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  • 701.
    Nguyen, Anh Mai
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Nguyen, Thanh Duc
    Irgum, Knut
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sizeable Macroporous Monolithic Polyamide Entities Prepared in Closed Molds by Thermally Mediated Dissolution and Phase Segregation2008Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 20, nr 19, s. 6244-6247Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A simple method is presented for the preparation of macroporous monoliths from an aliphatic polyamide in closed molds, based on swelling/dissolution in benzyl alcohol at elevated temperature, followed by precipitation into a continuous monolithic structure by cooling the solution below the upper critical solution temperature. Subsequent removal of the solvent led to the formation of rigid macroporous nylon monoliths with a continuous and evenly spaced macropore system. The intended use is as supports for flow-through systems, where efficient mass transport at low flow resistance is the key optimization criterion.

  • 702.
    Nikzad, Nadia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Optimisation of a small-scale ultrafiltration system for separation of humic substances from surface water2021Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Norrvatten är den fjärde största dricksvattenproducenten i Sverige. De producerar och distribuerar dricksvatten till 14 kommuner norr om Stockholm. Norrvatten har under en tid studerat alternativa processer för att optimera och öka produktionskapaciteten och effektiviteten i deras dricksvattenreningsverk vid Görvälnverket. 

    I detta projekt har en pilotanläggning använts för att studera och optimera ett hybridprocessteg bestående av ett koagulerings- och ultrafiltreringssteg med syfte att avlägsna humusämnen från ytvatten. Effekten av pH, reaktionstid och olika matarvattenkvaliteter (Görväln, Fyrisån och sandfiltrat) analyserades genom en serie experiment utförda med pilotanläggningen. Den mest optimala placeringen av ett eventuellt ultrafiltreringssteg i reningsprocessen studerades även.  

    Resultaten från experimenten påvisade att pH mellan 6.1 och 6.7 inte hade någon effekt på reningen av fDOM. Mer signifikanta skillnader i rening kunde observeras mellan de olika koaguleringsdoserna, vilket indikerar att denna parameter är viktigare än pH. Reaktionstiden hade ingen märkbar effekt på anläggningens reningseffektivitet. Däremot ökade transmembrantrycket tio gånger snabbare under experimenten med den kortare reaktionstiden. Dessa resultat antyder att de bildade flocken var mindre och därmed blev mer tätt packade i ultrafiltret vilket i sin tur lett till det snabbt ökande trycket i membranet. En avskiljning av minst 50 %, men inte mer än 60 %, av det ingående fDOM kunde uppnås med alla matarvatten utom sandfiltratet, som hade en reningseffektivitet på 18 %. Vattnet från Fyrisån visade sig vara en utmaning för anläggningen att hantera, då trycket snabbt byggdes upp i membranet vilket tyder på att anläggningen inte klarar för starkt förorenade vatten. Resultaten från sandfiltratexperimenten visade att ett ultrafiltreringssteg efter sandfiltren skulle kunna vara en möjlig placering av ultrafiltren. Ytterligare studier krävs dock för att med säkerhet kunna bestämma den mest optimala placeringen.  

    Sammanfattningsvis visar resultaten från experimenten lovande tecken på att en ultrafiltreringsprocess är ett möjligt alternativ för att öka Norrvattens dricksvattenreningsverks effektivitet och kapacitet.

    Fulltekst (pdf)
    fulltext
  • 703.
    Nilsson, Lars
    Luleå tekniska universitet.
    Studier av partikelemissioner vid hantering av polymera flockningskemikalier samt mätning av svavelväte vid avloppsreningsverket i Kiruna1982Rapport (Annet vitenskapelig)
  • 704.
    Niska, John
    et al.
    MEFOS, Luleå, Sweden.
    Rensgard, Anders
    MEFOS, Luleå, Sweden.
    Malmberg, Donald
    MEFOS, Luleå, Sweden.
    Combustion Control Using An IR Diode Laser2003Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Tunable diode laser absorption spectroscopy (TDLAS) is a recent development in process instrumentation. A commercial TDLAS instrument has been tested both in an industrial steel reheating furnace and in a pilot furnace at MEFOS for continuous oxygen analysis of the furnace combustion gases. Automatic control of the air-to-fuel ratio (AFR) was proven using a time-averaged oxygen concentration signal with a TDC2000 furnace controller at MEFOS. The oxygen concentrations measured by the TDLAS instrument compared well with local measurements of the oxygen concentration using a conventional zirconia probe in both furnaces. The diode laser has the advantages of high reliability for average gas concentration measurements in the path of the beam, when compared to point gas analysis with conventional zirconia instrumentation. Reliable gas analysis offers the benefits of improved process control, which for steel reheating furnaces include energy savings, reduced emissions and improved productivity.

  • 705.
    Niskanen, Kaarlo
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Lagra kol i form av trämaterial2014Annet (Annet (populærvitenskap, debatt, mm))
    Fulltekst (pdf)
    Lagra trämaterial
  • 706.
    Nobandegani, Mojtaba Sinaei
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Yu, Liang
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mayne, Benjamin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Adsorption and transport of CO2 and CH4 in CHA zeolite2019Konferansepaper (Annet vitenskapelig)
    Fulltekst (pdf)
    fulltext
  • 707.
    Nobandegani, Mojtaba
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Yu, Liang
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mass transport of CO2 over CH4 controlled by the selective surface barrier in ultra-thin CHA membranes2022Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 332, artikkel-id 111716Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The adsorption and mass transport of CO2 and CH4 in CHA zeolite were studied experimentally. First, large and well-defined CHA crystals with varying Si/Al ratios and morphologies ideal for adsorption studies were prepared. Then, adsorption isotherms were measured, and adsorption parameters were estimated from the data. In the next step, permeation experiments for pure components and mixtures were conducted for a defect-free CHA membrane with a Si/Al ratio of 80 and a thickness of 600 nm over a wide temperature range. A maximum selectivity of 243 in combination with a CO2 permeance of 70 × 10−7 mol/(m2 s Pa) was observed for a feed of an equimolar CO2/CH4 mixture at 273 K and 5.5 bar. Finally, a simple model accounting for adsorption and diffusion through the surface barriers and the interior of the pores of the membrane was fitted to the permeation data. The fitted model indicated that the surface barrier was a surface diffusion process at the pore mouth with higher activation energy than the diffusion process within the pores. The model also showed that the highly selective mass transport in the membrane was mostly a result of a selective surface barrier and, to a lesser extent, a result of adsorption selectivity.

  • 708.
    Nohlgren, Ingrid
    Luleå tekniska universitet.
    Recovery of kraft black liquor using the titanate process: kinetics of the direct causticization reaction between sodium tri-titanate and sodium carbonate1999Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The solid state reaction between sodium tri-titanate and sodium carbonate, forming mainly sodium penta-titanate, was investigated. Experiments were carried out in a micro-differential reactor made of quartz glass at various temperatures between 800°C and 880°C and in a pilot fluidized bed reactor operated in a semi-batch mode. In the micro-differential reactor, basic kinetic data was obtained by measuring the release of carbon dioxide during the reaction. Different kinetic models were considered to describe the conversion, such as the Valensi-Carter model for diffusion controlled reaction rates and the phase-boundary model for first-order reaction kinetics. Furthermore, a model that included both diffusion in the solid material and the chemical kinetics was derived. This model described the experimental data obtained in the micro-differential reactor very well. Finally, rating models describing the conversion obtained in a fluidized bed and in an entrained flow reactor were developed.

    Fulltekst (pdf)
    FULLTEXT01
  • 709.
    Nohlgren, Ingrid
    Luleå tekniska universitet.
    Recovery of kraft black liquor with direct causticization using titanates2002Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The feasibility of direct causticization of kraft black liquor using titanates has been evaluated. This has been done by studying the kinetics of the reaction between sodium tri-titanate and sodium carbonate and describing the kinetics by appropriate reaction models. Furthermore, three different chemical recovery processes have been studied from an energy point of view: the conventional kraft recovery cycle using lime, the borate causticization process (as an add-on to conventional kraft recovery process) and the titanate causticization process combined with black liquor gasification has been made. Finally the carbon and carbon species transition during black liquor pyrolysis and gasification in the presence of sodium titanium compounds was studied. The experimental studies have been carried out in three different reactors; a small scale fixed bed reactor, a fluidized bed reactor and a pressurized entrained flow reactor. In the small scale fixed bed reactor the kinetics of the direct causticization reaction between sodium tri-titanate and sodium carbonate was studied at various temperatures between 800°C and 880°C, and in pure nitrogen or in nitrogen with 0.5-5% CO2. By fitting different kinetic models to the experimental data the overall reaction rate was found to be diffusion controlled at the lower temperature and chemical reaction controlled at higher temperatures. Furthermore, this change in mechanism was seen to be influenced by the carbon dioxide concentration in the reaction atmosphere in the way that the mechanism change occurred at higher temperatures. In the semi-batch fluidized bed the direct causticization reaction was studies at temperatures between 800-825°C. Conversions of the sodium carbonate up to 88% were obtained. The fitting of different kinetic models to the experimental data showed that the overall reaction rate in this equipment was controlled by the time taken for the reactants to achieve physical contact. The studies in the pressurized entrained-flow reactor were done using both pure sodium carbonate and using black liquor solids. The experiments were carried out at 900°C, 950°C and 1000°C; at 0.5 MPa and 1 MPa; in pure nitrogen and in 2% carbon dioxide. The experimental results showed that sodium penta-titanate formation is faster with black liquor than with sodium carbonate and that the rate increases with temperature. Furthermore, carbon dioxide in the reaction gases slows down the reaction rate and no clear influence of pressure was seen on the reaction rate. Finally, the reaction rates for the direct causticization reaction between sodium tri-titanate and sodium carbonate was found to be fast enough to be carried out in an entrained flow reactor system, e.g. a Chemrec gasification system. Moreover, the char carbon was gasified both in the presence and absence of carbon dioxide. For the black liquor used in this work, the char carbon was gasified from two to four times faster in carbon dioxide than in nitrogen. Carbon was gasified faster at higher temperature in both the presence and absence of carbon dioxide. The rate of gasification was slightly faster at 0.5 MPa than at 1 MPa total pressure, both in nitrogen and in 2% carbon dioxide. CO was found to be the main carbon gas formed form the black liquor in all experiments. The comparison between the lime, borate and titanate based chemical recovery processes were made by mass and energy balances with the system defined from melted sodium carbonate to white liquor ready to be used in the digester. The lowest energy demand was found in the direct causticization process with titanates; it is only 27% of the energy demand for the other two processes.

    Fulltekst (pdf)
    FULLTEXT01
  • 710.
    Nohlgren, Ingrid
    et al.
    Luleå tekniska universitet.
    Edin, M.
    Theliander, H.
    Influence of carbon dioxide on the kinetics of the reaction between sodium carbonate and sodium trititanate2001Inngår i: Changing recovery technology to meet the challenges of the pulp and paper industry: June 11 - 14, 2001, Chateau Whistler Resort, Whistler, British Columbia, Canada: Oral presentations, Montreal: PAPTEC , 2001, s. 27-33Konferansepaper (Fagfellevurdert)
  • 711.
    Nohlgren, Ingrid
    et al.
    Luleå tekniska universitet.
    Edin, M.
    Luleå tekniska universitet.
    Theliander, Hans
    Chalmers University of Technology.
    Influence of carbon dioxide on the kinetics of the reaction between sodium carbonate and sodium trititanate2003Inngår i: Pulp & paper Canada, ISSN 0316-4004, Vol. 104, nr 1, s. 37-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of carbon dioxide on the kinetics for the reaction between sodium carbonate and sodium trititanate was studied. Experiments were carried out at four different temperatures (820-880°C) and with four different amounts of carbon dioxide (0.5-5%). The time to reach complete conversion was found to decrease with increasing temperature and increase compared to experiments in nitrogen atmosphere. The rate-determining step was determined by fitting different kinetic models to the experimental data

  • 712.
    Nohlgren, Ingrid
    et al.
    Luleå tekniska universitet. Inst. Paper Sci. Technol., Atlanta, GA, 500 10th St., NW, United States.
    Sricharoenchaikul, V.
    Sirindhorn Intl. Inst. Technol., Thammasat Univ., Pathumthani, Thailand.
    Singuefield, S.
    Inst. Paper Sci. Technol., Atlanta, GA, 500 10th St., NW, United States.
    Frederick Jr., W.J.
    Inst. Paper Sci. Technol., Atlanta, GA, 500 10th St., NW, United States; Dept. For. Prod. and Chem. Engin., Chalmers Univ. Technol., SE-41296 Gothenburg, Sweden.
    Theliander, Hans
    Dept. For. Prod. and Chem. Engin., Chalmers Univ. Technol., SE-41296 Gothenburg, Sweden.
    Black liquor gasification with direct causticization using titanates in a pressurized entrained-flow reactor: Part I: kinetics of the causticization reaction2003Inngår i: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 29, nr 4, s. 107-113Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The kinetics of the direct causticization reaction between sodium tri-titanate and sodium carbonate in a pressurized entrained-flow reactor has been studied using both pure sodium carbonate and black liquor solids. The experiments were carried out at 900, 950 and 1000°C, at pressures of 0.5 and 1 MPa, in pure nitrogen and in 2% carbon dioxide in nitrogen. The experimental results showed that sodium penta-titanate formation is faster with black liquor than with sodium carbonate, and that the rate increases with temperature. Furthermore, carbon dioxide in the reaction gases slows down the reaction rate and no clear influence of pressure was seen on the reaction rate. The reaction rates for the direct causticization reaction between sodium tri-titanate and sodium carbonate was found to be fast enough to be carried out in an entrained-flow reactor system, e.g. a Chemrec gasification system.

  • 713.
    Nohlgren, Ingrid
    et al.
    Luleå tekniska universitet. Energitekniskt Centrum i Piteå, SE-94128 Piteå, PO Box 726, Sweden.
    Sricharoenchaikul, V.
    Inst. Paper Sci. Technol., Atlanta, GA 30318-5794, 500 10th St., NW, United States; Sirindhorn Intl. Inst. Technol., Thammasat Univ., Pathumthani, Thailand.
    Singuefield, S.
    Inst. Paper Sci. Technol., Atlanta, GA 30318-5794, 500 10th St., NW, United States.
    Theliander, Hans
    Chalmers Univ. Technol., Dept. Forest Prod. Chem. Engin., SE-41296 Gothenburg, Sweden.
    Frederick Jr., W.J.
    Inst. Paper Sci. Technol., Atlanta, GA 30318-5794, 500 10th St., NW, United States.
    Black liquor gasification with direct causticization using titanates in a pressurized entrained-flow reactor: Part II: carbon and carbon species transitions2003Inngår i: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 29, nr 10, s. 348-355Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Experiments on black liquor conversion in the presence of sodium titanates were carried out in a pressurized entrained-flow reactor, at temperatures of 900, 950 and 1000°C, at pressures of 0.5 and 1 MPa and in atmospheres of pure nitrogen (N2) or N2 with 2% carbon dioxide (CO2). Up to 80-90% conversion of the carbon in black liquor to gases was obtained within 5 s at these conditions. This is a very promising result for industrial scale gasifiers. Char carbon was gasified two to four times faster in N2 with 2% CO2 than in N2 alone. Overall, carbon conversion increased with increasing temperature, but the gasification rate decreased with increasing temperature. CO was found to be the main carbon-containing gas formed.

  • 714.
    Nohlgren, Ingrid
    et al.
    Luleå tekniska universitet.
    Theliander, Hans
    Zhuang, Qianlin
    Dr. Jack McKenzie Limerick Pulp and Paper Research and Education Centre, University of New Brunswick.
    van Heiningen, Adriaan R.P
    Dr. Jack McKenzie Limerick Pulp and Paper Research and Education Centre, University of New Brunswick.
    Model study of the direct causticization reaction between sodium trititanate and sodium carbonate2000Inngår i: Canadian Journal of Chemical Engineering, ISSN 0008-4034, E-ISSN 1939-019X, Vol. 78, nr 3, s. 529-539Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The solid state reaction between sodium trititanate and sodium carbonate, forming mainly sodium pentatitanate, was investigated. Experiments were carried out in a micro-differential reactor made of quartz glass at various temperatures between 800 and 880°C and in a pilot fluidized bed reactor operated in a semi-batch mode. In the former reactor, basic kinetic data was obtained by measuring the release of carbon dioxide. Different kinetic models were considered to describe the conversion, such as the Valensi-Carter model for diffusion controlled reaction rates and the phase-boundary model for first-order reaction kinetics. Furthermore, a model that included both diffusion in the solid material and the chemical kinetics was derived. This model described the experimental data obtained in the micro-differential reactor very well. However, for the fluidised bed experiments, these different kinetic models did not accurately describe the experimental data. Therefore, an improved model was developed, which also took into account the time taken for the reactants to achieve physical contact. This model gave good agreement with the experimental data.

  • 715.
    Nohlgren, Ingrid
    et al.
    Luleå tekniska universitet.
    Zhuang, Qianlin
    Theliander, Hans
    van Heiningen, Adriaan
    Direct causticization using titanates in a fluidized bed reactor2002Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 17, nr 3, s. 246-253Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Experiments were carried out in a fluidized bed reactor operated in a semi-batch mode using TiO2 or sodium trititanate to causticize either sodium carbonate or the sodium carbonate in kraft black liquor at temperatures between 800-825°C. Conversions of sodium carbonate of up to 88% were obtained, with the main product being sodium penta-titanate. Sodium hexatitanate and sodium tri-titanate are reaction intermediates formed when TiO2 is used. The BET surface area of the reacted solids decreased with increasing formation of sodium penta-titanate. Upon leaching of the final product, the surface area is regained. The high surface area of the leached material allows for good mixing with black liquor when the solids are recycled to the reactor. EDX analysis along the cross-section of TiO2 particles showed that sodium diffuses into the TiO2 particle, forming a very sharp front. This indicates that the direct causticization reaction proceeds according to the shrinking-core model, i.e. the reaction at the reaction front is fast compared to the diffusion of Na2CO3 into the reaction interface

  • 716.
    Nookuea, Worrada
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Zambrano, Jesús
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Tan, Yuting
    Royal Institute of Technology, Sweden.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Thorin, Eva
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Institute of Technology, Stockholm, Sweden.
    Comparison of Mass Transfer Models on Rate-Based Simulations of CO2 Absorption and Desorption Processes2017Inngår i: Energy Procedia, ISSN 1876-6102, Vol. 142, s. 3747-3752Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One of the keys available options for the large scale carbon capture and storage is the solvent-based post-combustion capture. Due to the high reactivity between CO2 and aqueous amine solutions, chemical absorption is suitable for capturing the CO2 at low concentration such as from the flue gas. From techno-economic analyses of the CO2 chemical absorption plant, absorber and desorber columns are the main cost of the purchased equipment. Since the process involves complex reactive separations, the accurate calculation of hydrodynamic properties, mass and energy transfer are of importance for the design of the columns. Several studies have been done on the impact of different process and property models on the equilibrium and rate-based simulation of the absorption site. However, the impact study of process and property models on the desorption site are still lacking. This paper performs rate-based simulations of CO2 absorption by Monoethanolamine. The software Aspen Plus was used for the simulations. Different mass transfer models were implemented for the mass transfer calculation in gas and liquid phases. The temperature and concentration profiles along the columns are reported and discussed.

  • 717.
    Nordgreen, Thomas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Metallic iron: potential to function as tar breakdown catalyst in waste gasification2005Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 718.
    Nordgreen, Thomas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Liliedahl, Truls
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Sjöström, Krister
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Elemental iron as a tar breakdown catalyst in conjunction with atmospheric fluidized bed gasification of biomass: A thermodynamic study2006Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 20, nr 3, s. 890-895Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Metallic iron as a catalyst for tar cracking in biomass gasification has been investigated. Based on previous studies showing that iron must be in its elemental form to catalyze the tar breakdown reactions, thermodynamic calculations suggest the existence of an operating window where iron is neither oxidized nor contaminated by carbon deposits. A straightforward biomass gasification model has been derived and used in conjunction with thermodynamics for making plots that illustrate the mentioned operating window, which is achievable under real conditions. Experiments made under these specific calculated conditions confirm that elemental iron effectively acts as a tar breakdown catalyst, resulting in an improved gas yield and a decrease in tar concentration. The desired operating window is governed mainly by adjusting the oxygen input (i.e., the equivalence ratio) and the temperature.

  • 719.
    Nordgreen, Thomas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Liliedahl, Truls
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Sjöström, Krister
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Metallic iron as a tar breakdown catalyst related to atmospheric, fluidised bed gasification of biomass2006Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 85, nr 06-maj, s. 689-694Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tar formation is a major drawback when biomass is converted in a gasifier to obtain gas aimed for utilisation in power production plants or for production of chemicals. Catalytic cracking is an efficient method to diminish the tar content in the gas mixture. In this study, the capability of metallic iron and iron oxides to catalytically crack tars has been experimentally examined. To obtain metallic iron, small grains of hematite (Fe2O3) were placed in a secondary reactor downstream the gasifier and reduced in situ prior to catalytic operation. The fuel used in the atmospheric fluidised bed gasifier was Swedish birch with a moisture content of approximately 7 wt%. The influence of temperature in the range 700-900 degrees C and), values (i.e. equivalence ratio, ER) between 0 and 0.20 have been investigated. In essence, the results show that raising the temperature in the catalytic bed to approximately 900 degrees C yields almost 100% tar breakdown. Moreover, increasing the). value also improves the overall tar cracking activity. The iron oxides did not demonstrate any catalytic activity.

  • 720.
    Nordstrand, Johan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Material- och nanofysik. Stanford Univ, Dept Chem, Stanford, CA 94305 USA..
    Dutta, Joydeep
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Material- och nanofysik.
    Potential-driven mechanisms for raising the intercalation selectivity 100-fold in multi-ion removal from water2023Inngår i: Desalination, ISSN 0011-9164, E-ISSN 1873-4464, Vol. 565, artikkel-id 116865Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Intercalation host compounds (IHC) are promising for selective ion removal from water. Recent theoretical developments have suggested that electrochemical desalination with IHC (nickel hexacyanoferrate (NiHCF)) electrodes could separate K+ and Na+ by a factor of 160. However, the experiments only produce a selectivity of around 3. In this work, we derive theory and a finite-element (FEM) model to investigate the origins of time-dependent selectivity suppression. The first results show that ion starvation can severely limit selectivity. Surprisingly, we also find that operations at low state-of-charge produce theoretical selectivity of 600, which is way above what was previously thought to be the theoretical maximum. Also surprising is that the main cause of low selectivity is that the constant-current overpotential disproportionally favors the adsorption of the ion that is less selected in the equilibrium state. By implementing short charging cycles near the depleted state with rest periods at the ends, we raised the time-dependent selectivity from 3 to 450. Even higher output selectivity could be achieved by combining IHC cathodes with membrane-less carbon anodes. In conclusion, the insights and methods derived here could enable highly selective ion removal at the device level for a wide class of IHC materials.

  • 721.
    Nordström, Peter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Minimizing Liquid Waste in Peptide Synthesis: A New Application for the Rotating Bed Reactor2021Independent thesis Advanced level (professional degree), 300 hpOppgave
    Abstract [en]

    Peptide drugs are used to treat a broad spectrum of diseases such as cancer and HIV and have many more promising applications, such as new vaccines against SARS-CoV-2. The most popular manufacturing method for peptides is solid-phase peptide synthesis (SPPS). The main drawback of SPPS is that it is a costly and wasteful process. 

    SpinChem is a company that provides technology solutions for chemical processes. Recently, SpinChem has started investigating if their Rotating Bed Reactor (RBR) is suitable for peptide synthesis. The goal of this project is to investigate how the RBR can make processes like SPPS more resource-efficient. The idea is that the RBR-system can maximize the solid-phase to liquid ratio (STL). The STL is the ratio of the volume of solid-phase material and the volume of liquid. By maximizing the STL, it is possible to manufacture peptides using less solvents and chemicals. The main quest of the project is formulated into a single question: 

    How does a high STL affect the efficiency of the RBR-system? 

    To answer the question, Minitab's statistical software and design of experiments (DOE) will be used to plan and perform experiments in both lab- and industrial scales. DOE factorial experiments are used to gain as much information as possible about the new RBR-system. The results are analyzed and summarized to make a solid foundation for the continued work on the new RBR application. 

    Peptide synthesis efficiency in the RBR-system is measured using ionic adsorption. The ionic adsorption rate is measured in both lab-scale and industrial-scale experiments. In the lab-scale experiments, the decrease of ions was on average 86,5% after just 15 s with an average STL of 0,936. The industrial-scale experiments showed a similar result where the average decrease in ions was 92,9% after 20 s with an average STL of 0,947. It was concluded that the RBR-system can reduce the consumption of washing-solvent in SPPS by up to 82%.

    Fulltekst (pdf)
    Minimizing_Liquid_Waste_in_Peptide_Synthesis
  • 722. Norheim, Arnstein
    et al.
    Waernhus, Ivar
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Hustad, Johan E.
    Vik, Arild
    Experimental Studies on the Influence of H2S on Solid Oxide Fuel Cell Performance at 800 °C2007Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 21, nr 2, s. 1098-1101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Short-term tests showing the influence sulfur has on solid oxide fuel cell (SOFC) performance have been performed. The experiments were performed using two single-cell SOFC setups operated at 800 degrees C. In setup I, sulfur (H2S) was mixed into the fuel gas in concentrations ranging from 20 to 100 ppm. It was found that the performance decreased with increasing sulfur concentration up to 80 ppm. The performance loss at 80 and 100 ppm sulfur was equal. At a current density of 200 mA cm(-2), the operating voltage was reduced from 0.810 V at 0 ppm H2S to 0.790 V at 100 ppm H2S, corresponding to an increase in the area-specific cell resistivity (ASR) of 0.10 Omega cm(2). In setup II, sulfur levels of 80, 120, and 240 ppm were introduced. In all these three cases the ASR increased by around 0.13 Omega cm(2). Removing the sulfur impurity when the 240 ppm H2S exposure test was finished the cell performance fully recovered, indicating no irreversible changes in the cell structure.

  • 723.
    Nurdiawati, A.
    et al.
    Japan.
    Zaini, Ilman Nuran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Aziz, M.
    Japan.
    Efficient hydrogen production from algae and its conversion to methylcyclohexane2018Inngår i: Chemical Engineering Transactions, ISSN 1974-9791, E-ISSN 2283-9216, Vol. 70, s. 1507-1512Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Herein, the supercritical water gasification (SCWG) of microalgae combined with syngas chemical looping (SCL) for H2 production and storage employing liquid organic H2 carrier (LOHC) system have been proposed and analysed in terms of energy efficiency. Microalgae are converted to syngas in the SCWG module and then introduced into the SCL module to produce high-purity of H2 and a separated CO2 stream. H2 storage is achieved via the hydrogenation reaction using toluene to produce methylcyclohexane (MCH). The heat released from the exothermic hydrogenation reaction is exploited to generate steam for sustaining the SCWG reaction. Simulations were performed using Aspen Plus™ considering the feed concentration and SCWG temperature as the system variables. The simulation results show that the SCWG reaction can be energetically self-sustained using the proposed configuration. Based on the process modelling and calculations, the proposed integrated system exhibited of approximately 13.3 %, 42.5 %, and 55.8 % for power generation, H2 production, and total energy efficiency.

  • 724.
    Nyberg, Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Minami, Ichiro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Additives to Improve Tribological Properties of Ionic Liquid as Base Fluids2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Room temperature ionic liquids (RTILs) have several properties which make them interesting candidates as base fluids for extreme conditions. However, a lack of compatibility with tribo-improving additives combined with an often overly aggressive nature is limiting their use as base fluids. To overcome these drawbacks, hydrocarbon-imitating RTIL base fluids have recently been developed. These lubricants aim for a more balanced interaction with metal surfaces while enabling compatibility with common additives, so that the reactivity with the lubricated surface can be tuned in a manner similar to hydrocarbon base oil–additive systems. In this work, the effects of several common additives in the novel RTIL were examined by laboratory tribotesting. Surface analysis was performed in order to study the lubrication mechanisms.

  • 725.
    Nyberg, Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Minami, Ichiro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Formation of Boundary Film from Ionic Liquids Enhanced by Additives2017Inngår i: Applied Sciences, E-ISSN 2076-3417, Vol. 7, nr 5, artikkel-id 433Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Room temperature ionic liquids (RTILs) have several properties that make them interesting candidates as base fluids for extreme conditions. However, a lack of compatibility with tribo-improving additives combined with an often overly aggressive nature is limiting their use as base fluids. To overcome these drawbacks, hydrocarbon-imitating RTIL base fluids have recently been developed. In this study, the effects of several common additives in the novel RTIL (P-SiSO) were examined by laboratory tribotesting. A reciprocating steel-steel ball-on-flat setup in an air atmosphere was used, where the lubricant performance was evaluated over a range of loads and temperatures. Surface analyses after testing were carried out using optical profilometry, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Neat P-SiSO displayed high performance in the tribotests. At an elevated load and temperature, a shift in lubrication mode was observed with an accompanying increase in friction and wear. Surface analysis revealed a boundary film rich in Si and O in the primary lubrication mode, while P was detected after a shift to the secondary lubrication mode. An amine additive was effective in reducing wear and friction under harsh conditions. The amine was determined to increase formation of the protective Si–O film, presumably by enhancing the anion activity.

    Fulltekst (pdf)
    fulltext
  • 726. Obeso, Juan L.
    et al.
    Flores, J. Gabriel
    Flores, Catalina V.
    Rios-Escobedo, Reyna
    Aguilar-Pliego, Julia
    Inge, A. Ken
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    de los Reyes, José Antonio
    Peralta, Ricardo A.
    Ibarra, Ilich A.
    Leyva, Carolina
    Lewis Acid-Catalyzed Ring-Opening Alcoholysis of Cyclohexene Oxide: The Role of Open Metal Sites in the Bi(III)-based Metal-Organic Framework SU-1012023Inngår i: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 15, nr 13, artikkel-id e202300471Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    SU-101 was screened for the acid-catalyzed ring-opening alcoholysis of cyclohexene oxide. Results indicated access to open metal sites within SU-101, a fundamental requirement (Lewis acid Bi+3 sites) for this reaction. In addition, SU-101 exhibited high chemical stability, demonstrated by retaining its crystalline structure after the reaction. The cyclohexene conversion was estimated to be 99.8, 96.8, and 14.3 % at 40 °C for methanol, ethanol, and propanol, respectively. Also, SU-101 demonstrated an outstanding catalytic cyclability performance for five cycles without losing catalytic activity. 

  • 727.
    Ohlin, Lindsay
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Adsorption of water, carbon dioxide and methane in zeolite ZSM-5 studied using in-situ ATR-FTIR spectroscopy2013Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Global warming is believed to be caused by the extensive emission of greenhouse gases, such as carbon dioxide, into the atmosphere by combustion of fossil fuels, such as coal, oil and natural gas.To reduce the emission of carbon dioxide and hence avoid global warming, alternative fuels derived from renewable resources are desired. Another reason for the worldwide interest in finding alternative fuels is that the reserves of the fossile fuels are limited and the oil and gas resources will eventually run out.Biogas and natural gas are interesting alternatives with no or at least reduced emission of fossil carbon dioxide to the atmosphere as compared to coal and oil. Both gases mainly consist of methane (60–95%) but may also contain a large fraction of carbon dioxide and water. Removal of carbon dioxide and water from biogas and natural gas is of great importance mainly to lower the transportation costs and to increase the heat value of the gas. The most commonly used separation technique is amine absorption. This is an expensive and complex process and alternative techniques are desired. Zeolites are an interesting alternative due to their great potential both as selective adsorbents and membranes. Due to the unique pore structure zeolites are capable of separating species in a mixture based on the molecule size and adsorption properties. Since water, carbon dioxide and methane all have a molecular size smaller than the pore size of the zeolite ZSM-5 studied in the present work, the molecules can enter and adsorb in the pores and hence the separation is based on adsorption rather than size.In the present work, the single component adsorption of water, carbon dioxide and methane in zeolite ZSM-5 was studied using in-situ Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy and the method was successfully further used to study multicomponent adsorption in zeolites.For single gas adsorption experiments, recorded infrared spectra of adsorbed water, carbon dioxide and methane showed characteristic well separated bands for each gas. Adsorbed concentrations of water, carbon dioxide and methane were determined from the recorded infrared spectra. For single gas experiments, the Langmuir model was fitted to the adsorption isotherms and the model matched the experimental data very well. The fitted Langmuir parameters obtained in the present work showed good agreement with values reported in the literature.For multicomponent adsorption experiments, the Ideal Adsorbed Solution Theory (IAST) was used to predict the adsorbed concentrations of water, carbon dioxide and methane using the single component adsorption isotherm parameters as input. The IAST accurately predicted the adsorbed concentrations of both carbon dioxide and methane when adsorbed from binary mixtures. Internary mixtures, also including water, the IAST accurately predicted the adsorbed concentration of methane, however it severely underestimated the adsorbed concentration of carbon dioxide.The latter is probably an effect of a non-ideal behavior of carbon dioxide in the presence of water.The CO2/CH4 adsorption selectivity was determined for various gas compositions and temperatures showing a general increase in the selectivity with decreasing temperature, which is related to the higher heat of adsorption of carbon dioxide. This indicates that the separation of carbon dioxide from biogas and natural gas should be more efficient at lower temperatures. Compared to the literature, the selectivity observed in the present work is relatively high indicating that low silica Na-ZSN-5 may be an effective membrane material.

    Fulltekst (pdf)
    FULLTEXT01
  • 728.
    Ohlin, Lindsay
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    An in-situ ATR-FTIR Spectroscopy Study of Adsorption in MFI Zeolites: A step towards effective upgrading of biofuels2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Global warming is believed to be caused by the extensive emission of greenhouse gases, for example carbon dioxide, into the atmosphere by combustion of fossil fuels, such as coal, oil and natural gas. To reduce the emission of carbon dioxide and hence avoid global warming, alternative fuels derived from renewable resources are desired. Another reason for the worldwide interest in finding alternative fuels is that the reserves of the fossil fuels are limited and the oil and gas sources will eventually run out. Biogas and biobutanol are renewable biofuels which are interesting alternatives to fossil fuels. Biogas is produced during degradation of organic material forming a mixture of mainly methane and carbon dioxide with water as a common trace component. Biobutanol is produced from ABE (acetone, butanol and ethanol) fermentation of biomass. Purification of biogas and biobutanol is essential to increase the heat value of the fuels. Traditional purification processes are energy demanding and expensive. Therefore, other separation processes are currently sought for. Zeolites are promising alternatives due to their great potential both as selective adsorbents and as membranes. Due to the unique pore structure, zeolites are capable of separating components based on their adsorption properties. In the present work, single component adsorption of biogas components such as methane, carbon dioxide and water in zeolite ZSM-5 was studied as well as adsorption of water and butanol in silicalite-1 using in-situ ATR-FTIR spectroscopy. The method was successfully further used to study multicomponent adsorption. For single gas adsorption experiments, recorded infrared spectra of adsorbed methane, carbon dioxide and water showed characteristic, well separated, bands for each gas. Adsorbed concentrations were determined from the recorded infrared spectra. The Langmuir model was fitted to the adsorption isotherms and the model matched the experimental data very well. The fitted Langmuir parameters obtained in the present work was in agreement with values reported in the literature. For multicomponent adsorption experiments, the Ideal Adsorbed Solution Theory (IAST) was used to predict the adsorbed concentrations of methane, carbon dioxide and water using the single component adsorption isotherm parameters as input. In general, the IAST was shown to be a fairly good model for predicting the adsorbed concentrations of methane and carbon dioxide from binary mixtures. For the amount of adsorbed methane from mixtures including water, the IAST predicted the values fairly well. However, for mixtures containing water and carbon dioxide, the IAST could not fully describe the adsorption behavior of the two components. The CO2/CH4 adsorption selectivity was determined for various gas compositions and temperatures showing a general increase in the selectivity with decreasing temperature. This indicates that the separation of carbon dioxide from biogas should be more efficient at lower temperatures. Compared to the literature, the selectivity observed in the present work is relatively high indicating that Na-ZSM-5 may be an effective membrane material for upgrading biogas. Moreover, butanol was preferentially adsorbed over water in silicalite-1, indicating that silicalite-1 may be a promising material for recovery of butanol from dilute water solutions.

    Fulltekst (pdf)
    FULLTEXT01
  • 729.
    Ohlin, Lindsay
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Bazin, Philippe
    Laboratoire Catalyse and Spectrochimie, CNRS-ENSICAEN-Université de Caen, 6 Boulevard Marechal Juin, Caen Cedex 14050, France.
    Thibault-Starzyk, Frederic
    Laboratoire Catalyse and Spectrochimie, CNRS-ENSICAEN-Université de Caen, 6 Boulevard Marechal Juin, Caen Cedex 14050, France.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Adsorption of CO2, CH4, and H2O in zeolite ZSM-5 studied using in situ ATR-FTIR spectroscopy2013Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, nr 33, s. 16972-16982Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biogas and natural gas are interesting fuels with high H/C ratio. However, these gases frequently contain carbon dioxide and water which lowers the heat value of the gas and may induce corrosion. Therefore, the development of more efficient processes, such as membrane processes and improved adsorbents, for the separation of carbon dioxide and water from biogas and natural gas is of great importance. Zeolite ZSM-5 membranes are promising for this separation which is controlled by the adsorption and diffusion of the different species in the zeolite. Multicomponent adsorption data are therefore required for development of new membrane and adsorption processes. In the present work, the adsorption of water, carbon dioxide, and methane in a Na-ZSM-5 zeolite film at various temperatures was studied by in situ Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy for the first time. Adsorption isotherms were retrieved from the experimental data and the Langmuir model fitted the isotherms very well. Limiting heat of adsorption was determined from the Henrýs law regime and the values determined agreed well with previously reported data. A few experiments were conducted with multicomponent mixtures and the experimentally determined amounts adsorbed were compared with values predicted by the Ideal Adsorbed Solution Theory (IAST). It was found that for the binary mixture of carbon dioxide and methane there was good agreement between the experimental values and those predicted by the IAST. However, when water was also introduced, the IAST could not fully capture the adsorption behavior of the multicomponent mixture, probably because the adsorbed phase is not ideal. These findings are in line with previous reports for adsorption in zeolites. The multicomponent adsorption behavior of this system will be further investigated in forthcoming work.

  • 730.
    Ohlin, Lindsay
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Berezovsky, Vladimir
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Öberg, Sven
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Farzaneh, Amirfarrokh
    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.
    Effect of Water on the Adsorption of Methane and Carbon Dioxide in Zeolite Na-ZSM-5 Studied Using in Situ ATR-FTIR Spectroscopy2016Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, nr 51, s. 29144-29152Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Methane is the main component in biogas and natural gas along with contaminants such as water and carbon dioxide. Separation of methane from these contaminants is therefore an important step in the upgrading process. Zeolite adsorbents and zeolite membranes have great potential to be cost-efficient candidates for upgrading biogas and natural gas, and in both of these applications, knowing the nature of the competitive adsorption is of great importance to further develop the properties of the zeolite materials. The binary adsorption of methane and carbon dioxide in zeolites has been studied to some extent, but the influence of water has been much less studied. In the present work, in situ ATR (attenuated total reflection)–FTIR (Fourier transform infrared) spectroscopy was used to study the adsorption of water/methane and water/carbon dioxide from binary mixtures in a high-silica Na-ZSM-5 zeolite film at various gas compositions and temperatures. Adsorbed concentrations for all species were determined from the recorded IR spectra, and the experimental values were compared to values predicted using the ideal adsorbed solution theory (IAST). At lower temperatures (35, 50, and 85 °C), the IAST was able to predict the binary adsorption of water and methane, whereas the values predicted by the IAST deviated from the experimental data at the highest temperature (120 °C). For the binary adsorption of water and carbon dioxide, the IAST could not predict the adsorption values accurately. This discrepancy was assigned to the particular adsorption behavior of water in high-silica MFI forming clusters at hydrophilic sites. However, the predicted values did follow the same trend as the experimental values. The adsorption selectivity was determined, and it was found that the H2O/CH4 adsorption selectivity was decreasing with increasing water content in the gas phase at low temperatures whereas the selectivity was increasing at higher temperatures. The H2O/CO2 adsorption selectivity was increasing with increasing water content at all temperatures.

  • 731.
    Ohlin, Lindsay
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Farzaneh, Amirfarrokh
    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.
    Ternary Adsorption of Methane, Water and Carbon Dioxide in Zeolite Na-ZSM-5 Studied Using in Situ ATR-FTIR Spectroscopy2017Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, nr 27, s. 14703-14711Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main component in biogas and natural gas is methane but these gases also contain water and carbon dioxide that often have to be removed in order to increase the calorific value of the gas. Membrane and adsorbent-based technologies using zeolites are interesting alternatives for efficient separation of these components. To develop efficient processes, it is essential to know the adsorption properties of the zeolite. In the present work, adsorption of methane, carbon dioxide and water from ternary mixtures in high silica zeolite Na-ZSM-5 was studied using in-situ ATR (Attenuated Total Reflection) – FTIR (Fourier Transform Infrared) spectroscopy. Adsorbed concentrations were extracted from the infrared spectra and the obtained loadings were compared to values predicted by the Ideal Adsorbed Solution Theory (IAST). The IAST could not fully capture the adsorption behavior of this ternary mixture, indicating that the adsorbed phase is not behaving as an ideal mixture. The CO2/CH4 adsorption selectivities determined for the ternary mixtures were compared to selectivities determined for binary mixtures in our previous work, indicating that the presence of water slightly improves the CO2/CH4 adsorption selectivity at lower temperatures. Further, the results show that water and carbon dioxide are adsorbed preferentially over methane in high silica zeolite Na-ZSM-5.

  • 732.
    Ohlin, Lindsay
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Detailed Investigation of the Binary Adsorption of Carbon Dioxide and Methane in Zeolite Na-ZSM-5 Studied Using in Situ ATR-FTIR Spectroscopy2014Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, nr 12, s. 6207-6213Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The separation of carbon dioxide from methane is an important process when purifying biogas and natural gas. Zeolite membranes and adsorbents are among the technologies suggested for efficient separation of carbon dioxide from these gases. In the present work, the adsorption of carbon dioxide and methane from binary mixtures in a low alumina Na-ZSM-5 zeolite film at various gas compositions and temperatures was studied using in situ ATR-FTIR (attenuated total reflection Fourier transform infrared) spectroscopy. Adsorbed concentrations were successfully extracted from infrared spectra. The experimental values of the adsorbed phase mole fraction of carbon dioxide and methane were compared to values predicted using the ideal adsorbed solution theory (IAST). The values predicted with the IAST agreed very well with values determined experimentally. The CO2/CH4 adsorption selectivity was determined, and at 35 °C a selectivity of 15.4 was obtained for an equimolar gas mixture. At the highest (0.9) and lowest (0.03) investigated mole fractions of carbon dioxide in the gas phase, the selectivity was higher compared to the other investigated mole fractions. At 35 °C the highest observed selectivity values were 31.1 and 20.4 for the highest and the lowest adsorbed mole fraction, respectively. At compositions closest to those found in biogas and natural gas, there was a decrease in the selectivity at higher temperatures, indicating that separation of carbon dioxide from methane in biogas and natural gas may be more efficient at low temperatures

  • 733.
    Ohlsson, Lars-Ola
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Karlsson, Sebastian
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Framtidens substrat?: En tvåstegsprocess för rötning av alger och vass i pilotskala2017Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Detta arbete är en delstudie i projektet

    Seafarm. Syftet med denna studie är att utreda om algen Laminaria Digitata och vassen Phragmites Australis är lämpliga substrat i en samrötningsprocess för biogasproduktion. Metoden som användes är experimentell och utfördes under 35 dagar med en tvåstegsreaktor bestående av en lakbädd och en UASB-reaktor. Under försökets gång upptäcktes vissa fel och brister hos apparatuppställningen vilka orsakade läckage och andra brister. Detta resulterade i ett systemförslag med skiss till en ny lakbädd samt optimering av driftparametrar om försöket ska återupprepas.

    Efter 35 dagar avslutades försöket och utifrån den data som sammanställts uppvisar processen en bra metanpotential på 589 liter CH

    4/kg COD. Processen uppvisade en låg alkalinitet med ett sjunkande pH som till följd av inmatning. Detta var grunden för den låga belastningen som processen klarade av. För framtida försök för just dessa substrat så rekommenderas en tillförsel av buffert så att alkaliniteten ökar och även möjligheterna för en högre belastning.

    Fulltekst (pdf)
    fulltext
  • 734. Olofsson, Ingemar
    et al.
    Strandberg, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Pommer, Linda
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Nordin, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Oxygen enhanced torrefaction - An initial feasibility studyManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Upcoming world market prices on thermally treated and densified biomass to be feasible for coal replacement put a high demand on the process suppliers to deliver cost efficient and high energy yield conversion systems with a capacity to produce a high quality product. One of the more complex and vital parts in a torrefaction facility is the indirect or direct heat transfer system applied. This is a critical task that also may limit the scale-up potential and thus influence the economy of scale of a complete torrefaction system.

    In the present study, it was demonstrated that the torrefaction reactions in a rotary drum pilot reactor (20 kgDS/h) potentially may be operated autothermally by a low level injection of air directly into the reactor for controlled in-situ partial combustion of the released torrefaction gases. Both concurrent and countercurrent gas flow patterns were evaluated for different process temperatures. At higher temperatures (338°C) in countercurrent gas flow mode, steady-state torrefaction was reached without external heat supply. The resulting torrefied biomass had higher heating value, higher carbon content and lower milling energy consumption, compared to non-oxidative torrefied biomass with same mass yield. Condensation of torrefaction gas compounds is a suggested reason.No significant decrease in the combustibility of the torrefaction gas was experienced.  The demonstrated Oxygen Enhanced Torrefaction (OET) mode thus has the potential to improve the torrefaction systems in terms of scale-up performance with reduced investment and operational costs but further validation work is needed to confirm the present findings and also to identify working conditions.

  • 735.
    Olsson, Johanna
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Fuel dispersion and bubble flow distribution in fluidized beds2011Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Fluidized bed technology is used for thermal conversion of solid fuels (combustion and gasification) and is especially suitable for conversion of low-rank fuels such as biomass and waste. The performance of fluidized bed units depends on the fuel mixing and fuel-gas contact. Thus, it is important to understand these two phenomena in order to develop models for reliable design and scale up of fluidized bed units. This work investigates, under conditions representative for industrial fluidized bed units, the lateral fuel mixing (in a unit with a cross section of 1.44 m2 both at hot and cold conditions) and the bubble flow distribution (in a 1.2 m-wide 2-dimensional unit). The work confirms previous findings on the formation of preferred bubble paths and shows that these bubble paths are enhanced by lowering the fluidization velocity, increasing the dense bed height and reducing the pressure drop across the gas distributor. From the fuel mixing experiments, an estimation of the lateral effective dispersion coefficient to values in the order of 10-3 m2/s is obtained under both hot and cold conditions. The experiments under cold conditions give additional qualitative information on the fuel mixing patterns such as flotsam/jetsam tendencies. The camera probe developed for fuel tracking under hot conditions enables to study the fuel dispersion under real operation at relevant industrial scales. Based on the characteristics of the bubble path flow, a model for the horizontal fuel dispersion on a macroscopic scale is formulated and shown to be able to give a good description of the experimental data. As opposed to the commonly applied diffusion-type modeling of the lateral solids dispersion, the proposed model facilitates integration with models of the bubble flow. Thus, the present modeling work is a first step to provide a modeling of the fuel dispersion, which uses as inputs only the main operational parameters of the fluidized bed.

    Fulltekst (pdf)
    fulltext
  • 736.
    Olsson, Robert
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    van Stam, Jan
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Lestelius, Magnus
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Imbibition into model calcium carbonate coatings of fluids with different dipole moments2006Inngår i: Appita journal, ISSN 1038-6807, Vol. 59, nr 6, s. 471-485Artikkel i tidsskrift (Fagfellevurdert)
  • 737.
    Osadolor, Osagie Alex
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Nair, Ramkumar B
    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.
    Effect of media rheology and bioreactor hydrodynamics on filamentous fungi fermentation of lignocellulosic and starch-based substrates under pseudoplastic flow conditions2018Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 263, s. 250-257Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this work was to study how media rheology and bioreactor hydrodynamics would influence fermentation of lignocellulosic and starch-based substrates under pseudoplastic flow conditions. This was investigated using hydrolyzed wheat straw, wheat-based thin stillage and filamentous fungi as inoculum in bubble column, airlift and horizontal hybrid tubular/bubble column (textile bioreactor) bioreactors. The rheological models showed that the consistency index was dependent on biomass growth (R2 0.99) while the flow behavior index depended on biomass growth and suspended solid (R2 0.99). Oxygen transfer rate above 0.356 mmol-O2/L/h was needed for growing fungi with a cube-root growth rate constant of 0.03 g1/3/L1/3/h. At 1.4 VVM aeration the textile bioreactor performed better than others with minimal foaming, yields of 0.22 ± 0.01 g/g and 0.47 ± 0.01 g/g for ethanol and biomass, substrate consumption rate of 0.38 g/L/h. Operating the bioreactors with air-flowrate to cross-sectional area ratio of 8.75 × 10−3 (m3/s/m2) or more led to sustained foaming.

  • 738.
    Owusu-Agyeman, Isaac
    et al.
    Karlsruhe Institute of Technology (KIT), Germany.
    Jeihanipour, Azam
    Luxbacher, Thomas
    Schäfer, Andrea Iris
    Implications of humic acid, inorganic carbon and speciation on fluoride retention mechanisms in nanofiltration and reverse osmosis2017Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 528, s. 82-94Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The impact of pH and humic acid (HA) on the retention of fluoride (F) and inorganic carbon (IC) by nanofiltration (NF) and reverse osmosis (RO) membranes was determined. Synthetic waters were prepared using realistic ranges of F, IC and HA for carbonaceous waters found for example in the fluoride rich waters in Tanzania. These waters were filtered using NF270 and BW30 membranes to determine retention mechanisms. IC changes speciation with pH. The dominant species at pH < 6, 6-10 and > 10 are H2CO3, HCO3 and CO32- respectively. This results in changes in charge and size of the hydrated ion radius. The mechanism for IC retention by the NF270 and BW30 membranes are charge repulsion and size exclusion, respectively. F retention increases with pH. IC influenced F retention at pH > 10 where IC exists as divalent CO32- and is retained more easily than the monovalent F. HA enhances the retention of F by NF/RO membranes under certain conditions. The enhancement effect is more pronounced at neutral than at acidic pH and basic pH. The mechanism for the enhancement is attributed to the change in surface charge of the membranes by adsorption of HA. At high HA concentration the F retention enhancement is annulled by deposit formation on the membrane. The results obtained in this study indicate the complexity of retention in real surface- and ground waters that can alter significantly in pH as well as IC and HA content. The research is situated in the context of developing membrane technologies for autonomous systems in remote locations where water quality is variable and mechanisms of membrane performance are poorly understood.

  • 739.
    Owusu-Agyeman, Isaac
    et al.
    Karlsruhe Institute of Technology (KIT), Germany.
    Shen, J
    Schäfer, Andrea Iris
    Renewable energy powered membrane technology: Impact of pH and ionic strength on fluoride and natural organic matter removal2018Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 621, s. 138-147Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Real water pH and ionic strength vary greatly, which influences the performance of membrane processes such as nanofiltration (NF) and reverse osmosis (RO). Systematic variation of pH (3 − 12) and ionic strength (2–10 g/L as total dissolved solids (TDS)) was undertaken with a real Tanzanian water to investigate how water quality affects retention mechanisms of fluoride (F) and natural organic matter (NOM).

    An autonomous solar powered NF/RO system driven by a solar array simulator was supplied with constant power from a generator. An open NF (NF270) and a brackish water RO (BW30) membrane were used. A surface water with a very high F (59.7 mg/L) and NOM (110 mgC/L) was used. Retention of F by NF270 was < 20% at pH < 6, increased to 40% at pH 6, and 60–70% at pH 7–12, indicating a dominance of charge repulsion while being ineffective in meeting the guideline of 1.5 mg/L. Increase in ionic strength led to a significant decline in retention of F (from 70 to 50%) and electrical conductivity (from 60 to 10%) by NF270, presumably due to charge screening. In contrast, BW30 retained about 50% of F at pH 3, > 80% at pH 4, and about 99% at pH > 5, due to the smaller pore size and hence a more dominant size exclusion. In consequence, only little impact of ionic strength increase was observed for BW30. The concentration of NOM in permeates of both NF270 and BW30 were typically < 2 mg/L. This was not affected by pH or ionic strength due to the fact that the bulk of NOM was rejected by both membranes through size exclusion.

    The research is carried out in the context of providing safe drinking water for rural and remote communities where infrastructure is lacking, and water quality varies significantly. While other studies focus on energy fluctuations, this research emphasises on feed water quality that affects system performance and may alter due to a number of environmental factors.

  • 740.
    Paet, Laura
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Framtagande av mätmetod för koncentration av fixativ i bakvatten: Undersökning om FTIR lämpar sig som analysmetod med processvatten för en mjukpapperstillverkning2023Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Rexcell Tissue & Airlaid AB is a producer of paper products such as coloured tissue, where it is important to manufacture a product that does not release any colour during usage. To prevent colour bleeding, a fixative is added during the paper dyeing process. However, excessive fixative can cause issues to the papermaking process due to its charge. Currently, charge measurements on the water flow are used to detect fixative overdose, but a more precise method is desired. This study explores using FTIR spectroscopy and existing charge measurements (PCD and Z-potential) to analyse process water for different dye types (Red, Black, Green). The ATR-FTIR technique shows that fixative is detectable only at higher concentrations than present in the water. By reducing the process water to measurable fixative levels, concentration determination is possible using IR peaks associated with the amine bond. Comparing concentration values with charge values, a good agreement is observed for two dye types, but the green whitewater shows discrepancies. This could be due to the charged dye molecules influencing the fixative spectrum, affecting concentration determination. The study suggests using an ATR crystal allowing multiple reflections to enhance the fixative signal for accurate concentration measurement. Further investigation is needed to understand the impact of coloured molecules on fixative properties and the FTIR spectrum. In summary, it is feasible to determine fixative concentration in whitewater using FTIR-ATR, but refining the methodology is essential for reliable results

    Fulltekst (pdf)
    fulltext
  • 741.
    Palme, Anna
    et al.
    Chalmers University of Technology, Sweden.
    Peterson, Anna
    Chalmers University of Technology, Sweden.
    de la Motte, Hanna
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Brelid, Harald
    Södra Innovation, Sweden..
    Development of an efficient route for combined recycling of PET and cotton from mixed fabrics2017Inngår i: Textiles and Clothing Sustainability, ISSN 2197-9936, Vol. 3, nr 4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Most textile waste is either incinerated or landfilled today, yet, the material could instead be recycled through chemical recycling to new high-quality textiles. A first important step is separation since chemical recycling of textiles requires pure streams. The focus of this paper is on the separation of cotton and PET (poly(ethylene terephthalate), polyester) from mixed textiles, so called polycotton. Polycotton is one of the most common materials in service textiles used in sheets and towels at hospitals and hotels. A straightforward process using 5–15 wt% NaOH in water and temperature in the range between 70 and 90 °C for the hydrolysis of PET was evaluated on the lab-scale. In the process, the PET was degraded to terephthalic acid (TPA) and ethylene glycol (EG). Three product streams were generated from the process. First is the cotton; second, the TPA; and, third, the filtrate containing EG and the process chemicals. The end products and the extent of PET degradation were characterized using light microscopy, UV-spectroscopy, and ATR FT-IR spectroscopy, as well as solution and solid-state NMR spectroscopy. Furthermore, the cotton cellulose degradation was evaluated by analyzing the intrinsic viscosity of the cotton cellulose. The findings show that with the addition of a phase transfer catalyst (benzyltributylammonium chloride (BTBAC)), PET hydrolysis in 10% NaOH solution at 90 °C can be completed within 40 min. Analysis of the degraded PET with NMR spectroscopy showed that no contaminants remained in the recovered TPA, and that the filtrate mainly contained EG and BTBAC (when added). The yield of the cotton cellulose was high, up to 97%, depending on how long the samples were treated. The findings also showed that the separation can be performed without the phase transfer catalyst; however, this requires longer treatment times, which results in more cellulose degradation.

    Fulltekst (pdf)
    fulltext
  • 742.
    Palmér, Matilda
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Energiprocesser.
    Integrating Chemical Looping Gasification for Hydrogen Generation and CO2 Capture in Pulp Mills2022Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Utsläpp av CO2 till atmosfären bidrar till ökningen av globala temperaturer. Industrisektorn står för 20 % av utsläppen och utav dessa kommer 6 % från pappers- och massaindustrin. För att lyckas minska den globala temperaturhöjningen till under 1,5 °C hjälper det inte bara att minska utsläppen. Även negativa utsläpp måste genereras. Syftet med denna studie är att undersöka implementeringen av CLG för att separera CO2 på ett energieffektivt sätt och samtidigt generera H2 och elektricitet. Processanalyser genomfördes för att undersöka möjligheten att implementera CLG-processen till ett typiskt massabruk. Processmodeller togs fram for att undersöka CLG, värmeåtervinning samt elektricitetsgenerering.

    Processmodellerna utvecklades med hjälp av Aspen Plus och Aspen HYSYS. De framtagna modellerna analyserades sedan med avseende på olika designparametrar inom CLG-processen. På ett typiskt massabruk som producerar 800 000 adt varje år kan 375 kg CO2/adt separeras och då uppnå negativa utsläpp, genom att byta ut multi-fuel forsrännaren med en CLG process. Den framtagna processmodellen skulle också kunna generera 360-504 kWh/adt av H2 beroende på de designparametrar som används för CLG-processen. Enligt modellen kan värme som återvinns från processen användas för att fånga upp ytterligare 13 % av CO2 från andra delar av bruket. Processanalys för olika designparametrar inom CLG systemet så som temperatur, luftflöde och flödet av syrgasbärare har presenterats. Nyckeltalen som undersöktes var den mängd CO2 som kunde fångas upp, mängd H2 genererad samt överskottet av elektricitet som produceras när multi-fuel förbränningen byts ut mot en CLG-process på ett typiskt massa bruk.

    Fulltekst (pdf)
    fulltext
  • 743.
    Pamér, Matilda
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Energiprocesser.
    Integrating Chemical Looping Gasification for Hydrogen Generation and CO2 Capture in Pulp Mills2022Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Utsläpp av CO2 till atmosfären bidrar till ökningen av globala temperaturer. Industrisektorn står för 20 % av utsläppen och utav dessa kommer 6 % från pappers- och massaindustrin. För att lyckas minska den globala temperaturhöjningen till under 1,5 °C hjälper det inte bara att minska utsläppen. Även negativa utsläpp måste genereras. Syftet med denna studie är att undersöka implementeringen av CLG för att separera CO2 på ett energieffektivt sätt och samtidigt generera H2 och elektricitet. Processanalyser genomfördes för att undersöka möjligheten att implementera CLG-processen till ett typiskt massabruk. Processmodeller togs fram for att undersöka CLG, värmeåtervinning samt elektricitetsgenerering.

    Processmodellerna utvecklades med hjälp av Aspen Plus och Aspen HYSYS. De framtagna modellerna analyserades sedan med avseende på olika designparametrar inom CLG-processen. På ett typiskt massabruk som producerar 800 000 adt varje ˚ar kan 375 kg CO2/adt separeras och då uppnå negativa utsläpp, genom att byta ut multi-fuel forsrännaren med en CLG process. Den framtagna processmodellen skulle också kunna generera 360-504 kWh/adt av H2 beroende på de designparametrar som används för CLG-processen. Enligt modellen kan värme som ˚återvinns från processen användas för att fånga upp ytterligare 13 % av CO2 från andra delar av bruket. Processanalys för olika designparametrar inom CLG systemet så som temperatur, luftflöde och flödet av syrgasbärare har presenterats. Nyckeltalen som undersöktes var den mängd CO2 som kunde fångas upp, mängd H2 genererad samt överskottet av elektricitet som produceras när multi-fuel förbränningen byts ut mot en CLG-process på ett typiskt massa bruk.

    Fulltekst (pdf)
    fulltext
  • 744.
    Parsland, Charlotte
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Einvall, Jessica
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Brandin, Jan
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Scale-up and Assessment of Water Gas Shifts2010Rapport (Annet vitenskapelig)
    Abstract [en]

    Synthesis gas consists of a mixture between hydrogen, carbon monoxide, carbon dioxide and water. This gas is normally generated by gasification of a carbon containing fuel, to be used as a feedstock for various synthesis processes. The actual composition of the gas depends on many different factors such as type of fuel, type of gasifier, mode of operation of the gasifier etc. The producer gas, i.e. the gas after the gasification step, usually need upgrading since it contains lower hydrocarbons and tars that needs to be converted. This upgrading, from producer gas into synthesis gas is done in the reformer step. The resulting synthesis gas is not necessarily suited for the subsequent synthesis step; it might need to be processed further. For instance the carbon dioxide level might need to be decreased and/or the hydrogen-carbon dioxide ratio to be adjusted. The water gas shift (WGS) process is the process where the ratio between hydrogen and carbon monoxide in the synthesis gas can be tuned.

  • 745.
    Parsland, Charlotte
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Einvall, Jessica
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Brandin, Jan
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Benito, Patricia
    Dipartimento di Chimica Industriale e dei Materiali, Bologna University, Italy.
    Albertazzi, Simone
    Dipartimento di Chimica Industriale e dei Materiali, Bologna University, Italy.
    Basile, Francesco
    Dipartimento di Chimica Industriale e dei Materiali, Bologna University, Italy.
    Trifiró, Ferruccio
    Dipartimento di Chimica Industriale e dei Materiali, Bologna University, Italy.
    Siedlecki, Marcin
    Delft University of Technology, Process&Energy Department, the Netherlands.
    de Jong, Wiebren
    Delft University of Technology, Process&Energy Department, the Netherlands.
    Effect on Catalytic Activity and Stability of the Gas Coming from a Gasifier2010Rapport (Annet vitenskapelig)
    Abstract [en]

    This deliverable contains both laboratory experiments and experiments where the watergas-shift catalyst has been exposed to gas and particles generated by biomass gasification.The gasification experiments took place in the 100 kWth CFB gasifier at Delft University of Technology in Delft in July 2008 and in February and August 2009.

  • 746.
    Parsland, Charlotte
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Ho, Phuoc Hoang
    Univ Bologna, Italy.
    Benito, Patricia
    Univ Bologna, Italy.
    Larsson, Ann-Charlotte
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Fornasari, Giuseppe
    Univ Bologna, Italy.
    Brandin, Jan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Ba-Ni-Hexaaluminate as a New Catalyst in the Steam Reforming of 1-Methyl Naphthalene and Methane Long-Term Studies on Sulphur Deactivation and Coke Formation2020Inngår i: Catalysis Letters, ISSN 1011-372X, E-ISSN 1572-879X, Vol. 150, s. 1605-1617Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work investigates the long-term performance of Ba-Ni-hexaaluminate, BaNixAl12-xO19 as a catalyst in reforming of 1-methyl naphthalene and/or methane in a model-gas simulating that from a circulating fluidized bed (CFB) gasifier during 23-29 h in a lab scale set-up, as well as the tendency for coke formation, sintering and sulphur poisoning. 1-Methyl naphthalene is used as a tar model substance. The Ba-Ni-hexaaluminate induces a high conversion of both compounds in the temperatures investigated (850 and 950 degrees C) under sulphur-free conditions. In sulphur-containing gas, the methane conversion stops at 20 ppm H2S and the reforming of 1-MNP at 850 degrees C is slightly reduced at 100 ppm.

  • 747.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Antonopoulou, Io
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Enman, Josefine
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Lipids detection and quantification in oleaginous microorganisms: an overview of the current state of the art2019Inngår i: BMC Chemical Engineering, ISSN 2524-4175, Vol. 1, artikkel-id 13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Oleaginous microorganisms are among the most promising feedstocks for the production of lipids for biofuels and oleochemicals. Lipids are synthesized in intracellular compartments in the form of lipid droplets. Therefore, their qualitative and quantitative analysis requires an initial pretreatment step that allows their extraction. Lipid extraction techniques vary with the type of microorganism but, in general, the presence of an outer membrane or cell wall limits their recovery. This review discusses the various types of oleaginous microorganisms, their lipid accumulating capabilities, lipid extraction techniques, and the pretreatment of cellular biomass for enhanced lipid recovery. Conventional methods for lipid quantification include gravimetric and chromatographic approaches; whereas non-conventional methods are based on infrared, Raman, nuclear magnetic resonance, and fluorescence spectroscopic analysis. Recent advances in these methods, their limitations, and fields of application are discussed, with the aim of providing a guide for selecting the best method or combination of methods for lipid quantification.

  • 748. Pattison, Richard
    et al.
    Touretzky, Cara R.
    Johansson, Ted
    KTH, Skolan för kemivetenskap (CHE).
    Baldea, Michael
    Harjunkoski, Iiro
    Moving Horizon Scheduling of an Air Separation Unit under Fast-Changing Energy Prices2016Inngår i: IFAC PAPERSONLINE, Elsevier, 2016, Vol. 49, nr 7, s. 681-686Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Maximizing the benefits of time-of-use pricing for industrial electricity consumers requires varying production rates, such that energy use is shifted from peak price periods to off-peak times dining the day. Assuming that excess capacity and product storage arc available, production of energy intensive processes can be increased at off-peak times beyond nominal rates, and the stored product can be used at peak times when the production rate is lowered. Under these rapidly changing circumstances, scheduling calculations must take into consideration explicitly the dynamic model of the process, often rendering the scheduling problem intractable in practical amounts of time. To address this challenge, we introduce a class of scheduling-relevant low-order process models, which capture the closed-loop input-output behavior of a plant. We use these models to close the scheduling loop, whereby the scheduling problem is formulated over a moving horizon with feedback. We apply the theoretical concepts to an industrial-scale air separation unit model, demonstrating that variable production rate operation with product storage has the potential for significant operating cost savings while abiding by product quality and safety constraints.

  • 749.
    Paulraj, Alagar Raj
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Processteknologi.
    Studies on Rechargeable Fe-air electrodes in Alkaline electrolyte2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Energy storage system is an important component in the energy system based on variable renewable energy sources into the grid. Energy storage system could contribute to decarbonization, energy security, offset the demand and supply of the electricity sector, especially for the electric grid. These can be either mechanical, electrochemical, chemical, electromagnetic or thermal devices. The most important functional characteristics of an energy storage system are capital cost, roundtrip efficiency, energy and power rating, response times and cycle life. Electrochemical energy storage systems (EES) have the following edge over the other systems: fast response time, relatively short duration of storage, size, high efficiency, a decentralized installation which is closer to generation or consumption site.

    The focus of this thesis is on the development of cost-effective iron anode materials and electrocatalytic air electrodes for Fe-air batteries that potentially could become as an energy storage system. Iron-based systems are attractive due to their safety, cheapness, non-toxicity and ubiquitous availability of materials. However, both the anode and cathode parts have numerous drawbacks that need to be addressed. The anode exhibits poor charge efficiency, rate capability and low capacity utilization while the cathode has sluggish kinetics, poor activity, structural stability and the numbers of active non-noble metal catalysts are limited.

    This work utilized Cu and Sn-doped iron nanomaterials and different additives (Bi2S3, CNT, LiOH) to enhance the performance of the iron electrode. The performance of the electrodes were evaluated using the charge/discharge cycling, rate capability, cyclic voltammetry (CV), galvanostatic and potentiodynamic polarization measurements, in operando charging measurements combined with mass spectrometry. The fresh and cycled electrodes and powders were characterized by ex-situ XRD, BET, SEM, TEM , XPS and Raman spectroscopy. The most striking results are the prevention of nanoparticle agglomeration, increased charging efficiency (80-91%), effect of Cu and Sn dopants on specific capacity (367-603 mAh g-1) and improved performance of the electrodes at high charge current densities.

    In the subsequent air electrode part, non-precious metal La-doped CaMnOx, nano Co3O4 and NiFeOX electrocatalysts were synthesized using co-precipitation and hydrothermal methods. Both the single and mixed catalysts were used as bi-functional catalysts for oxygen reduction and evolution reactions (ORER). The catalysts were characterized by XRD, SEM, TEM, BET, Raman and XPS. The electrocatalytic activity and stability were assessed in alkaline solutions on gas diffusion electrodes and glassy carbon electrode by linear sweep voltammetry (LSV), CV and rotating disk electrode (RDE). Furthermore, the mixed catalyst and NiFeOX showed excellent bifunctional performance such as high activity and stability achieved by the hybridization of the two catalysts and the effect of catalyst loading on the electrocatalytic performance. These findings can help to develop a cost-effective material for Fe-air batteries.

    Fulltekst (pdf)
    Thesis Alagar Raj Paulraj
  • 750.
    Paulraj, Alagar Raj
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Processteknologi.
    Kiros, Yohannes
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Processteknologi.
    Chamoun, Mylad
    Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
    Svengren, Henrik
    Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
    Noréus, Dag
    Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
    Göthelid, Mats
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Skårman, Björn
    Höganäs AB, SE-263 83 Höganäs, Sweden.
    Vidarsson, Hilmar
    Höganäs AB, SE-263 83 Höganäs, Sweden.
    Johansson, Malin B
    Division of Physical Chemistry, Department of Chemistry, The Ångström Laboratory, Uppsala University, P.O. Box 523, SE-75120 Uppsala, Sweden.
    Electrochemical Performance and in Operando Charge Efficiency Measurements of Cu/Sn-Doped Nano Iron Electrodes2019Inngår i: Batteries, E-ISSN 2313-0105, nr 1Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Fe-air or Ni-Fe cells can offer low-cost and large-scale sustainable energy storage. At present, they are limited by low coulombic efficiency, low active material use, and poor rate capability. To overcome these challenges, two types of nanostructured doped iron materials were investigated: (1) copper and tin doped iron (CuSn); and (2) tin doped iron (Sn). Single-wall carbon nanotube (SWCNT) was added to the electrode and LiOH to the electrolyte. In the 2 wt. % Cu + 2 wt. % Sn sample, the addition of SWCNT increased the discharge capacity from 430 to 475 mAh g−1, and charge efficiency increased from 83% to 93.5%. With the addition of both SWCNT and LiOH, the charge efficiency and discharge capacity improved to 91% and 603 mAh g−1, respectively. Meanwhile, the 4 wt. % Sn substituted sample performance is not on par with the 2 wt. % Cu + 2 wt. % Sn sample. The dopant elements (Cu and Sn) and additives (SWCNT and LiOH) have a major impact on the electrode performance. To understand the relation between hydrogen evolution and charge current density, we have used in operando charging measurements combined with mass spectrometry to quantify the evolved hydrogen. The electrodes that were subjected to prolonged overcharge upon hydrogen evolution failed rapidly. This insight could help in the development of better charging schemes for the iron electrodes.

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