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  • 51. Argyropoulos, Dimitris D. S.
    et al.
    Crestini, Claudia
    Dahlstrand, Christian
    Furusjö, Erik
    Gioia, Claudio
    Jedvert, Kerstin
    Henriksson, Gunnar
    Hulteberg, Christian
    Lawoko, Martin
    Pierrou, Clara
    Samec, Joseph S. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Ren Fuel K2B AB, Sweden; RenFuel Materials AB, Sweden; Chulalongkorn University, Thailand.
    Subbotina, Elena
    Wallmo, Henrik
    Wimby, Martin
    Kraft Lignin: A Valuable, Sustainable Resource, Opportunities and Challenges2023Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 16, nr 23, artikkel-id e202300492Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Kraft lignin, a by-product from the production of pulp, is currently incinerated in the recovery boiler during the chemical recovery cycle, generating valuable bioenergy and recycling inorganic chemicals to the pulping process operation. Removing lignin from the black liquor or its gasification lowers the recovery boiler load enabling increased pulp production. During the past ten years, lignin separation technologies have emerged and the interest of the research community to valorize this underutilized resource has been invigorated. The aim of this Review is to give (1) a dedicated overview of the kraft process with a focus on the lignin, (2) an overview of applications that are being developed, and (3) a techno-economic and life cycle asseeements of value chains from black liquor to different products. Overall, it is anticipated that this effort will inspire further work for developing and using kraft lignin as a commodity raw material for new applications undeniably promoting pivotal global sustainability concerns.

  • 52.
    Arkhipov, Victor P.
    et al.
    Kazan National Research Technological University.
    Idiyatullin, Zhamil Sh
    Kazan National Research Technological University.
    Potapova, Elisaveta
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Antzutkin, Oleg
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Filippov, Andrei
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Micelles and aggregates of oxyethylated isononylphenols and their extraction properties near cloud point2014Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 118, nr 20, s. 5480-5487Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We used nuclear magnetic resonance (NMR) spectroscopy and dynamic light scattering (DLS) techniques to study the structural and dynamic properties of micellar solutions of nonionic surfactants of a homologous series of oxyethylated isononylphenols - C9H19C6H 4O(C2H4O)nH, where n = 6, 8, 9, 10, or 12 - in a wide range of temperatures, including cloud points. The radii of the micelles and aggregates, as well as their compositions at different concentrations of surfactant, were determined. Using aqueous phenol solutions as a model, we studied the process of cloud point extraction with oxyethylated isononylphenols

  • 53.
    Arkhipov, Victor
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Potapova, Elisaveta
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Antzutkin, Oleg
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Filippov, Andrei
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Micelle structure and molecular self-diffusion in isononylphenol ethoxylate–water systems2013Inngår i: Magnetic Resonance in Chemistry, ISSN 0749-1581, E-ISSN 1097-458X, Vol. 51, nr 7, s. 424-430Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structure and dynamic properties of micellar solutions of nonionic surfactants of a series of isononylphenol ethoxylates, C9H19C6H4O(C2H4O)nH (where n = 6,8,9,10, and 12), were studied by NMR diffusometry, dynamic light scattering, and viscosimetry. The sizes of the micelles were determined for different surfactants and at different surfactant concentrations. The numbers of water molecules bound by a micelle and by one oxyethylene group of the surfactant were estimated

  • 54.
    Arksand, Elsa
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Parametrization of a Lithium-ion battery2021Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Batterimodeller används för att representera batterier. För ändamål som batterihanteringssystem används idag främst empiriska modeller som representerar ett batteri med en motsvarande kretsmodell. Några nackdelar för dessa modeller ligger i dess oförmåga att simulera interna tillstånd och en tidskrävande parametriseringsprocess. Dessa nackdelar motiverar ingenjörer att vända sig till modeller som är baserade på fysiska lagar som ett alternativ eftersom de kan ge insikt i vad som händer inuti batteriet. Batterimodellerna som är baserade på de fysiska lagarna har alltför krävande beräkningar för att kunna användas för vissa applikationer, som batterihanteringssystem. Singel-partikelmodellen (SPM) är en fysikbaserad modell som används i detta avhandlingsprojekt. Syftet med projektet var att hitta en metod för att parametrisera SPM för nya kommersiella cylindriska HTPFR18650 1100mAh 3.2V litiumjärnfosfatceller. En litteraturundersökning och experiment användes för att extrahera parametervärdena. 17 parametrar valdes från litteraturundersökningen eftersom de kunde användas för att parametrisera modellen. Geometriska parametrar hittades genom en cellöppning. Tre typer av icke-destruktiva experiment som var inspirerade av litteraturen utfördes för att extrahera värden för de andra icke-geometriska parametrarna. Ett cykeltest med låg strömhastighet utfördes för att få en pseudo-OCV-kurva och för att extrahera kapacitetsrelaterade parametrarna. En känslighetsanalys genomfördes för galvanostatisk intermittent titreringsteknik testet (GITT) och pulstestet för de parametrar som var kopplade till transportoch kinetiska fenomen. Python matematisk batterimodellering (PyBaMM) användes för att simulera experimenten. Parametersamlingen Prada 2013 användes som standardvärden. Standardvärdena för de valda parametrarna ersattes av de värden som hittades genom experiment. Känslighetsanalysen visade att några av de valda parametrarna var känsliga för experimenten medan andra inte var det. Parametrarna extraherades genom fysiska relationer och genom att anpassa parametervärde för simuleringen så att den passar den experimentella datan under urladdningsförloppet. Värden för 14 av de 17 parametrarna extraherades i metoden. Den parametriserade modellen validerades mot två potentiella applikationer, en för ett batterielfordon och den andra för ett mild-hybridfordon. Den parametriserade modellen visade att den negativa partikelradien inte kan hittas med den föreslagna parametriseringsmetoden. Simuleringen visade sig också matchade den experimentella datan bättre under urladdning av cellerna jämfört till uppladdning. Flera förbättringar för framtida arbete har föreslagits, såsom att utvidgning av känslighetsanalysen, att erhålla OCV-kurvan från GITT istället för att använda pseudo-OCVkurvan, att använda strängare gränser vid kurvanpassningarna samt att skapa mer optimala tester för att extrahera parametervärdena.

    Fulltekst (pdf)
    fulltext
  • 55.
    Arman, S.Y.
    et al.
    Department of Mining and Metallurgical Engineering, Amirkabir University of Technology.
    Omidvar, H.
    Department of Mining and Metallurgical Engineering, Amirkabir University of Technology.
    Tabaian, S.H.
    Department of Mining and Metallurgical Engineering, Amirkabir University of Technology.
    Sajjadnejad, M.
    Department of Mining and Metallurgical Engineering, Amirkabir University of Technology.
    Fouladvand, Shahpar
    Department of Mining and Metallurgical Engineering, Amirkabir University of Technology.
    Afshar, Sh.
    Department of Chemistry, Iran University of Science and Technology.
    Evaluation of nanostructured S-doped TiO2 thin films and their photoelectrochemical application as photoanode for corrosion protection of 304 stainless steel2014Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 251, s. 162-169Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Undoped and S-doped TiO2 thin films were prepared on titanium substrate through a sol–gel method. The photoelectrochemical behavior of S-doped TiO2 thin film (as photoanode) was studied. The effect of Sulfur doping on structural, optical and morphological properties of TiO2 was studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), FT-IR, UV–ViS and FE-SEM. Superiority of the S-doped TiO2 film was shown through taking advantage of linear sweep voltametry measurement, open-circuit potential of 304 stainless steel as well as potetiodynamic polarization technique. Results showed that S-doped TiO2 thin film is an efficient photoanode with long term stability (several hours).

  • 56.
    Arnau, Laurent
    KTH, Skolan för kemivetenskap (CHE).
    Techno-Economic Feasibility Study for the Production of Microalgae Based Plant Biostimulant2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Microalgae are considered as a potential feedstock for many promising applications. Some active substances in microalgae have plant biostimulation effects potentially useful in agriculture. However, to produce such a microalgal biomass, specific microalgae cultivation and post-treatment processes must be designed to preserve active substances. A particular focus is provided on cultivation (tubular photobioreactor) and different plausible post-treatment scenarios for microalgae separation (flocculation and centrifugation) and preservation (sterilization and drying). For each step, yield and energy consumption are modeled using data taken from literature or lab and pilot scale experiments. Industrial equipment for scale-up process is also studied by comparing existing systems. These models enable to make an economic evaluation of the whole process and to study its profitability for each scenario. The breakeven price is calculated as a function of the production rate. Several parameters are suggested to improve system efficiency and profitability at the end of this study. However, a better microalgae characterization and more experiments on potential post-treatment systems are required to improve the accuracy of the model.

    Fulltekst (pdf)
    fulltext
  • 57.
    Aronsson, Tim
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Chromatographic separation of rare earth elements using a novel extractant mixture2021Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Sällsynta jordartsmetaller är en kritisk råvara som står inför viktiga utmaningar gällande utbud och efterfrågan. För att överkomma dessa utmaningar behövs det effektiva separationsmetoder. Den här rapporten studerar separationen av sällsynta jordartsmetaller med extraktionskromatografi. Tre olika extrakt-modifierade HPLC kolonner användes för att separera en samling av åtta sällsynta jordartsmetaller; lantan, cerium, praseodym, neodym, samarium, gadolinium, dysprosium och yttrium. Den första kolonnen innehöll ren HDEHP som extraktant, den andra ren HEHEHP som extraktant. Den tredje kolonnen innehöll en blandning av de två extrakanterna. Blandningen bestod av 15–30% HDEHP. Eluering genomfördes med salpetersyra i olika koncentrationer och applicering. Forskningsfrågan som rapporten bygger på gäller hurvida blandningen av extraktanterna kan förbättra separationen gentemot att endast använda de rena extraktanterna. Jämförelsen kolonnerna emellan baserades huvudsakligen på två parameterar, salpetersyraförbrukning och upplösning av toppar. 

    Resultaten visar att kolonnen med endast HEHEHP hade minst salpetersyraförbrukning men gav sämst upplösning. Kolonnen med endast HDEDP hade högst salpetersyraförbrukning men gav bäst upplösning, speciellt för de fyra tyngsta ämnena; samarium, gadolinium, dysprosium och yttrium. Kolonnen med extraktantblandningen gav god upplösning för alla ämnen, speciellt för de fyra lättaste ämnena; lantan, cerium, praseodym och neodym. Eftersom denna kolonn dessutom hade relativt låg salpetersyraförbrukning är den preliminära slutsatsen att denna presterade bäst generellt. Slutsatsen är därmed att extraktantblandningen kan förbättra separationen.

    Fulltekst (pdf)
    fulltext
  • 58.
    Arroyo Molina, Javier
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Towards a virtual climate chamber – A physical experimental study2020Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This project focuses on experimentally characterizing one of the tools used at Ericsson AB to test product performance, the climatic chamber. By conducting experiments inside the climate chamber and post processing the data obtained, the airflow inside it can be understood and compared to outdoor experimental data. One of the main sections of this work is to prove the hypothesis: The energy potential of the wind outdoors is greater than indoors, which is shown to be true when comparing values for the integral length scales of the flow, at the same mean wind speed. The second main part of this project is to obtain valuable experimental input that will serve to construct a virtual model of the climate chamber. With the conclusions drawn from the experiments, which involve heat transfer, boundary conditions for the numerical model can be established.

    Fulltekst (pdf)
    fulltext
  • 59.
    Asfaw, Habtom Desta
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteriesManuskript (preprint) (Annet vitenskapelig)
  • 60.
    Astorsdotter, Jennifer
    KTH, Skolan för kemivetenskap (CHE).
    Dewatering Cellulose Nanofibril Suspensions through Centrifugation2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Cellulose nanofibrils (CNF) is a renewable material with unique strength properties. A difficulty in CNF production is that CNF suspensions contain large amounts of water. If CNF suspension volume can be decreased by dewatering facilitated by centrifugation, then transportation costs and storage costs can be reduced. The aim of this thesis is to investigate the impact various parameters have on CNF centrifugation dewatering and identify optimal conditions for maximal water removal.

    A laboratory study was conducted using four materials; 2.0 w% enzymatically treated CNF (CNF1), 1.9 w% carboxymethylated CNF (CNF2) and two commercial samples (1.9 w% CNFA and 1.8 w% CNFB). The main method was analytical centrifugation up to 2330 g. Parameters tested were initial concentration before centrifugation, temperature, NaCl addition, pH, and applied solid compressive pressure (g-force and surface weight). In addition to centrifugation experiments the four materials were characterized with laser diffraction, UV-vis absorption, Dynamic light scattering, and dry weight measurements.

    Analysis of the experimental data collected show that increase in initial concentration give a higher final concentration, but less water is removed. Furthermore, temperature changes have no effect on separation of CNF and water. At an applied solid compressive pressure of 3 kPa and initial concentration at 1.5 w% the concentrations 5.5 w%, 1.5 w%, 4.0 w%, and 4.3 w% can be reach for CNF1, CNF2, CNFA, and CNFB respectively. After extrapolation of polynomial functions fitted to experimental data an applied solid compressive pressure of 22 kPa and initial concentration at 1:5 w%, the concentrations 9.1 w%, 1.5 w%, 6.9 w%, and 7.9 w% are predicted for CNF1, CNF2, CNFA, and CNFB respectively. The thickening of CNF suspensions achieved and predicted in this thesis implies possibilities for large amounts of water removal, e.g. the water content in a CNF1 suspension is reduced from 65.7 litres/kg CNF to 10.0 litres/kg CNF at the solid compressive pressure 22 kPa. The concentrations at 22 kPa are determined by extrapolation from experimental data <3 kPa solid compressive pressure. The carboxymethylated CNF2 can not be dewatered unless it is diluted or if salt or pH is adjusted. This is directly correlated to the electrostatic forces in the suspension and the Debye length. Addition of salt or lowered pH also eliminate any concentration gradients in diluted and centrifuged CNF2 suspensions.

    Fulltekst (pdf)
    fulltext
  • 61.
    Asuquo, Asuquo Jackson
    et al.
    University of Strathclyde, UK.
    Zhang, Xiaolei
    University of Strathclyde, UK.
    Lin, Leteng
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Li, Jun
    University of Strathclyde, UK.
    Green heterogeneous catalysts derived from fermented kola nut pod husk for sustainable biodiesel production2024Inngår i: International Journal of Green Energy, ISSN 1543-5075, E-ISSN 1543-5083Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of green heterogeneous catalysts that are obtained from waste agricultural biomass can make the production of biodiesel more economical. In this research, three solid base heterogeneous catalysts (Catalyst A, B, and C) were synthesized from kola nut pod husks, and the synergistic effects of the elemental composition on catalytic activities for biodiesel production were studied. The results revealed a high surface area of Catalysts A, B, and C at 419.90 m2/g, 430.54 m2/g, and 432.57 m2/g, respectively. Their corresponding pore diameters are 3.53 nm, 3.48 nm, and 3.32 nm, showing that the catalysts are mesoporous in nature. The X-ray Fluorescence (XRF) results revealed the presence of a variety of alkaline earth metals and their corresponding metal oxides in substantial amounts. Catalyst A was produced with the highest concentration of calcium at 40.84 wt.% and calcium oxide at 68.02 mole%. The substantial concentration of other elements, such as potassium, magnesium, and aluminum, and their corresponding metal oxides are the proof of high catalytic activity of the produced green catalysts. The high CaO contents of all three produced catalysts and their high surface areas indicate their strong potential for good catalytic activities applied to the synthesis of biodiesel.

  • 62.
    Atakan, Aylin
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Keraudy, Julien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Mäkie, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Hulteberg, Christian
    Lund Univ, Sweden.
    Björk, Emma
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Impact of the morphological and chemical properties of copper-zirconium-SBA-15 catalysts on the conversion and selectivity in carbon dioxide hydrogenation2019Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 546, s. 163-173Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A hybrid catalyst consisting of Zr-doped mesoporous silica (Zr-SBA-15) supports with intergrown Cu nanoparticles was used to study the effects of a catalysts chemical states on CO2 hydrogenation. The chemical state of the catalyst was altered by using tetraethyl orthosilicate (TEOS) or sodium metasilicate (SMS) as the silica precursor in the synthesis of the Zr-SBA-15 framework, and infiltration (Inf) or evaporation induced wetness impregnation (EIWI) as the Cu loading method. As a result, the silica precursor mainly affects the activity of the catalyst whereas the Cu loading method alters the selectivity of the products. TEOS materials exhibit a higher catalytic activity compared to SMS materials due to different Zr dispersion and bonding to the silica matrix. EIWI catalysts display selectivity for methanol formation, while the Inf ones enable methanol conversion to DME. This is correlated to a higher Zr content and lower Cu oxidation states of EIWI prepared catalysts. (C) 2019 Elsevier Inc. All rights reserved.

  • 63.
    Augustsson, Jimmy
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Högfeldt, Jonathan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Produktion av polyhydroxyalkanoater (PHA) av avloppsvatten från massa och pappersindustri: En studie kring bakteriernas förmåga att ackumulera PHA beroende på sammansättning av karboxylsyror2020Independent thesis Basic level (degree of Bachelor), 15 poäng / 22,5 hpOppgave
    Abstract [en]

    Since the beginning of the 20th century plastic has been a widely used material, which has resulted in large quantities of plastic being produced in the last century. The plastics of today are mainly produced from fossil raw materials, which gives it a high climate impact. Plastic also has a long service life, which creates problems with handling after the new period when new plastic is produced at a faster rate than plastic debris can be recycled or incinerated. One possible approach is to switch from plastic from fossil sources to bioplastics, which is produced by renewable sources. This means a reduction in the environmental impact as the amount of fossil CO2 emissions from combustion of plastics would decrease. Polyhydroxyalkanoates (PHAs) are created by short volatile fatty acids (VFAs) added to bio sludge from a wastewater treatment plant at a pulp and paper mill where there is a lot of bacteria and microorganisms. Some of the bacteria in the sludge have the ability to accumulate PHA when VFA is added in excess and then be able to use it as an energy and carbon source in cases of starvation. This means that PHA produced in this way can be degraded by bacteria making it biodegradable while having similar properties as oil-based plastics. Production of PHA is currently expensive as it is often necessary to purchase VFA for production. To make it economically sustainable to replace oil-based plastics with PHA, the cost of PHA production must therefore be reduced. This can be done by using mixed bacterial cultures from, for example, industrial wastewater treatment plants and by creating their own composition of VFA through fermentation. At the paper mill at BillerudKorsnäs Gruvön there are several process streams that today are led to the water treatment plant, one of which is from PM6 (Paper Machine 6). By fermenting that stream, VFA can be formed with a composition of acetic acid, propionic acid, and butyric acid. The current may thus be suitable to use as a substrate in PHA production. Another way to produce VFA is to ferment the residual flow from hydrothermal carbonation (HTC) of bio sludge. According to (Samorì et al., 2019), acetic acid, butyric acid and valeric acid are formed, which means that even this stream may be suitable as a substrate for PHA production. The purpose of this thesis is to investigate the effects of the composition of VFA on the production of PHA from forest industrial bio sludge. The study covers two different cases, Case PM6 and Case HTC, where two different types of composition of VFA are added to paper sludge from the paper mill. The experiments were performed in cylindrical tanks on three occasions where the first two experiments had a volume of 30 liters and the last experiment a volume of 10 liters. On the first occasion, the maximum accumulation rate in the growth phase was studied. In the second instance, a high accumulation rate was sought, but also survival after the growth phase. The first two trials were batch trials where the sludge was dosed until saturation was achieved. On the third occasion, the possibility of carrying out PHA production with a continuous sludge exchange was studied. The experiments were analyzed by FTIR which provided information on the absorbance of the sludge which shows how the PHA concentration increased during the course of the experiments. Extractions were then performed to obtain the concentration of PHA that eventually accumulated in the sludge. The results show that biomass from BillerudKorsnäs Gruvön's mills accumulated PHA faster with VFA composition from fermented PM6 effluent compared to VFA composition from fermented HTC condensate. Calculations made with input from the experiments indicate that it is possible to produce a larger amount of PHA per year with Case PM6. The conclusion is therefore that Case PM6 is preferable if as large a PHA production as possible wants to be achieved. Case HTC is instead preferred if reduced PHA production can be tolerated in favor of biocarbon production.

    Fulltekst (pdf)
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  • 64.
    Awad, A.
    et al.
    University of Faisalabad, PAK ; Universiti Teknologi PETRONAS, MYS.
    Ahmed, I.
    National University of Science and Technology, PAK.
    Qadir, D.
    Universiti Teknologi PETRONAS, MYS.
    Khan, M. S.
    Texas A&M University at Qatar, QAT.
    Idris, Alamin
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Catalytic decomposition of 2% methanol in methane over metallic catalyst by fixed-bed catalytic reactor2021Inngår i: Energies, E-ISSN 1996-1073, Vol. 14, nr 8, artikkel-id 2220Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structure and performance of promoted Ni/Al2O3 with Cu via thermocatalytic decomposition (TCD) of CH4 mixture (2% CH3OH) were studied. Mesoporous Cat-1 and Cat-2 were synthesized by the impregnation method. The corresponding peaks of nickel oxide and copper oxide in the XRD showed the presence of nickel and copper oxides as a mixed alloy in the calcined catalyst. Temperature program reduction (TPR) showed that Cu enhanced the reducibility of the catalyst as the peak of nickel oxide shifted toward a lower temperature due to the interaction strength of the metal particles and support. The impregnation of 10% Cu on Cat-1 drastically improved the catalytic performance and exhibited 68% CH4 conversion, and endured its activity for 6 h compared with Cat-1, which deactivated after 4 h. The investigation of the spent carbon showed that various forms of carbon were obtained as a by-product of TCD, including graphene fiber (GF), carbon nanofiber (CNF), and multi-wall carbon nanofibers (MWCNFs) on the active sites of Cat-2 and Cat-1, following various kinds of growth mechanisms. The presence of the D and G bands in the Raman spectroscopy confirmed the mixture of amorphous and crystalline morphology of the deposited carbon.

  • 65.
    Axelsson, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Stabilisering av Aluminiumreducerad AOD-slagg.2019Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Slagg har historiskt använts som konstruktionsmaterial i olika applikationer. Alla typer av slagg passar inte på grund av otillräckliga egenskaper. Vid produktion av höglegerat rostfritt stål så är slaggen mycket kalkrik, vilket leder till sönderfall på grund av absorption av vatten. Vissa stålsorter hos Sandvik tillverkas med ett tvåslaggsförfarande där en första reduceringsslagg först används för att sedan ersättas av en raffineringsslagg. Denna rapport behandlar förändringar i slaggsammansättning för att förbättra slaggens egenskaper gällande volymstabilitet efter deponering. I synnerhet så behandlas volymstabilitet av reduceringsslagg och om möjligheterfinns att kombinera bra stålproduktion med volymstabil slagg.Projektet har syftat till att kartlägga hur slaggen fungerar i dagsläget med provtagning nära konverter men även hur förändrade sammansättningar påverkar slaggen som svalnar enligt normal praxis utanför stålverket. Slagger som faller sönder av fasomvandlingar har observerats. Slutligenhar en sammansättning som ser lovande ut ur produktionsperspektiv och stabilitetsperspektivhittats. Slaggen blir då stabil även efter försök att orsaka sönderfall i extrem miljö. Vid produktionmed minskad kalktillsats under reducering kan ungefär två tredjedelar av ingående charger somska reduceras med aluminium hanteras. Med en mindre förändring i AOD processen vid reduceringså skulle ca 6000ton/år kunna skiftas från att sönderfalla till att bli stabil.

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  • 66.
    Ayub, Rabia
    et al.
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi.
    Raheel, Ahmad
    Quaid-i-Azam University, Pakistan.
    High-Value Chemicals from Electrocatalytic Depolymerization of Lignin: Challenges and Opportunities2022Inngår i: International Journal of Molecular Sciences, ISSN 1661-6596, E-ISSN 1422-0067, Vol. 23, nr 7, artikkel-id 3767Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lignocellulosic biomass is renewable and one of the most abundant sources for the production of high-value chemicals, materials, and fuels. It is of immense importance to develop new efficient technologies for the industrial production of chemicals by utilizing renewable resources. Lignocellulosic biomass can potentially replace fossil-based chemistries. The production of fuel and chemicals from lignin powered by renewable electricity under ambient temperatures and pressures enables a more sustainable way to obtain high-value chemicals. More specifically, in a sustainable biorefinery, it is essential to valorize lignin to enhance biomass transformation technology and increase the overall economy of the process. Strategies regarding electrocatalytic approaches as a way to valorize or depolymerize lignin have attracted significant interest from growing scientific communities over the recent decades. This review presents a comprehensive overview of the electro-catalytic methods for depolymerization of lignocellulosic biomass with an emphasis on untargeted depolymerization as well as the selective and targeted mild synthesis of high-value chemicals. Elec-trocatalytic cleavage of model compounds and further electrochemical upgrading of bio-oils are discussed. Finally, some insights into current challenges and limitations associated with this approach are also summarized. © 2022 by the authors. 

  • 67.
    Babu, Aishwarya
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Effect of various rate promoters on the absorption rate of carbon dioxide in potassium carbonate solvents2022Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Det ständigt växande behovet av att minska CO2-utsläpp har lett till en ökad tonvikt på teknik för avskiljning av koldioxid från rökgas. MEA (monoetanolamin) anses vara riktmärket för lösningsmedel för att fånga in koldioxid på grund av dess höga absorptionshastighet. MEA är dock benäget att brytas ner, bilda giftiga biprodukter och dess regenerering har ett högt energibehov. Ett annat lösningsmedel med liknande teknisk mognad är vattenlösning med kaliumkarbonat (K2CO3) som används i den så kallade hot-potash carbonate (HPC)-processen. Emellertid är absorptionshastigheten i K2CO3-lösningen låg i jämförelse med MEA, vilket kräver tillsats av hastighetspromotorer för att öka absorptionshastigheten.

    Denna avhandling undersöker effekten av olika hastighetspromotorer på absorptionshastigheten av kaliumkarbonat. För detta utfördes absorptionsexperiment i laboratorieskala i en autoklavreaktor av rostfritt stål under kontrollerade förhållanden. Olika promotorer har undersökts, nämligen de organiska promotorerna glycin, piperazin och MEA, och de oorganiska promotorerna borsyra och vanadinpentoxid. Promotorkoncentrationen varierades mellan 3 vikt% till 7 vikt% samtidigt som koncentrationen av K2CO3 hölls konstant vid 25 vikt%. Driftförhållandena såsom det initiala partialtrycket av CO2 och temperaturen var respektiva 5 bar och 50 °C. De oorganiska promotorerna studerades enskilt såväl som i blandningar med K2CO3 för att studera effekten av varje promotor.

    De organiska promotorerna visade en signifikant förbättring av absorptionshastigheten jämfört med icke promoterad K2CO3. När det gäller de oorganiska promotorerna visade vanadinpentoxid jämförbara resultat med organiska promotorer med endast 3 vikt%. Ökad tillsatts av borsyra minskade absorptionshastigheten av lösningen promoterad av vanadin. Den experimentellt uppmätta absorptionshastigheten är anpassad till en enkel absorptionsmodell från vilken en skenbar absorptionshastighet för de främjade lösningsmedlen härleddes

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  • 68.
    Baldassarre, Venezia
    KTH, Skolan för kemivetenskap (CHE).
    Fischer-Tropsch Synthesis on ZrO2-promoted Co/Al2O3 Catalysts: Effect of Catalyst Support Preparation Methods2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Alumina is considered to be an effective catalyst support in the Fischer-Tropsch synthesis, owing to its favourable mechanical properties. However, if cobalt is deposited over alumina, the formation of active phase-support species decreases the catalyst reducibility and can be detrimental to the reaction performance. Recently, according to some reports, zirconia has attracted attention as a cobalt catalyst promoter for improving reducibility, activity and C5+ selectivity.

    This experimental work is aimed at studying the influence of zirconia promotion on cobalt-based catalysts. Two different support preparation methods were investigated: the pH-controlled precipitation of the zirconia promoter over a gamma alumina carrier from a one-phase and from a microemulsion solution. Two microemulsion systems were used: the water-in-oil and the oil-in-water techniques. The zirconia loading target over alumina was 20 wt% for all the promoted carriers. The cobalt active phase was deposited via the incipient wetness impregnation, reaching a concentration of 12 wt% over all the catalysts, including on a non-promoted one. Moreover, a further support was prepared using the oil-in-water microemulsion technique and impregnated with 15 wt% Co.

    X-ray diffraction, N2 adsorption and H2 chemisorption characterisations revealed comparable catalyst porosities and cobalt dispersions. Furthermore, TPR analyses showed that reducibility is not influenced by the addition of zirconia.

    The catalyst activation treatment was performed under pure hydrogen at 1 atm, 350 °C for 16 h. The syngas flow, passing through a fixed bed reactor, was first set to 250 NmL/min and then decreased until 30%, 40% and 50% CO conversion values were reached. The catalytic test results revealed an increase in activity and enhancement of C5+ selectivity for the catalyst prepared by pH-controlled precipitation of zirconia from the ordinary solution, relative to the non-promoted one. On the other hand, the “microemulsion” catalysts showed a significant decrease in turnover frequency compared to the Co/Al2O3 catalyst performance. Selectivity to C5+ and CH4 were respectively enhanced and reduced by promoting the catalyst with zirconia, for each conversion step. Olefin-to-paraffin content ratio in the fraction of C2, C3 and C4, along with the deactivation trend, were also analysed and discussed.

  • 69.
    Barrientos, Javier
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    González, N.
    Lualdi, Matteo
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Boutonnet, Magali
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    The effect of catalyst pellet size on nickel carbonyl-induced particle sintering under low temperature CO methanation2016Inngår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 514, s. 91-102Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract The present work aims to evaluate the effect of catalyst pellet size on deactivation due to nickel carbonyl-induced particle sintering. For that purpose, a γ-Al2O3-supported nickel catalyst was prepared and tested under low temperature and high CO partial pressure. A total of four different pellet sizes were employed in the present study. It was found that the deactivation rate decreases with increasing pellet size. A very severe deactivation was observed when using small pellets. Large pellets exhibited instead a more stable performance. This difference in catalyst stability was explained by X-ray diffraction analyses which revealed that the growth of the nickel particles was very severe when using small pellets. An evaluation of heat and mass transfer phenomena in these four pellets was also conducted. It was found that, under the present low temperature reaction conditions, the temperature at the catalyst external surface can greatly differ from that in the bulk gas when using sufficiently large pellets. It was also shown that, for large pellets, the major part of the interior of the catalyst is exposed to negligible CO partial pressures and high temperatures, fact that can reduce the potential for nickel carbonyl formation.

  • 70.
    Barrientos, Javier
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Montes, V.
    Boutonnet, Magali
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Further insights into the effect of sulfur on the activity and selectivity of cobalt-based Fischer–Tropsch catalysts2016Inngår i: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 275, s. 119-126Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

     A sulfur poisoning study was performed by ex situ poisoning of a platinum-promoted cobalt/alumina catalyst with different sulfur amounts. The poisoned catalyst samples were tested at relevant Fischer–Tropsch reaction conditions and at the same CO conversion in order to evaluate the effect of sulfur on catalyst activity and product selectivity. It was found that the activity and the selectivity to long-chain hydrocarbons decrease with increasing sulfur content. Moreover, it was found that sulfur has no significant effect on the CO2 selectivity. It was also shown that sulfur significantly enhances olefin hydrogenation. Finally, a deactivation model relating the catalyst activity and the sulfur to cobalt active site ratio was proposed and used to describe the experimental results.

  • 71.
    Battestini Vives, Mariona
    et al.
    Lund University.
    Abdelaziz, Omar
    Lund University.
    Thuvander, Johan
    Lund University.
    Arkell, Anders
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Hulteberg, Christian
    Lund University.
    Lipnizki, Frank
    Lund University.
    Recovery and Characterization of Low-Molecular-Weight Lignin from Ultrafiltered Kraft Black Liquor2022Inngår i: 10th Nordic Wood Biorefinery Conference / [ed] Atte Virtanen, Helsinki, 2022, s. 218-219Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Kraft lignin is an aromatic polymer found in black liquor, a side stream of the kraft pulping industry.Usually, lignin is burned in the recovery boiler of the pulp mill as a fuel for energy generation. However,lignin has great potential as a raw material for the production of fossil-free fuels, chemicals, andmaterials. Membrane filtration has been studied in the last decades as a key separation method torecover lignin from black liquor. Further studies to concentrate lignin using membrane filtration arerequired, as well as characterization of the resulting lignin fractions for the development of moleculartailored lignin-based applications.

    In the present work, nanofiltration (NF) was used to concentrate and recover the low-molecularweightlignin obtained from the permeate of ultrafiltration of kraft black liquor. The concentration wasperformed using a NF090801 polymeric NF membrane (SolSep) with a molecular weight cut-off of 350Da. A transmembrane pressure of 25 bar and 50 °C during the filtration increased the lignin contentfrom 27 to 52 g/l, whereas a transmembrane pressure of 15 bar and 70 °C gave an increase from 18 to45 g/l in lignin content. The lignin fraction recovered in the retentate of the NF step was analyzed bysize-exclusion chromatography to ascertain the molecular weight of the lignin. Moreover, Fouriertransform infrared spectroscopy and thermogravimetric analysis were carried out to evaluate thethermal properties and functionalities of the obtained fractions.

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  • 72.
    Bayat, Mohammad
    et al.
    Faculty of Chemical Engineering, Research and Technology Centre for Membrane Processes, Iran University of Science and Technology (IUST), Tehran, Iran.
    Nabavi, Mohammad Sadegh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mohammadi, Toraj
    Faculty of Chemical Engineering, Research and Technology Centre for Membrane Processes, Iran University of Science and Technology (IUST), Tehran, Iran.
    An experimental study for finding the best condition for PHI zeolite synthesis using Taguchi method for gas separation2018Inngår i: Chemical papers, ISSN 2585-7290, Vol. 72, nr 5, s. 1139-1149Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Phillipsite zeolite particles and membranes were successfully synthesized at different operational and environmental conditions. Using an L9 orthogonal array of the Taguchi method, effects of experimental condition—synthesis temperature (130–150 °C), synthesis time (2–3 days), number of synthesized layers (1–3), and seeding suspension percentage—for membrane preparation with respect to CO2/CH4 ideal selectivity were investigated. The results showed that the ideal selectivity was improved up to 4.20 from 1.15 by increasing the number of synthesized layers, synthesis temperature, and seed solution concentration and by decreasing synthesis time. Moreover, the best synthesis conditions were defined based on the Taguchi method results and the membrane was synthesized with the highest ideal selectivity which was around 4.40. In addition, it was shown that T zeolite is formed beside PHI zeolite at low temperature even with long synthesis time.

  • 73.
    Becker, Sebastian
    KTH, Skolan för kemivetenskap (CHE).
    Inverkan av olika joner och jonconcentrationer på porstorleksfördelningen i trämassa-fibrer2011Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    The basic ingredient of paper is the individual wood fibers. The property of the fibers depends on a variety of factors e.g., method of pulp production and processing. The final sheet quality depends in part on how the fibers interface between each other and therefore factors that affect the fiber size are of interest.

    The flexibility of the fibers depends in part on the pore water i.e., the fiber swelling. The sheet becomes less flexible at low water content which gives a loss in strength. Thus it becomes desirable to increase the water uptake.

    The experimental investigation described in this report consists of exposing the wood fibers to different ions and ionic strength and then measure the pore size by thermoporosimetry where a DSC (Differential Scanning Calorimeter) is used. DSC measures the freezing point of water in the pores of the wood fibers. As the freezing point varies with the pore size the size distribution can be determined.

    The results show that there are complications with thermoporosimetry measurements at different ion concentrations. The strength of the ionic solutions will contribute to a fictitious pore volume, which makes analysis difficult to interpret.

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  • 74. Berglund, Linn
    et al.
    Anugwom, Ikenna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Turku, Finland.
    Hedenström, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Aitomäki, Yvonne
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Turku, Finland.
    Oksman, Kristiina
    Switchable ionic liquids enable efficient nanofibrillation of wood pulp2017Inngår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, nr 8, s. 3265-3279Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Use of switchable ionic liquid (SIL) pulp offers an efficient and greener technology to produce nanofibers via ultrafine grinding. In this study, we demonstrate that SIL pulp opens up a mechanically efficient route to the nanofibrillation of wood pulp, thus providing both a low cost and chemically benign route to the production of cellulose nanofibers. The degree of fibrillation during the process was evaluated by viscosity and optical microscopy of SIL treated, bleached SIL treated and a reference pulp. Furthermore, films were prepared from the fibrillated material for characterization and tensile testing. It was observed that substantially improved mechanical properties were attained as a result of the grinding process, thus signifying nanofibrillation. Both SIL treated and bleached SIL treated pulps were fibrillated into nanofibers with fiber diameters below 15 nm thus forming networks of hydrophilic nature with an intact crystalline structure. Notably, it was found that the SIL pulp could be fibrillated more efficiently than traditional pulp since nanofibers could be produced with more than 30% less energy when compared to the reference pulp. Additionally, bleaching reduced the energy demand by further 16%. The study demonstrated that this switchable ionic liquid treatment has considerable potential in the commercial production of nanofibers due to the increased efficiency in fibrillation.

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  • 75. Bergman, Susanna
    et al.
    Dahlin, Sandra
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Processteknologi.
    Mesilov, Vitaly
    Xiao, Yang
    Englund, Johanna
    Xi, Shibo
    Tang, Chunhua
    Skoglundh, Magnus
    Pettersson, Lars
    Bernasek, Steven
    In-situ studies of oxidation/reduction of copper in Cu-CHA SCR catalysts:comparison of fresh and SO2-poisoned catalystsInngår i: Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    SO2-poisoning results in deactivation of Cu-CHA SCR under standard SCR conditions; however regeneration at 700 ◦C completely restores the SCR performance. To understand the nature of these effects, Cu-species in the fresh and poisoned catalystswere characterized by in-situ temperature-dependent time-resolved Cu K-edge X-ray absorption spectroscopy using the multivariate curve resolution alternating least squares (MCR-ALS) approach and continuous Cauchy wavelet transforms. The extracted chemically-meaningful reference spectra of Cu-species were analyzed by DFT-assisted XANES calculations. Cu-bisulfates werefound as the most energetically favorable poisoned Cu-species. The response of Cu-species to a reducing environment differs inthe fresh and SO2-poisoned catalysts. Differences in reducibility are related to the formation of quasi-linear Cu-complexes in the SO2-poisoned catalyst formed during heating in H2/He. Heating in H2/He leads to partial desulfurization of the poisoned catalyst. Cooling in H2/He after heating results in more facile formation of Cu-metal clusters in fresh catalyst than in SO2-poisoned.

  • 76.
    Bergvall, Niklas
    et al.
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi.
    Sandström, Linda
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi.
    Cheah, Y. W.
    Chalmers University of Technology, Sweden.
    Öhrman, Olov
    Preem Ab, Sweden.
    Slurry Hydroconversion of Solid Kraft Lignin to Liquid Products Using Molybdenum- and Iron-Based Catalysts2022Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 36, nr 17, s. 10226-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Kraft lignin is an abundantly available and largely underutilized renewable material with potential for production of biobased fuels and chemicals. This study reports the results of a series of slurry hydroprocessing experiments with the aim of converting solid Kraft lignin to liquid products suitable for downstream refining in more conventional reactors. Experiments reported in this study were conducted by feeding a lignin slurry to an already hot, liquid-filled reactor to provide momentaneous heating of the lignin to the reaction temperature. This modified batch procedure provided superior results compared to the regular batch experiments, likely since unwanted repolymerization and condensation reactions of the lignin during the heating phase was avoided, and was therefore used for most of the experiments reported. Experiments were performed using both an unsupported Mo-sulfide catalyst and Fe-based catalysts (bauxite and hematite) at varied reaction temperatures, pressures, and catalyst loadings. The use of Mo-sulfide (0.1% Mo of the entire feed mass) at 425 °C and 50 bar resulted in complete conversion of the Kraft lignin to nonsolid products. Very high conversions (>95%) could also be achieved with both sulfided bauxite or hematite at the same temperature and pressure, but this required much higher catalyst loadings (6.25% bauxite or 4.3% hematite of the total feed mass), and around 99% conversion could be achieved at higher temperatures but at the expense of much higher gas yields. Although requiring much higher loadings, the results in this study suggest that comparatively nonexpensive Fe-based catalysts may be an attractive alternative for a slurry-based process aimed at the hydroconversion of solid lignin to liquid products. Possible implementation strategies for a slurry-based hydroconversion process are proposed and discussed. © 2022 The Authors.

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  • 77.
    Bernemyr, Hanna
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Förbränningsmotorteknik.
    Pavlou, Charis
    Scania CV AB.
    Ersson, Andreas
    Scania CV AB.
    Regali, Francesco
    Scania CV AB.
    Theoretical Assessment of Rigs for Accelerated Ash Accumulation in Diesel Particulate Filters2020Inngår i: SAE technical paper series, ISSN 0148-7191, nr 2020Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Renewable fuels from different feedstocks can enable sustainable transport solutions with significant reduction in greenhouse gas emissions compared to conventional petroleum-derived fuels. Nevertheless, the use of biofuels in diesel engines will still require similar exhaust gas cleaning systems as for conventional diesel. Hence, the use of diesel particulate filters (DPF) will persist as a much needed part of the vehicle's aftertreatment system. Combustion of renewable fuels can potentially yield soot and ash with different properties as well as larger amounts of ash compared to conventional fossil fuels. The faster ash build-up and altered ash deposition pattern lead to an increase in pressure drop over the DPF, increase the fuel consumption and call for premature DPF maintenance or replacement. Prolonging the maintenance interval of the DPF for heavy-duty trucks, having a demand for high up-Time, is highly desirable. Understanding the mechanisms of ash formation and build-up in the DPF, especially for renewable fuels, is therefore of uttermost importance. Techniques using accelerated ash accumulation methods offer a way to cut down on the costly and time consuming field tests, as well as offering a robust method to perform tests under conditions relevant for real-driving. This paper presents a literature review regarding accelerated ash accumulation methods by summarizing these methods and giving an overview of the various rigs found in literature. Moreover, the paper outlines the strengths and weaknesses of the different methods. Furthermore, it offers a simplistic route to choose between the different techniques based on the particular research question to be addressed.

  • 78.
    Bertini, Lorenzo
    KTH, Skolan för kemivetenskap (CHE).
    Modeling and Optimization of a Fuel Cell Hybrid System2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The purpose of this project was the modeling, optimization and prediction of a hybrid system composed of a fuel cell, a dc-dc converter and a supercapacitor in series. Lab tests were performed for each device to understand their behavior, and then each one was modeled using software (Simulink). The validation of the model was done by comparing its results with measured data; finally the model was used for the optimization and the prediction of the hybrid system

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  • 79.
    BHANDARI, SHASHANK
    KTH, Skolan för kemivetenskap (CHE).
    Design of a solvent recovery system in a pharmaceutical manufacturing plant2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Solvents play a crucial role in the Active Pharmaceutical Ingredient (API) manufacturing and are used in large quantities. Most of the industries incinerate the waste solvents or send it to waste management companies for destruction to avoid waste handling and cross-contamination. It is not a cost effective method and also hazardous to the environment. This study has been performed at AstraZeneca’s API manufacturing plant at Sodertalje, Sweden. In order to find a solution, a solvent recovery system is modeled and simulated using ASPEN plus and ASPEN batch modeler. The waste streams were selected based on the quantity and cost of the solvents present in them. The solvent mixture in the first waste stream was toluene-methanol in which toluene was the key-solvent whereas in the second waste stream, isooctane-ethyl acetate was the solvent mixture in which isooctane was the key-solvent. The solvents in the waste stream were making an azeotrope and hence it was difficult to separate them using conventional distillation techniques. Liquid-Liquid Extraction with water as a solvent followed by batch distillation was used for the first waste stream and Pressure Swing Distillation was used for the second waste stream. The design was optimized based on cost analysis and was successful to deliver 96.1% toluene recovery with 99.5% purity and 83.6% isooctane recovery with 99% purity. The purity of the solvents was decided based on the quality conventions used at AstraZeneca so that it can be recovered and recycled in the same system. The results were favorable with a benefit of €335,000 per year and preventing nearly one ton per year carbon dioxide emissions to the environment. A theoretical study for the recovery system of toluene-methanol mixture was performed. The proposed design was an integration of pervaporation to the batch distillation. A blend of polyurethane / poly(dimethylsiloxane) (PU / PDMS) membrane was selected for the separation of methanol and toluene mixture. The results of preliminary calculations show 91.4% toluene recovery and 72% methanol recovery with desired purity.

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  • 80.
    Bhattacharya, Aparajita
    et al.
    Department of Geology and Geochemistry, Stockholm University, 10691 Stockholm, Sweden.
    Routh, Joyanto
    Department of Geology and Geochemistry, Stockholm University, 10691 Stockholm, Sweden.
    Jacks, Gunnar
    Department of Land and Water Resources Engineering, KTH, 10044 Stockholm, Sweden.
    Bhattacharya, Prosun
    Department of Land and Water Resources Engineering, KTH, 10044 Stockholm, Sweden.
    Morth, Magnus
    Department of Geology and Geochemistry, Stockholm University, 10691 Stockholm, Sweden.
    Environmental assessment of abandoned mine tailings in Adak, Vasterbotten district (northern Sweden)2006Inngår i: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 21, nr 10, s. 1760-1780Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sulfide-rich mine tailings in Adak that are exposed to weathering cause acid mine drainage characterized by low PH (2-4) and high SO4 (UP to 800 mg L-1). Surface water, sediment and soil samples collected in this study contain higher concentrations of As, Cu, Fe and Zn, compared to the target and/or intervention limits set by international regulatory agencies. In particular, high As concentrations in water (up to 2900 mu g L- 1) and sediment (up to 900 mg kg(-1)) are of concern. There is large variability in trace element concentrations, implying that both physical (grain size) and chemical factors (pH, secondary phases as sulfides, Al-oxides or clay minerals) play an important role in their distribution. The low PH keeps the trace elements dissolved, and they are transported farther downstream. Trace element partition coefficients are low (log K-d = 0.3-4.3), and saturation indices calculated with PHREEQC are < 0 for common oxide and sulfidic minerals. The sediment and soil samples indicate an enhanced pollution index (up to 17), and high enrichment factors for trace elements (As up to 38,300; Zn up to 800). Finally, leaves collected from different plant types indicate bioaccumulation of several elements (As, Al, Cu, Fe and Zn). However, some of the plants growing in this area (e.g., Salix, Equisetum) are generally resistant to metal toxicity, and hence, liming and phytoremediation could be considered as potential on-site remediation methods.

  • 81.
    Bhuiyan, Iftekhar Uddin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Characterization of iron ore green pellets by scanning electron microscopy and X-ray microtomography2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Cryogenic scanning electron microscopy (cryo-SEM), image analysis (IA) of SEM micrographs and X-ray microtomography (XMT) were used to obtain new information about the morphology of iron ore green pellets in this work. Cryo-SEM and freeze fracturing was used to observe entrapped air bubbles and arrangement of particles around the bubbles and in the matrix of wet green pellets. The observations of samples prepared by plunge and unidirectional freezing indicate that unidirectional freezing facilitates the observation of entrapped bubbles with minimum formation of artifacts, whereas plunge freezing enables observation of the degree of water filling at the outer surface of wet pellets with minimum amount of artifacts. It was also observed in the wet pellets that the size of the water domains in the matrix is quite small and the finer grains are mixed with coarser grains resulting in a denser matrix, whereas no fine grains were observed in the vicinity of the air bubbles. Two types of pellets prepared with and without addition of extra flotation reagent prior to balling were studied using IA and XMT. IA of scanning electron micrographs of epoxy impregnated pellets was used to separate bubble porosity from packing porosity and to quantify the former. The individual SEM micrographs acquired by a backscattered electron detector were reconstructed to provide the entire two-dimensional (2D) sections of the pellets. The 2D data obtained by IA were unfolded to three-dimensional (3D) by stereology and relatively good agreement with XMT data was observed. The size and amount of air bubbles could be quantified with both techniques. The addition of extra flotation reagent was found to increase the number of entrapped air bubbles and slightly decrease the median bubble diameter. The additional entrapped air bubbles due to the addition of extra flotation reagent was shown to be responsible for the difference in total porosity observed by mercury porosimetry between the two types of pellets. Mercury intrusion porosimetry (MIP) is shown in this work to produce inappropriate results with regard to the porosity due to bubble entrapment, it only provides values for total porosity and the throat size distribution of the porosity. In summary, this work has shown that cryo-SEM, IA of SEM micrographs and XMT are powerful and very useful methods for characterization of the morphology of iron ore green pellets.

    Fulltekst (pdf)
    FULLTEXT01
  • 82.
    Bhuiyan, Iftekhar Uddin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Microstructural characterization of iron ore green pellets2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The aim of this thesis work was to develop new methodologies to characterize iron ore green pellets, in wet and dry state. The new characterization methods applied and developed in this work were mainly based on scanning electron microscopy (SEM) to gather both qualitative and quantitative data on different components of the pellets, i.e. mineral particles, water, bentonite and entrapped bubbles.In a first attempt to preserve the structure of wet iron ore green pellets by freezing before investigation by cryogenic SEM, wet pellets were frozen in liquid nitrogen by direct plunging or a new method developed in the present work denoted unidirectional freezing. The former method was found useful to study the degree of water filling at the outer surface of the pellet but led to artifacts in the interior of the pellet. The latter method was developed to confirm that the spherical cavities observed in dry pellets were related to entrapped bubbles in wet pellets. Capillaries were observed at the outer surface of the pellets and fine particles were lacking within a layer of approximately 100 µm from the outer surface and also in the direct vicinity of the air bubbles in the interior of the pellets.More advanced freezing methods were subsequently employed to reveal the artifact free microstructure of bentonite in wet pellets. In order to verify the observations made on a slice of a wet pellet frozen by plunging in liquid ethane, SEM investigations were also carried out on a bentonite suspension and a bentonite-iron ore slurry, which could be cryo-fixed by the most reliable freezing method, i.e. high pressure freezing. All microstructures were comparable and consisted in a voluminous network of well-dispersed clay platelets. This network was found to collapse upon drying. Bentonite was drawn to the contact points between the particles and formed what appeared as bridges, which may impart strength to the dry pellets. A combination of energy dispersive spectroscopy (EDS) and imaging by low-loss backscattered electrons at low voltage evidenced the presence of very finely divided silicate species on the magnetite particles. In order to visualize the three dimensional structure of dispersed bentonite clay with unprecedented resolution, a method based on SEM imaging with a monochromatic and decelerated beam was used for the first time. The recorded images showed very well-dispersed clay platelets forming a fine network of Y shaped contacts, which is quite different from earlier reports of much coarser structures formed as a result of poor sample preparation. Finally, in order to gain quantitative data about the porosity due to bubble entrapment in dry pellets, the entire cross-section of dry epoxy embedded and polished pellets were recorded by SEM. The three-dimensional bubble size distribution was unfolded from 2D SEM data using image processing, image analysis and stereological principles. The same type of pellets was also investigated by X-ray micro-tomography (XMT). The resulting three-dimensional dataset allowed the validation of the unfolding procedure based on stereology. However, the lack of resolution obtained by XMT was shown to lead to slight discrepancies with the SEM data for small bubble sizes. Entrapped air bubbles due to the addition of extra flotation reagent in pellets were shown to be responsible for additional porosity observed by mercury intrusion porosimetry (MIP). In summary, useful characterization methods for iron ore pellets based on SEM have been developed in this work, which opens up new possibilities to for instance study agglomeration processes in more detail.

    Fulltekst (pdf)
    FULLTEXT01
  • 83.
    Bhuiyan, Iftekhar Uddin
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Forsberg, Fredrik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Forsmo, S.P.E.
    LKAB, Research & Development, 983 81 Malmberget.
    Sjödahl, Mikael
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Consideration of X-ray microtomography to quantitatively determine the size distribution of bubble cavities in iron ore pellets2013Inngår i: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 233, s. 312-318Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    X-ray microtomography data of iron ore green pellets of approx. 12 mm in diameter were recorded using a commercial instrument. The reconstructed volume after thresholding represented a unique dataset consisting of a three-dimensional distribution of equiaxed objects corresponding to bubble cavities. This dataset was used to successfully validate a stereological method to determine the size distribution of spherical objects dispersed in a volume. This was achieved by investigating only a few cross-sectional images of this volume and measuring the profiles left by these objects in the cross-sectional images. Excellent agreement was observed between the size distribution of the bubble cavities obtained by directly classifying their size in the reconstructed volume and that estimated by applying the aforementioned stereological method to eight cross-sectional images of the reconstructed volume. Subsequently, we discuss the possibility of calibrating X-ray tomography data quantitatively using the size distribution of the bubble cavities as a figure of merit and the results obtained by applying the stereological method to SEM images as reference data. This was justified by considering the validity of the stereological method demonstrated by tomography, the accurate thresholding made possible by back-scattered electron imaging and the solid reproducibility of the results obtained by SEM. Using different threshold values for binarization of the X-ray microtomography data and comparing the results to those obtained by SEM, we found that X-ray microtomography can be used after proper calibration against SEM data to measure the total porosity of the bubble cavities but can only provide a rough estimate of the median diameter because of the limited resolution achieved in this study.

  • 84.
    Bhuiyan, Iftekhar Uddin
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Forsmo, S.P.E.
    LKAB.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Quantitative image analysis of bubble cavities in iron ore green pellets2011Inngår i: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 214, nr 3, s. 306-312Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Scanning electron microscopy and image analysis was used for quantitative analysis of bubble cavities in iron ore green pellets. Two types of pellets prepared with and without addition of flotation reagent prior to balling were studied. The bubble cavity porosity amounted to 2.8% in the pellets prepared without addition of flotation reagent prior to balling. When flotation reagent was added prior to balling, the bubble cavity porosity increased by a factor of 2.4 and the median bubble diameter was decreased slightly. It was also shown that mercury intrusion porosimetry is not suitable for determination of the distribution of bubble cavities. Finally, our data suggested that the difference in total porosity determined by mercury intrusion porosimetry and pycnometry between the two types of pellets was due to the bubble cavities.

  • 85.
    Bhuiyan, Iftekhar Uddin
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Forsmo, S.P.E.
    LKAB Research and Development.
    Forsberg, Fredrik
    Air bubbles in iron ore green pellets due to flotation reagent: characterization by scanning electron microscopy and X-ray microtomography2011Konferansepaper (Annet vitenskapelig)
    Fulltekst (pdf)
    FULLTEXT01
  • 86.
    Bhuiyan, Iftekhar Uddin
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Schröppel, Birgit
    Natural and Medical Sciences Institute (NMI), University of Tübingen.
    Kaech, Andres
    Center for Microscopy and Image Analysis, University of Zurich.
    Dobryden, Illia
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Forsmo, Seija P.E.
    LKAB, Research & Development, 983 81 Malmberget.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Microstructure of Bentonite in Iron Ore Green Pellets2014Inngår i: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 20, nr 1, s. 33-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sodium-activated calcium bentonite is used as a binder in iron ore pellets and is known to increase strength of both wet and dry iron ore green pellets. In this article, the microstructure of bentonite in magnetite pellets is revealed for the first time using scanning electron microscopy. The microstructure of bentonite in wet and dry iron ore pellets, as well as in distilled water, was imaged by various imaging techniques (e.g., imaging at low voltage with monochromatic and decelerated beam or low loss backscattered electrons) and cryogenic methods (i.e., high pressure freezing and plunge freezing in liquid ethane). In wet iron ore green pellets, clay tactoids (stacks of parallel primary clay platelets) were very well dispersed and formed a voluminous network occupying the space available between mineral particles. When the pellet was dried, bentonite was drawn to the contact points between the particles and formed solid bridges, which impart strength to the solid compact.

  • 87.
    Bi, Ran
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Huang, Shan
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. Linnaus University, Sweden.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Isolation of exceedingly low oxygen consuming fungal strains able to utilize lignin as carbon sourceInngår i: Cellulose Chemistry and Technology, ISSN 0576-9787Artikkel i tidsskrift (Fagfellevurdert)
  • 88.
    Bi, Ran
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Spadiut, Oliver
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Brumer, Harry
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Isolation and identification of microorganisms from soil able to live on lignin as acarbon source and to produce enzymes which cleave the β-o-4 bond in a lignin model compound2012Inngår i: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 46, nr 3-4, s. 227-242Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several strains of fungi were isolated and identified from Scandinavian soil using agar plates with lignin as a carbon source. The strains grew significantly faster on this medium than on control plates without lignin. Different types of technical lignins were used, some of which contained trace amounts of sugars, even if the increased growth rate seemed not related to the sugar content. Some strains were cultivated in shaking flask cultures with lignin as a carbon source, with lignin apparently consumed by microbes - while accumulation of the microorganism biomass occurred. The cell-free filtrates of these cultures could reduce the apparent molecular weights of lignosulphonates, while the culture filtrate of one strain could cleave the beta-O-4 bond in a lignin model compound.

    Fulltekst (pdf)
    fulltext
  • 89. Biasi, Pierdomenico
    et al.
    Serna, Juan Garcia
    Salmi, Tapio O.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Chemical Engineering, Process Chemistry Centre (PCC), Laboratory of Industrial Chemistry and Reaction Engineering, Åbo Akademi University, ÅBO-TURKU, Finland.
    Hydrogen Peroxide Direct Synthesis: Enhancement of Selectivity and Production with non-Conventional Methods2013Inngår i: ICHEAP-11: 11TH INTERNATIONAL CONFERENCE ON CHEMICAL AND PROCESS ENGINEERING, PTS 1-4 / [ed] Pierucci, S, Klemes, JJ, AIDIC - associazione italiana di ingegneria chimica, 2013, s. 673-678Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The present work is part of a comprehensive study on the direct synthesis of hydrogen peroxide in different fields, from chemistry to chemical engineering. Working on the different fields of the direct synthesis gave the possibility to look at the results and the challenges from different viewpoints. Here was investigated one parameter that enhances the direct synthesis. The H-2/Pd ratio is the key parameter that has to be investigated and optimize to enhance the hydrogen peroxide direct synthesis. Two reactors were built to study deeply the H-2/Pd ratio and to demonstrate how this parameter can affect the direct synthesis both in batch and continuous reactor with non-conventional experiments/methods. 1) A batch reactor was utilized as a "starving reactor" to enhance the productivity of hydrogen peroxide and to try to keep constant the selectivity. The starving method consists in refilling the hydrogen when it is consumed in the reactor. 2) A trickle bed reactor was utilized with a gradient of catalyst along the reactor to maximize both production and selectivity of hydrogen peroxide. The distribution of the catalyst along the bed gave the possibility to significantly improve the selectivity and the production of hydrogen peroxide (up to 0.5% in selected conditions). Higher production rate and selectivity were found when the catalyst concentration decreases along the bed from the top to the bottom compared to the uniformly dispersed catalyst. Selectivity in the batch reactor was enhanced by 5% and in the continuous reactor of 10%. The non-conventional experimental methods have been found to be novelty concepts to enhance the hydrogen peroxide direct synthesis.

  • 90. Billeter, J.
    et al.
    Rodrigues, Diogo
    Laboratoire d'Automatique, École Polytechnique Fédérale de Lausanne, Lausanne, CH-1015, Switzerland.
    Srinivasan, S.
    Amrhein, M.
    Bonvin, D.
    On decoupling rate processes in chemical reaction systems – Methods and applications2018Inngår i: Computers and Chemical Engineering, ISSN 0098-1354, E-ISSN 1873-4375, Vol. 114, s. 296-305Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Models of chemical reaction systems can be complex as they need to include information regarding the reactions and the mass and heat transfers. The commonly used state variables, namely, concentrations and temperatures, express the interplay between many phenomena. As a consequence, each state variable is affected by several rate processes. On the other hand, it is well known that it is possible to partition the state space into a reaction invariant subspace and its orthogonal complement using a linear transformation involving the reaction stoichiometry. This paper uses a more sophisticated linear transformation to partition the state space into various subspaces, each one linked to a single rate process such as a particular reaction, mass transfer or heat transfer. The implications of this partitioning are discussed with respect to several applications related to data reconciliation, state and rate estimation, modeling, identification, control and optimization of reaction systems.

  • 91.
    BIN HANNAN, KHALID
    KTH, Skolan för kemivetenskap (CHE).
    Organiska kväveföreningars påverkan på vätebehandlingsanläggningens prestanda2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Various distillates are treated with hydrogen gas during hydrotreatment in the presence of catalyst in order to reduce the sulfur and aromatic content of the product. Optimal hydrotreater performance is essential for producing Nynas specialty oils, in order to fulfill the planned production volume and to meet the product specification. Loss of catalyst activity is inevitable during the production. To adjust for the impact of catalyst deactivation, different process variables are manipulated. Different distillates affect the catalyst in different ways due to the variation in distillate composition. Distillates with higher organic nitrogen content and running at a lower temperature tend to deactivate the catalyst more due to the adsorption of nitrogen compounds on the active sites of the catalyst and their slow nature of desorption.

    In this master thesis, different catalyst deactivation mechanisms with a focus on nitrogen deactivation have been studied. Since nitrogen is not normally measured at Nynas, nitrogen content of different distillates and products and how these values change during operation was not known. Different distillates, blend of distillates and different products were measured to estimate roughly the typical nitrogen value of the distillates and products. The temperature data inside the reactors were analyzed to calculate and plot WABT (weighted average bed temperature) during different product runs and to see whether there is a correlation between the nitrogen content of the feed and operation severity (increase in WABT). Historical process data from hydrotreater unit 2 (mostly from 2013-2014) were analyzed with a view to finding out signs of catalyst deactivation. Similar product runs were also analyzed and compared to see how the catalysts performed at different periods of time. A kinetic model, based on HDS kinetics, has been used for following up two product runs. To do so, sulfur content of the feed and product were measured. Aromatic content of the product was also measured to see whether the product was on specification.

    .From the calculation and plotting of WABTs, it could be seen that there is an increase in WABT during the product runs operating at lower temperatures and with higher nitrogen content. From the comparison of two P3 product runs at two different time periods, it could be seen that ∆T development over one bed (amount of reaction over the bed) was much lower at one time. This can possibly be a sign of catalyst deactivation since it contributed to lesser amount of reaction over the bed.

    From the calculations by using the kinetic model, it could be seen that the actual temperatures were higher than the predicted temperatures. The increase in WABTs could also be noticed. These observations can possibly be coupled with nitrogen deactivation of the catalysts.  However, more tests are required to verify whether the temperature differences were significant or not. Other parameters which are also important from product selling point of view such as viscosity, color, flash point, acid number etc. and have not been covered in this degree project need to be taken into consideration before making further conclusions.

    Fulltekst (pdf)
    fulltext
  • 92.
    Biollaz, S.
    et al.
    PSI.
    Calbry-Muzyka, A.
    PSI.
    Rodriguez, S.
    PSI.
    Sárossy, Z.
    DTU.
    Ravenni, G.
    DTU.
    Fateev, A.
    DTU.
    Seiser, R.
    UCSD.
    Eberhard, M.
    KIT.
    Kolb, T.
    KIT.
    Heikkinen, N.
    VTT.
    Reinikainen, M.
    VTT.
    Brown, R.C.
    Iowa State University, USA.
    Johnston, P.A.
    Iowa State University, USA.
    Nau, P.
    DLR.
    Geigle, K.P.
    DLR.
    Kutne, P.
    DLR.
    Işık-Gülsaç, I.
    TÜBİTAK Mam.
    Aksoy, P.
    TÜBİTAK Mam.
    Çetin, Y.
    TÜBİTAK Mam.
    Sarıoğlan, A.
    TÜBİTAK Mam.
    Tsekos, C.
    Delft University of Technology, Netherlands.
    de Jong, W.
    Delft University of Technology, Netherlands.
    Benedikt, F.
    TU Wien, Austria.
    Hofbauer, H.
    TU Wien, Austria.
    Waldheim, L.
    SFC.
    Engvall, K.
    KTH Royal instute of technology, Sweden.
    Neubauer, Y.
    Technical University of Berlin, Germany.
    Funcia, I.
    CENER.
    Gil, J.
    CENER.
    del Campo, I.
    CENER.
    Wilson, I.
    University of Glasgow, UK.
    Khan, Z.
    University of Glasgow, UK.
    Gall, D.
    University of Gothenburg, Sweden.
    Gómez-Barea, A.
    University of Seville, Spain.
    Schmidt, F.
    Umeå University, Sweden.
    Lin, Leteng
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Strand, Michael
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Anca-Couce, A.
    Graz University of Technology, Austria.
    von Berg, L.
    Graz University of Technology, Austria.
    Larsson, A.
    GoBiGas.
    Sánchez Hervás, J.M.
    CIEMAT.
    van Egmond, B.F.
    ECN part of TNO.
    Geusebroek, M.
    ECN part of TNO.
    Toonen, A.
    ECN part of TNO.
    Kuipers, J.
    ECN part of TNO.
    Cieplik, M.
    ECN part of TNO.
    Boymans, E.H.
    ECN part of TNO.
    Grootjes, A.J.
    ECN part of TNO.
    Fischer, F.
    TUM.
    Schmid, M.
    University of Stuttgart, Germany.
    Maric, J.
    Chalmers University of Technology, Sweden.
    Defoort, F.
    CEA.
    Ravel, S.
    CEA.
    Thiery, S.
    CEA.
    Balland, M.
    CEA.
    Kienzl, N.
    Bioenergy 2020+.
    Martini, S.
    Bioenergy 2020+.
    Loipersböck, J.
    Bioenergy 2020+.
    Basset, E.
    ENGIE Lab CRIGEN.
    Barba, A.
    ENGIE Lab CRIGEN.
    Willeboer, W.
    RWE-Essent.
    Venderbosch, R.
    BTG.
    Carpenter, D.
    NREL.
    Pinto, F.
    LNEG.
    Barisano, D.
    ENEA.
    Baratieri, M.
    UNIBZ.
    Ballesteros, R.
    UCLM.
    Mourao Vilela, C. ()
    ECN part of TNO.
    Vreugdenhil, B.J. ()
    ECN part of TNO.
    Gas analysis in gasification of biomass and waste: Guideline report: Document 12018Rapport (Fagfellevurdert)
    Abstract [en]

    Gasification is generally acknowledged as one of the technologies that will enable the large-scale production of biofuels and chemicals from biomass and waste. One of the main technical challenges associated to the deployment of biomass gasification as a commercial technology is the cleaning and upgrading of the product gas. The contaminants of product gas from biomass/waste gasification include dust, tars, alkali metals, BTX, sulphur-, nitrogen- and chlorine compounds, and heavy metals. Proper measurement of the components and contaminants of the product gas is essential for the monitoring of gasification-based plants (efficiency, product quality, by-products), as well as for the proper design of the downstream gas cleaning train (for example, scrubbers, sorbents, etc.). In practice, a trade-off between reliability, accuracy and cost has to be reached when selecting the proper analysis technique for a specific application. The deployment and implementation of inexpensive yet accurate gas analysis techniques to monitor the fate of gas contaminants might play an important role in the commercialization of biomass and waste gasification processes.

    This special report commissioned by the IEA Bioenergy Task 33 group compiles a representative part of the extensive work developed in the last years by relevant actors in the field of gas analysis applied to(biomass and waste) gasification. The approach of this report has been based on the creation of a team of contributing partners who have supplied material to the report. This networking approach has been complemented with a literature review. The report is composed of a set of 2 documents. Document 1(the present report) describes the available analysis techniques (both commercial and underdevelopment) for the measurement of different compounds of interest present in gasification gas. The objective is to help the reader to properly select the analysis technique most suitable to the target compounds and the intended application. Document 1 also describes some examples of application of gas analysis at commercial-, pilot- and research gasification plants, as well as examples of recent and current joint research activities in the field. The information contained in Document 1 is complemented with a book of factsheets on gas analysis techniques in Document 2, and a collection of video blogs which illustrate some of the analysis techniques described in Documents 1 and 2.

    This guideline report would like to become a platform for the reinforcement of the network of partners working on the development and application of gas analysis, thus fostering collaboration and exchange of knowledge. As such, this report should become a living document which incorporates in future coming progress and developments in the field.

  • 93.
    Biollaz, S.
    et al.
    PSI.
    Calbry-Muzyka, A.
    PSI.
    Rodriguez, S.
    PSI.
    Sárossy, Z.
    DTU.
    Ravenni, G.
    DTU.
    Fateev, A.
    DTU.
    Seiser, R.
    UCSD.
    Eberhard, M.
    KIT.
    Kolb, T.
    KIT.
    Heikkinen, N.
    VTT.
    Reinikainen, M.
    VTT.
    Brown, R.C.
    Iowa State University, USA.
    Johnston, P.A.
    Iowa State University, USA.
    Nau, P.
    DLR.
    Geigle, K.P.
    DLR.
    Kutne, P.
    DLR.
    Işık-Gülsaç, I.
    TÜBİTAK Mam.
    Aksoy, P.
    TÜBİTAK Mam.
    Çetin, Y.
    TÜBİTAK Mam.
    Sarıoğlan, A.
    TÜBİTAK Mam.
    Tsekos, C.
    Delft University of Technology, Netherlands.
    de Jong, W.
    Delft University of Technology, Netherlands.
    Benedikt, F.
    TU Wien, Austria.
    Hofbauer, H.
    TU Wien, Austria.
    Waldheim, L.
    SFC.
    Engvall, K.
    KTH Royal instute of technology, Sweden.
    Neubauer, Y.
    Technical University of Berlin, Germany.
    Funcia, I.
    CENER.
    Gil, J.
    CENER.
    del Campo, I.
    CENER.
    Wilson, I.
    University of Glasgow, UK.
    Khan, Z.
    University of Glasgow, UK.
    Gall, D.
    Gothenburg University, Sweden.
    Gómez-Barea, A.
    University of Seville, Spain.
    Schmidt, F.
    Umeå University, Sweden.
    Lin, Leteng
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Strand, Michael
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Anca-Couce, A.
    Graz University of Technology, Austria.
    von Berg, L.
    Graz University of Technology, Austria.
    Larsson, A.
    GoBiGas.
    Sánchez Hervás, J.M.
    CIEMAT.
    van Egmond, B.F.
    ECN part of TNO.
    Geusebroek, M.
    ECN part of TNO.
    Toonen, A.
    ECN part of TNO.
    Kuipers, J.
    ECN part of TNO.
    Cieplik, M.
    ECN part of TNO.
    Boymans, E.H.
    ECN part of TNO.
    Grootjes, A.J.
    ECN part of TNO.
    Fischer, F.
    TUM.
    Schmid, M.
    University of Stuttgart, Germany.
    Maric, J.
    Chalmers University of Technology, Sweden.
    Defoort, F.
    CEA.
    Ravel, S.
    CEA.
    Thiery, S.
    CEA.
    Balland, M.
    CEA.
    Kienzl, N.
    Bioenergy 2020+.
    Martini, S.
    Bioenergy 2020+.
    Loipersböck, J.
    Bioenergy 2020+.
    Basset, E.
    ENGIE Lab CRIGEN.
    Barba, A.
    ENGIE Lab CRIGEN.
    Willeboer, W.
    RWE-Essent.
    Venderbosch, R.
    BTG.
    Carpenter, D.
    NREL.
    Pinto, F.
    LNEG.
    Barisano, D.
    ENEA.
    Baratieri, M.
    UNIBZ.
    Ballesteros, R.
    UCLM.
    Mourao Vilela, C. ()
    ECN part of TNO.
    Vreugdenhil, B.J. ()
    ECN part of TNO.
    Gas analysis in gasification of biomass and waste: Guideline report: Document 2 - Factsheets on gas analysis techniques2018Rapport (Fagfellevurdert)
    Abstract [en]

    Gasification is generally acknowledged as one of the technologies that will enable the large-scale production of biofuels and chemicals from biomass and waste. One of the main technical challenges associated to the deployment of biomass gasification as a commercial technology is the cleaning and upgrading of the product gas. The contaminants of product gas from biomass/waste gasification include dust, tars, alkali metals, BTX, sulphur-, nitrogen- and chlorine compounds, and heavy metals. Proper measurement of the components and contaminants of the product gas is essential for the monitoring of gasification-based plants (efficiency, product quality, by-products), as well as for the proper design of the downstream gas cleaning train (for example, scrubbers, sorbents, etc.). The deployment and implementation of inexpensive yet accurate gas analysis techniques to monitor the fate of gas contaminants might play an important role in the commercialization of biomass and waste gasification processes.

    This special report commissioned by the IEA Bioenergy Task 33 group compiles a representative part of the extensive work developed in the last years by relevant actors in the field of gas analysis applied to (biomass and waste) gasification. The approach of this report has been based on the creation of a team of contributing partners who have supplied material to the report. This networking approach has been complemented with a literature review. This guideline report would like to become a platform for the reinforcement of the network of partners working on the development and application of gas analysis, thus fostering collaboration and exchange of knowledge. As such, this report should become a living document which incorporates in future coming progress and developments in the field.

  • 94.
    Biswas, Amit Kumar
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Thermochemical behavior of pretreated biomass2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Mankind has to provide a sustainable alternative to its energy related problems. Bioenergy is considered as one of the potential renewable energy resources and as a result bioenergy market is also expected to grow dramatically in future. However, logistic issues are of serious concern while considering biomass as an alternative to fossil fuel. It can be improved by introducing pretreated wood pellet.

    The main objective of this thesis is to address thermochemical behaviour of steam exploded pretreated biomass. Additionally, process aspects of torrefaction were also considered in this thesis. Steam explosion (SE) was performed in a laboratory scale reactor using Salix wood chips. Afterwards, fuel and thermochemical aspects of SE residue were investigated. It was found that Steam explosion pretreatment improved both fuel and pellet quality. Pyrolysis of SE residue reveals that alerted biomass composition significantly affects its pyrolysis behaviour. Contribution from depolymerized components (hemicellulose, cellulose and lignin) of biomass was observed explicitly during pyrolysis. When devolatilization experiment was performed on pellet produced from SE residue, effect of those altered components was observed. In summary, pretreated biomass fuel characteristics is significantly different in comparison with untreated biomass. On the other hand, Process efficiency of torrefaction was found to be governed by the choice of appropriate operating conditions and the type of biomass.

    Fulltekst (pdf)
    fulltext
  • 95.
    Biswas, Amit Kumar
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Devolatilization characteristics of steam explosion pretreated wood pelletInngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188Artikkel i tidsskrift (Annet vitenskapelig)
  • 96.
    Biswas, Amit Kumar
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Steam pretreatment of Salix to upgrade biomass fuel for wood pellet production2011Inngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 92, nr 9, s. 1711-1717Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Steam explosion (SE) pretreatment is served to separate the main components of woody biomass. In general there is a noticeable gap in literature in terms of application of steam explosion process to upgrade biomass fuel for wood pellet production. In order to study the influence of steam explosion pretreatment on biomass fuel, Salix wood chips was used as raw material. Four different SE experiments were performed by varying two key process factors; time and temperature. Elementary quality and ash properties of the pretreated residue were investigated. Moreover, physical and thermochemical properties of the pellet, produced from the residue, were also investigated. Reduction in ash content especially in alkali metals was observed in steam treated residue. Pretreatment of biomass also enhanced carbon content and reduced oxygen amount in the fuel which enhanced the heating value of the fuel. Moreover, pretreatment enhanced pellet density, impact resistance, and abrasive resistance of pellet. However, small degradation in ash fusion characteristics and char reactivity was also observed as the severity of the process increased.

  • 97.
    Bjervås, Jens
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Simulation of dry matter loss in biomass storage2019Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Material degradation and a decrease of fuel quality are common phenomena when storing biomass. A magnitude of 7.8% has been reported to degrade over five months when storing spruce wood chips in the winter in Central Europe. This thesis presents a theoretical study of biomass storage. It includes investigations of bio-chemical, chemical and physical processes that occur during storage of chipped woody biomass. These processes lead to degradation caused by micro-activity, chemical oxidation reactions and physical transformation of water. Micro-activity was modeled with Monod kinetics which are Michaelis-Menten type of expressions. The rate expressions were complemented with dependency functions describing the impact of oxygen, moisture and temperature. The woody biomass was divided into three fractions. These fractions represent how hard different components of the wood are to degrade by microorganisms. Chemical oxidation was modeled as a first order rate expression with respect to the active components of the wood. Two different cases have been simulated during the project. Firstly, an isolated system with an initial oxygen concentration of air was considered. This case displayed a temperature increase of approximately 2˚C and a material degradation less than 1%. The second case considered an isolated system with an endless depot of oxygen. This case resulted in degradation losses around 0.45-0.95% in the temperature range between 65-80˚C during approximately 300 days of storage. The temperature increased slowly due to chemical oxidation.

    Fulltekst (pdf)
    fulltext
  • 98.
    Bjorklund, Robert B.
    et al.
    Linköping University.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Sterte, Johan
    Arwin, Hans
    Linköping University.
    Vapor adsorption in thin silicalite-1 films studied by spectroscopic ellipsometry1998Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 102, nr 12, s. 2245-2250Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thin films of silicalite-1 grown on silicon substrates were studied by spectroscopic ellipsometry. Analysis of spectra using an optical model consisting of a single porous layer on silicon yielded average film thicknesses of 84 and 223 nm for films synthesized for 10 and 30 h. Void fraction for the films was 0.32-0.33. Vapor adsorption from a nitrogen carrier gas at room temperature was monitored by ellipsometry. Isotherms for different adsorbates were obtained by analysis of spectra taken at different vapor concentrations using an optical model where the void volume was filled with both nitrogen and condensed vapors. Quantification of the condensed vapor amount was based on the changes in refractive index when adsorbates replaced nitrogen in the pores. Adsorbate volumes for water, toluene, 1-propanol, and hexane were 0.12, 0.12, 0.15, and 0.17 cm3 liquid g-1 film, respectively.

  • 99.
    Björk, Emma
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten. University of Nacl Rio Cuarto, Argentina.
    Militello, Maria P.
    University of Nacl Rio Cuarto, Argentina.
    Tamborini, Luciano H.
    University of Nacl Rio Cuarto, Argentina.
    Coneo Rodriguez, Rusbel
    University of Nacl Rio Cuarto, Argentina.
    Planes, Gabriel A.
    University of Nacl Rio Cuarto, Argentina.
    Acevedo, Diego F.
    University of Nacl Rio Cuarto, Argentina; University of Nacl Rio Cuarto, Argentina.
    Sergio Moreno, M.
    Consejo Nacl Invest Cient and Tecn, Argentina.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Barbero, Cesar A.
    University of Nacl Rio Cuarto, Argentina.
    Mesoporous silica and carbon based catalysts for esterification and biodiesel fabrication-The effect of matrix surface composition and porosity2017Inngår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 533, s. 49-58Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of catalyst matrix porosity composition on the catalytic performance have been studied using sulfonated mesoporous SBA-15 silica. The matrix was sulfonated with three different methods grafting, in situ oxidation, and carbon infiltration. Additionally, unordered sulfonated mesoporous carbon, and the commercial catalysts Amberlite IR-120 and Nafion 117 were tested. The catalytic performance was evaluated in a Fischer esterification using acetic acid and ethanol, as well as in a transesterification of triglycerides (sunflower oil) and ethanol to produce biodiesel. The study shows that for long carbon chains, the effective wetting of the porous catalyst matrix by the reactants is most important for the catalytic efficiency, while for shorter carbon chain, the mass transport of the reagents trough the porous structure is more important. The catalysts were analysed using electron microscopy and physisorption. The study shows that the reactions are faster with carbon infiltrated materials than the silica materials due to a higher concentration of sulfonic groups linked to the carbon. The in situ functionalized SBA-15 is a more efficient catalyst compared to the post grafted one. All the synthesized catalysts outperform the commercial ones in both reactions in terms of conversion. (C) 2017 Elsevier B.V. All rights reserved.

    Fulltekst (pdf)
    fulltext
  • 100.
    Björk, Jonas
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materialdesign. Linköpings universitet, Tekniska fakulteten.
    Halim, Joseph
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materialdesign. Linköpings universitet, Tekniska fakulteten.
    Zhou, Jie
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materialdesign. Linköpings universitet, Tekniska fakulteten.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materialdesign. Linköpings universitet, Tekniska fakulteten.
    Predicting chemical exfoliation: fundamental insights into the synthesis of MXenes2023Inngår i: NPJ 2D MATERIALS AND APPLICATIONS, ISSN 2397-7132, Vol. 7, nr 1, artikkel-id 5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The factors controlling the top-down synthesis of MXenes, by selectively removing the A elements from parent MAX phases, is still under debate. In particular, understanding why some MAX phases can be used for creating MXenes, while others cannot, is of immense interest and would greatly support computational screening and identification of new two-dimensional materials that could also be created by chemical exfoliation. Here we computationally study the etching of MAX phases in hydrofluoric acid, considering the complete exfoliation process and competing processes during the initial steps of the synthesis. The results are compared to experiments and MAX phases successfully converted to MXenes, as well as so far unsuccessful attempts, including previously unpublished experimental data, rationalizing why some MAX phases are exfoliable while others are not. Our results provide an improved understanding of the synthesis of MXenes under acid conditions, anticipated to be vital for our ability to discover novel two-dimensional materials.

    Fulltekst (pdf)
    fulltext
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