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  • 151.
    Cardenas, Edgar
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Chemistry Research Institute, San Andrés Mayor University, UMSA, La Paz, Bolivia.
    Aguilar-Mamani, Wilson
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Department of Chemistry, Science and technology Faculty, San Simon University, Cochabamba, Bolivia.
    Tai, Cheuk-Wai
    Department of Environmental and Materials Chemistry, Stockholm University, 106 91 Stockholm, Sweden.
    Cabrera, Saul
    Chemistry Research Institute, San Andrés Mayor University, UMSA, La Paz, Bolivia.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Microstructural evolution of condensed aggregates during the crystallization of ZSM-5 from a heterogeneous system2021Inngår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 568–569, artikkel-id 126188Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The microstructural evolution of precursors of ZSM-5 zeolite crystallized from a heterogeneous system using fumed silica, sodium aluminate and tetrapropylammonium ions as reagents is investigated. Entities previously described by Ren et al. (Chem. Mater. 2012, 24, 10, 1726–1737) as condensed aggregates, were extensively studied using scanning electron microscopy, and energy dispersive spectroscopy. It was observed that the condensed aggregates first comprise a core of nanocrystals that is enveloped by a shell of amorphous gel phase. During crystallization, the amorphous shell surrounding the core is converted into ZSM-5 crystals that grow to a film surrounding the core. The crystals in the film grow competitively with nutrients provided by the liquid phase from the surroundings, while the nanocrystals in the core show little or no signs of growth.

  • 152.
    Cardenas, Edgar
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Cabrera, Saul
    Chemistry Research Institute, San Andres Mayor University.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Zeolite Y from diatomaceous earth as catalytic cracking catalystManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    A zeolite Y cracking catalyst in the lanthanum form was synthetized from Bolivian diatomite. Characterization was conducted through x-ray diffraction, scanning electron microscopy, nitrogen adsorption and energy dispersive spectroscopy. The catalyst was evaluated in the catalytic cracking of cumene and the results were compared with that of a catalyst prepared from commercial zeolite Y powder. It was shown that the catalytic performance of the catalyst prepared from diatomite was comparable to that for the catalyst prepared from commercial zeolite Y powder.

  • 153.
    Carlsson, Gunilla
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Axrup, Lars
    Stora Enso, Karlstad Res Ctr, SE-65009 Karlstad, Sweden.
    Ljungqvist, Carl-Henrik
    Stora Enso, Karlstad Res Ctr, SE-65009 Karlstad, Sweden..
    Nyflott, Asa
    Stora Enso, Karlstad Res Ctr, SE-65009 Karlstad, Sweden.;Karlstad Univ, SE-65188 Karlstad, Sweden..
    The use of fluorescence microscopy and image analysis to characterize the porous structure in micro fibrillar cellulose gel - Part I: Brownian motion2013Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, nr 2, s. 190-197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The porous structure of a micro fibrilar cellulose, MFC, gel was studied by fluorescence microscopy and image analysis. The Brownian motion of fluorescent labelled carboxylated latex spheres, probes, was investigated at both high, 0.1-5 wt%, and low, 0-20 ppm, concentrations of MFC. The developed tracking program provides trajectories for probes. The trajectories can be studied according to either the individual approach or the ensemble approach to give complementary information regarding the fibrilar system. The Brownian motion can be used in the range 0 to 1.0 wt% MFC and the percentage of idle probes can be used when the concentrations exceeds 1.0 wt% MFC. The Brownian motion was found to be pH dependent both for the low and the high concentration regimes.

  • 154.
    Carlsson, Magnus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Stenman, David
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Merényi, Gabor
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Reitberger, Torbjörn
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    A comparative study on the degradation of cotton linters induced by carbonate and hydroxyl radicals generated from peroxynitrite2005Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 59, nr 2, s. 132-142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carbonate (CO3.(-)) and hydroxyl (HO.) radicals were chemically produced in cotton linter suspensions using peroxynitrite as a radical precursor. Both radicals could degrade cotton linters, as shown by viscosity and GPC-SEC measurements. As evidenced by the viscosity measurements, the presence of oxygen during the cotton linter treatments slightly increased cellulose degradation by both radicals. For the carbonate radical, more than 90% of the viscosity losses could be recovered by reductive NaBH4 treatment before measuring the viscosity, whereas only approximately 40% of the viscosity was recovered after hydroxyl radical degradation and subsequent NaBH4 treatment. This indicates that carbonate radicals mainly abstract H-atoms adjacent to hydroxyl groups, i.e., at C-2, C-3 and C-6. This intramolecular selectivity may reflect a polar effect, whereby hydrogen atom abstractions from these positions are favoured. In addition, abstraction at C-6 would be sterically and statistically favoured.

  • 155. Carlsson, Per
    et al.
    Ma, Charlie
    Luleå University of Technology, Energy Engineering, Division of Energy Science, SE-971 87, Luleå, Sweden.
    Molinder, Roger
    Weiland, Fredrik
    Wiinikka, Henrik
    Öhman, Marcus
    Öhrman, Olov
    Slag Formation During Oxygen Blown Entrained-Flow Gasification of Stem Wood2014Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, nr 11, s. 6941-6952Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Stem wood powders were fired in a mullite-lined pilot-scale oxygen-blown pressurized entrained-flow gasifier. During repeated campaigns involving increases in fuel load and process temperature, slag formations that eventuated in the blockage of the gasifier outlet were observed. These slags were retrieved for visual and chemical characterization. It was found that the slags had very high contents of Al and, in particular, high Al/Si ratios that suggest likely dissolution of the mullite-based refractory of the gasifier lining due to interactions with the fuel ash. Possible causes for the slag formation and behavior are proposed, and practical implications for the design of future stem wood entrained-flow gasifiers are also discussed

  • 156.
    Carreno-Quintero, Natalia
    et al.
    Royal Holloway Univ London, Biochem Dept, Egham Hill, Egham TW20 0EX, Surrey, England.;Vegetable Crop Res Unit, Keygene NV, Agro Business Pk 90, NL-6708 PW Wageningen, Netherlands..
    Tohge, Takayuki
    Max Planck Inst Mol Plant Physiol, Muhlenberg 1, D-14476 Potsdam, Germany..
    Van Acker, Rebecca
    Univ Ghent, Dept Plant Biotechnol & Bioinformat, Technol Pk 927, B-9052 Ghent, Belgium.;Ctr Plant Syst Biol VIB, Technol Pk 927, B-9052 Ghent, Belgium..
    McKee, Lauren S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Zhou, Qi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Bolze, Antje
    Max Planck Inst Mol Plant Physiol, Muhlenberg 1, D-14476 Potsdam, Germany..
    Xing, Xiaohui
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Ozparpucu, Merve
    Swiss Fed Inst Technol, Swiss Fed Inst Technol Zurich ETH Zurich, Swiss Fed Inst Technol Zurich, Zurich, Switzerland.;Swiss Fed Labs Mat Sci & Technol Empa, Appl Wood Mat, Dubendorf, Switzerland..
    Ruggeberg, Markus
    Swiss Fed Inst Technol, Swiss Fed Inst Technol Zurich ETH Zurich, Swiss Fed Inst Technol Zurich, Zurich, Switzerland.;Swiss Fed Labs Mat Sci & Technol Empa, Appl Wood Mat, Dubendorf, Switzerland..
    Piofczyk, Thomas
    Pilot Pflanzenoltechnol Magdeburg eV, Berliner Chaussee 66, D-39114 Magdeburg, Germany..
    Koram, Yaw
    Neutral Supply Chain Ltd, 337 Bath Rd, Slough SL1 5PR, Berks, England..
    Bulone, Vincent
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. Univ Adelaide, ARC Ctr Excellence Plant Cell Walls, Waite Campus, Urrbrae, SA 5064, Australia.;Univ Adelaide, Sch Agr Food & Wine, Waite Campus, Urrbrae, SA 5064, Australia..
    Boerjan, Wout
    Univ Ghent, Dept Plant Biotechnol & Bioinformat, Technol Pk 927, B-9052 Ghent, Belgium.;Ctr Plant Syst Biol VIB, Technol Pk 927, B-9052 Ghent, Belgium..
    Fernie, Alisdair R.
    Max Planck Inst Mol Plant Physiol, Muhlenberg 1, D-14476 Potsdam, Germany..
    Fraser, Paul D.
    Royal Holloway Univ London, Biochem Dept, Egham Hill, Egham TW20 0EX, Surrey, England..
    Non-targeted discovery of high-value bio-products in Nicotiana glauca L: a potential renewable plant feedstock2024Inngår i: Bioresources and bioprocessing, ISSN 2197-4365, Vol. 11, nr 1, artikkel-id 12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The evaluation of plant-based feedstocks is an important aspect of biorefining. Nicotiana glauca is a solanaceous, non-food crop that produces large amounts of biomass and is well adapted to grow in suboptimal conditions. In the present article, compatible sequential solvent extractions were applied to N. glauca leaves to enable the generation of enriched extracts containing higher metabolite content comparing to direct leaf extracts. Typically, between 60 to 100 metabolite components were identified within the fractions. The occurrence of plant fatty acids, fatty acid alcohols, alkanes, sterols and terpenoids was detected by gas liquid chromatography-mass spectrometry (GC-MS) and metabolite identification was confirmed by comparison of physico-chemical properties displayed by available authentic standards. Collectively, co-products such waxes, oils, fermentable sugars, and terpenoids were all identified and quantified. The enriched fractions of N. glauca revealed a high level of readily extractable hydrocarbons, oils and high value co-products. In addition, the saccharification yield and cell wall composition analyses in the stems revealed the potential of the residue material as a promising lignocellulosic substrate for the production of fermentable sugars. In conclusion a multifractional cascade for valuable compounds/commodities has been development, that uses N. glauca biomass. These data have enabled the evaluation of N. glauca material as a potential feedstock for biorefining.

  • 157.
    Carvalho, Lara
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Furusjö, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. IVL – Swedish Environmental Institute, Stockholm, Sweden.
    Ma, Chunyan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Ji, Xiaoyan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Lundgren, Joakim
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Öhrman, Olov G. W.
    IVL – Swedish Environmental Institute, Stockholm, Sweden;RISE Energy Technology Center AB, Piteå, Sweden.
    Wetterlund, Elisabeth
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria.
    Alkali enhanced biomass gasification with in situ S capture and a novel syngas cleaning: Part 2: Techno-economic analysis2018Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 165, nr Part B, s. 471-482Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Previous research has shown that alkali addition has operational advantages in entrained flow biomass gasification and allows for capture of up to 90% of the biomass sulfur in the slag phase. The resultant low-sulfur content syngas can create new possibilities for syngas cleaning processes. The aim was to assess the techno-economic performance of biofuel production via gasification of alkali impregnated biomass using a novel gas cleaning systemcomprised of (i) entrained flow catalytic gasification with in situ sulfur removal, (ii) further sulfur removal using a zinc bed, (iii) tar removal using a carbon filter, and (iv) CO2 reductionwith zeolite membranes, in comparison to the expensive acid gas removal system (Rectisol technology). The results show that alkali impregnation increases methanol productionallowing for selling prices similar to biofuel production from non-impregnated biomass. It was concluded that the methanol production using the novel cleaning system is comparable to the Rectisol technology in terms of energy efficiency, while showing an economic advantagederived from a methanol selling price reduction of 2–6 €/MWh. The results showed a high level of robustness to changes related to prices and operation. Methanol selling prices could be further reduced by choosing low sulfur content feedstocks.

  • 158.
    Cazot, Mathilde
    KTH, Skolan för kemivetenskap (CHE).
    Empirical Modeling of a full-iron redox flow battery2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The need for energy storage is growing to reduce the carbon footprint of electricity

    production. Among the conceivable storage solutions, the redox flow battery (RFB) is

    one of the most promising. The best-researched type is the vanadium flow battery, but

    extensive research is underway to develop a cheaper and more compact system. The full-

    iron redox flow battery is an attractive alternative. A testing module has been developed,

    in order to study the influence of different operating parameters on the system output.

    The experiments highlight that the electrode compression, the stacking of single cells and

    the charge and discharge rates are design key factors and need a precise optimization. A

    35% electrode compression is a good trade-off between pump power losses and low contact

    resistances inside the cell. Single cells undergo a higher self-discharge when they are piled

    up; it is the direct effect of a power leakage called shunt current. The stack design must

    be thought with caution to lessen this power loss. The cycling profile also influence the

    battery performance. The findings confirm that optimizing the charge and discharge rates

    can prolong the system lifespan.

  • 159.
    Ceder, Joakim
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Characterization of uranium oxide powders and sinterability2021Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Uranoxid (UOx) är ett energitätt material som ofta används i kärnbränsle. UOx-pulver pressas och sintras för att tillverka urandioxidkutsar som förs in i bränslestavar. Stavarna monteras slutligen ihop till ett bränsleknippe. Tillverkningsprocessens stabilitet och förutsägbarhet är viktiga. För att åstadkomma önskvärda egenskaper hos UO2-kutsarna är karaktärisering av UOx-pulvret centralt. Sintringsaktivitet är den viktigaste egenskapen när det kommer till att beskriva hur UOx-pulvret beter sig vid reduktion i högtemperatursintring. Återcyklat UO2 oxideras till U3O8 och kan användas till att styra sintringsaktiviteten tack vare dess porbildande egenskaper.

    Denna rapport beskriver karaktäriseringen av UOx-pulver och kuts med avseende på fysiokemiska egenskaper relaterade till sintringsaktivitet. Statistiska analyser av historiska data utfördes även och visade på en komplex relation mellan pulveregenskaper och sintringsaktivitet. Effekten av U3O8-pulver i blandningar av UO2-pulver med hög och låg sintringsaktivitet undersöktes. Att variera U3O8-batch hade ingen inverkan på diameterkrympning efter sintring utom i ett fall. Blandningar av UO2-pulver visade på avvikande egenskaper jämfört med det jungfruliga pulvret. UO2-pulvrets kemiska aktivitet undersöktes via oxidering med H2O2.

    Förbrukningshastigheten av H2O2 var densamma för hög- och lågaktiva UO2-pulver vid samma förhållande mellan specifik yta och lösningsvolym.

    Fulltekst (pdf)
    fulltext
  • 160.
    Chang, Jo-Shu
    et al.
    Research Centre for Smart Sustainable Circular Economy, Tunghai 407, Taiwan; Department of Chemical and Materials Engineering, College of Engineering, Tunghai University, Taichung 407, Taiwan; Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan.
    Show, Pau Loke
    Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Broga Road, 43500 Semenyih, Selangor Darul Ehsan, Malaysia.
    Lee, Duu-Jong
    Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Recent advances in lignocellulosic biomass refinery2022Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 347, artikkel-id 126735Artikkel i tidsskrift (Annet vitenskapelig)
  • 161.
    Chavez Varela, Camila
    KTH, Skolan för kemivetenskap (CHE).
    Elektrokemisk sensor för styrning av bränslecell2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Telecommunication stations for surveillance, wireless communication nodes, and other applications require a main energy source, energy storage unit and a back-up energy system. In the last years, fuel cells have become a good replacement for diesel generators in remote and off-grid applications. Fuel cells provide several advantages like high energy efficiency, no moving parts, silent, scaling is a function of their surface area instead of volume, and reliability. Among the disadvantages there are equipment cost, and difficulties in hydrogen storage. Simplifying the control system of the hydrogen feed control will lower the equipment costs and allow the use of this technology for remote applications where the system is mainly fed by renewable sources, like solar panels, and constant maintenance represents an issue.

    For this purpose the present work investigates the use of a single air-breathing micro fuel cell, used as a sensor cell that can serve to control a fuel cell energy backup system. First the sensor cell was tested under different conditions of temperature, hydrogen humidity, flooding, and hydrogen inlet flow in order to determine optimum operation conditions. Then the sensor cell was connected to the hydrogen outlet of a single cell or stack, receiving the remaining hydrogen that was not consumed by the stack. Further tests were performed by modifying the hydrogen flow, resistance value, and stack current output. During the experiments the sensor cell voltage was monitored. The results show that the micro fuel cell delivers a cell voltage signal sensible to the hydrogen inlet flow, which means it can be used to control the operation of a fuel cell stack. The sensibility of the voltage signal can be modified by means of the resistance connected to its circuit. The stability in time of the voltage signal was achieved by setting the sensor cell to 45 °C or higher.

  • 162.
    Chipakwe, Vitalis
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Application of Chemical Additives in Minerals Beneficiation – Implications on Grinding and Flotation Performance2023Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The application of chemical additives, known as grinding aids (GAs), dates to 1930 in the cement industry. Unlike the cement industry, where the use of GAs is in the final processing step, it could be one of the first processing steps in ore beneficiation. Further to grinding performance, the successful application of GAs requires understanding the effect on ground products and possible interaction of the GAs in view of downstream processes. Understanding and controlling any GA-separation reagent interactions is critical to ensure that the required downstream process efficiency and integrity of the entire value chain are maintained. In this thesis, the effect of selected chemical additives on dry grinding performance and product properties is investigated. Second, the effect of the additives on surface properties and pulpchemistry, together with the resulting behavior in subsequent froth flotation separation, is investigated.

    The use of environmentally benign and sustainable alternatives to conventional surfactants is growing within mineral processing. To this end, a polysaccharide-based grinding aid (PGA) (natural polymer) together with a polyacrylic acid-based grinding aid (AAG) (synthetic polymer) were used as grinding aids. The effect of PGA and AAG at varying concentrations was investigated with respect to energy consumption, particle size distribution, BET surface area, roughness, and rheology. The resulting grinding parameters were correlated with the measured rheology indices from the automated FT4 powder rheometer. Moreover, the effect of the GAs on the flotation of quartz from magnetite was investigated using an artificial mixture ore. Zeta potentials, stability measurement, adsorption test, and FTIR analyzes were performed to understand the mechanisms of surface interaction and adsorption.

    The grinding results indicated that the application of GAs reduced energy consumption by up to 31.1 % and gave a finer-uniform product size, higher specific surface area, and increased surface roughness compared to grinding without. Further studies on powder rheology indicated that the GAs used resulted in improved material flowability compared to grinding without additives. There was a strong correlation (r > 0.93) between the grinding and the flow parameters. Flotation tests on pure samples illustrated that PGA has beneficial effects on magnetite depression (with negligible impact on quartz floatability) through reverse flotation separation. The benefits were further confirmed by the flotation of the artificial mixture in the presence of PGA. The PGA adsorption mechanism was mainly through physical interaction based on UV-Vis spectra, zeta potential tests, Fourier transform infrared spectroscopy (FT-IR), and stability analyses. Additionally, single mineral flotation tests indicated that AAG enhanced quartz collection with minimal effect on magnetite. Mixed mineral flotation revealed that, by using AAG, comparable metallurgical performance could be achieved at a lower collector dosage. The zeta potentials and stability measurements showed that AAG shifts the potential, thus improving the stability and dispersion of the suspension. Adsorption tests revealed that AAG adsorbed on both quartz and magnetite, with the former having a higher capacity. Fourier transform infrared spectroscopy showed that the interaction between AAG and the minerals occurs via a physical interaction.

    The findings illustrate that GAs improved grinding efficacy at optimum dosage and enhanced product properties. Furthermore, the predominant mechanism of GAs is based on the alteration of rheological properties. Importantly, the feasibility of using GAs to improve grinding performance has been demonstrated with secondary beneficial effects on flotation.

    Fulltekst (pdf)
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  • 163.
    Chipakwe, Vitalis
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Karlkvist, Tommy
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Rosenkranz, Jan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Chelgani, Saeed Chehreh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Exploring the effect of a polyacrylic acid-based grinding aid on magnetite-quartz flotation separation2023Inngår i: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 305, artikkel-id 122530Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is well documented that the use of grinding aids (GAs) can reduce milling energy consumption. However, the impact of GAs on downstream processes must be addressed in view of complex processes such as froth flotation separation. This study investigates the effects of polyacrylic-based grinding aids (Zalta™ GR20-587: AAG) on the grinding performance and quartz flotation from magnetite. Various AAG dosages and conditions were examined. The grinding results showed lower energy consumption and a finer, more uniform product size with roughened surfaces for AAG compared to grinding without the grinding aid. Flotation tests of single pure minerals showed that AAG enhanced quartz collection with minimal effect on magnetite. Mixed mineral flotation showed that by using AAG, Fe recovery of 92.1 % and 64.5 % Fe grade could be achieved with a lower collector dosage of 100 g/t compared to 200 g/t in the absence of AAG. Zeta potentials and stability measurements showed that AAG shifts the potential, thus improving the stability and dispersion of the suspension. Adsorption tests illustrated that AAG adsorbed on both quartz and magnetite, the former having a higher capacity. FTIR indicated the physisorption interaction between AAG and the minerals. Therefore, the presence of AAG not only improved grinding efficiency but could potentially decrease the amount of collector required to achieve comparable metallurgical performance.

    Fulltekst (pdf)
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  • 164. Cloete, Schalk
    et al.
    Khan, Mohammed Nazeer
    Nazir, Shareq Mohd
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Energiprocesser.
    Amini, Shahriar
    Cost-effective clean ammonia production using membrane-assisted autothermal reforming2021Inngår i: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 404Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ammonia is a widely produced industrial chemical, primarily for use in the fertilizer industry. Recently, interest has also grown in ammonia as a carbon-free energy carrier because it is easier to store and transport than hydrogen. However, ammonia is primarily produced from natural gas with a considerable carbon footprint if the produced CO2 is not captured and stored. This work therefore presents a new ammonia production method based on membrane-assisted autothermal reforming (MA-ATR) for hydrogen production from natural gas with integrated CO2 capture. The MA-ATR reactor offers great process intensification benefits, leading to considerable efficiency gains as well as a simpler and cheaper plant. In the base case, MA-ATR achieves 10.7% greater efficiency, 14.9% lower NH3 production costs and 16.5%-points greater CO2 avoidance than a conventional ammonia plant where captured CO2 is compressed for transport and storage. This economic advantage of MA-ATR increases with higher natural gas prices, lower electricity prices, lower membrane costs and higher CO2 prices. All elements of the proposed plant are mature technologies aside from the membranes and the oxygen carrier material. Further development and demonstration of these two elements is therefore recommended to realize the promising techno-economic performance reported in this study.

    Fulltekst (pdf)
    fulltext
  • 165. Codan, Lorenzo
    et al.
    Bäbler, Matthäus
    Institute of Process Engineering, ETH Zurich.
    Mazzotti, Marco
    Phase Diagram of a Chiral Substance Exhibiting Oiling Out in Cyclohexane2010Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, nr 9, s. 4005-4013Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work investigates the ternary phase diagram of the enantiomers of ethyl-2-ethoxy-3-(4-hydroxyphenyl)propanoate (EEHP) in cyclohexane. The enantiomers of EEHP form aconglomerate, and both the pure enantiomer and the racemic mixture exhibit stable oilingout in cyclohexane. Our analysis shows that the ternary phase diagram of such a system assumes a unique structural evolution around the onset temperature of oiling out; that is, we found that the onset of oiling out strictly occurs through the emergence of a second liquid phase of racemic composition. Furthermore, we found that the further evolution of the ternary phase diagram, i.e., above the onset temperature of oiling out, is dictated by the properties of the phase diagrams pure enantiomer/solvent and racemic mixture/solvent. Our theoretical considerations are in excellent agreement with experimental measurements of EEHP in cyclohexane. 

  • 166.
    Conte, Ricardo Pezoa
    et al.
    Industrial Chemistry and Reaction Engineering Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Ravanal, M. Cristina
    Centre for Biochemical Engineering and Biotechnology, Department of Chemical Engineering and Biotechnology, University of Chile, Santiago, Chile.
    Mäki-Arvela, Päivi
    Industrial Chemistry and Reaction Engineering Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Willför, Stefan
    Wood and Paper Chemistry Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Lienqueo, M. Elena
    Centre for Biochemical Engineering and Biotechnology, Department of Chemical Engineering and Biotechnology, University of Chile, Santiago, Chile.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry and Reaction Engineering Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Bioethanol production from the green alga ulva rigida and the brown algae macrocystis pyrifera2015Inngår i: NWBC 2015: the 6th Nordic Wood Biorefinery Conference, VTT Technical Research Centre of Finland , 2015, s. 319-325Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Macroalgae are suitable bioresources to be explored as raw material for bioethanol production, as about 40 wt.% of its mass is composed of carbohydrates and they completely lack lignin. In this work the simultaneous saccharification and fermentation (SSF) of the green alga Ulva rigida and the brown alga Macrocystis pyrifera was performed. The algae were initially pretreated in deionized water or diluted sulfuric acid at 125°C in an autoclave for 60 min, respectively. Commercial cellulolytic enzymes and yeast were used for ethanol production. The carbohydrate composition of the fresh alga, pretreated alga and glucose and ethanol concentrations in the SSF processing are given. The water pretreatment solubilized 82 wt.% of the ulvan (rhamno-glucuroxylan) contained in U. rigida and 73 wt.% of the glucan remained in the residue. The diluted acid treatment removed 93 wt.% of the carbohydrates contained in U. rigida. The SSF of U. rigida pretreated with water produced 0.47 g EtOH/g sugar, with a 92 wt.% theoretical yield. In turn, water and diluted acid pretreatment of M. pyrifera increased 8.4 and 14.8 fold the carbohydrate content in the pretreated alga compared to the SSF of the fresh alga. The SSF of M. pyrifera pretreated with dilute sulfuric acid produced 0.15 g EtOH/g sugar, 29 wt.% theoretical yield. The production of ethanol was demonstrated for U. rigida and M. pyrifera with mild pretreatments. Especially in case of U. rigida simple water treatment allows to isolate ulvan for other purposes and efficiently ferment the remaining fibers.

  • 167.
    Cornell, Ann
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Chlorate cathodes and electrode design2014Inngår i: Encyclopedia of applied electrochemistry / [ed] R.F. Savinell,K. Ota,G. Kreysa, Springer, 2014, s. 175-181Kapittel i bok, del av antologi (Fagfellevurdert)
  • 168.
    Cornell, Ann
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Chlorate synthesis cells and technology2014Inngår i: Encyclopedia of applied electrochemistry / [ed] R.F. Savinell, K. Ota, G. Kreysa, Springer, 2014, s. 181-187Kapittel i bok, del av antologi (Fagfellevurdert)
  • 169.
    Cornell, Ann
    et al.
    KTH, Skolan för kemivetenskap (CHE).
    Simonsson, Daniel
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Ruthenium Dioxide as Cathode Material for Hydrogen Evolution in Hydroxide and Chlorate Solutions1993Inngår i: Chlor-Alkali and Chlorate Production/New Mathematical and Computational Methods in Electrochemical Engineering / [ed] T. Jeffrey, K. Ota, J. Fenton och H. Kawamoto, Pennington, New Jersey, USA: The Electrochemical Society , 1993, s. 191-Kapittel i bok, del av antologi (Fagfellevurdert)
  • 170.
    Correa Zapisotski, David
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Carbon dioxide separation by disc stack centrifuge at low CO2 concentration2022Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Medan världen undergår en klimatkris, nya sätt för att mildra den har undersökts till det korta och långa loppet. Koldioxid är ett ämne som uppmärksammats då stora mängder av den släpps ut till atmosfären på grund av förbränningsprocesser. Då detta sker, ett sätt för att mildra klimatomställningen är genom ”Carbon Capture and Storage”, CCS. Det finns redan metoder för att fånga och separera CO2, genom exempelvis roterande packade säng eller vattnade vägg kolumner. Dock har staplade disk centrifug inte undersökts. Denna rapport har undersökt och använt en staplad disk centrifug för just koldioxid separering, genom användning av vatten och NaOH-lösning som absorbenter. Några parametrar har varierats såsom koncentrationen på NaOH-lösningen, luftflödeshastighet och koldioxid koncentration. Resultaten visade att användning av en staplad disk centrifug separerade inte märkvärdiga mängder av CO2. Det hittades däremot förklaringar till detta och det var att den låga halten CO2, de begränsade mätinstrumenten och det experimentella uppställningen som ej gav tid för absorption att ske.

    Fulltekst (pdf)
    fulltext
  • 171.
    Creaser, D.
    et al.
    Luleå tekniska universitet.
    Andersson, B.
    Chalmers University of Technology.
    Hudgins, R.R.
    University of Waterloo.
    Silveston, P.L.
    University of Waterloo.
    Oxygen partial pressure effects on the oxidative dehydrogenation of propane1999Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 54, nr 20, s. 4365-4370Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of the gas-phase oxygen partial pressure for the oxidative dehydrogenation of propane over a V-Mg-O catalyst was investigated to explore reasons for improved propene yields when dehydrogenation was carried out under periodic operation. Steady-state experiments were performed in which the oxygen partial pressure was varied over a large range at constant propane partial pressures. In addition, the catalyst mass was varied to control the propane conversion so that selectivity and yield could be compared at a constant propane conversion. At the same propane conversion, propene selectivity increased as the partial pressure of oxygen decreased. Thus, propene yields can be improved at steady state by employing low oxygen partial pressures. It is likely that this is the reason for the higher propene yields observed under unsteady-state or periodic operation. It appears that the reaction mechanism must consist of more than one pathway for production of carbon oxides

  • 172.
    Creaser, Derek
    Luleå tekniska universitet.
    Crystal population balance model for nucleation and growth of colloidal TPA-silicalite-11999Inngår i: Porous materials in environmentally friendly processes: Proceedings of the 1st International FEZA Conference, Eger, Hungary, 1-4 September, 1999, Amsterdam: Elsevier, 1999, s. 117-124Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A model describing the crystallization of colloidal TPA-silicalite-1 is developed and tested. The nucleation rate is approximated from experimental data. Crystal growth is surface-reaction limited and the Gibbs-Thomson effect suppresses growth of small crystals, resulting in an induction period. Slow crystal growth during the nucleation period results in the narrow crystal size distribution typically observed for colloidal TPA-silicalite-1 syntheses.

  • 173.
    Creaser, Derek
    et al.
    Luleå tekniska universitet.
    Andersson, B.
    Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.
    Hudgins, R.R.
    Department of Chemical Reaction Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Silveston, P.L.
    Department of Chemical Reaction Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Cyclic operation of the oxidative dehydrogenation of propane1999Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 54, nr 20, s. 4437-4448Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The cyclic operation of the oxidative dehydrogenation of propane over a V-Mg-O catalyst by the alternate feeding of propane and oxygen gas mixtures was investigated. Generally, the response of the reaction products following a step-change in composition determined the cyclic conditions that resulted in an improved yield of propene. By alternating propane and oxygen with a 1 : 1 cycle split, time-average propene yields higher than steady state could be obtained. The optimal cycle period was about 60 s. This same period provided high propane conversion, as well as high propene selectivity. The cycle split could be varied by shortening the oxygen-feed half of the cycle with little effect on the time-average results. The oxygen half-cycle needed only to be long enough to reoxidize the catalyst. The propane feed scheme was varied by feeding increasing amounts of propane in the oxygen half-cycle. The change in feed scheme caused an increase in the time-average propane conversion that resulted in some further improvement in the propene yield despite some loss in propene selectivity.

  • 174.
    Creaser, Derek
    et al.
    Luleå tekniska universitet.
    Andersson, B.
    Chalmers University of Technology, Department of Chemical Reaction Engineering.
    Hudgins, R.R.
    Department of Chemical Engineering, University of Waterloo.
    Silveston, P.L.
    Department of Chemical Engineering, University of Waterloo.
    Transient kinetic analysis of the oxidative dehydrogenation of propane1999Inngår i: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 182, nr 1, s. 264-269Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Oxidative dehydrogenation of propane was studied using various transient techniques. Results support a redox mechanism in which propane reduces the catalyst, which is reoxidized by gas-phase oxygen. Only lattice oxygen participates in propene formation. Desorbable oxygen is a major source of poor selectivity, although lattice oxygen also causes total oxidation. Consequently, propene selectivity in the absence of gas-phase O2is superior to co-feed, steady-state selectivity at the same propane conversion. Propene selectivity is further improved by increasing the degree of catalyst reduction.

  • 175.
    Creaser, Derek
    et al.
    Luleå tekniska universitet.
    Andersson, B.
    Chalmers University of Technology, Department of Chemical Reaction Engineering.
    Hudgins, R.R.
    Department of Chemical Engineering, University of Waterloo.
    Silveston, P.L.
    Department of Chemical Engineering, University of Waterloo.
    Transient study of oxidative dehydrogenation of propane1999Inngår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 187, nr 1, s. 147-160Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Kinetics and the mechanism of the oxidative dehydrogenation of propane were investigated using various transient techniques. Results support a redox reaction mechanism in which propane and intermediate products react with lattice oxygen, reducing the catalyst surface, which is reoxidized by gas-phase O2. Partial reduction of the catalyst occurs during the start-up to a steady state. Successive pulsing with C3H8 reduced V5+ in the magnesium ortho-vanadate phase to V2+. Carbon-containing species were observed upon interruption of the reaction, although only minute amounts were formed. Cycling increases the amount of the carbon deposited, but this carbon is reactive and most of it is oxidized in the succeeding O2 pulse. Temperature-programmed oxidation (TPO) experiments on the catalyst used in steady-state operation revealed mainly strongly bound carbonaceous matter on the catalyst, but this carbon deposition did not affect catalyst activity. Thus, adsorbed oxygen is an important source of total combustion. Our experiments show, however, that lattice oxygen also produces total oxidation. Propene selectivity of the reaction in the absence of gas-phase O2 was superior to steady-state selectivity, at the same propane conversion. Propene selectivity could be further improved by increasing the degree of reduction of the catalyst

  • 176.
    Creaser, Derek
    et al.
    Luleå tekniska universitet.
    Andersson, Bengt
    Chalmers University of Technology, Department of Chemical Reaction Engineering.
    Hudgins, Robert
    Department of Chemical Engineering, University of Waterloo.
    Silveston, Peter
    Department of Chemical Engineering, University of Waterloo.
    Kinetic modelling of oxygen dependence in oxidative dehydrogenation of propane2000Inngår i: Canadian Journal of Chemical Engineering, ISSN 0008-4034, E-ISSN 1939-019X, Vol. 78, nr 1, s. 182-193Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several Mars-Van Krevelen-type redox kinetic models were developed for the catalytic oxidative dehydrogenation of propane and examined for their ability to predict high propene yields at low oxygen/propane feed ratios. The intent in this study was to use modelling as a means of extracting further mechanistic insight from experimental data rather than to identify the best model. Thus, a conventional redox model with a consecutive reaction mechanism and a single pathway for the production of carbon oxides predicts higher propene selectivity but only at the expense of low propane conversion. Experimental data indicated, however, that even at the same propane conversion, propene selectivity increased as the oxygen partial pressure was lowered. Models that successfully describe the data had an additional carbon oxide production path involving the reaction of propane with deeply oxidizing surface oxygen species. Kinetic models and experimental data examined do not fully resolve how these deeply oxidizing surface oxygen species are formed. However, they do reflect the accepted view that lattice oxygen selectively produces propene whereas more weakly bound surface adsorbed oxygen reacts to completely oxidize propane.

  • 177.
    Cuvilas, Carlos Alberto
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Mild Wet Torrefaction and Characterization of Woody Biomass from Mozambique for Thermal Applications2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Mozambique has vast forestry resources and also considerable biomass waste material such as bagasse, rice husks, sawdust, coconut husks and shells, cashew nut shell and lump charcoal waste. The potential of the total residues from the agricultural sector and the forest industry is estimated to be approximately 13 PJ. This amount of energy covers totally the production of charcoal which amounted to approximately 12.7 PJ in 2006. Although biomass is an attractive renewable source of energy, it is generally difficult to handle, transport, storage and use due to its lower homogeneity, its lower energy density and the presence of non-combustible inorganic constituents, which leads to different problems in energy conversion units such as deposition, sintering, agglomeration, fouling and corrosion. Therefore, a pretreatment of the biomass to solve these problems could lead to a change of current biomass utilization situation. The aim of this study is to convert Mozambican woody biomass residue into a solid biochar that resembles low-grade coal.

    In this work the current energy situation in Mozambique has been reviewed, and the available and potential renewable sources including residues from agricultural crops and forest industry as energy have been assessed. It was found that the country is endowed with great potential for biofuel, solar, hydro and wind energy production. However, the production today is still far from fulfilling the energy needs of the country, and the majority of people are still not benefiting from these resources. Charcoal and firewood are still the main sources of energy and will continue to play a very important role in the near future. Additionally, enormous amounts of energy resources are wasted, especially in the agricultural sector. These residues are not visible on national energy statistics. The chemical composition and the fuelwood value index (FVI) showed that by failing to efficiently utilise residues from Afzelia quanzensis, Millettia stuhlmannii and Pterocarpus angolensis, an opportunity to reduce some of the energy related problems is missed. An evaluation of effect of a mild wet torrefaction pretreatment showed that the chemical composition of the biochar is substantially different than the feedstock. The use of diluted acid as catalysts improves the biochar quality, namely in terms of the energy density and ash characteristics; however, the increment of the S content in the final product should be considered for market acceptance (because the fuels have a maximum allowance for S concentration). The thermal behaviour of the untreated and treated biomass was also investigated. The pyrolytic products of umbila and spruce were affected by the treatment and catalyst in terms of yield and composition of the vapours.

    Fulltekst (pdf)
    Thesis
  • 178.
    Dahlin, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Na/S balances at Skoghall mill 2015: Balances after reconstruction of the fiber line2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The scope of this master thesis was to investigate how a reconstruction at Skoghall Mill had changed the Na/S balance as well as evaluating how a new chemical plant manufacturing the mill’s chlorine dioxide would affect the balance. This was done by analyzing ingoing and outgoing process streams at the mill for sodium and sulfur and using obtained flow data for the period after the reconstruction. A balance was made to simulate how the system behaved at the time as well as balances simulating different shares of bleached pulp being manufactured. Balances with three possible types of chemical plants were also made, as well as calculations of the operating cost for each type of plant. From the balances and the operating costs it was concluded that the HPA process was the most beneficial for the Na/S balance as well as having the lowest operating cost.

    Fulltekst (pdf)
    Na/S balances at Skoghall mill 2015
  • 179.
    Dahlin, Sandra
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Processteknologi.
    Deactivation of emission control catalysts for heavy-duty vehicles: Impact of biofuel and lube oil-derived contaminants2020Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Catalytic emission control is used to reduce the negative impact of pollutants from diesel exhausts on our health and on the environment. For a heavy-duty truck, such a system consists of a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), a selective catalytic reduction (SCR) catalyst, and an ammonia slip catalyst (ASC). Due to greenhouse-gas induced global warming, it is necessary to decrease the emissions of such gases. Two strategies for this reduction are: 1) to produce engines that are more fuel efficient, 2) to use sustainably produced renewable fuels such as biodiesel and HVO. However, both these strategies may pose additional challenges for the emission control system: a colder exhaust due to the higher fuel-efficiency requires the use of highly active catalysts; catalyst deactivation related to impurities in biofuels, which requires very robust catalysts.   The objective of this thesis was to study the impact of biofuel as well as lubrication oil-related contaminants on the performance of emission control catalysts (DOC and SCR catalysts) for heavy-duty diesel engines. The main focus has been on the low-temperature performance of V2O5-WO3/TiO2 (VWTi) and Cu-SSZ-13 SCR catalysts.    Results from the project have shown that both Cu-SSZ-13 and VWTi catalysts capture and can be deactivated by phosphorus (P), while only the Cu-SSZ-13 is deactivated by sulfur (S). The degree of the P-related deactivation depends on the concentration in the catalyst, which depends on content of P in the exhaust and the exposure time, as well as the type of catalyst. S-deactivation of Cu-SSZ-13 is observed at low temperatures, where un-poisoned Cu-SSZ-13 are significantly more active than VWTi catalysts. As a contrast, the VWTi-performance can even be improved by sulfur; but alkali metals are severe poisons to VWTi catalysts. Partial performance-recovery of S-poisoned Cu-SSZ-13 can be obtained by exposing it to sulfur-free exhausts at elevated temperatures. The use of an upstream DOC, providing fast SCR conditions to the SCR catalyst, considerably improves the low-temperature performance of the VWTi, as well as sulfur-poisoned Cu-SSZ-13 catalysts. An upstream DOC also protects the SCR catalysts from phosphorus deactivation, as it can trap large amounts of P. However, if too much phosphorus is captured by the DOC, severe deactivation of this catalyst results, which lowers the overall performance of the exhaust treatment system.  Insights from this project will guide the development of robust exhaust treatment systems for various applications. Additionally, it could aid in developing more durable emission control catalysts.

    Fulltekst (pdf)
    Sandra Dahlin PhD thesis
  • 180.
    Dahlin, Sandra
    et al.
    Department of Chemical Engineering, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden.
    Lantto, Cornelia
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Scania CV AB, 151 87 Södertälje, Sweden.
    Englund, Johanna
    Competence Centre for Catalysis, Chalmers University of Technology, Gothenburg, Sweden.
    Westerberg, Björn
    Scania CV AB, 151 87 Södertälje, Sweden.
    Regali, Francesco
    Scania CV AB, 151 87 Södertälje, Sweden.
    Skoglundh, Magnus
    Competence Centre for Catalysis, Chalmers University of Technology, 412 96 Gothenburg, Sweden.
    Pettersson, Lars J.
    Department of Chemical Engineering, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden.
    Chemical aging of Cu-SSZ-13 SCR catalysts for heavy-duty vehicles – Influence of sulfur dioxide2019Inngår i: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 320, s. 72-83Artikkel i tidsskrift (Fagfellevurdert)
  • 181. Dahlquist, Erik
    et al.
    Mirmoshtaghi, Guilnaz
    Larsson, Eva K.
    Thorin, Eva
    Yan, Jinyue
    Engvall, Klas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Processteknologi.
    Liliedahl, Truls
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Dong, C.
    Hu, X.
    Lu, Q.
    Modelling and simulation of biomass conversion processes2015Inngår i: 2013 8TH EUROSIM CONGRESS ON MODELLING AND SIMULATION (EUROSIM), 2015, s. 506-512Konferansepaper (Fagfellevurdert)
    Abstract [en]

    By utilizing biomass gasification, the energy content of the biomass can be utilized to produce gas to be used for cogeneration of heat and power as well as other energy carriers such as fuels for vehicles. The concept is suitable for application to existing CHP plants as well as for utilizing spent liqour in small scale pulp and paper mills. The introduction would enable flexible energy utilization, use of problematic fuels as well as protects the environment by e.g. avoiding the release of toxic substances. In this paper, the possibilities to develop this concept is discussed. In this paper we compare different gasification processes with respect to what gas quality we get, and how the gasification can be modelled using different modelling approaches, and how these can be combined. Results from simulations are compared to experimental results from pilot plant operations in different scales and with different processes like CFB and BFB Technologies, athmospheric and pressurized, and using steam, air and oxygen as oxidizing media.

  • 182.
    Danish, Muhammad
    et al.
    E China Univ Sci & Technol, Peoples R China; Gujarat Univ, Pakistan.
    Naqvi, Muhammad
    Malardalen Univ.
    Farooq, Usman
    Gujarat Univ, Pakistan.
    Naqvi, Salman
    Univ Teknol PETRONAS, Malaysia..
    Characterization of South Asian agricultural residues for potential utilization in future 'energy mix'2015Inngår i: Energy Procedia / [ed] J. Yan, T. Shamim, H Li SK Chou, Elsevier, 2015, Vol. 75, s. 2974-2980Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper characterizes various locally available agricultural residues in South Asian region to evaluate their potential as feedstock for renewable energy production and contributing toward solving energy crisis and environmental issues. The thermo-chemical characterization has been performed in order to determine if the residues have potential to be used in biomass conversion technologies producing combined heat and power. The characterization methods for comparing different agricultural residues include proximate and ultimate analysis, heating value, ash content, thermo gravimetric analysis (TGA) and structural composition analysis (SCA). Widely available agricultural wastes in South Asian region were selected for the characterization i.e. bagasse, almond shell, corn cob, cotton stalks, wheat straw, sawdust, corn leaf, rice husk, rice straw, and corn straw. The analysis showed that the corn cob had the highest moisture content that will result in low energy efficiency of the thermal conversion technology due to energy requirement for drying. Whereas almond shell had the lowest moisture content. Ash and volatile contents were found to be highest in rice straw and almond shell respectively. The thermo gravimetric analysis showed that most of the agricultural residues can be easily decomposed and represent potential feedstock for biomass flexible combined heat and power systems through pyrolysis or gasification.

  • 183.
    Dannelind, Filip
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Hydrogen on demand for vessels: Using ammonia for hydrogen storage2022Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The use of an ammonia and hydrogen mixture in an internal combustion engine has previously been tested.  Limited number of studies have been done on how such a system efficiently can be adopted onboard a vessel and remain competitive to today’s fossil power solutions. A literature study was done to evaluate different aspect of the study such as what concentrations of ammonia and hydrogen that could be usable for an internal combustion engine, what storage tanks that could be used and how the reforming process could be optimized. 

    The study showed that in order for an ammonia and hydrogen on demand power/fuel system to be competitive, focus must be on how to minimize the external thermal input to the system and using a beneficial storage method for the specific vessel. The system has a cold side in which thermal energy is needed and a hot side in which thermal heat needs to be dissipated, comparing option 1-3 shows that managing these two sides of the system greatly increased the efficiency. 

    The study also shows that having an increased hydrogen mixture above   might be deemed unnecessary since it increases the cracker size needed and amount of ammonia tap off from both the main-stream and combustion-stream. Further investigations are needed on how to optimize the schematical design of the system if the temperature of the mixed-stream is deemed to be too high for the engine, this heat could then be utilized in another part of the cold side of the system.

    Fulltekst tilgjengelig fra 2025-05-25 13:00
  • 184.
    Das, Oisik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Mensah, Rhoda Afriyie
    School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
    George, Gejo
    Research and Post Graduate Department of Chemistry, St. Berchmans College, Changanacherry, Kerala, India.
    Jiang, Lin
    School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
    Xu, Qiang
    School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
    Neisiany, Rasoul Esmaeely
    Department of Materials and Polymer Engineering, Faculty of Engineering, Hakim Sabzevari University, Sabzevar, 9617976487, Iran.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Jose E, Tomal
    Research and Post Graduate Department of Chemistry, St. Berchmans College, Changanacherry, Kerala, India.
    Phounglamcheik, Aekjuthon
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hedenqvist, Mikael S.
    Department of Fibre and Polymer Technology, Polymeric Materials Division, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm100 44, Sweden.
    Restás, Ágoston
    Department of Fire Protection and Rescue Control, National University of Public Service, H-1011 Budapest, Hungary.
    Sas, Gabriel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Försth, Michael
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Berto, Filippo
    Department of Mechanical Engineering, Norwegian University of Science and Technology, Trondheim, 7491, Norway.
    Flammability and mechanical properties of biochars made in different pyrolysis reactors2021Inngår i: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 152, artikkel-id 106197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of pyrolysis reactors on the properties of biochars (with a focus on flammability and mechanical characteristics) were investigated by keeping factors such as feedstock, carbonisation temperature, heating rate and residence time constant. The reactors employed were hydrothermal, fixed-bed batch vertical and fixed-bed batch horizontal-tube reactors. The vertical and tube reactors, at the same temperature, produced biochars having comparable elemental carbon content, surface functionalities, thermal degradation pattern and peak heat release rates. The hydrothermal reactor, although, a low-temperature process, produced biochar with high fire resistance because the formed tarry volatiles sealed water inside the pores, which hindered combustion. However, the biochar from hydrothermal reactor had the lowest nanoindentation properties whereas the tube reactor-produced biochar at 300 °C had the highest nanoindentation-hardness (290 Megapascal) and modulus (ca. 4 Gigapascal) amongst the other tested samples. Based on the inherent flammability and mechanical properties of biochars, polymeric composites’ properties can be predicted that can include them as constituents.

  • 185.
    Das, Rasel
    et al.
    Department of Chemistry, Stony Brook University, Stony Brook, NY, 11794-3400, USA;.
    Lindström, Tom S. C.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Teknisk mekanik, Farkostteknik och Solidmekanik, Hållfasthetslära.
    Khan, Madani
    Department of Chemistry, Stony Brook University, Stony Brook, NY, 11794-3400, USA;.
    Rezaei, Mahdi
    Department of Chemistry, Stony Brook University, Stony Brook, NY, 11794-3400, USA;.
    Hsiao, Benjamin S.
    Department of Chemistry, Stony Brook University, Stony Brook, NY, 11794-3400, USA;.
    Nanocellulose Preparation from Diverse Plant Feedstocks, Processes, and Chemical Treatments: A Review Emphasizing Non-woods2024Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 19, nr 1Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Low-cost production of nanocellulose from diverse lignocellulosic feedstocks has become an important topic for developing sustainable nanomaterials. The available feedstocks include both woody and non-woody plants, where the latter are relatively underutilized. Interestingly, the porous structure and low lignin content in most non-woody plants, such as agricultural residues and natural fibers, also makes them ideal sources for lower energy nanocellulose production using simpler methods than those required to process woody plants. To enhance the goal of circularity, this review first provides an overview of the nanocellulose conversion from cellulose and then comprehensively discusses the use of non-woody feedstocks for nanocellulose production. Specifically, the availability of suitable non-woody feedstocks and the use of low-cost processes for pulping and cellulose oxidation treatments, including alkaline, solvent pulping, and nitrogen-oxidation treatments, are discussed. The information in this review can lead to new opportunities to achieve greater sustainability in biobased economies. Additionally, demonstrations of nanocellulose-based water purification technologies using agricultural residues derived remediation materials are highlighted at the end of this review.

  • 186.
    Das, Supriyo K.
    et al.
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Routh, Joyanto
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Roychoudhury, Alakendra N.
    Department of Geological Sciences, University of Cape Town, Rondebosch, South Africa.
    Klump, J. Val
    Department of Biological Sciences and Department of Geosciences, Great Lakes WATER Institute, University of Wisconsin-Milwaukee, Milwaukee, USA.
    Elemental (C, N, H and P) and stable isotope (del15 N and del13C) signatures in sediments from Zeekoevlei, South Africa: a record of human intervention in the lake2007Inngår i: Journal of Paleolimnology, ISSN 0921-2728, E-ISSN 1573-0417, Vol. 39, nr 3, s. 349-360Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We used elemental carbon, nitrogen, phosphorus and hydrogen ratios (C/N, N/P and H/C) with total organic carbon (TOC) and total phosphorus (TP) as well as stable carbon and nitrogen isotopes (δ13C and δ15N) to investigate the source and depositional conditions of organic matter in sediments from Zeekoevlei, the largest freshwater lake in South Africa. Typical C/N (10–12), H/C ratios (≥1.7) and δ13Corganic values (−22 to −19‰) together with the increase in TOC concentration indicate elevated primary productivity in lower middle (18–22 cm) and top (0–8 cm) sections of the sediment cores. Seepage of nutrients from a nearby waste water treatment plant, rapid urbanization and heavily fertilized farming in the catchments are responsible for the increased productivity. Consistent with this, measured δ15Norganic values (∼11‰) indicate increased raw sewage input towards the top-section of the core. Although cyanobacterial blooms are evident from the low δ15N values (∼3‰) in mid-section of the core, they did not outnumber the phytoplankton population. Low N/P ratio (∼0) and high TP (100–2,200 mg l−1) support cyanobacterial growth under N limited condition, and insignificant input of macrophytes towards the organic matter pool. Dredging in 1983, caused sub-aerial exposure of the suspended and surface sediments, and affected organic matter preservation in the upper mid-section (12–14 cm) of the core.

  • 187.
    Dashti, Somayeh
    et al.
    School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155/4563, Tehran, Iran; The Robert M. Buchan Department of Mining, Queen's University, 25 Union Street, Kingston, ON, K7L 3N6, Canada.
    Shakibania, Sina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Rashchi, Fereshteh
    School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155/4563, Tehran, Iran.
    Ghahreman, Ahmad
    The Robert M. Buchan Department of Mining, Queen's University, 25 Union Street, Kingston, ON, K7L 3N6, Canada.
    Synergistic, extractive, and selective separation of light, medium, and heavy rare earth elements using Cyanex 572 and Alamine 336 from a chloride medium2023Inngår i: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 204, artikkel-id 108447Artikkel i tidsskrift (Fagfellevurdert)
  • 188. Dau, H.
    et al.
    Fujita, E.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Artificial Photosynthesis: Beyond Mimicking Nature2017Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, nr 22, s. 4228-4235Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this Editorial, Guest Editors Holger Dau, Etsuko Fujita, and Licheng Sun introduce the Special Issue of ChemSusChem on “Artificial Photosynthesis for Sustainable Fuels”. They discuss the need for non-fossil based fuels, introduce both biological and artificial photosynthesis, and outline various important concepts in artificial photosynthesis, including molecular and solid-state catalysts for water oxidation and hydrogen evolution, catalytic CO2 reduction, and photoelectrochemical systems.

  • 189.
    Dayama, Parth Omprakash
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    A Comparative Study of Electrodes and Membranes for Anion Exchange Membrane Water Electrolysis Systems2021Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Vätgas kan framställas från förnybara energikällor genom vattenelektrolys med anjonbytande membran (AEMWE). AEMWE har vissa fördelar jämfört med traditionell alkalisk vattenelektrolys och elektrolysmed protonledande membran. Till exempel finns det möjlighet att använda alkalisk elektrolyt (även rent vatten) och billiga platinagruppsmetallfria katalysatorer tillsammans med ett anjonbytesmembran. Den största utmaningen med tekniken är att uppnå utmärkt och stabil prestanda för membran och elektroder. AemionTM anjonbytande membran (AEMs) av olika tjocklek, vattenupptag och kapacitet undersöktes i ett AEMWE system med 5 cm2 elektrodarea. Elektrokemisk prestanda hos dessa kommersiella AEM studerades med hjälp av porösa nickel elektroder. Bland de undersökta membranen visade AF2-HWP8-75-X stabil prestanda med en högfrekvent resistans (HFR) på 90 mΩ•cm2 och kunde nå en strömtäthet på 0,8 A/cm2 vid 2,38 V med 1 M KOH vid 60 ˚C. 

    AEMWE med AF2-HWP8-75-X och olika elektrodkombinationer undersöktes under samma driftsförhållanden. En elektrodkombination med Raney-Ni och NiFeO som katod respektive anod visade bäst prestanda under utvärderingen och gav en strömtäthet på 1,06 och 3,08 A/cm2 vid 2,00 respektive 2,32 V. KOH-lösningens temperatur och koncentration sänktes till 45 ˚C respektive 0,1 M för att undersöka effekten av driftsparametrar på flödescellens prestanda. Flödescellen uppvisade god stabilitet under de nya driftsförhållandena, men dess prestanda minskade avsevärt. Den nådde en strömtäthet på 0,8 A/cm2 vid 2,25 V.

    Fulltekst (pdf)
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  • 190.
    Dedic, Dina
    et al.
    KTH Royal Institute of Technology, Sweden.
    Sandberg, Teresia
    KTH Royal Institute of Technology, Sweden.
    Iversen, Tommy
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Larsson, Tomas
    RISE., Innventia.
    Ek, Monica
    KTH Royal Institute of Technology, Sweden.
    Analysis of lignin and extractives in the oak wood of the 17th century warship Vasa2014Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 68, nr 4, s. 419-425Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The wood in the 17th century Swedish warship Vasa is weak. A depolymerization of the wood's cellulose has been linked to the weakening, but the chemical mechanisms are yet unclear. The objective of this study was to analyze the lignin and tannin moieties of the wood to clarify whether the depolymerization of cellulose via ongoing oxidative mechanisms is indeed the main reason for weakening the wood in the Vasa. Lignin was analyzed by solid-state nuclear magnetic resonance [cross-polarization/magic-angle spinning (CP/MAS) 13C NMR] and by means of wet chemical degradation (thioacidolysis) followed by gas chromatography-mass spectrometry (GC-MS) of the products. No differences could be observed between the Vasa samples and the reference samples that could have been ascribed to extensive lignin degradation. Wood extracts (tannins) were analyzed by matrix-assisted laser desorption ionization (MALDI) combined with time-of-flight (TOF) MS and 13C NMR spectroscopy. The wood of the Vasa contained no discernible amounts of tannins, whereas still-waterlogged Vasa wood contained ellagic acid and traces of castalagin/vescalagin and grandinin. The results indicate that the condition of lignin in the Vasa wood is similar to fresh oak and that potentially harmful tannins are not present in high amounts. Thus, oxidative degradation mechanisms are not supported as a primary route to cellulose depolymerization.

  • 191. Deiana, Luca
    et al.
    Rafi, Abdolrahim A.
    Tai, Cheuk-Wai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Mid Sweden University, Sweden.
    Cordova, Armando
    Artificial Arthropod Exoskeletons/Fungi Cell Walls Integrating Metal and Biocatalysts for Heterogeneous Synergistic Catalysis of Asymmetric Cascade Transformations2023Inngår i: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 15, nr 15, artikkel-id e202300250Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel and sustainable tandem-catalysis system for asymmetric synthesis is disclosed, which is fabricated by bio-inspired self-assembly of artificial arthropod exoskeletons (AAEs) or artificial fungi cell walls (AFCWs) containing two different types of catalysts (enzyme and metal nanoparticles). The heterogeneous integrated enzyme/metal nanoparticle AAE/AFCW systems, which contain chitosan as the main structural component, co-catalyze dynamic kinetic resolution of primary amines via a tandem racemization/enantioselective amidation reaction process to give the corresponding amides in high yields and excellent ee. The heterogeneous AAE/AFCW systems display successful heterogeneous synergistic catalysis at the surfaces since they can catalyze multiple reaction cycles without metal leaching. The use of natural-based and biocompatible structural components makes the AAE/AFCW systems fully biodegradable and renewable, thus fulfilling important green chemistry requirements. 

  • 192.
    Deng, Tengfei
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mikro-modellering.
    Du, Sichen
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mikro-modellering.
    Study of Lime Dissolution Under Forced Convection2012Inngår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 43, nr 3, s. 578-586Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dissolution of different CaO cubes under force convection in liquid CaO-"FeO"-SiO2 slag was studied at 1873 K (1600 A degrees C). A linear relationship between normalized lengths and time was obtained after the experiment. It was evidently observed that the removal of the interface layer(s) including 2CaO center dot SiO2 by shear stress was the main mechanism for the dissolution. A stirring rate of approximately 100 rpm was found to be efficient to remove the interface layer(s). The limes with different structures had different dissolution rates.

  • 193.
    Derelöv, Sara
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Investigation of the effect of waterwork sludge on the pre-precipitation at the wastewater treatment plant in Norrköping2023Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Fulltekst (pdf)
    Investigation of the effect of waterwork sludge on the pre-precipitation at the wastewater treatment plant in Norrköping
  • 194.
    Deshpande, Raghu
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    The initial phase of the sodium bisulfite pulping of softwood dissolving pulp2015Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The sulfite pulping process is today practised in only a small number of pulp mills around the globe and the number of sulfite mills that use sodium as the base (cation) is less than five. However, due to the increasing interest in the wood based biorefinery concept, the benefits of sulfite pulping and especially the sodium based variety, has recently gained a lot of interest. It was therefore considered to be of high importance to further study the sodium based sulfite process to investigate if its benefits could be better utilized in the future in the production of dissolving pulps. Of specific interest was to investigate how the pulping conditions in the initial part of the cook (≥ 60 % pulp yield) should be performed in the best way.

    Thus, this thesis is focused on the initial phase of single stage sodium bisulfite cooking of either 100 % spruce or 100 % pine wood chips. The cooking experiments were carried out with either a lab prepared or a mill prepared cooking acid and the temperature and cooking time were varied. Activation energies for different wood components were investigated as well as side reactions concerning the formation of thiosulfate and sulfate.

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  • 195.
    Dey, Ananta
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Mendalz, Amal
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Wach, Anna
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland.;Jagiellonian Univ, SOLARIS Natl Synchrotron Radiat Ctr, Krakow, Poland..
    Vadell, Robert Bericat
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Silveira, Vitor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Leidinger, Paul Maurice
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Huthwelker, Thomas
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Shtender, Vitalii
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Tillämpad materialvetenskap.
    Novotny, Zbynek
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Artiglia, Luca
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Sá, Jacinto
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Polish Acad Sci, Inst Phys Chem, Marcina Kasprzaka 44-52, PL-01224 Warsaw, Poland..
    Hydrogen evolution with hot electrons on a plasmonic-molecular catalyst hybrid system2024Inngår i: Nature Communications, E-ISSN 2041-1723, Vol. 15, artikkel-id 445Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Plasmonic systems convert light into electrical charges and heat, mediating catalytic transformations. However, there is ongoing controversy regarding the involvement of hot carriers in the catalytic process. In this study, we demonstrate the direct utilisation of plasmon hot electrons in the hydrogen evolution reaction with visible light. We intentionally assemble a plasmonic nanohybrid system comprising NiO/Au/[Co(1,10-Phenanthrolin-5-amine)2(H2O)2], which is unstable at water thermolysis temperatures. This assembly limits the plasmon thermal contribution while ensuring that hot carriers are the primary contributors to the catalytic process. By combining photoelectrocatalysis with advanced in situ spectroscopies, we can substantiate a reaction mechanism in which plasmon-induced hot electrons play a crucial role. These plasmonic hot electrons are directed into phenanthroline ligands, facilitating the rapid, concerted proton-electron transfer steps essential for hydrogen generation. The catalytic response to light modulation aligns with the distinctive profile of a hot carrier-mediated process, featuring a positive, though non-essential, heat contribution. Direct participation of plasmon-induced hot electrons in the photoelectrocatalytic synthesis of hydrogen. This report solves a long-lasting contentious issue surrounding plasmonic materials on catalytic applications.

    Fulltekst (pdf)
    FULLTEXT01
  • 196.
    Diklev, Eliot
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Ultrasonication of Spiral Wound Membranes to Mitigate Fouling in Reverse Osmosis2022Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Syftet med den här studien var att undersöka en alternativ slamningsreducerande teknik till spolning, som effektivt kan ta bort biologisk påväxt. Ultraljud undersöktes som en möjlig metod för att ta bort igenslamningen från omvänd osmos med ett spirallindat membran. Tidigare forskning har föreslagit att ultraljud skulle kunna vara effektivt på platta membran men inte på spirallindade membran, på grund av packningsdensiteten som spirallindan medför. Därför genomfördes inom denna studie försök med spirallindade membran och ultraljud, för att få en förståelse av dess effekter inom det spirallindade membranet. För det första undersöktes tidsberoendet av ultraljud, vilket visade liknande resultat som tidigare forskning, att ultraljudet uppnådde effekt inom några minuter. För det andra behandlades två membran en gång om dagen under 12 dagar, med undantag för dag 6 och 7. Ett behandlades med ultraljud och ett med spolning, och den mikrobiologiska kontamineringen i permeatet analyserades sedan. Det ultraljudsbehandlade membranet producerade mindre kontaminering under de 12 dagarna. Det krävs dock fler experiment och analyser för att bekräfta detta, eftersom tidsbegränsningar inte möjliggjorde repetitioner. En ekonomisk utvärdering genomfördes också för att undersöka möjligheten att implementera ultraljud i kommersiell skala. Den ekonomiska aspekten är en avvägning mellan vattenkostnad och energikostnad, som är beroende av geografiskt läge. Överlag indikerar resultaten att det sparade vattnet kostar mer än den energi som krävs, vilket är fördelaktigt för implementering av ultraljudsbehandling. Sammanfattningsvis visade ultraljudsbehandlingen bättre resultat än spolning inom några minuter, och hade även en ekonomisk fördel, men kostnaden för energi till vatten är beroende av geografisk plats.

    Fulltekst (pdf)
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  • 197.
    Ding, Saiman
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Processteknologi.
    Kantarelis, Efthymios
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Processteknologi.
    Engvall, Klas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Processteknologi.
    Potassium-Induced Phenomena and Their Effects on the Intrinsic Reactivity of Biomass-Derived Char during Steam Gasification2023Inngår i: ACS Omega, E-ISSN 2470-1343, Vol. 8, nr 32, s. 29131-29142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mineral content of biomass plays an important role in the gasification rate of biomass-derived char. The understanding and quantification of mineral-related phenomena are thus of importance when considering gasification reactor design. In the present work, the potassium-induced catalytic phenomena during gasification of biomass-derived char have been studied. Char samples with similar structure and different intrinsic potassium content were gasified in a steam atmosphere at a temperature range of 700-800 °C. It was found that for all the samples, irrespective of the temperature and the initial potassium content, there is a critical K/C ratio (5 × 10-3), whereafter the catalytic phenomena prevail. The instantaneous conversion rate of the char is positively correlated with the potassium content and the progressively increasing conversion. The application of the modified random pore model was able to capture the later stages of conversion by the introduction of two additional parameters (c and p). It was found that these constants are not just fitting parameters but that there is an underlying physical significance with c being directly related to the intrinsic potassium content while being temperature independent and with p being temperature dependent.

  • 198.
    Dobryden, Illia
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mensi, Elizaveta
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Almqvist, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Surface Forces between Nanomagnetite and Silica in Aqueous Ca2+ Solutions Studied with AFM Colloidal Probe Method2020Inngår i: Colloids and Interfaces, ISSN 2504-5377, Vol. 4, nr 3, artikkel-id 41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dispersion and aggregation of nanomagnetite (Fe3O4) and silica (SiO2) particles are of high importance in various applications, such as biomedicine, nanoelectronics, drug delivery, flotation, and pelletization of iron ore. In directly probing nanomagnetite–silica interaction, atomic force microscopy (AFM) using the colloidal probe technique has proven to be a suitable tool. In this work, the interaction between nanomagnetite and silica particles was measured with AFM in aqueous Ca2+ solution at different pH levels. This study showed that the qualitative changes of the interaction forces with pH and Ca2+ concentrations were consistent with the results from zeta-potential measurements. The repulsion between nanomagnetite and silica was observed at alkaline pH and 1 mM Ca2+ concentration, but no repulsive forces were observed at 3 mM Ca2+ concentration. The interaction forces on approach were due to van der Waals and electrical double-layer forces. The good fitting of experimental data to the DLVO model and simulations supported this conclusion. However, contributions from non-DLVO forces should also be considered. It was shown that an increase of Ca2+ concentration from 1 to 3.3 mM led to a less pronounced decrease of adhesion force with increasing pH. A comparison of measured and calculated adhesion forces with a few contact mechanics models demonstrated an important impact of nanomagnetite layer nanoroughness.

  • 199.
    Dobryden, Illia
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Potapova, Elisaveta
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Almqvist, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Weber, Hans
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Application of AFM to probe micro- and nano-sized magnetite particle interaction in Ca2+ solution2014Inngår i: Proceedings of the International Summer School on Application of Scanning Probe Microscopy in Life Sciences, Soft Matter and Nanofabrication", Aalborg: River Publishers, 2014Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Natural magnetite is used for producing iron ore pellets, one of the raw materials in steel production. The quality of produced pellets depends on many factors, including the properties of the magnetite concentrate fed to pelletization. To be able to minimize the effect of the variations in feed properties on pellets quality, investigation of magnetite particle interaction with a focus on the surface properties is required. Atomic force microscopy (AFM), using the colloidal probe technique, is a suitable tool for measuring such particle-particle interaction in-situ. Natural particles are usually of micro-sizes (m-s) and have different sizes and shapes, which complicates an accurate investigation of particle interaction with AFM. To overcome such difficulties, synthetic nanoparticles are used instead. Process water chemistry is one of the factors affecting magnetite surface properties. Partial dissolution of calcite and apatite minerals, present in iron ore, results in high Ca2+ concentrations in the process water, which has been shown to have a major effect on the charge of the magnetite particles [1, 2]. The aim of this study was therefore to investigate forces and aggregation between magnetite particles, of micro- and nano-size (n-s), in Ca2+ solutions at various pH values. The spherical monodispersed magnetite nano-sized particles, with a diameter of approx. 10 nm, were synthesized by the precipitation technique [3]. Measurements were performed for m-s probe/m-s layer and m-s probe/n-s layer systems. Natural magnetite particles of 10-30 µm size were glued to NP-S cantilevers (Digital Instruments/Bruker, Santa Barbara, CA) with a measured spring constant of 0.12 N/m. Nano-sized particles were deposited on the glass slides by dip-coating. Roughness (Ra) of the n-s layers was measured with AFM and was about 10 nm for areas 1×1µm2, a representative high-resolution image is shown in Figure 1. Particle interaction was similar for m-s and n-s magnetite particles at pH 4 and 6. At pH 10, the interaction behavior was different due to probable surface modification of natural magnetite particles by ions from process water. The adhesion force for both interacting systems was measured, see ref. [4] for a detailed description of the results. To verify that ϛ-potential measurements could be used to predict the interaction between charged particles (in this case silica and magnetite) in solutions containing inorganic ions, force measurements between n-s magnetite layer and a SiO2 spherical probe (3.5 µm in diameter) were performed and correlated with the ϛ-potential results for these particles in the same solutions. Also, a DLVO simulation was performed to theoretically confirm the experimental interaction based on surface charge trends. An example of the simulated force curves is shown in Figure 2. The interaction between the probe and the magnetite surface was attractive at pH 4 and 6 but became repulsive at pH 8 and 10, which is in agreement with what could be expected from the ϛ-potential results for these particles.

    Fulltekst (pdf)
    FULLTEXT01
  • 200.
    Dobryden, Illia
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Potapova, Elisaveta
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Weber, Hans
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Almqvist, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Force interactions between magnetite, silica, and bentonite studied with atomic force microscopy2015Inngår i: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 42, nr 4, s. 319-326Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Iron ore pellets consist of variety of mineral particles and are an important refined product used in steel manufacturing. Production of high-quality pellets requires good understanding of interactions between different constituents, such as magnetite, gangue residues, bentonite, and additives. Much research has been reported on magnetite, silica, and bentonite surface properties and their effect on pellet strength but more scant with a focus on a fundamental particle–particle interaction. To probe such particle interaction, atomic force microscopy (AFM) using colloidal probe technique has proven to be a suitable tool. In this work, the measurements were performed between magnetite–magnetite, bentonite–magnetite, silica–bentonite, and silica–magnetite particles in 1 mM CaCl2 solution at various pH values. The interaction character, i.e., repulsion or attraction, was determined by measuring and analyzing AFM force curves. The observed quantitative changes in interaction forces were in good agreement with the measured zeta-potentials for the particles at the same experimental conditions. Particle aggregation was studied by measuring the adhesion force. Absolute values of adhesion forces for different systems could not be compared due to the difference in particle size and contact geometry. Therefore, the relative change of adhesion force between pH 6 and 10 was used for comparison. The adhesion force decreased for the magnetite–magnetite and bentonite–silica systems and slightly increased for the magnetite–bentonite system at pH 10 as compared to pH 6, whereas a pronounced decrease in adhesion force was observed in the magnetite–silica system. Thus, the presence of silica particles on the magnetite surface could have a negative impact on the interaction between magnetite and bentonite in balling due to the reduction of the adhesion force.

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