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  • 151.
    Farzaneh, Amirfarrokh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Richards, Tobias
    University of Borås.
    Heiningen, Adrian van
    Aalto University, Espoo.
    Sklavounos, Evangelos
    Aalto University, Espoo.
    A Kinetic Study of CO2 and Steam Gasification of Char from Lignin Produced in the SEW Process2014Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, nr 2, s. 3052-3063Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The reaction kinetics of gasification are important for the design of gasifiers using biomass feedstocks, such as lignin, produced in biorefinery processes. Condensed and uncondensed lignin samples used in the present study were prepared using the SEW (SO2-ethanol-water) fractionation process applied to spruce wood chips: the dissolved lignin is precipitated during the recovery of SO2 and ethanol from the spent fractionation liquor. The gasification of char made from condensed and uncondensed SEW lignin was investigated using thermogravimetric analysis (TGA) at atmospheric pressure using either CO2 or steam. The main aim of this study was to quantify the reaction rate during the gasification process, which was found to be best described as zero-order. All experiments were performed at constant temperatures between 700 and 1050 °C to obtain the necessary information for describing the reaction rate equation in an Arrhenius form; the heating rate was 20 °C/min for both samples. The experiments led to almost similar results for both samples. The activation energies of CO2 gasification were approximately 160 kJ/mol and 170 kJ/mol for uncondensed and condensed lignin char, respectively. The activation energies of steam gasification were approximately 90 kJ/mol and 100 kJ/mol for uncondensed and condensed lignin char, respectively.

  • 152.
    Farzaneh, Amirfarrokh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Zhou, Ming
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Antzutkin, Oleg
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Bacsik, Zoltan
    Department of Materials and Environmental Chemistry, Stockholm University.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Adsorption of Butanol and Water Vapors in Silicalite‑1 Films with a Low Defect Density2016Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 32, s. 11789-11798Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pure silica zeolites are potentially hydrophobic and have therefore been considered to be interesting candidates for separating alcohols, e.g., 1-butanol, from water. Zeolites are traditionally synthesized at high pH, leading to the formation of intracrystalline defects in the form of silanol defects in the framework. These silanol groups introduce polar adsorption sites into the framework, potentially reducing the adsorption selectivity toward alcohols in alcohol/water mixtures. In contrast, zeolites prepared at neutral pH using the fluoride route contain significantly fewer defects. Such crystals should show a much higher butanol/water selectivity than crystals prepared in traditional hydroxide (OH−) media. Moreover, silanol groups are present at the external surface of the zeolite crystals; therefore, minimizing the external surface of the studied adsorbent is important. In this work, we determine adsorption isotherms of 1-butanol and water in silicalite-1 films prepared in a fluoride (F−) medium using in situ attenuated total reflectance−Fourier transform infrared (ATR−FTIR) spectroscopy. This film was composed of well intergrown, plate-shaped b-oriented crystals, resulting in a low external area. Single-component adsorption isotherms of 1-butanol and water were determined in the temperature range of 35− 80 °C. The 1-butanol isotherms were typical for an adsorbate showing a high affinity for a microporous material and a large increase in the amount adsorbed at low partial pressures of 1-butanol. The Langmuir−Freundlich model was successfully fitted to the 1-butanol isotherms, and the heat of adsorption was determined. Water showed a very low affinity for the adsorbent, and the amounts adsorbed were very similar to previous reports for large silicalite-1 crystals prepared in a fluoride medium. The sample also adsorbed much less water than did a reference silicalite-1(OH−) film containing a high density of internal defects.The results show that silicalite-1 films prepared in a F− medium with a low density of defects and external area are very promising for the selective recovery of 1-butanol from aqueous solutions.

  • 153.
    Farzaneh, Amirfarrokh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Zhou, Ming
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Potapova, Elisaveta
    Bacsik, Zoltan
    Department of Materials and Environmental Chemistry, Stockholm University.
    Ohlin, Lindsay
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Adsorption of Water and Butanol in Silicalite-1 Film Studied with in-situ ATR-FTIR Spectroscopy2015Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, nr 17, s. 4887-4894Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biobutanol produced by, e.g., acetone–butanol–ethanol (ABE) fermentation is a promising alternative to petroleum-based chemicals as, e.g., solvent and fuel. Recovery of butanol from dilute fermentation broths by hydrophobic membranes and adsorbents has been identified as a promising route. In this work, the adsorption of water and butanol vapor in a silicalite-1 film was studied using in situ attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy to better understand the adsorption properties of silicalite-1 membranes and adsorbents. Single-component adsorption isotherms were determined in the temperature range of 35–120 °C, and the Langmuir model was successfully fitted to the experimental data. The adsorption of butanol is very favorable compared to that of water. When the silicalite-1 film was exposed to a butanol/water vapor mixture with 15 mol % butanol (which is the vapor composition of an aqueous solution containing 2 wt % butanol, a typical concentration in an ABE fermentation broth, i.e., the composition of the gas obtained from gas stripping of an ABE broth) at 35 °C, the adsorption selectivity toward butanol was as high as 107. These results confirm that silicalite-1 quite selectively adsorbs hydrocarbons from vapor mixtures. To the best of our knowledge, this is the first comprehensive study on the adsorption of water and butanol in silicalite-1 from vapor phase.

  • 154. Fatehi, Hesameddin
    et al.
    Qu, Zhechao
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Schmidt, Florian M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Bai, Xue-Song
    Effect of Volatile Reactions on the Thermochemical Conversion of Biomass Particles2017Inngår i: 8TH INTERNATIONAL CONFERENCE ON APPLIED ENERGY (ICAE2016) / [ed] Yan, J Sun, F Chou, SK Desideri, U Li, H Campana, P Xiong, R, ELSEVIER SCIENCE BV , 2017, Vol. 105Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A numerical and experimental study on the conversion of a biomass particle is carried out to quantify the effect of homogeneous volatile combustion on the biomass pyrolysis. The numerical domain consists of a particle and its surrounding and the model considers detailed chemical kinetic mechanism for reaction of pyrolysis products. A detailed pyrolysis model is employed which provides the composition of pyrolysis products. The effect of gas phase reaction on the conversion time and temperature of the particle is analyzed and it was shown that the gas phase reactions results in shorter pyrolysis time. H2O mole fraction and temperature above a biomass pellet from wheat straw (WS) and stem wood (SW) were experimentally measured using tunable diode laser absorption spectroscopy (TDLAS) while recording the particle mass loss. The TDLAS data were used to validate the numerical model developed for biomass conversion. The results showed that by considering the gas phase reactions a good agreement between the measurement and the model prediction for mass loss and temperature can be achieved. For H2O mole fraction on top of the particle, on the other hand, some discrepancy between the model prediction and the experimental data was observed. Nevertheless, the difference in H2O mole fraction would be much larger by neglecting the gas phase reaction at the particle boundary.

  • 155.
    Fatima, Nowshir
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Marklund, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Degradation mechanism of water contaminated automatic transmission fluid (ATF) in wet clutch system2013Konferansepaper (Fagfellevurdert)
  • 156.
    Fatima, Nowshir
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Marklund, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Minami, Ichiro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Degradation Mechanism of Automatic Transmission Fluid by Water as a Contaminant2015Inngår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 229, nr 1, s. 74-85Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The degradation mechanism of water contaminated Automatic Transmission Fluids (ATF) was experimentally investigated. Water contaminated ATF was tribotested in a full-scale wet clutch test rig to monitor the friction durability during clutch ageing, and was also statically aged in oven to evaluate the interaction of ATF with water. The bulk properties and chemical nature of the ATF were analysed using viscosity measurements, Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). It was shown that water presence in the ATF can increase the mean friction coefficient over a short time period, though in the long term perspective there is a higher loss of mean friction. Phase separation of the water-in-oil emulsion by centrifugation at 20000 rpm made it possible to examine the water phase using infrared 2spectroscopy. The spectroscopic analysis revealed the hydrophilic nature of certain ATF constituents, although the impact of water on the bulk properties like lubricant viscosity and thermal stability was insignificant. The analysis of the tribotests showed that the friction increase for water contamination was a short-term effect and likely due to the interaction between polar surface active additives and water. Even though no significant change has been found for thermal degradation or in bulk properties of the lubricant, the initially changed action of the water soluble additives and generation of high friction resulted in a total deterioration of the clutch performance during long term use.

  • 157. Fatima, Nowshir
    et al.
    Minami, Ichiro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Marklund, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Berglund, Kim
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Influence of water on the tribological properties of zinc dialkyl-dithiophosphate and over-based calcium sulfonate additives in wet clutch contacts2015Inngår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 87, s. 113-120Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Usually the wet clutch lubricant properties vary with different formulations of base oil types and additives. The aim of this paper was to evaluate the effect of water on the performance of additives in ATF. Simplified lubricants, ZDDP and over-based Ca-sulfonates detergent additives in an API Group I mineral base oil, were employed to compare with the commercial fully-formulated automatic transmission fluid (DEXRON®VI) during water-contamination. A full-scale wet clutch test rig was used to evaluate the frictional response due to water contamination of the lubricants. Fourier Transform Infrared Spectroscopy was utilized to evaluate the variation in the solubility of these polar organic additives in the water phase and Karl-Fischer titration was utilized to evaluate the post-test water content for different formulations.

  • 158.
    Fatima, Nowshir
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Minami, Ichiro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Marklund, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Adsorption of ATF additives on wet clutch friction interfaces under water contaminated lubricant conditions2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Stable friction and positive slope of friction-speed is the typical criterion for a good clutch performance. Lubricated friction interfaces used for wet clutches produces different friction behavior depending on the lubricant conditions. Usually the lubricant conditions vary for different automatic transmission fluid (ATF) formulations implying e.g. water contamination and these conditions might influence the deterioration of the clutch plates. The aim of this paper is to verify additive adsorption on friction interfaces and ageing of the friction material in wet clutch system for a water contaminated commercial ATF (DEXRON® VI). Standard clutch plates are employed in an automated wet clutch test rig to evaluate the friction characteristics of the tested lubricant. For controlled test conditions (speed, contact pressure, oil temperature) and specific number of test cycles, the mean friction coefficient and the friction vs. speed relations are monitored during sliding test. The resultant tribofilms on the tested friction interface surfaces are characterized by means of Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy (SEM- EDS), Attenuated Total Reflectance -Fourier Transform Infrared Spectroscopy (ATR-FTIR) and X-ray Photoelectron Spectroscopy (XPS analysis). The spectroscopic techniques were used to analyse adsorbed additives on friction interfaces and made it possible to correlate measured data to the specific friction behavior obtained after water contamination of the ATF.

  • 159.
    Fatima, Nowshir
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Minami, Ichiro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Marklund, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Adsorption of ATF additives on wet clutch friction interfaces under water contaminated lubricant conditions2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Stable friction and positive slope of friction-speed is the typical criterion for a good clutch performance. Lubricated friction interfaces used for wet clutches produces different friction behavior depending on the lubricant conditions. Usually the lubricant conditions vary for different automatic transmission fluid (ATF) formulations implying e.g. water contamination and these conditions might influence the deterioration of the clutch plates. The aim of this paper is to verify additive adsorption on friction interfaces and ageing of the friction material in wet clutch system for a water contaminated commercial ATF (DEXRON® VI). Standard clutch plates are employed in an automated wet clutch test rig to evaluate the friction characteristics of the tested lubricant. For controlled test conditions (speed, contact pressure, oil temperature) and specific number of test cycles, the mean friction coefficient and the friction vs. speed relations are monitored during sliding test. The resultant tribofilms on the tested friction interface surfaces are characterized by means of Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy (SEM- EDS), Attenuated Total Reflectance -Fourier Transform Infrared Spectroscopy (ATR-FTIR) and X-ray Photoelectron Spectroscopy (XPS analysis). The spectroscopic techniques were used to analyse adsorbed additives on friction interfaces and made it possible to correlate measured data to the specific friction behavior obtained after water contamination of the ATF.

  • 160. Fatima, Nowshir
    et al.
    Minami, Ichiro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Marklund, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Surface chemistry of wet clutch influenced by water contamination in automatic transmission fluids2016Inngår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 96, s. 395-401Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lubricated friction interfaces used for wet clutches produces different friction behaviour depending on the lubricant conditions. Usually the lubricant conditions vary for water contamination in automatic transmission fluid (ATF). The presence of water retards the ATF performance by increasing the friction and can influence the deterioration of the clutch plates. Water as a polar contaminant can change the absorbability of the surface active additives, which might cause the characteristic friction behaviour. The aim of this paper is to verify the surface chemistry of tribotested standard friction interfaces lubricated with water contaminated commercial ATF (DEXRON® VI). The evidences of the influence of water on ATF performances were shown by surface analyses

  • 161.
    Fernandez, Hanna
    et al.
    KTH, Skolan för kemivetenskap (CHE).
    Johansson, Tova
    KTH, Skolan för kemivetenskap (CHE).
    Renholm, Pontus
    KTH, Skolan för kemivetenskap (CHE).
    Stauber Alfredsson, Malin
    KTH, Skolan för kemivetenskap (CHE).
    Design och tillverkning av automatiserat bryggverk2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Alkoholhaltiga drycker har konsumerats länge i Sverige, idag är öl en av de mest förekommande dryckerna. Med tanke på hur få ingredienser öl innehåller och att smaken trots detta kan varieras i det oändliga är det lätt att förstå att alla delsteg måste genomföras med precision. De olika delstegen i ölbryggningsprocessen är mältning, mäskning, lakning, humlekokning och jäsning.

    Ett försök till att bygga ett automatiserat bryggverk har gjorts. Komponenter till bryggverket har köpts in och bryggverket har byggts från grunden. Det var inte möjligt att göra alla delsteg i processen automatiserade, till exempel flödesstyrningar och tillsats av ingredienser. Detta gjorde att manuella insatser krävdes. För att styra bryggningen programmerades mikrokontrollerkortet Arduino Uno i programmeringsspråket C. Med hjälp av programmeringen har de delsteg av bryggningen, som går att automatisera, automatiserats.

    Vid testbryggningen uppstod praktiska problem som inte kunde förutsägas i teorin, exempelvis gick pumpen torrt ibland, reläerna fungerade inte som tänkt samt att en oväntad temperaturgradient uppstod. Dessa problem kan eventuellt lösas med ytterligare insatser i framtida försök. Vidare genomfördes tester innan bryggningen med endast vatten i kärlen för att undersöka temperaturregleringen. Det visade sig dock vara stora skillnader mellan vatten och mäsk, vilket gjorde att dessa tester inte kunde förutsäga alla problem. Trots detta resulterade bryggningen i en besk men drickbar öl.

  • 162.
    Ferreira, Jorge A.
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Lennartsson, Patrik R.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Taherzadeh, Mohammad J
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Airlift bioreactors for fish feed fungal biomass production using edible filamentous fungi2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Airlift bioreactors are generally considered to be better alternatives for cultivation of filamentous fungi in comparison to stirred-tank bioreactors or bubble columns bioreactors. The reason for the former includes fungal growth around all internal parts including impellers, baffles or pH, temperature and oxygen probes limiting mass transfer, whereas the latter is limited by air flow rates that can be applied before the system provides deficient mixing and so mass transfer rates. Spent sulphite liquor, a by-product from the paper pulp industry, was used for cultivation of edible Rhizopus sp., a strain isolated from Indonesian tempeh used as human food, using a 26 L airlift bioreactor. Increasing the aeration rate from 0.15 to 1 vvm led to increased biomass production (1 vs 7 g/L). The aeration rate was also found to influence fungal morphology and metabolite production during batch cultivation. Rhizopus sp. shifted from mycelial suspensions at 0.15 and 0.5 vvm to small compact pellets of regular size at 1 vvm. The production of ethanol and lactic acid, a proof of sub-optimal aeration conditions, was also reduced when increasing the aeration rate from 0.15 to 1 vvm. The produced biomass was found to be composed, on a dry weight basis, of 30-50% protein, 2-7% lipids, and 3-9% glucosamine. Considering the edible character of the fungus used as well as its biomass nutritional characteristics, there is a potential for its use as fishmeal replacement within the increasing aquaculture sector.

  • 163.
    Filippov, Andrei
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Dvinskikh, Sergey V.
    Royal Institute of Technology.
    Khakimov, Aidar
    Kazan (Volga Region) Federal University, Kazan.
    Grahn, Mattias
    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.
    Furo, Istvan
    Royal Institute of Technology.
    Antzutkin, Oleg
    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.
    Dynamic properties of water in silicalite-1 powder2012Inngår i: Magnetic Resonance Imaging, ISSN 0730-725X, E-ISSN 1873-5894, Vol. 30, nr 7, s. 1022-1031Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Self-diffusion of D 2O in partially filled silicalite-1 crystals was studied at 25°C by 2H nuclear magnetic resonance (NMR) with bipolar field gradient pulses and longitudinal Eddy-current-delay. For the first time, reliable experimental diffusion data for this system were obtained. Analysis of NMR diffusion decays revealed the presence of a continuous distribution of apparent self-diffusion coefficients (SDCs) of water, ranging from 10 -7 to ~10 -10 m 2/s, which include values much higher and lower than that of bulk water (~10 -9 m 2/s) in liquid phase. The observed distribution of SDC changes with variation of the diffusion time in the range of 10-200 ms. A two-site Kärger exchange model was successfully fitted to the data. Finally, the water distribution and exchange in silicalite-1 pores were described by taking into account (a) a gas-like phase in the zeolite pores, a gas-like phase in mesopores and an intercrystalline gas-like phase and (b) intercrystalline liquid droplets with intermediate exchange rate with the other phases. The other phases experience fast exchange on the NMR diffusion time scale. Diffusion coefficients and mean residence times of water in some of these states were estimated

  • 164.
    Forsling, Willis
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Sterte, Johan
    Skogsindustrin satsar på forskning och utbildning i Luleå: professur i Kemisk Apparatteknik inrättad1997Inngår i: Svensk papperstidning, Nordisk cellulosa, ISSN 1101-766X, nr 9, s. 49-50Artikkel i tidsskrift (Annet vitenskapelig)
  • 165.
    Fouladvand, Shahpar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Study of MFI zeolite membrane for CO2 separation2016Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Nowadays, the need and interest for renewable sources of energy has increased. Biogas is a renewable source of energy that can be considered as a sustainable substitute for natural gas. Biogas is mainly composed of CH4 and CO2, and normally the CO2 content of the gas has to be reduced as it decreases the calorific value of the gas and it may also cause corrosion in pipes and other equipment. Most today’s technologies used for upgrading biogas have been adapted from upgrading of natural gas. However, these technologies are best suited for large scale operation; whereas, production of biogas is typically several orders of magnitude smaller. This leads to high costs for removal of CO2 from biogas and consequently, new efficient technologies for upgrading biogas should be developed. Membrane-based separations are generally considered as energy efficient and are suitable for a wide range in scale of production due to their modular design. Zeolite membranes have been singled out as especially attractive membranes for gas separations. In this work, we therefore study separation of CO2 from CH4 and H2 using zeolite MFI membranes. 

    The performance of a high-silica (Si/Al ca. 139) MFI membrane for CO2/CH4 separation was investigated in a wide temperature range i.e. 245 K to 300 K. The separation factor increased with decreasing temperatures as is typically the case for adsorption governed separations. The highest separation factor observed was about 10 at 245 K. The CO2 permeance was very high in the whole temperature studied, varying from ca. 60 × 10-7 mol s-1 m -2 Pa-1 at the lowest temperature to about 90 × 10-7 mol s-1 m -2 Pa-1 at the highest temperature studied. The CO2 permeance was higher than that reported previously in the open literature for this separation. Modeling of the experimental data revealed that the membrane performance was adversely affected by pressure drop over the support, whereas the effect of concentration polarization was small. Removing the former effect would improve both the permeance and selectivity of the membrane. 

    In order to investigate the impact of the aluminum content on the performance of MFI membranes for the CO2/CH4 separation, MFI membranes with different Si/Al ratios were prepared. Increasing the aluminum content makes the zeolite II more polar which should increase the CO2/CH4 adsorption selectivity. Again the effect of temperature on the performance was investigated by varying the temperature in a range almost similar as above. Altering the Si/Al ratio in MFI zeolite membranes indeed changed the separation performances. At the lower temperatures the separation performance increased with increasing aluminum content in the zeolite as a result of larger adsorption selectivity. However, as the temperature was decreased, the selectivity of the membrane with the highest aluminum content went through a maximum, whereas for the other membranes the selectivity continued to increase with decreasing temperature under the conditions studied. At the same time, the CO2 permeances were high for all membranes studied and for the membrane with the highest selectivity, the CO2 permeance increased from 65 × 10-7 to 100 × 10-7 mol s-1 m -2 Pa-1 with increasing temperature. 

    High-silica MFI membranes were also evaluated for CO2/H2 separation, which is critical for syngas purification and H2 production. The highest CO2 permeance at the feed pressure of 9 bar was about 78 × 10-7 mol s-1 m -2 Pa-1 at around 300 K, which is one or two order of magnitude higher than those reported previously in the literature. By decreasing the temperature, separation factor reached its highest value of 165 at 235 K. 

    In summary, zeolite membranes show great potential for CO2 separation from industrial gases, in particular for CO2 removal from synthesis gas. For the CO2/CH4 separation the selectivity of the MFI membranes should be improved or other frameworks relying on molecular sieving e.g. the CHA framework should be explored. 

  • 166.
    Gao, Qiuju
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Edo, Mar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, Sylvia H.
    Collina, Elena
    Rudolfsson, Magnus
    Gallina, Marta
    Oluwoye, Ibukun
    Altarawneh, Mohammednoor
    Dlugogorski, Bogdan Z.
    Jansson, Stina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Formation of PCDDs and PCDFs in the torrefaction of biomass with different chemical composition2017Inngår i: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 123, s. 126-133Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Torrefaction is a thermal pre-treatment technology used to refine biomass, mainly for energy production purposes. However, there is currently a lack of information on the potential formation of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in the torrefaction process. In this study, torrefaction was conducted using five different types of feedstock: stemwood, bark, wood from a discarded telephone pole, cassava stems and particle board. The feedstock as well as the torrefied biomass (chars) and the volatiles (non-condensable and condensable) generated during torrefaction were analyzed for PCDDs and PCDFs. PCDD concentrations in the torrefaction products were about 2-5 fold of those in the feedstocks. Torrefaction of particle board resulted in extensive formation of PCDDs (7200 ng kg(-1)) compared to the other four feedstocks (13-27 ng kg(-1)). Examination of the homologue profiles suggested that the observed PCDDs in the torrefaction products partly originated from new formation and partly physical transformation from volatilization and re-condensation of PCDDs present in the feedstock. Dechlorination of highly chlorinated compounds (HpCDD and OCDD) in the feedstock to form less chlorinated PCDDs was also observed. Compared to PCDDs, the net formation of PCDFs in the torrefaction process was low, except for the telephone pole sample, for which a dramatic increase (44-fold) of PCDFs was observed. PCDDs and PCDFs were mainly retained in the chars, accounting for 76-96% and 39-74% of the total concentration, respectively. It was also found that the highly chlorinated congeners tended to be retained in the chars, whereas the less chlorinated ones were predominantly volatilized into the gas phase.

  • 167.
    Garcia, Gustavo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Synthesis of Zeolites from Bolivian Raw Materials for Catalysis and Detergency Applications2014Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Zeolites are very useful in many technological applications such as catalysis, separation and purification of gases and solvents, ion-exchange, etc. The production of zeolites is nowadays carried out with a variety of reagents, such starting materials render large scale production of zeolites expensive. Hence alternative synthesis routes for zeolite production at a lower cost are currently under investigation. One of these routes involves the use of natural aluminosilicate raw materials which have many advantages such as their availability, low price, workability, etc. The aim of the present work was to provide routes to produce synthetic zeolites of industrial attractiveness derived from non-expensive Bolivian raw materials like clays and diatomites. In particular, the work was focused on the synthesis of intermediate- and low-silica zeolites: zeolite Y and zeolite A. The raw materials as well as intermediate materials and final zeolite products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen gas adsorption, inductively coupled plasma mass spectrometry (ICP-SFMS), and UV-VIS spectroscopy.The first part of the study addressed the synthesis and characterization of intermediate silica zeolite Y from diatomite. Prior to synthesis, the diatomite was leached in sulfuric acid to remove impurities, but this step also resulted in dealumination. Therefore, aluminum sulfate was used as an extra source of aluminum. The raw materials were reacted hydrothermally at 373 K in aqueous medium with sodium hydroxide. Variations in parameters like the Na2O/SiO2 ratio and synthesis time were investigated. As a result, micro-sized crystals of zeolite Y were obtained. It was possible to achieve high zeolite yield at a Na2O/SiO2 ratio of 0.9, which produced zeolite Y with a SiO2/Al2O3 ratio of 3.9. Also, synthesis of almost pure zeolite Y with a SiO2/Al2O3 ratio of 5.3 in low yield at a Na2O/SiO2 ratio of 0.6 was achieved. In this respect, diatomite behaved similarly to colloidal silica in traditional syntheses, with both sources of silica having a high degree of polymerization. Zeolite Y with the latter SiO2/Al2O3 ratio might be useful for the production of ultra-stable zeolite Y for use as FCC catalyst.A similar acid leaching procedure, this time with hydrochloric acid, was used for dealumination of diatomite to increase the SiO2/Al2O3 ratio and to reduce the amount of iron in producing well-crystallized ZSM-5 from diatomite in combination with sodium hydroxide and n-butyl amine under appropriate synthesis conditions.The second part of this study dealt with the synthesis of low silica zeolite A from Bolivian montmorillonite-type clay. This clay did contain significant amounts of quartz. Hence, an alkali fusion treatment was applied to the clay by fusing the clay at high temperature with NaOH to make the material more reactive and to take advantage of all the silica present in the clay. The raw clay had a SiO2/Al2O3 ratio of 4, and sodium aluminate was added to the mixture to decrease this ratio to 2. An optimization of the synthesis time was performed. The final zeolite product exhibited high brightness despite the presence of iron in appreciable amount in the starting material and the final product. This was attributed to the magnesium in the raw material, which exerted a masking effect on iron. The latter was incorporated into extraneous magnesium aluminosilica compounds, thereby increasing brightness and strongly decreasing the overall yellowness. This simple method appears as a promising alternative to the complex and costly techniques suggested to reduce the iron content in natural raw materials, especially kaolin.To summarize, this work reports the synthesis of zeolites with promising characteristics from Bolivian raw materials. However, further optimization is required to qualify these products for industrial applications. Moreover, this study might help in the development of poor regions of the Bolivian Altiplano and open up for large scale production, since the methods developed in this work are simple and non-expensiveand other impurities for synthesis of high silica ZSM-5 zeolite. This procedure was successful in producing well-crystallized ZSM-5 from diatomite in combination with sodium hydroxide and n-butyl amine under appropriate synthesis conditions.The second part of this study dealt with the synthesis of low silica zeolite A from Bolivian montmorillonite-type clay. This clay did contain significant amounts of quartz. Hence, an alkali fusion treatment was applied to the clay by fusing the clay at high temperature with NaOH to make the material more reactive and to take advantage of all the silica present in the clay. The raw clay had a SiO2/Al2O3 ratio of 4, and sodium aluminate was added to the mixture to decrease this ratio to 2. An optimization of the synthesis time was performed. The final zeolite product exhibited high brightness despite the presence of iron in appreciable amount in the starting material and the final product. This was attributed to the magnesium in the raw material, which exerted a masking effect on iron. The latter was incorporated into extraneous magnesium aluminosilica compounds, thereby increasing brightness and strongly decreasing the overall yellowness. This simple method appears as a promising alternative to the complex and costly techniques suggested to reduce the iron content in natural raw materials, especially kaolin.To summarize, this work reports the synthesis of zeolites with promising characteristics from Bolivian raw materials. However, further optimization is required to qualify these products for industrial applications. Moreover, this study might help in the development of poor regions of the Bolivian Altiplano and open up for large scale production, since the methods developed in this work are simple and non-expensive.

  • 168.
    Garcia, Gustavo
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Aguilar, Wilson
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Carabante, Ivan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Cabrera, Saúl
    Chemistry Research Institute IIQ, San Andres Mayor University UMSA, La Paz.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Preparation of zeolite A with excellent optical properties from clay2015Inngår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 619, s. 771-777Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Discoloration of zeolite A powder is a common problem when natural raw materials such as kaolin clay are used because of the formation of colored iron compounds. In this study, we report on a novel method to produce zeolite A with excellent optical properties, from clays. The brightness is as high as 94.5 and the yellowness is as low as 3.0. The product is comprised of intergrown zeolite A crystals with cubic habit and a length ranging between 0.5 and 2 μm. Good optical properties are obtained when the raw material contains magnesium, as some natural raw materials do, or alternatively, when a magnesium compound is added to the raw material. Magnesium probably forces iron inside colorless extraneous magnesium aluminosilicate compounds. This simple process appears very promising for the preparation of zeolite A with good optical properties from inexpensive natural raw materials.

  • 169.
    Garcia, Gustavo
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Solid State and Theoretical Chemistry, Chemistry Research Institute, San Andres Mayor University.
    Cabrera, Saúl
    Solid State and Theoretical Chemistry, Chemistry Research Institute, San Andres Mayor University, University Campus.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Selective synthesis of FAU-type zeolites2018Inngår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 489, s. 36-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present work, parameters influencing the selectivity of the synthesis of FAU-zeolites from diatomite were studied. The final products after varying synthesis time were characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and gas adsorption. It was found that high concentrations of NaCl could completely inhibit the formation of zeolite P, which otherwise usually forms as soon as maximum FAU crystallinity is reached. In the presence of NaCl, the FAU crystals were stable for extended time after completed crystallization of FAU before formation of sodalite. It was also found that addition of NaCl barely changed the crystallization kinetics of FAU zeolite and only reduced the final FAU particle size and SiO2/Al2O3 ratio slightly. Other salts containing either Na or Cl were also investigated. Our results suggest that there is a synergistic effect between Na+ and Cl-. This is attributed to the formation of (Na4Cl)3+ clusters that stabilize the sodalite cages. This new finding may be used to increase the selectivity of syntheses leading to FAU-zeolites and avoid the formation of undesirable by-products, especially if impure natural sources of aluminosilica are used.

  • 170.
    Garcia, Gustavo
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Cardenas, Edgar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Cabrera, Saúl
    Chemistry Research Institute IIQ, San Andres Mayor University UMSA, La Paz.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Synthesis of zeolite Y from diatomite as silica source2016Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 219, s. 29-37Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bolivian diatomite was successfully used as a silica source for the synthesis of zeolite Y. Prior to synthesis, the diatomite was leached with sulfuric acid to remove impurities and aluminum sulfate was used as an aluminum source. The raw materials were reacted hydrothermally at 100 °C in water with sodium hydroxide and different Na2O/SiO2 ratios were investigated. The final products were characterized by scanning electron microscopy, X-ray diffraction, gas adsorption and inductively coupled plasma-atomic emission spectroscopy. Diatomites originating from different locations and therefore containing different types and amounts of minerals and clays as impurities were investigated. After optimization of synthesis time, zeolite Y with low SiO2/Al2O3 ratio (3.0–3.9) was obtained at a high yield for high alkalinity conditions (Na2O/SiO2 = 0.85–2.0). Lower Na2O/SiO2 ratios resulted in incomplete dissolution of diatomite and lower yield. Nevertheless, decreasing alkalinity resulted in a steady increase of the SiO2/Al2O3 ratio in zeolite Y. Consequently, it was possible to synthesize almost pure zeolite Y with a SiO2/Al2O3 ratio of 5.3 for a Na2O/SiO2 ratio of 0.6, albeit at a low yield. In this respect, diatomite enables the synthesis of high silica zeolite Y and behaves similarly to colloidal silica in traditional syntheses, with both sources of silica having in common a high degree of polymerization. Interestingly, the presence of minerals and clays in the starting diatomite had marginal effects on the outcome of the synthesis. However, their dissolution resulted in presence of calcium and magnesium in the zeolite Y crystals. Finally, overrun of all investigated compositions resulted in the formation of zeolite P nucleating and growing onto dissolving zeolite Y crystals, which was shown to be triggered when aluminum was completely depleted at high alkalinity

  • 171.
    Gavrilovic, Ljubisa
    et al.
    Norwegian University of Science and Technology, Norway.
    Brandin, Jan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Holmen, Anders
    Norwegian University of Science and Technology, Norway.
    Venvik, Hilde
    Norwegian University of Science and Technology, Norway.
    Myrstad, R.
    SINTEF Materials and Chemistry, Norway.
    Blekkan, Edd
    Norwegian University of Science and Technology, Norway.
    Deactivation of Co-based Fischer-Tropsch catalyst by aerosol deposition of potassium salts2018Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 57, nr 6, s. 1935-1942Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 20%Co/0.5%Re/γAl2O3 Fischer-Tropsch catalyst was poisoned by four potassium salts (KNO3, K2SO4, KCl, K2CO3) using the aerosol deposition technique, depositing up to 3500 ppm K as solid particles. Standard characterization techniques (H2 Chemisorption, BET, TPR) showed no difference between treated samples and their unpoisoned counterpart. The Fischer-Tropsch activity was investigated at industrially relevant conditions (210 °C, H2:CO = 2:1, 20 bar). The catalytic activity was significantly reduced for samples exposed to potassium, and the loss of activity was more severe with higher potassium loadings, regardless of the potassium salt used. A possible dual deactivation effect by potassium and the counter-ion (chloride, sulfate) is observed with the samples poisoned by KCl and K2SO4. The selectivity towards heavier hydrocarbons (C5+) was slightly increased with increasing potassium loading, while the CH4 selectivity was reduced for all the treated samples. The results support the idea that potassium is mobile under FT conditions. The loss of activity was described by simple deactivation models which imply a strong non-selective poisoning by the potassium species.

  • 172.
    Gavrilovic, Ljubisa
    et al.
    Norwegian University of Science and Technology, Norway.
    Brandin, Jan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Holmen, Anders
    Norwegian University of Science and technology, Norway .
    Venvik, Hilde
    Norwegan University of Science and technology, Norway.
    Myrstad, Rune
    SINTEF Industry, Norway.
    Blekkan, Edd
    Norwegan University of Science and Technology, Norway.
    Fischer-Tropsch synthesis: Investigation of the deactivation of a Co catalyst by exposure to aerosol particles of potassium salt2018Inngår i: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 230, s. 203-209Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of potassium species on a Co based Fischer-Tropsch catalyst was investigated using an aerosol deposition technique. This way of poisoning the catalyst was chosen to simulate the actual potassium behaviour during the biomass to liquid (BTL) process utilizing gasification followed by fuel synthesis. A reference catalyst was poisoned with three levels of potassium and the samples were characterized and tested for the Fischer-Tropsch reaction under industrially relevant conditions. None of the conventional characterization techniques applied (H2 Chemisorption, BET, TPR) divulged any difference between poisoned and unpoisoned samples, whereas the activity measurements showed a dramatic drop in activity following potassium deposition. The results are compared to previous results where incipient wetness impregnation was used as the method of potassium deposition. The effect of potassium is quite similar in the two cases, indicating that irrespective of how potassium is introduced it will end up in the same form and on the same location on the active surface. This indicates that potassium is mobile under FTS conditions, and that potassium species are able to migrate to sites of particular relevance for the FT reaction.

  • 173.
    Gerger, Marcus
    KTH, Skolan för kemivetenskap (CHE).
    Centrifugal Separation of 1-Methylnaphthalene2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In this report, modifications and experimental tests with an early stage test rig intended for producing a commercial solution to fractionating pyrolysis oil are described. The idea is to use centrifugal force to separate the formed aerosols from condensible gases with a lower volatility. A stacked disc centrifuge prototype built to work at high temperature was used. The experiment was done with a single component, 1-Methylnaphtalene (1-MN) to evaluate the functionality of the test rig. No separation was achieved, concluding that further work need to be done at different operating parameters with 1-Methylnaphtalene prior to including more components. The reason for the negative separation result is probably due to that the saturation ratio was to low resulting in that no aerosol was formed during the experiments. Further work includes improving the stability of the inlet stream to the centrifuge. Perform more experiments with other process parameters, recommendation is to decreasing the temperature at the inlet to the centrifuge to increase the saturation ratio. It is also suggested that an optical in situ measuring devise is added to the test rig to facilitate operation.

  • 174.
    Ghaly, Montaser
    et al.
    National Research Centre (NRC), Chemical Engineering and Pilot Plant Department, Cairo, Egypt.
    Ali, Mohamed Eid
    National Research Centre (NRC), Water Pollution Research Department, P.O. 11312, Cairo, Egypt.
    Österlund, Lars
    FOI CBRN Defence and Security, Umeå.
    Khattab, Ibrahim
    National Research Centre (NRC), Chemical Engineering and Pilot Plant Department, Cairo, Egypt.
    Badawy, Mohamed
    National Research Centre (NRC), Water Pollution Research Department, P.O. 11312, Cairo, Egypt.
    Farah, Joseph
    National Research Centre (NRC), Chemical Engineering and Pilot Plant Department, Cairo, Egypt.
    Zaher, Fatama
    National Research Centre (NRC), Chemical Engineering and Pilot Plant Department, Cairo, Egypt.
    Al-Maghrabi, Mohammednoor
    Faculty of Engineering, King Abdul-Aziz University, Jedddah, Saudi Arabia.
    ZnO/spiral-shaped glass for solar photocatalytic oxidation of Reactive Red 1202014Inngår i: Arabian Journal of Chemistry, ISSN 1878-5352Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    ZnO/glass spiral (GS) was prepared by immobilization of ZnO on GS with facilemethod, and was characterized by X-ray diffraction analysis (XRD), scanning electron microscope(SEM) and the crystallite size of ZnO on GS surface was calculated. SEM showed rod-like shape ofZnO particles on GS surface. Photocatalytic activity of prepared immobilized photocatalyst wasinvestigated for decolourization and degradation of C.I. Reactive Red 120 (RR-120) dye under sunlight.The kinetics of decolourization and degradation removal has been investigated. The effect ofpH on decolourization and degradation of dye was studied. The decolourization and degradation ofdye were followed by pseudo-first order reaction. The decolourization and degradation of RR-120dye were enhanced by H2O2 addition to definite dosage beyond that the effect is diminished. Also,the reusability of immobilized ZnO on GS was tested for photocatalytic degradation of dye and itwas worth noting that it has high efficiency with slight decrease (5%) after five successive runs.

  • 175.
    Gharib Ali Jalal, Ibrahim
    et al.
    KTH, Skolan för kemivetenskap (CHE).
    Abdulaziz Ali, Abdulbasit
    KTH, Skolan för kemivetenskap (CHE).
    The Sustainability related opportunities and challenges with various transformer insulation fluids and business case on re-refining2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Transformers are electrical devices used in practice to increase or decrease voltages. Transformers are of various sizes and used mainly in power distribution. To provide cooling and insulation, transformer oils are used together with cellulose that acts as a solid insulation.

    The most common type of transformer oil is mineral oil and is a product derived from the refining of crude oil. Its low cost and good compatibility with cellulose are two factors that have led to its predominant position as the common transformer oil. There are also synthetic ester based transformer oils, and following an increased interest in environmentally friendly products, transformer oils made from natural esters such as sunflower, soybean and rapeseed.

    Mineral oil is not biodegradable and is deemed as hazardous waste. The ester based oils are biodegradable and promoted as a more environmentally friendly alternative to mineral oil.

    In this thesis, the possibility of re-refining used mineral transformer oil is assessed from a financial perspective in the form of a business case and an LCA study has been done to compare the environmental impacts between ester based transformer oils and mineral based transformer oil.

    The results from the LCA study showed that from a cradle-to-gate perspective, mineral oil has a lower environmental impact than ester-based transformer oils. The re-refining of used mineral transformer oil further reduces the environmental impact. The results from the business case showed that a small scale re-refining facility is financially feasible but highly dependent on the supply and demand of used transformer oil.

    It is recommended to pursue further studies before making any decision. There is lack of data regarding the re-refining market in Eastern Europe and the accuracy of the LCA study can be further improved by having emissions data from re-refining used mineral transformer oil.

  • 176.
    Gilardi, Lorenza
    KTH, Skolan för kemivetenskap (CHE).
    Removal of hydrogen sulfide from an air stream using UV light2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Volatile sulfur compounds are cause of concern because, when present in high concentrations, they constitute a danger for health because of their strong toxicity. Furthermore, for low concentrations, they are often a cause of complaint, because of their low odor threshold. In this context, the purpose of this Thesis is to evaluate a new technology for the abatement of sulfur-based malodorous compounds. The investigated technology consists in the use of ozone generating low-pressure UV mercury lamps, operating at room temperature. Hydrogen sulfide is often found in industrial processes, (e.g. WWTPs (Wastewater Treatment Plants), leather production, sewage treatment, garbage disposal, etc). Moreover, it presents both a very high toxicity a low odor threshold. Thus, due to its high representativeness of the case, hydrogen sulfide was chosen as reference compound for the purposes of this project. In order to evaluate a wide range of cases, several experiments using different residence times, humidity contents and inlet concentrations of the pollutant were conducted. The obtained results show that this technology generally presents discrete conversion efficiencies, although not suffcient to be used as freestanding process. For this reason, a pretreatment is revealed to be necessary. The best conversion efficiency was obtained for low flow rates and high moisture content. At the end of the project, as side-study, a possible pretreatment using an adsorbent bed constituted by granular ferric oxide was evaluated.

     

  • 177.
    Glenngård, Anton
    et al.
    KTH, Skolan för kemivetenskap (CHE).
    Helmersson, Sofia
    KTH, Skolan för kemivetenskap (CHE).
    Kessler, Amanda
    KTH, Skolan för kemivetenskap (CHE).
    Nilsson, Elisabeth
    KTH, Skolan för kemivetenskap (CHE).
    Utformning av Bränslecellsystem för Autonom Undervattensfarkost2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Avdelningen Marina System på Kungliga Tekniska Högskolan har designat och konstruerat en autonom undervattensfarkost (AUV). I dagsläget drivs farkosten drivs av ett litiumpolymerbatteri. Ett bränslecellssystem bestående utav PEM-bränslecellsstackar (Polymerelektrolytbränslecell), metallhydrid och trycksatt syrgas har designats för att byta ut det befintliga litiumpolymerbatteriet. För att få ett säkert system är det utrustat med vätgassensor, trycksensor, voltmätare samt temperatursensor. Eftersom både syrgas och vätgas måste medföras i farkosten, jämfört med landgående fordon som kan utnyttja syret från omgivande atmosfär, har olika bränslelagringsmetoder undersökts. För att lagra syrgas har trycksatt gas valts, denna lagras i en tank gjord av kolfiber och ett har ett tryck på 300 bar. Vätgasen väljs att lagras i en FeTi-metallhydrid på grund av dess volymmässiga fördel. Metallhydrid är en volymeffektiv men viktineffektiv lagringsmetod, vilket gör att den är perfekt till en undervattensfarkost. Metallhydriden förvaras i en tank gjord av aluminium. Eftersom bränslecellerna producerar vatten har olika sätt att fånga upp detta undersökts. Regenerad cellulosa (disktrasa) har hög absorptionsförmåga och har därför valts för systemet.

    De bränslecellesstackar som införskaffades har testats med hjälp av programvaran Labview. De presterade något under vad tillverkaren hävdade, något som antas bero på effektbehov hos kontroller och fläktar. Olika driftbetingelser har undersökts för att kunna använda bränslecellsstackarnas fulla potential.

    Det slutgiltiga systemet får ej plats i farkosten. En teoretisk studie för när bränsleceller blir mer volymeffektiva än batterier visar att för ett helt optimerat system går gränsen vid 3 liter, vilket motsvarar att 822 normalliter vätgas måste tas med.

    I framtiden skulle en kemisk lagringsmetod av syrgas vara att föredra, exempelvis väteperoxid. Metallhydrid är ett bra sätt att lagra vätgas men tankmaterialet skulle kunna vara exempelvis rostfritt stål istället för aluminium så att tanken blir mer volymeffektiv på grund av den högre brottgränsen hos stålet. Ett syrgasflöde till bränslecellen istället för ut i farkostens atmosfär skulle kunna öka verkningsgraden och därmed räckvidden.

  • 178.
    Golets, Mikhail
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Heterogeneously Catalyzed Valorization of Monoterpenes to High Value-Added Chemicals2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    A potential industrial process is profitable only if it is successfully implemented by the continuously developing chemical industry. Throughout last decades heterogeneous catalysis has opened doors to the creation of various know-how products which previously were considered unfeasible. Moreover, the use of heterogeneous catalysts allows improving existing processes to shift towards more ecological and cost efficient practices. In particular, polymer or fuel compounds could be eco-friendly produced from wood extractives, as an alternative to the conventional oil resources. This goal becomes even more attractive in light of the upcoming peak-oil.

    In the Nordic pulping industry turpentine is widely available as a tonnage by-product. Despite its interesting properties and promising application possibilities this fraction is commonly burned in the recovery boilers for energy. Although the chemical composition of turpentine depends strongly on the specific pulping process, α-pinene is the predominant compound and as such most studied. The general message of this thesis is the successful implementation of the heterogeneous catalysts in one-pot value-added upgrading of crude turpentine and specific terpenes, particularly α-pinene. Concepts allowing the production of fragrances, resins, plastics and pharmaceutical compounds are presented in the current study. Both commercial (Amberlyst 70) and self-prepared (Me/Al-SBA-15 or TiO2) catalysts were studied in several reactions including: acetoxylation, isomerization, dehydroisomerisation and oxidation. Both commercially purified α-pinene and crude thermo-mechanical turpentine were used as raw materials in the catalytic one-pot synthesis of value-added compounds.

    The experiments were performed in both batch and continuous reactor systems depending on the studied reaction. Successful results were obtained in case of several reactions. As an example, upon acetoxylation of α-pinene valuable fragrances – α-terpinyl and bornyl acetates – were produced with yields of 35 and 40 wt-%, respectively. Furthermore, in the dehydroisomerisation reaction of α-pinene, a yield of around 80 wt-% of an important fragrance, solvent and plastics precursor, ρ-cymene, was obtained. In the last case, thermo-mechanical turpentine was also successfully utilized. Still, some α-pinene oxidation tests leading to α-pinene oxide and verbenone fragrances were also carried out. Upon this study, further oxidation of ρ-cymene lead to the formation of ρ-methyl-acetophenone, a product essential for perfumery, pharmaceutical and pesticide industry as well as a potent polymer precursor. In addition, isomerization reactions were performed. Additionally, the catalytic materials were thoroughly characterized and analyzed.

  • 179.
    González Guisasola, Carlos
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Temperature dependence of the electro-oxidation of D-glucose and D-sorbitol in a PEMFC2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The influence of temperature on the electro-oxidation of glucose and sorbitol has been studied in this work. The oxidation reaction was carried out on the anode of a direct sugar fuel cell with the help of a porous carbon supported Pt-RuO2 electrode. Temperature showed to increase cathodic current densities in the measurements of cyclic voltammetry. The direct glucose fuel cell constructed in the laboratory with Pt on carbon as cathode and PtRu/C as anode gave 8.6 mW/cm2 peak power density in 1M glucose at 800 C. In the case of sorbitol; 5.8 mW/cm2 were obtained. When compared with measurements in the literature, the results obtained in this study were ten times better, when normalized to the amount of Pt in the electrodes. Deactivation of catalyst was observed when using glucose and sorbitol. Activation procedures were tested on the membrane-electrode assembly to reverse catalyst poisoning.

  • 180.
    Gorski, Dmitri
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Hill, Jan
    QualTech AB (Previously Norske Skog ASA), SE-282 21, Tyringe, Sweden.
    Improved quality of SC magazine paper through enhanced fibre development using the ATMP process2012Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, nr 1, s. 35-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A pilot scale refining trial was conducted using the ATMP (Advanced Thermomechanical Pulp) refining concept with White spruce as raw material. Low-intensity TMP and high-intensity TMP with mechanical pre-treatment of chips were compared to ATMP (Mg+P), where development of fibres was enhanced using hydrogen peroxide and magnesium hydroxide. The main goal of the trial was to evaluate the potential of using ATMP process for production of SC (supercalendered) magazine paper. SC paper is especially demanding when it comes to the paper surface structure which is strongly influenced by the development of fibre properties.

    Improvement in individual fibre properties such as flexibility, fibre split index and fibre surface area index achieved using ATMP process was found to translate into decreased surface roughness and air permeability of calendered laboratory sheets. Both the refining process configuration and the addition of process chemicals were found to have significant impacts though the process configuration had major role. The influence of process chemicals on PPS was mainly pronounced after second stage refining. The magnitude of surface roughening (fibre rising) was found to be influenced mainly by the process configuration.

  • 181.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Development of a novel experimental technique for studying zeolites: combining zeolite coated ATR elements and FTIR spectroscopy2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Thin zeolite films have great potential in several novel application areas such as structured catalysts, membranes and sensors. To fully exploit the advantages of these films it is of great importance to determine the adsorption properties of the films. A powerful technique for studies of phenomena at surfaces or in thin films is FTIR/ATR-spectroscopy (Fourier Transform Infra Red / Attenuated Total Reflection). In this work, MFI zeolite films were prepared on ATR elements using two methods. One method produced 200 nm thick films with small crystals (<200nm). The other method was used for preparing b-oriented ZSM-5 films. These films were discontinuous and ca 420 nm thick and consisted of well intergrown, and substantially larger crystals, ca 1.1 ìm in diameter. Silicalite-1 coated elements were evaluated as gas sensors and the sensitivity for a hydrocarbon for zeolite-coated elements was compared with a standard 10 cm gas cell. The sensitivity was approximately 85 times higher for the coated elements at low hydrocarbon concentration. The response time was investigated by exposing the coated element to a step increase of an analyte and recording the response as a function of time. The response was relatively fast, equilibrium was achieved after approximately 250 s, but already after a few seconds, a strong signal could be detected. The coated elements were also used for determining single gas adsorption isotherms. The studied systems were n-hexane/silicalite-1, p-xylene/silicalite-1 and p-xylene/ZSM-5. The observed isotherms for temperatures between 323 and 423 K were typical for microporous materials with a fast increase of the amount adsorbed at low partial pressures. p-Xylene isotherms of type I were observed as opposed to the type IV isotherms reported in literature for powders. This difference was assigned to strain in the films and/or to reduced flexibility of the MFI framework when attached to a support. Further, some capillary condensation occurred at higher pressures in the films consisting of smaller crystals, which was assigned to condensation in open grain boundaries. Henry's constants and heats of adsorption determined from low-pressure data agreed well with previous reports. Measurements with polarized radiation revealed that p- xylene molecules are mainly oriented with their long axis in the b- direction of the crystals and it was also observed that some kind of rearrangement of n-hexane occurs with increasing loading, both of these findings were in agreement with previously reported results.

  • 182.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Development of a novel zeolite coated ATR-FTIR sensor2004Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Thin zeolite films have great potential in several novel application areas such as: structured catalysts, membranes and sensors. To fully exploit the advantages of these films it is of great importance to determine the properties of the films. A powerful technique for studies of phenomena at surfaces or in thin films is FTIR/ATR-spectroscopy (Fourier Transform Infra Red / Attenuated Total Reflection). Furthermore, thin zeolite films may be utilized for enhanced selectivity and sensitivity for this technique. In this work films with a thickness of 200 nm of the zeolites ZSM-5 and silicalite-1 were grown on ZnSe, ZnS, ZrO2, Si and Ge ATR elements using a method that had been developed previously. The coated elements were evaluated in a gas sensor application by comparing the sensitivity for a hydrocarbon of zeolite-coated elements versus a standard 10 cm gas cell. The sensitivity was approximately 85 times higher for the coated elements compared to the gas cell at low hydrocarbon concentration. The response time was investigated by exposing the coated element to a step increase of an analyte and recording the response as a function of time. The response was relatively fast, equilibrium was achieved after approximately 250 s, but already after a few seconds a strong signal could be detected. The coated elements were also used to determine single gas adsorption isotherms. The systems studied were n-hexane/silicalite-1 and p-xylene/silicalite-1. Adsorption isotherms determined at varying temperatures were typical for microporous materials. Capillary condensation was observed at higher concentration of the adsorbent. Henry constants and heats of adsorption determined from low-pressure data agreed well with previously reported data in the literature.

  • 183. Grahn, Mattias
    et al.
    Agarwal, Shilpa
    Luleå tekniska universitet.
    Holmgren, Allan
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    In-situ ATR-FTIR spectroscopy of structured zeolite H-ZSM-5 catalysts2010Konferansepaper (Annet vitenskapelig)
  • 184.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Maxwell-Stefan modelling of High flux tubular silicalite-1 membranes for CO2 removal from CO2/H2 gas mixtures2014Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 471, s. 328-337Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, a Maxwell-Stefan model for high flux tubular silicalite-1 membranes for separation of CO2 from a CO2/H2 mixture was developed. The model concerns tubular membranes operating in a counter flow module and includes transport through flow-through defects in the silicalite-1 film and pressure drop over the graded alumina support. Adsorption and diffusion parameters for perfect silicalite-1 crystals were taken from literature. The flux and selectivity predicted by the model were in reasonably good agreement with experimentally observed data for a ZSM-5 membrane without any fitting of the model. However, the CO2 flux and selectivity measured experimentally for the ZSM-5 membrane were higher than that predicted by the model for a silicalite-1 membrane.The model was used to investigate a case with a 20 000 Nm3/d feed comprised of a 50/50 mixture of CO2/H2 at pressure of 25 bar and a membrane temperature of 296 K. The permeate pressure was 1 bar and 90% of the CO2 permeated the membrane. In this case, the membrane permselectivity and CO2 flux varied along the length of the tubes between 20–26 and 950–396 kg/(m2 h), respectively. Further, both defects and pressure drop over the support were shown to have an adverse effect on the selectivity, which indicates that membrane selectivity can be improved by reducing the flow-through defects and/or by preparing supports with less flow resistance. For a one-stage process, the required membrane area is as small as ca 0.85 m2 and the hydrogen loss through the membrane was 12.4%. For a two-stage process the required membrane area almost doubled to 1.6 m2, however the hydrogen loss through the second membrane is reduced to as little as 2.5%. In summary, this work shows that high flux zeolite membranes may be an interesting option for CO2 removal from synthesis gas.

  • 185.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Holmgren, Allan
    Hedlund, Jonas
    Adsorption of n-hexane and p-xylene in thin silicalite-1 films studied by FTIR/ATR spectroscopy2008Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 112, nr 20, s. 7717-7724Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Adsorption isotherms for p-xylene and n-hexane in silicalite-1 films with a thickness of 200 nm were determined at 323, 343, 368, 393, and 423 K using Fourier transform infrared/attenuated total reflection (FTIR/ATR) spectroscopy. For both adsorbates, the low-pressure data agreed with literature data for MFI powder and the estimated Henry's constant and adsorption enthalpy were close to previously reported results. The upper region of the n-hexane isotherm (p > 2 kPa at 323 K) was likely influenced by micropores in open grain boundaries, as expected for a polycrystalline film of small (<200 nm) crystals. As for n-hexane, the first part (0 ≤ p ≤ 65 Pa at 323 K) of the p-xylene isotherm agreed with data for powder. However, the saturation capacity was only about half of that previously reported for powders, which indicates that p-xylene molecules do not adsorb in the sinusoidal channels in the film. We speculate that the small crystals used in the present work may behave differently from the larger crystals in previous works. Another explanation for the lower saturation capacity may be the bonding of crystals to the supports, which are known to induce strain in the attached crystals.

  • 186.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Lobanova, Antonia
    Luleå tekniska universitet.
    Holmgren, Allan
    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.
    A novel experimental technique for estimation of molecular orientation in zeolite2007Inngår i: Studies in Surface Science and Catalysis, ISSN 0167-2991, Vol. 170, s. 724-731Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    FTIR spectroscopy in combination with polarized light and an ATR probe coated with a b-oriented ZSM-5 film was for the first time used to determine the orientation of adsorbed molecules in the ZSM-5 structure. Two adsorbates were studied, n-hexane and p-xylene and the results agreed with previously reported results obtained by other experimental techniques.

  • 187.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Lobanova, Antonina
    Luleå tekniska universitet.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Hedlund, Jonas
    Orientational analysis of adsorbates in molecular sieves by FTIR/ATR spectroscopy2008Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 20, nr 19, s. 6270-6276Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    ZnS ATR elements were coated with well-defined b-oriented ZSM-5 films by in situ growth. Both adsorption isotherms, as well as molecular orientation of p-xylene adsorbed in the films, were measured at 323 and 373 K by FTIR/ATR spectroscopy. The observed isotherms for the b-oriented ZSM-5 films in the present work were very similar to previously reported isotherms of supported MFI films, albeit the crystals in the latter films were aluminum free (silicalite-1) and orientated differently relative to the support surface than the crystals in the films studied in the present work. The novel technique facilitated, for the first time, the examination of how the tilt angle varies with loading and temperature. The data obtained in the present work showed that the p-xylene molecules were mainly oriented with their long axis parallel to the b-direction of the MFI crystals in concert with previously reported results based on FTIR microscopy, Monte Carlo simulations, NMR, and XRD data. At high concentrations, the tilt angle was in good agreement with observations by FTIR microscopy. It was also found that the orientation of the molecules changed with loading, this might be due to different adsorption geometries in the channel intersection as reported previously. The observed tilt angles may also be influenced from competitive adsorption on silanol groups, as was also indicated in the spectra. The results also indicate that the adsorption properties of zeolite films and powders may differ. Hence, adsorption parameters determined for zeolite powders may not necessarily be applicable to films.

  • 188.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Suarez, Aldara Naveira
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Pasaribu, Rihard
    Luleå tekniska universitet.
    Effect of ZDDP on friction and wear in fretting contacts2010Inngår i: 14th Nordic Symposium on Tribology: NORDTRIB 2010 : Storforsen, Sweden, June 8-11, 2010, Luleå: Luleå tekniska universitet, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The effect of ZDDP on fretting wear was investigated in a ball on flat machine. The results confirm previous work that anti-wear agents may reduce friction and wear in fretting contacts. It was further found that temperature, adsorption time and base oil polarity were all important parameters affecting the ability of ZDDP to protect the surfaces against fretting wear.

  • 189.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Suarez, Aldara Naveira
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Pasaribu, Rihard
    SKF Engineering & Research Center, Nieuwegein.
    Effect of ZDDP on friction in fretting contacts2011Inngår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 273, nr 1, s. 70-74Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of ZDDP on fretting wear was investigated in a ball on flat machine. The results confirm previous work that anti-wear agents may reduce friction and wear in fretting contacts. It was further found that temperature, adsorption time, base oil polarity as well as the presence of other surface active additives in the oil were all important parameters affecting the ability of ZDDP to protect the surfaces against fretting wear.

  • 190.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Wang, Zheng
    Luleå tekniska universitet.
    Lidström-Larsson, Margareta
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Hedlund, Jonas
    Sterte, Johan
    Silicalite-1 coated ATR elements as sensitive chemical sensor probes2005Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 81, nr 1-3, s. 357-363Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 191.
    Granberg, Hjalmar
    et al.
    RISE, Innventia.
    Coppel, L.G.
    RISE, Innventia.
    Eita, M.
    De, Mayolo E.A.
    Arwin, H.
    Wågberg, L.
    Dynamics of moisture interaction with polyelectrolyte multilayers containing nanofibrillated cellulose2012Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, nr 2, s. 496-499Artikkel i tidsskrift (Fagfellevurdert)
  • 192.
    Granlund, Moa Z.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Görke, Oliver
    Pfeifer, Peter
    Pettersson, Lars J.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Comparison between a micro reactor with multiple air inlets and a monolith reactor for oxidative steam reforming of diesel2014Inngår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, nr 31, s. 18037-18045Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract In order to lower the emission from idling heavy-duty trucks auxiliary power units can be implemented. Due to limited space available on-board the truck the units needs to be both efficient and compact. One alternative for these units is a fuel cell supplied with hydrogen from a fuel reformer. Today, mostly monolithic reactors are used in the field of oxidative steam reforming of fuels, which has some challenges that need to be addressed before a possible breakthrough occurs on the market. One is the temperature gradient developed over the length of the monolith as a consequence of the sequential reactions. This could be improved by using a metallic micro reactor with better heat integration between the reaction zones and further improving the integration with multiple air inlets along the catalytic bed. The aim with this study was to compare a conventional monolith reactor for oxidative steam reforming of fuel with a novel micro reactor design where air was dosed at four different positions along the reactor channels. The experiments were not necessarily conducted autothermal, i.e. a heating jacket was applied for operation.

  • 193.
    Granlund, Moa Z.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Jansson, Kjell
    Stockholm University, Arrhenius Laboratory, Department of Materials and Environmental Chemistry.
    Nilsson, Marita
    Scania CV AB, Materials Technology, Engine Performance and Emissions.
    Dawody, Jazaer
    Volvo Group Trucks Technology, Advanced Technology & Research, Energy Efficiency & Environmen.
    Pettersson, Lars. J.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel2014Inngår i: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 154, s. 386-394Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this paper was to study the influence three promoters (Co, La, Mn) had on the catalytic activity of Rh-based catalysts for autothermal reforming of diesel. The catalysts were supported on CeO2ZrO2 and the loading was 1 wt.% Rh and 6 wt.% promoter. The catalytic activity was evaluated in a monolith bench scale reactor with Swedish Environmental diesel, MK1. The process parameters employed at the ATR experiments were; O-2/C similar to 0.45, H2O/C similar to 2.5 and GHSV similar to 50,000h(-1), meanwhile the reactor temperature was ramped from 700 degrees C to 950 degrees C. The catalysts were compared based on their fuel conversion, H-2 yield and the selectivity of different short-chain hydrocarbons. The results showed that all three catalysts had both high fuel conversion and H-2 yield in the optimal ATR operation temperatures. The H-2 yield and fuel conversion were increasing in the order Rh/Mn, Rh/La, Rh/Co. To get further insight in the difference between the materials the fresh and aged catalytic materials were characterized. The characterization methods used were H-2-temperature programmed reduction (H-2-TPR), powder X-ray diffraction (XRD), and BET surface measurements. The BET surface measurements showed that promotion with La gave improved thermal stability of the material. The XRD showed a high dispersion of all metals except Co, which was present as crystals in the size range of the particles of the support.

  • 194.
    Granlund, Moa Z.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Jansson, Kjell
    Stockholm University.
    Nilsson, Marita
    Dawody, Jazaer
    Pettersson, Lars J.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel: Aging and characterization2015Inngår i: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 172, s. 145-153Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study three bimetallic catalysts are evaluated for autothermal reforming (ATR) of fuels (1 wt.% Rh and 6 wt.% X (X = Co, La or Mn) supported on high-surface area CeO2-ZrO2). The catalysts are aged for approximately 35 h and carefully characterized both as fresh and aged materials. The objective is to illuminate the changes in material properties after time on stream as well as the differences among the materials. The changes in material properties are evaluated by H2-TPR, BET surface area analysis, TEM, SEM and STEM. The material’s tendency to coke is investigated by TPO analysis.

    The three materials exhibit promising initial activity. However, the Co-promoted sample decreases sharply in activity after 25 h of operation. Meanwhile, the other two materials display a more stable activity throughout the evaluated time. The deactivation of the Co-promoted material could be linked to the high amount of coke deposited during operation. Based on the results from the activity evaluation and characterization, the material promoted with lanthanum displays the most promising results. The addition of lanthanum resulted in a catalyst that was both stable and had high activity, even though a low rhodium loading is used. The material also shows superior thermal resistance compared to the other two materials. In addition, the tendency to coke is significantly lower compered to the other materials, which is especially beneficial when dealing with ATR of complex fuels. 

  • 195.
    Granlund, Moa Z.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Zacherl, Sabina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Pettersson, Lars J.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi. Univ Stellenbosch, South Africa.
    Comparison between ceria-zirconia and alumina as supports for oxidative steam reforming of biodiesel2015Inngår i: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 58, nr 14-17, s. 933-938Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    The objective of the study is to illustrate the advantages with using ceria–zirconia instead of promoted alumina as support for rhodium-based catalysts in oxidative steam reforming of biodiesel. The evaluation is based on long-term oxidative steam reforming experiments where the stability and durability of the catalysts are evaluated. The durability and fuel conversion of the two catalysts were comparable. However, the H2 yield of the ceria–zirconia supported catalyst was 10 % higher than for the catalyst supported on promoted alumina after 65 h on stream. Included are also measurements of the acidity of the catalysts, where it was concluded that the promoted alumina catalyst was significantly more acidic. The acidity of the materials could then be related to the amount of coke deposited, where the amount of coke on the alumina catalyst was almost five times higher after 50 h of operation compared to the ceria–zirconia catalyst.

  • 196.
    Gren Vikander, Lukas
    KTH, Skolan för kemivetenskap (CHE).
    Purification oflignin-based oil2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The combustion of petroleum-based fuels in the transportation sector is a major contributor to the carbon footprint humans make on the Earth. There is a big need for innovative solutions replacing today’s crude oil based fuels. RenFuel has come up with a pioneering solution to enable co-processing of lignin with crude oil fractions at refineries. This thesis is focused on proof of concept for liquid-liquid extraction purification of lignin-based oil, which will enable further processing to diesel and gasoline additives.

    Liquid-liquid extraction has been considered as the method of purification and was prove meet the separation criteria. Later laboratory trials was carried out to find design parameters for the full-scale purification procedure, which has led to a process route that has been suggested. The proposed process route meets the criteria for the separation. On a second thought, the process route will not be recommended for RenFuel´s pilot plant, the main reason for this is that it limits the plant's flexibility. Propositions for alternative purification methods and future research have been presented.

  • 197.
    Grimler, Henrik
    KTH, Skolan för kemivetenskap (CHE).
    Investigating Urea Vaporization in a Controlled Environment Using Infrared Thermography2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    As the emission legislation becomes more stringent, higher demands are put on the aftertreatment system in trucks. For dealing with nitrous oxides, AdBlue® (urea–water solution) is injected into the exhausts which evaporates and reduces nitrous oxides to nitrogen. At low exhaust temperatures, it is more difficult to evaporate the injected AdBlue® as the exhausts contain less energy. The injected solution may instead form a wall film. In this wall film, side reactions can occur which leads to the formation of deposits.

    This thesis aims at understanding how and when wall films and deposits are formed. To achieve this, a test rig that allowed visual and infrared observations of the process and variation of governing properties was designed and built.

    The results show that thicker plates can sustain higher dosages than thinner plates since the temperature drop and film area are smaller for the thicker plate. It was also observed that at plate temperatures >340 °C, the water in the impacting spray evaporated, leaving a urea dust in the gas phase.

    It is also clear that deposits form faster at higher gas temperatures (> 350 °C) compared to at lower temperatures (200–250 °C). The deposits form at the edge of the wall film in a region with a temperature higher than in the middle of the wall film. At lower temperatures, a wall film that spreads out over a very large area is formed and after a longer time period, deposits form at obstacles and at the wall film edge. Experiments for 2 h at lower temperatures left approximately the same amount of deposits as experiments for 30 min at higher temperatures.

  • 198.
    Gruvnäs, Filip
    KTH, Skolan för kemivetenskap (CHE).
    Modellering av åldring av dieseloxidationskatalysatorer2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    A conventional exhaust gas after treatment system (EATS) for the Euro VI legislation contains four different catalyst. The first two (particulate filter system) remove particulates and the last two (SCR system) remove nitrogen oxides (NOx). The particulate filter system also optimizes the gas composition with respect to nitrogen monoxide (NO) and nitrogen dioxide (NO2). The performance of the SCR system has a strong dependency on the NO:NO2 ratio as the so called selective catalytic reduction (SCR) reaction is kinetically favored at a NO:NO2 ratio of 1:1.

    The diesel oxidation catalyst (DOC) is placed first in the EATS. Due to this placement, the DOC is subjected to a rough environment, e.g. high temperatures and oil/fuel impurities that with time will affect its performance, i.e. the catalyst ages.

    In this master thesis, the aging of the DOC has been empirically correlated to thermal load and sulfur exposure. The study shows that it is possible to predict how the NO oxidation performance decays as a function of thermal and sulfur exposure. The empirical relation was fitted against two aging cycles and validated against an additional four. The results show that the loss of catalytic activity can to a large extent be explained by the cycle it has been used on.

  • 199.
    Grönkvist, Stefan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Bryngelsson, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Westermark, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Oxygen efficiency with regard to carbon capture2006Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 31, nr 15, s. 3220-3226Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carbon capture is often discussed in the literature with the sole focus on power processes, despite the fact that carbon dioxide emissions from other sources are just as relevant for the impact on the atmosphere. Furthermore, some carbon capture methods are relatively inefficient when applied to power production processes. Carbon capture should preferably be performed where the cost is as low as possible, i.e. not necessarily from power production processes. As an example, carbon capture using combustion with pure oxygen is far more energy efficient if it is used together with lime kilns or cement kilns than together with power production processes. A new concept termed "oxygen efficiency" is introduced in this paper. It describes the amount of carbon dioxide that can potentially be captured per unit of oxygen. As such, the oxygen efficiency quantifies the value of a certain unit of oxygen for carbon capture reasons. The base concept is that the energy penalty for the production of one part of oxygen is the same no matter where it is produced; hence, if this unit of oxygen can be used to capture more carbon dioxide, it is more efficient. Typically, the oxygen efficiency would be five times greater for carbon capture when utilising pure oxygen together with cement kilns rather than together with methane-fired power plants. Furthermore, the concept of oxygen efficiency illustrates the importance of considering how carbon capture methods can be utilised in the most efficient way, in addition to evaluating which carbon capture method is the most suitable for a particular technology.

  • 200.
    Gualtieri, Magdalena
    Luleå University of Technology.
    Synthesis and characterization of zeolite films and membranes2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In this work, a seeding technique was used to synthesize films and membranes of FAU, LTA and MFI type zeolites. In the first part, hydrothermal growth was performed without organic template molecules, which resulted in template-free zeolite films and membranes. The samples were characterized by Scanning Electron Microscopy, X-ray Powder Diffraction and permeation measurements with gaseous probe molecules. Thin films of FAU-type zeolite were prepared on polished single crystals. The thickness and morphology of the films could be controlled by varying the synthesis conditions. Preparation of LTA-type membranes was also attempted. However, the membranes cracked during drying at temperatures above room temperature. Template free MFI membranes with higher quality could be prepared. These membranes had a maximum separation factor alpha of 17.8 at 220°C for a n-butane/i-butane mixture. Cracks formed at temperatures higher than 250°C. Crack formation in zeolite membranes at high temperatures has also been reported by several other groups. Since no model for the crack formation process has been established in the literature, the second part of this work was devoted to study crack formation and to develop a model. Relatively thick (ca 1800 nm) alpha-alumina supported MFI films, prepared using organic template molecules (TPA+), were selected for the study since data on crack formation in the form of SEM images and permeation measurements for these membranes had been obtained in earlier work by the group. These membranes were further studied by in-situ High Temperature X-ray Powder Diffraction experiments in the present work. In addition, MFI powder and a blank alpha-alumina support were also investigated. Data were collected with the aid of a Synchrotron radiation facility as well as with a conventional laboratory instrument for the temperature cycle 25-500-25°C. The Rietveld method was used to determine the unit cell parameters of MFI and alpha-alumina as well as the TPA+ occupancy of MFI. The out-of- plane strain (i.e. strain in the direction perpendicular to the film surface) in the film and the support was calculated. In addition, the microstructure of the support was investigated by pattern decomposition and Williamson-Hall plots. In agreement with previous reports in the literature, it was found that the TPA-MFI structure contracts as a consequence of template removal and possibly also a structure intrinsic mechanism and the alpha-alumina support expands. Hence, a large thermal expansion mismatch occurs in the membranes during heating. An overall out- of-plane compressive strain was observed for the MFI film during heating, which indicates an in-plane tensile stress (i.e. in the direction parallel to the film surface) in the film. This result was explained by the larger expansion of the support, compared to the film. The alpha-alumina support was also found to be under an overall out-of-plane compressive strain at non-ambient temperatures, presumably due to zeolite in the pores of the support. The microstrain for the MFI coated alpha-alumina support increased during heating, and remained during cooling, which indicate the formation of structural defects in the support. Based on these results and results from earlier work, a model for crack formation was proposed: In the thick films (ca 1800 nm) studied in the present work, the crystals are well intergrown. During heating, the MFI crystals contracts and the alpha- alumina support expands. Consequently, a thermal stress develops in the composite which eventually leads to formation of cracks. In addition, part of the stress is also released via formation of structural defects in the alpha-alumina support. In thinner films (ca 500 nm), the crystals are less well intergrown and the thermal expansion mismatch between the crystals in the film and the support leads to opening of grain boundaries in the film rather than cracks.

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