We designed a series of porous graphene as the separation membrane for hydrogen gas in coal gas. The permeation process of different gas molecules (H-2, CO, CH4, and H2S) in porous graphene was evaluated under the atmospheric pressure and high pressure conditions. Our results indicate the hydrogen permeability and selectivity could be tuned by the size and the shape of the porous graphene. For graphene with bigger pores, the selectivity for hydrogen gas could decrease. In the porous graphene with same pore area, the hydrogen gas selectivity could be affected by the shape of the pore. The potential of mean force (PMF) of different gases to pass through a good separation candidate was calculated. The order of PMF for different gases to pass through the good separation candidate is H-2 < CO < CH4 approximate to H2S, which is also confirmed by the first-principle density function theory (DFT) calculation.

  • 344. Li, Hongliang
    et al.
    Yu, Xinhai
    Tu, Shan-Tung
    Yan, Jinyue
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Wang, Zhengdong
    Catalytic performance and characterization of Al2O3-supported Pt-Co catalyst coatings for preferential CO oxidation in a micro-reactor2010Inngår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 387, nr 1-2, s. 215-223Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Platinum-cobalt (Pt-Co) catalyst coatings are studied for preferential oxidation of carbon monoxide (PROX) ill hydrogen-rich gas streams. Experimental results show a role for cobalt in improving catalytic activity. The most active catalyst coating can decrease carbon monoxide concentrations from 1% to a value of less than 10 ppm for GHSV values ranging from 40,000 to 120,000 ml g(-1) h(-1). This catalyst coating can work at a wide window of operation ill terms of temperature. Transmission electron microscopy, selected-area electron diffraction, and diffuse reflectance infrared Fourier transform spectroscopy show that the addition of Co forms Pt3Co intermetallic compounds and slightly increases the average particle size. In situ laser Raman spectroscopy reveals the co-existence of Co metal and its oxides on the catalyst surface, due to gradual oxidation of Co by gas phase oxygen within the initial stage of the PROX reaction. The promotional effect of Co during PROX is confirmed and ascribed to this Pt3Co intermetallic compound and the synergetic effect of Co-0 and Co chi+. The high accessibility of the reactant to Pt3Co species appears favorable and crucial for PROX.

  • 345.
    Li Jansson, Zheng
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Brännvall, Elisabet
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Effect of Kraft Cooking Conditions on the Chemical Composition of the Surface and Bulk of Spruce Fibers2014Inngår i: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, Vol. 34, nr 4, s. 291-300Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    By varying cooking temperature, alkali charge, ionic strength, and cooking time in Kraft pulping of spruce chips, pulps ranging between kappa numbers 20-80 were obtained. The unbleached Kraft pulp fibers were subjected to mechanical peeling in order to separate the surface material from the bulk of the fibers and the carbohydrate composition and lignin content of the two fractions were analyzed. As expected, the lignin and xylan contents were higher on the fiber surface than in the fiber wall. The percentage of xylan on the fiber surface was fairly constant, independent of different pulping conditions or degree of delignification. The lignin proportion on the fiber surface gradually decreased with decreasing kappa number. At a given kappa number, pulping at a higher temperature resulted in less lignin on the fiber surface, probably because of the higher solubility of lignin at higher temperature. Cooking at lower alkali charge also resulted in lower lignin content on the fiber surface at a given kappa number. In this case, there was more time available for degradation of the surface lignin since the lower alkali charge resulted in longer cooking time needed to reach a certain kappa number.

  • 346.
    Li Jansson, Zheng
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Brännvall, Elisabet
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Effect of kraft cooking conditions on the chemical composition ofthe surface and bulk of spruce fibers2011Manuskript (preprint) (Annet vitenskapelig)
  • 347.
    Li, Q.
    et al.
    Luleå tekniska universitet.
    Creaser, Derei
    Luleå tekniska universitet.
    Sterte, Johan
    Nucleation period for TPA-silicalite-1 crystallization determined by a two-stage varying-temperature synthesis1999Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 31, nr 1, s. 141-150Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A two-stage-varying-temperature synthesis procedure, which involves a rapid change in temperature at some point during the course of crystallization, was applied to the synthesis of discrete colloidal particles of TPA-silicalite-1. As the duration of the period at the initial synthesis temperature was extended, the crystal concentration and ultimate crystal size varied until they were approximately equal to those obtained for a complete synthesis at the initial temperature. At this point in the crystallization, it was concluded that the nucleation stage was completed. For syntheses performed at 60, 80 and 100°C, the duration of the nucleation period determined by this method was about 100 h, between 4 and 6 h and less than 2 h, respectively. Thus, nucleation, for this system, is a continuous process, and it was found that the rate of nucleation, which is initially high, declines, throughout the nucleation period. In all cases, nucleation occurred during an induction period when little or no crystal growth was observed, which explains why the syntheses yielded a product with a rather narrow crystal size distribution. If, for the two-stage syntheses, the temperature change was made after completion of the nucleation period, the second synthesis temperature controlled only the linear growth rate of the crystals and the final yield of silicalite-1 obtained

  • 348.
    Li, Qinghua
    Luleå tekniska universitet.
    Colloidal zeolites: from nucleation to zoned films by seeded growth2002Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The work presented in this thesis concerns the investigation of nucleation kinetics for colloidal zeolites, especially the determination of the nucleation period during crystallization. It also concerns the use of colloidal TPA-silicalite-1 for the preparation of zoned MFI films. A novel method, a two-stage varying-temperature procedure, involving starting a crystallization at a certain temperature, and then rapidly changing temperature at some point during the crystallization, was developed for the investigation of nucleation kinetics of colloidal zeolites. As the duration of the crystallization at the initial temperature was extended, the ultimate crystal size and crystal concentration varied until they were approximately equal to those obtained for a complete synthesis at the initial temperature. At this point, the nucleation stage during the crystallization was completed. For the synthesis of colloidal TPA-silicalite- 1, the nucleation process occurred over a substantial period of time, extending over the induction period, but was completed before crystal growth was detected, independent of aging time and silica source. For the synthesis of colloidal zeolite Y, the nucleation and crystal growth processes occurred simultaneously and the nucleation period was significantly longer than the induction period. The two-stage varying-temperature synthesis procedure was used to synthesize particularly small colloidal crystals of TPA-silicalite-1 with a high yield for short synthesis time. In addition, midsynthesis addition of sodium after the nucleation of zeolite Y produced pure colloidal zeolite Y with slightly larger crystals (less than 110 nm) and a high yield. Colloidal TPA-silicalite-1 crystals with a size of 60 nm were used as seeds to prepare different types of zoned MFI films on various substrates by a two- step crystallization method. In the first step a type of MFI film was synthesized on the seeded substrate by hydrothermal treatment. In the second step crystallization of another type of MFI film was achieved by further hydrothermal treatment. The structural configuration of the films was characterized by SEM, EDS, XRD and TEM techniques. The channel continuity at the interface between two different layers depended on both the composition and synthesis conditions used and the order of the layers in the film.

  • 349.
    Li, Qinghua
    Luleå tekniska universitet.
    Crystallization of colloidal TPA-silicalite-1 by a two-stage varying-temperature synthesis2000Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    A novel synthesis method called a two-stage varying-temperature synthesis was developed for the investigation of kinetics and mechanism of the crystallization of discrete colloidal crystals of TPA-silicalite-1. Briefly, this method involves a rapid change in treatment temperature at some point during the crystallization. By extending the duration of the period at the initial synthesis temperature, the crystal concentration and final crystal size varied until they were approximately equal to those obtained for a complete synthesis at the initial temperature. At this point in the crystallization, it was concluded that the nucleation stage was completed. In the TPAOH-TEOS-H2O system, the nucleation was a continuous process and the rate of nucleation was initially high immediately after the start of hydrothermal treatment, but then exponentially declined throughout the nucleation period. In the TPAOH-SiO2-H2O-ethanol system, where SiO2 was colloidal amorphous silica, the nucleation was still a successive process, whereas the nucleation profile was more similar to that usually considered to occur during zeolite syntheses with an autocatalytic increase in the nucleation rate. When the synthesis conditions were identical, except for the silica source in the above two systems, the nucleation period for the TPAOH-SiO2-H2O-ethanol system was longer than that for the TPAOH-TEOS-H2O system. This was presumably due to the fact that the colloidal silica particles needed to depolymerize to reach a supersaturation concentration in order for nucleation and crystal growth to occur. Also, it was found that irrespective of silica sources, the vast majority of nucleation occurred during an induction period before linear crystal growth started. The two-stage synthesis method could also be used to produce particularly small colloidal crystals of TPA-siliclaite-1 with reduced synthesis times and high yields. Using this method involves starting a synthesis at a lower temperature and ending the synthesis at a higher temperature. After determining the nucleation stage, an elevated temperature can be used to accelerate the crystal growth and reach higher equilibrium yields controlled by the final temperature. The effects of temperature, dilution and alkalinity on the synthesis were studied to optimize syntheses. The effect of aging on the kinetics and mechanism for crystallization of colloidal TPA-silicalite-1 with varying silica source was also investigated with the two-stage synthesis procedure. With the TEOS silica source, aging for up to 15 days at room temperature had no significant effect on the nucleation and crystallization at a low synthesis temperature. Whereas with amorphous silica, aging caused the nucleation kinetics to become increasingly similar to those for syntheses with TEOS. Thus, with sufficient aging of more economical amorphous silica sources, the properties of the final products approached that with the more exotic TEOS silica source, viz., small colloidal crystals with a narrow crystal size distribution.

  • 350.
    Li, Qinghua
    et al.
    Luleå tekniska universitet.
    Creaser, Derek
    Luleå tekniska universitet.
    Sterte, Johan
    High yield synthesis of collodial crystals of zeolite Y2001Inngår i: Zeolites and mesoporous materials at the dawn of the 21st century: proceedings of the 13th International Zeolite Conference, Amsterdam: Elsevier, 2001, s. 140-Konferansepaper (Fagfellevurdert)
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