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  • 1.
    Aguirre Castillo, José
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Heidelberg Materials Cement Sverige AB, Slite, Sweden.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Eriksson, Matias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Swedish Mineral Processing Research Association (MinFo), Stockholm, Sweden.
    Phase evolution and burnability of cement raw meal2023Inngår i: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 35, nr 12, s. 577-587Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of high-temperature X-ray diffraction (HT-XRD) to study the mass transfer of raw meal constituents towards forming clinker phases and the occurrence of free lime (calcium oxide), also known as burnability, was assessed. A measuring strategy with temperature ranging from 1000°C to 1450°C was developed and compared with a conventional burnability method. The free lime determined by the methods showed that HT-XRD produced good results for the evaluation of burnability. In addition, HT-XRD revealed the formation of intermediate phases, providing insight into early reactions in a cement kiln. The particle size of quartz was found to affect crystal expansion of the phase at a high temperature, subsequently affecting the formation of silica polymorphs. The different raw meals used in this study also indicate that the formation of different silica polymorphs affects the formation of C2S. The lack of knowledge regarding the influence of β-quartz on the reduction of free lime is highlighted.

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  • 2.
    Aguirre Castillo, José
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Eriksson, Matias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    The reactivity of spent raw meal used in the post-combustion calcium looping decarbonisation process2023Konferansepaper (Annet vitenskapelig)
  • 3.
    Aguirre Castillo, José
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Cementa AB, Slite, Sweden .
    Eriksson, Matias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Swedish Mineral Processing Research Association – MinFo, Stockholm, Sweden.
    Impact of solid alternative fuels on cement kiln operation2022Inngår i: Proceedings of the 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment / [ed] Markus Broström, Department of Applied Physics and Electronics, Umeå University , 2022Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Cement production involves preparing a raw material mix that is burned at 1450 ⁰C in a direct-fired rotatory kiln to produce cement clinker. In this paper, a stable kiln operation has been referred to as a stable burning and constant high product quality. For the burning, conventional fuels such as coal and petcoke are partially replaced with alternative fuels. Properties of alternative fuels like water content, particle size and higher heating value in RDF (Refuse derived fuel), TDF (Tyre derived fuel) and MDM (Meat and bone meal) disturb the establishment of an ideal flame, which affects the burning and product quality. The chemistry of the fuels also influences the product quality as the ash is incorporated in the cement clinker. Evaporation and heavy condensation of volatiles from alternative fuels hinder the streams of gas and material in the kiln system. This paper summarises some experiences cement manufacturers can consider when operating with alternative fuels. 

  • 4.
    Albán Reyes, Diana Carolina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden .
    Svedberg, Anna
    Eliasson, Bertil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sundman, Ola
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    The influence of different parameters on the mercerisation of cellulose for viscose production2016Inngår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, nr 2, s. 1061-1072Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A quantitative analysis of degree of transformation from a softwood sulphite dissolving pulp to alkalised material and the yield of this transformation as a function of the simultaneous variation of the NaOH concentration, denoted [NaOH], reaction time and temperature was performed. Samples were analysed with Raman spectroscopy in combination with multivariate data analysis and these results were confirmed by X-ray diffraction. Gravimetry was used to measure the yield. The resulting data were related to the processing conditions in a Partial Least Square regression model, which made it possible to explore the relevance of the three studied variables on the responses. The detailed predictions for the interactive effects of the measured parameters made it possible to determine optimal conditions for both yield and degree of transformation in viscose manufacturing. The yield was positively correlated to the temperature from room temperature up to 45 A degrees C, after which the relation was negative. Temperature was found to be important for the degree of transformation and yield. The time to reach a certain degree of transformation (i.e. mercerisation) depended on both temperature and [NaOH]. At low temperatures and high [NaOH], mercerisation was instantaneous. It was concluded that the size of fibre particles (mesh range 0.25-1 mm) had no influence on degree of transformation in viscose processing conditions, apparently due to the quick reaction with the excess of NaOH.

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  • 5. Aldea, Steliana
    et al.
    Snåre, Mathias
    Eränen, Kari
    Grenman, Henrik
    Rautio, Anne-Riika
    Kordás, Krisztian
    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, Biskopsgatan 8, 20500 Åbo-Turku, Finland.
    Salmi, Tapio
    Murzin, Dmitry Y.
    Crystallization of Nano-Calcium Carbonate: The Influence of Process Parameters2016Inngår i: Chemie Ingenieur Technik, ISSN 0009-286X, E-ISSN 1522-2640, Vol. 88, nr 11, s. 1609-1616Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Precipitated calcium carbonate was synthesized by carbonation of calcium hydroxide in the presence and absence of ultrasound (conventional stirring) at atmospheric as well as at elevated pressures and different initial concentrations of Ca(OH)2. Spherical morphology of the formed calcite was favored at high Ca(OH)2 concentrations and low CO2 pressures. The presence of ultrasound did not show any influence on the reaction rate in case of efficient mixing. A small increase of the reaction rate was observed at lower CO2 pressures. Elevated pressures in combination with ultrasound did not lead to notable changes of reaction rate or particle morphology.

  • 6.
    Andersson, C. David
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Forsgren, Nina
    Swedish Defense Research Agency, CBRN Defense and Security, Umeå.
    Akfur, Christine
    Swedish Defense Research Agency, CBRN Defense and Security, Umeå.
    Allgardsson, Anders
    Swedish Defense Research Agency, CBRN Defense and Security, Umeå.
    Berg, Lotta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Engdahl, Cecilia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Swedish Defense Research Agency, CBRN Defense and Security, Umeå.
    Qian, Weixing
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratories for Chemical Biology Umeå (LCBU), Umeå University,.
    Ekström, Fredrik
    Swedish Defense Research Agency, CBRN Defense and Security, Umeå.
    Linusson, Anna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Divergent Structure-Activity Relationships of Structurally Similar Acetylcholinesterase Inhibitors2013Inngår i: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 56, nr 19, s. 7615-7624Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The molecular interactions between the enzyme acetylcholinesterase (AChE) and two compound classes consisting of N-[2-(diethylamino)ethyl]benzenesulfonamides and N-[2-(diethylamino)ethyl]benzenemethanesulfonamides have been investigated using organic synthesis, enzymatic assays, X-ray crystallography, and thermodynamic profiling. The inhibitors' aromatic properties were varied to establish structure activity relationships (SAR) between the inhibitors and the peripheral anionic site (PAS) of AChE. The two structurally similar compound classes proved to have distinctly divergent SARs in terms of their inhibition capacity of AChE. Eight X-ray structures revealed that the two sets have different conformations in PAS. Furthermore, thermodynamic profiles of the binding between compounds and AChE revealed class-dependent differences of the entropy/enthalpy contributions to the free energy of binding. Further development of the entropy-favored compound class resulted in the synthesis of the most potent inhibitor and an extension beyond the established SARs. The divergent SARs will be utilized to develop reversible inhibitors of AChE into reactivators of nerve agent-inhibited AChE.

  • 7.
    Antlauf, Mathis
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Andersson, Ove
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Thermal Conductivity of Porous and Dense Networks of Cellulose Nanocrystals2022Inngår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 55, nr 13, s. 5326-5331Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cellulose is a crystalline polymer with intriguing, amorphous-like, temperature dependence of thermal conductivity κ. To determine its origin, we have studied κ of cellulose nanocrystals (CNCs) derived from cotton by sulfuric acid hydrolysis, in both porous and nonporous states by pressure densification; κ increases weakly with increasing temperature and density, like in a fully amorphous material, and it is remarkably similar to that of cellulose fibers (CFs) and cellulose nanofibers (CNFs). For a powder derived from a natural material, like cellulose, amorphous-like κ may originate from poor thermal contact between particles or a high amorphous content, but the latter is not the case for CNCs. Moreover, the amorphous-like behavior is unaffected by densification and, therefore, improved thermal contacts. Instead, we attribute the behavior to CNCs' nanometer-sized fibrils, which limit the phonon mean free path to a few nanometers in a network of randomly oriented CNCs. This explains why κ is essentially the same in networks of CNCs, CFs, and CNFs, which are materials with the same structural unit-elementary fibrils of 3-5 nm in diameter. We obtain κ = (0.60 ± 0.01) W m-1 K-1 for a nonporous network of randomly oriented CNCs at 295 K and atmospheric pressure, and κ increases by only 14% GPa-1, which is unusually weak for a polymer. By using a model for such a network, we find κ = 1.9 W m-1 K-1 along a CNC and argue that this is a good estimate also along a CNF and a CF at room temperature.

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  • 8.
    Anugwom, Ikenna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku FI-20500, Finland.
    Rujana, L.
    Wärnå, J.
    Hedenström, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku FI-20500, Finland.
    In quest for the optimal delignification of lignocellulosic biomass using hydrated, SO2 switched DBU MEASIL switchable ionic liquid2016Inngår i: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 297, s. 256-264Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, various process parameters aiming at optimal short-time-high-temperature (STHT) process were studied upon fractionation of Nordic woody biomass into its primary constituents. Highly diluted, aqueous 'SO2-switched' switchable ionic liquid (SIL) based on an alkanol amine (monoethanol amine, MEA) and an organic superbase (1,8-diazabicyclo-[5.4.0]-undec-7-ene, DBU) was applied. The ultimate goal was to develop a more sustainable, environmentally friendly and cost efficient systems for efficient separation of the lignocellulosic fractions. One of the main products from the SIL fractionation is cellulose-rich pulp with very low lignin content, complemented with hemicelluloses. The NMR results reveal that substantial removal of lignin occurs even when relatively low amount of SIL was used. Further, a simple mathematical model describing the dissolution of the lignocellulose components (hemicellulose and lignin) and weight loss of wood as a function of time is described. Moreover, the most efficient process involved the use of SpinChem (R) rotating bed reactor while upon use of a flow through (loop) reactor, promising results were obtained at a treatment time of 4 h. Still, all the reactor systems studied gave rise to a rather low removal of hemicelluloses which mean that the solvent system is primary selective towards lignin dissolution.

  • 9.
    Azam, Asad Muhammad
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ali, A.
    Khan, H.
    Yasin, T.
    Mehmood, M. S.
    Analysis of degradation in UHMWPE a comparative study among the various commercial and laboratory grades UHMWPE2016Inngår i: 14TH INTERNATIONAL SYMPOSIUM ON ADVANCED MATERIALS (ISAM 2015) / [ed] Qaisar, S., Khan, A.N., Mukhtar, E.A., IOP PUBLISHING LTD , 2016, Vol. 146, artikkel-id 012025Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Oxidative degradation of the ultra-high molecular weight polyethylene ( UHMWPE) limits the life of implants. This degradation can be monitored to estimate the service life of UHMWPE following the standard protocols as defined by American Standards for Testing Materials ( ASTM). In this work, a comparative study has been carried on two commercially available UHMWPE grades i. e. GUR 1020 and GUR 1050 and one laboratory grade UHMWPE which was purchased from Sigma Aldrich. These powder samples were pressed while using hot press with controlled heating and cooling setup in open air under 200 bar of external pressure. These sheets were then subjected to accelerated aging in an oven at 80 degrees C for three weeks. The degradation of the UHMWPE was monitored by ATR-FTIR techniquefor three weeks. The oxidation index ( OI) measurement showed that the commercial grade UHMWPE i. e. GUR-1020 and GUR-1050 degrade more as compared to laboratory grade UHMWPE. The values of OI after three weeks of accelerating aging were found 0.18, 0.14, and 0.09 for GUR-1020, GUR-1050, and Sigma Aldrich, respectively. In addition to this, it was found that commercial grades of UHMWPE suffer more structural alterations as compared to laboratory grade one. We hope that these results will be of particular and fundamental importance for the researchers and orthopaedic industry.

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  • 10. 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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  • 11.
    Bi, Zenghui
    et al.
    School of Electronic Communication Technology, Shenzhen Institute of Information Technology, Shenzhen, China; Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Materials and Energy, Yunnan University, Kunming, China.
    Wang, Yuwen
    Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Materials and Energy, Yunnan University, Kunming, China.
    Chen, Jianbing
    Research Academy of Non-metallic Mining Industry Development, Materials and Environmental Engineering College, Chizhou University, Chizhou, China.
    Zhang, Xianxi
    School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, China.
    Zhou, Shuxing
    Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices, Hubei University of Arts and Science, Xiangyang, China.
    Wang, Xinzhong
    School of Electronic Communication Technology, Shenzhen Institute of Information Technology, Shenzhen, China.
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Hu, Guangzhi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Materials and Energy, Yunnan University, Kunming, China.
    Three dimensional star-like mesoporous nitrogen-doped carbon anchored with highly dispersed Fe and Ce dual-sites for efficient oxygen reduction reaction in Zn-air battery2022Inngår i: Colloid and Interface Science Communications, ISSN 2215-0382, Vol. 49, artikkel-id 100634Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Metal‑nitrogen‑carbon materials (M-N-C) have attracted much attention due to their low cost, high abundance, and efficient catalytic performance. Nevertheless, Fe-N-C materials are considered the most promising oxygen reduction reaction (ORR) catalysts for replacing noble metals. Ce is chemically active and has many metal valence states, and empty orbitals that can participate in coordination. On this basis, Fe, Ce-codoped catalyst was constructed in this study. The synergistic effect of the dual metal centers was verified, and a Fe, Ce-codoped nitrogen-doped carbon (FeCeNC) with six equal branch angles was proposed. The half-wave potential for the ORR catalyzed by FeCeNC is 0.855 V. As a rechargeable Zn-air battery cathode catalyst, FeCeNC exhibits excellent electrochemical performances, with an open-circuit voltage of 1.427 V, a maximum power density of 169.2 mW cm−2 and a stable cycling time of 80 h, demonstrating an excellent cycle performance.

    Fulltekst (pdf)
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  • 12.
    Bi, Zenghui
    et al.
    School of Materials and Energy, Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, China.
    Zhang, Hua
    School of Materials and Energy, Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, China.
    Zhao, Xue
    School of Materials and Energy, Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, China.
    Wang, Yuwen
    School of Materials and Energy, Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, China.
    Tan, Fang
    School of Materials and Energy, Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, China.
    Chen, Songqing
    School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, China.
    Feng, Ligang
    School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, China.
    Zhou, Yingtang
    National Engineering Research Center for Marine Aquaculture, Marine Science and Technology College, Zhejiang Ocean University, Zhoushan, China.
    Ma, Xin
    School of Energy and Chemical Engineering, Xinjiang Institute of Technology, Akesu, China.
    Su, Zhi
    School of Energy and Chemical Engineering, Xinjiang Institute of Technology, Akesu, China.
    Wang, Xinzhong
    School of Electronic Communication Technology, Shenzhen Institute of Information Technology, Shenzhen, China.
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Hu, Guangzhi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. School of Materials and Energy, Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, China.
    Highly dispersed La−O/N−C sites anchored in hierarchically porous nitrogen-doped carbon as bifunctional catalysts for high-performance rechargeable Zn−air batteries2023Inngår i: Energy Storage Materials, ISSN 2405-8289, E-ISSN 2405-8297, Vol. 54, s. 313-322Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Inexpensive, high-activity bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are imperative for the development of energy storage and conversion systems. A nitrogen-doped carbon material with a micro−meso−macroporous structure doped with La (LaPNC) containing La−O/N−C active sites is prepared using SiO2 particle templating of carbon and a metal node exchange strategy. The coordination environment of La sites stabilized by two oxygen and four nitrogen atoms (LaO2N4), is further verified by X-ray absorption spectroscopy. The ORR half-wave potential reaches 0.852 V, and the OER overpotential reaches 263 mV at 10 mA cm−2. The Zn−air battery, with LaPNC as the air cathode, has a maximum power density of 202 mW cm−2 and achieves stable charge−discharge for at least 100 h without a significant increase or decrease in the charge or discharge voltages, respectively. Density functional theory calculations suggest that LaO2N4 sites exhibit the lowest activation free energy and the most easily desorbed oxygen capacity. This study provides new insights into the design of efficient, durable bifunctional catalysts as alternatives to precious-metal-based catalysts.

    Fulltekst (pdf)
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  • 13.
    Biasi, P.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo Akad Univ, Dept Chem Engn, Lab Ind Chem & React Engn, Johan Gadolin Proc Chem Ctr PCC, Biskopsgatan 8, FI-20500 Turku, Finland.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo Akad Univ, Dept Chem Engn, Lab Ind Chem & React Engn, Johan Gadolin Proc Chem Ctr PCC, Biskopsgatan 8, FI-20500 Turku, Finland.
    Sterchele, S.
    Salmi, T.
    Gemo, N.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Centomo, P.
    Zecca, M.
    Canu, P.
    Rautio, A. -R
    Kordàs, K.
    Revealing the role of bromide in the H2O2 direct synthesis with the catalyst wet pretreatment method (CWPM)2017Inngår i: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 63, nr 1, s. 32-42Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A tailor-made Pd0/K2621 catalyst was subjected to post synthesis modification via a wet treatment procedure. The aimwas the understanding of the role of promoters and how—if any—improvements could be qualitatively related to the cat-alyst performance for the H2O2direct synthesis. The Catalyst Wet Pretreatment Method was applied in different metha-nolic solutions containing H2O2, NaBr, and H3PO4, either as single modifiers or as a mixture. The catalyst wascharacterized by Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy. It was concluded that themodified catalysts give rise to higher selectivities compared to the pristi ne reference catalyst thus opening a possibilityto exclude the addit ion of the undesirable selectivity enhancers in the reaction medium. This work provides original evi-dence on the role of promoter s, especially bromide, allowing the formulation of a new reaction mechanism for one ofthe most challenging reactions recognized by the world.

  • 14. 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.

  • 15.
    Biasi, Pierdomenico
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry and Reaction Engineering, Process Chemistry Center (PCC), Department of Chemical Engineering, Åbo Akademi University,Turku/Åbo, Finland.
    Sterchele, Stefano
    Bizzotto, Francesco
    Manzoli, Maela
    Lindholm, Sten
    Ek, Paul
    Bobacka, Johan
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry and Reaction Engineering, Process Chemistry Center (PCC), Department of Chemical Engineering, Åbo Akademi University,Turku/Åbo, Finland.
    Salmi, Tapio
    Application of the Catalyst Wet Pretreatment Method (CWPM) for catalytic direct synthesis of H2O22015Inngår i: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 246, nr Special Issue, s. 207-215Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work concerns a new technique to post-modify the catalytic material intended for use in H2O2 direct synthesis. The catalyst chosen was a commercially available 1 wt.% Pd/C. The catalyst was modified with the so-called Catalyst Wet Pretreatment Method (CWPM) that is used to post-modify prepared catalysts with aqueous solutions of NaBr, in different concentrations. The performance of pristine and the pretreated materials were then compared in the H2O2 direct synthesis and characterized before and after the catalytic tests in order to understand the role of the different concentrations of bromide in the CWPM procedure. The surface features of the different catalysts were analyzed with CO chemisorption (metal dispersion and mean particle size), Transmission Electron Microscopy (TEM, for Pd morphology and Pd particle size distributions), Inductive Coupled Plasma (ICP, for Pd content) and Ion Chromatography (IC, for bromide content). Various features of the materials prepared with the CWPM were correlated with the catalytic performance. It was found that the bromide has an active role in the reconstruction of metal phase and it does not only act as a poison for the most active catalytic sites as often reported in literature. By using this new protocol, the production H2O2 was almost doubled compared to the non-modified material when no direct promoters were added to the reaction environment.

  • 16.
    Björnwall, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Impact of calcination temperature and time on quicklime slaking reactivity2021Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    In this master thesis work calcination parameters' impact on the resulting quicklimes slaking reactivity is investigated. This is done by calcination of three different sedimentary limestones in an N2 atmosphere according to a design of experiment matrix. The limestones are from Wolica Poland, Slite Sweden and Jutjärn Sweden. The temperatures and residence times are varied between 1000ºC, 1050ºC, and 1100ºC for 5 min, 27.5 min, and 60 min. There were seven experiments per limestone sample. The calcination experiments were conducted in an electrical muffle furnace.When the limestone samples were calcined, the resulting quicklimes slaking reactivity was tested according to standard SS-EN 459-2:2010 Building lime - Part 2: Test methods. Four different parameters were used to determine the slaking reactivity, these were the maximum temperature, how much the temperature increases under the initial 30 s, the time it takes for the temperature to reach 60ºC, and the time for the slaking to become 80% finished.From the slaking reactivity experiments, the calcination parameters to produce the most reactive quicklime for the limestone from Wolica and Jutjärn are 1000ºC for 60 min, and for the limestone from Slite 1100ºC for 5 min. For all three limestones the least reactive quicklime was received by calcining at 1100ºC for 60 min. The most and least reactive quicklimes were analyzed in SEM, where it could be seen that the least reactive quicklime samples were coarser compared to the most reactive samples. Depending on what slaking reactivity parameter is of interest, the calcination settings should be different and can be an indication for operation parameters for industrial kilns. The statistical analysis on the experimental model showed that the experiment had a poor statistical fit for most of the experiment. This could be due to that the model possibly was too simple to describe the calcination parameters complex impact on the slaking reactivity.

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  • 17.
    Borén, Eleonora
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Off-gassing from thermally treated lignocellulosic biomass2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Off-gassing of hazardous compounds is, together with self-heating and dust explosions, the main safety hazards within large-scale biomass storage and handling. Formation of CO, CO2, and VOCs with concurrent O2 depletion can occur to hazardous levels in enclosed stored forest products. Several incidents of CO poisoning and suffocation of oxygen depletion have resulted in fatalities and injuries during cargo vessel discharge of forest products and in conjunction with wood pellet storage rooms and silos. Technologies for torrefaction and steam explosion for thermal treatment of biomass are under development and approaching commercialization, but their off-gassing behavior is essentially unknown.

    The overall objective of this thesis was to provide answers to one main question: “What is the off-gassing behaviour of thermally treated lignocellulosic biomass during storage?”. This was achieved by experimental studies and detailed analysis of off-gassing compounds sampled under realistic conditions, with special emphasis on the VOCs.

    Presented results show that off-gassing behavior is influenced by numerous factors, in the following ways. CO, CO2 and CH4 off-gassing levels from torrefied and stream-exploded biomass and pellets, and accompanying O2 depletion, are comparable to or lower than corresponding from untreated biomass. The treatments also cause major compositional shifts in VOCs; emissions of terpenes and native aldehydes decline, but levels of volatile cell wall degradation products (notably furans and aromatics) increase. The severity of the thermal treatment is also important; increases in torrefaction severity increase CO off-gassing from torrefied pine to levels comparable to emissions from conventional pellets, and increase O2 depletion for both torrefied chips and pellets. Both treatment temperature and duration also influence degradation rates and VOC composition. The product cooling technique is influential too; water spraying in addition to heat exchange increased CO2 and VOCs off-gassing from torrefied pine chips, as well as O2 depletion. Moreover, the composition of emitted gases co-varied with pellets’ moisture content; pellets of more severely treated material retained less moisture, regardless of their pre-conditioning moisture content. However, no co-variance was found between off-gassing and pelletization settings, the resulting pellet quality, or storage time of torrefied chips before pelletization. Pelletization of steam-exploded bark increased subsequent VOC off-gassing, and induced compositional shifts relative to emissions from unpelletized steam-exploded material. In addition, CO, CO2 and CH4 off-gassing, and O2 depletion, were positively correlated with the storage temperature of torrefied softwood. Similarly, CO and CH4 emissions from steam-exploded softwood increased with increases in storage temperature, and VOC off-gassing from both torrefied and steam-exploded softwood was more affected by storage temperature than by treatment severity. Levels of CO, CO2 and CH4 increased, while levels of O2 and most VOCs decreased, during storage of both torrefied and steam-exploded softwood.CO, CO2 and O2 levels were more affected by storage time than by treatment severity. Levels of VOCs were not significantly decreased or altered by nitrogen purging of storage spaces of steam-exploded or torrefied softwood, or controlled headspace gas exchange (intermittent ventilation) during storage of steam-exploded bark.

    In conclusion, rates of off-gassing of CO and CO2 from thermally treated biomass, and associated O2 depletion, are comparable to or lower than corresponding rates for untreated biomass. Thermal treatment induces shifts in both concentrations and profiles of VOCs. It is believed that the knowledge and insights gained provide refined foundations for future research and safe implementation of thermally treated fuels as energy carriers in renewable energy process chains.

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  • 18.
    Borén, Eleonora
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Industrial Doctoral School for Research and Innovation, Umeå University, Umeå, Sweden.
    Larsson, Sylvia H.
    Biomass Technology Centre, Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Andreas, Averheim
    Mikael, Thyrel
    Biomass Technology Centre, Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Reducing VOC off-gassing during the production of pelletized steam-exploded bark: impact of storage time and controlled ventilation2018Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, nr 4, s. 5181-5186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Volatile organic compound (VOC) off-gassing behavior of thermally treated biomass intended for bioenergy production has recently been shown to be vastly different from that of untreated biomass. Simple measures to reduce emissions, such as controlled ventilation and prolonged storage time, have been suggested but not yet studied in detail. In the present study, we monitored how VOC off-gassing was reduced over time (24–144 h) in enclosed storage with and without ventilation. Steam-exploded bark was collected directly from a pilot-scale steam explosion plant as well as before and after subsequent pelletizing. Active Tenax-TA absorbent sampling of VOCs was performed from the headspaces of a bench-scale sample storage setup. The impact of storage time and ventilation on VOC levels was evaluated through multivariate statistical analysis. The results showed that relative VOC concentrations in the headspace were reduced by increased storage time, with heavier VOCs reduced at a higher rate. VOC composition was neither reduced nor shifted by controlled intermittent ventilation during storage; instead, VOC levels equilibrated at the same levels as those stored without ventilation, and this was independent of the process step, storage time, or number of ventilations.

  • 19.
    Borén, Eleonora
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Larsson, Sylvia H.
    Averheim, Andreas
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Reducing VOCs off-gassing during production of pelletized steam exploded bark: impact of storage time and controlled ventilationManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    VOC off-gassing behavior of thermally treated biomass intended for bioenergy production has recently been shown to be vastly different to that of untreated biomass. Simple measures to reduce emissions, such as controlled ventilation and prolonged storage time, has been suggested but not previously studied in detail. In the present study, we monitored how VOC off-gassing was reduced over time (24–144h) in closed storage with and without ventilation. Steam exploded bark was collected directly from a pilot scale steam explosion plant, and before and after subsequent pelletizing. Storage and active sampling of VOCs in the headspace was done in a bench-scale set-up using Tenax-TA absorbent. The impact of storage time and ventilation to reduce VOCs was evaluated through multivariate statistical analysis. The results showed that VOC concentrations in the headspace were reduced by increased storage time, and that heavier VOCs reduced faster. No impact on either reducing or shifting VOC composition could be achieved by controlled ventilation during storage; instead, VOCs emitted to the same concentrations anew, independent of process step, storage time, or number of ventilations.

  • 20.
    Borén, Eleonora
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Larsson, Sylvia H.
    Thyrel, Mikael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Averheim, Andreas
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    VOC off-gassing from pelletized steam exploded softwood bark: emissions at different industrial process steps2018Inngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 171, s. 70-77Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Formation of hazardous gases during transport and storage of biomass for large-scale bioenergy production is an important safety concern. While off-gassing has been addressed in numerous studies for raw woody biomass, very few describe it in the context of biomass for bioenergy production pre-treated by thermal technologies such as steam explosion. Volatile Organic Components (VOCs) are expected to be altered by the treatment, but until now there is no research published on VOC profiles of steam exploded materials in industrial scale. In the present study, VOCs emitted from the products were evaluated by sampling from different production steps from steam explosion of softwood bark, and following the production chain including also pelletization. Off-gasses were actively sampled using Tenax TA absorbent and analyzed by GC-MS. The VOC formation dependency of operation and storage conditions at different process steps was evaluated by multivariate statistical analysis. We showed that the different process steps along the production line was the main influencing factor for VOC off-gassing amounts, with highest VOC levels directly after the steam explosion process. Treatment severity mainly altered the relative composition of VOC profiles with more terpenes emitted from milder treatment, whereas more severe treatment shifted VOCs composition to contain more furans, e.g. furfural. In summary, treatment by steam explosion leads to potentially problematic VOC off-gassing profiles from the material, and levels vary considerable along the production line. The findings are important from a fuel handling and working environment perspective.

  • 21.
    Borén, Eleonora
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Department of Water Supply, Sanitation and Environmental Engineering, IHE Delft Institute for Water Education, Delft, The Netherlands.
    Lindgren, Robert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Carlborg, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Kaolin as fuel additive in grate combustion of biomass to mitigate ash related problems and particle emissions2022Inngår i: Proceedings of the 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment / [ed] Markus Broström, Department of Applied Physics and Electronics, Umeå University , 2022Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Bioenergy is a fundamental part in sustainable development but use of novel fuel feedstocks potentiallymore sustainable may also bring associated ash-related challenges in practical operation that could bemitigated by co-conversion or additives. Kaolin, a clay mineral, is an additive known to be beneficialfor reduction of slagging tendencies and particulate matter formation in combustion of traditionalwoody-type biomass but its impact on thermal conversion of other biomasses still warrantsinvestigation. The aim of the present work is therefore to investigate how thermal conversion of atypical K-Ca-rich woody-type biomass, poplar, and a K-Si-rich annual crop, grass, is affected by kaolinaddition in fixed bed combustion. Additivation levels were calculated according to amount of alkaliintroduced with the two feedstocks, and incorporated by co-pelletization, in the case of poplar, anadditional blending d method was tested, by powder coating of pellets The results show that kaolinaddition improved the bottom ash characteristics, especially for grass, but the main differencesbetween feedstocks were found in particulate matter and flue gas composition. The particulate matterconcentrations were reduced with kaolin addition due to removal of gaseous K compounds which inturn caused higher SOx and HCl concentrations due to the lower amount of gaseous alkali for reaction.Further, initially high CO levels observed for both fuel feedstocks were reduced with the addition ofkaolin where co-pelletization with poplar proved more effective than powder coating the fuel particlesurfaces. This suggests that high concentrations of gaseous K-compounds may impact conversion ofthe carbonaceous matrix negatively.

  • 22.
    Borén, Eleonora
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå University, Industrial Doctoral School for Research and Innovation, Umeå, Sweden.
    Pommer, Linda
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Nordin, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Larsson, Sylvia H.
    Off-gassing from pilot-scale torrefied pine wood chips: impact of torrefaction severity, cooling technology, and storage time2020Inngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 202, artikkel-id 106380Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During handling and storage of conventional wood pellets, O2 depletion as well as CO and CO2 off-gassing can reach acutely hazardous levels and certain Volatile Organic Compounds (VOCs) may reach concerning levels from an occupational health and safety perspective. With new thermally pre-treated biomass commodities entering consumer markets, corresponding knowledge is needed on these assortments' off-gassing behaviour. In this study, relative concentrations of VOCs, CO, CO2, and O2 in the closed storage space of five different pilot-scale torrefied pine wood chip assortments were monitored over 12 days. The VOCs composition in the storage space differed between torrefaction treatment settings; terpenes decreased while furans and lignin degradation products peaked at narrow ranges with increased torrefaction severity, indicating that VOC off-gassing composition of individual compounds is highly specific. Generally, VOC amounts decreased with storage time, but for the mildest torrefied chips certain VOCs increased, predominantly compounds of higher volatility such as hexanal, acetone, and 2-pentylfuran. Also, the newly produced torrefied chips were cooled with two different post-process technologies: i) heat exchanging, and ii) heat exchanging with additional water spraying. Water spraying resulted in higher VOC concentrations, stronger O2 depletion, and factor four higher concentration of CO2 in the storage headspace.

  • 23.
    Borén, Eleonora
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Rudolfsson, Magnus
    Nordin, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Pommer, Linda
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Larsson, Sylvia H.
    Off-gassing from 16 pilot-scale produced pellets assortments of torrefied pine: impact of torrefaction severity, storage time, pelletization parameters, and pellet qualityManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Off-gassing from wood pellets poses risks in large scale handling chains - yet little is known on off-gassing from pellets of torrefied wood. This study reports CO, CO2, and O2 concentrations in off-gases during storage of 16 torrefied and two untreated pellets assortments. According to an experimental design, pellets were produced in pilot scale from pine chips torrefied at five different set points. Off-gassing was assessed in relation to storage conditions, torrefaction and pelletization parameters, and pellet quality. Pellets from the most severely torrefied pine formed CO, CO2, and consumed O2 similarly to untreated pellets. Off-gassing was positively correlated to pellet moisture content; however, the most severely torrefied also retained the least moisture. Open air storage (20–270 days) of torrefied chips prior to pelletization did not affect off-gassing levels. Results are important for safe handling; torrefied pellets can cause comparable levels as untreated pellets of CO, CO2, and O2.

  • 24.
    Borén, Eleonora
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå University Industrial Doctoral School for Research and Innovation.
    Yazdanpanah, Fahimeh
    Lindahl, Roger
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Schilling, Christoph
    Chandra, Richard P.
    Ghiasi, Bahman
    Tang, Yong
    Sokhansanj, Shahabaddine
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Larsson, Sylvia H.
    Off-gassing of VOCs and permanent gases during storage of torrefied and steam exploded wood2017Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, nr 10, s. 10954-10965Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thermal treatment for upgrading of low-value feedstocks to improve fuel properties has gained large industrial interest in recent years. From a storage and transport perspective, hazardous off-gassing could be expected to decrease through the degradation of reactive biomass components. However, thermal treatment could also shift chemical compositions of volatile organic components, VOCs. While technologies are approaching commercialization, off-gassing behavior of the products, especially in terms of VOCs, is still unknown. In the present study, we measured off-gassing of VOCs together with CO, CO2, CH4, and O2 depletion from torrefied and steam exploded softwood during closed storage. The storage temperature, head space gas (air and N2), and storage time were varied. VOCs were monitored with a newly developed protocol based on active sampling with Tenax TA absorbent analyzed by thermal desorption-GC/MS. High VOC levels were found for both untreated and steam exploded softwood, but with a complete shift in composition from terpenes dominating the storage gas for untreated wood samples to an abundance of furfural in the headspace of steam exploded wood. Torrefied material emitted low levels of VOCs. By using multivariate statistics, it was shown that for both treatment methods and within the ranges tested, VOC off-gassing was affected first by the storage temperature and second by increasing treatment severity. Both steam exploded and torrefied biomass formed lower levels of CO than the reference biomass, but steam explosion caused a more severe O2 depletion.

  • 25.
    Boström, Dan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Lindström, Erika
    Boman, Christoffer
    Backman, Rainer
    Öhman, Marcus
    Grimm, Alejandro
    Ash transformation chemistry during energy conversion of agricultural biomass2009Inngår i: International Conference on Solid Biofuels, ICSB2009, Beijing, China, 2009Konferansepaper (Annet vitenskapelig)
  • 26.
    Boström, Dan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Grimm, Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Ash transformation chemistry during energy conversion of biomass2010Inngår i: Impacts of Fuel Quality on Power Production & Environment: 29/08/2010 - 03/09/2010, Impacts of Fuel Quality , 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    There is relatively extensive knowledge available concerning ash transformation reactions during energy conversion of woody biomass. Traditionally, these assortments have constituted the main resources for heating in Sweden. In recent decades the utilization of these energy carriers has increased, from a low technology residential small scale level to industrial scale (e.g. CHP plants). Along this evolution ash-chemical related phenomena for woody biomass has been observed and studied. So, presently the understanding for these are, if not complete, fairly good. Briefly, from a chemical point of view the ash from woody biomass could be characterized as a silicate dominated systems with varying content of basic oxides and with relatively high degree of volatilization of alkali sulfates and chlorides. Thus, the main ash transformation mechanisms in these systems have been outlined. Here, an attempt to give a general description of the ash transformation reactions of biomass fuels is presented, with the intention to provide guidance in the understanding of ash matter behavior in the utilization of any biomass fuel, primarily from knowledge of the concentrations of ash forming elements but also by considering the physical condition in the specific combustion appliance and the physical characteristic of the biomass fuel. Furthermore, since the demand for CO2-neutral energy resources has increased the last years and will continue to do so in the foreseeable future, other biomasses as for instance agricultural crops has become highly interesting. Globally, the availability of these shows large variation. In Sweden, for instance, which is a relatively spare populated country with large forests, these bio-masses will play a secondary role, although not insignificant. In other parts of the world, more densely populated and with a large agricultural sector, such bio-masses may constitute the main energy bio-mass resource in the future. However, the content of ash forming matter in agricultural bio-mass is rather different in comparison to woody biomass. Firstly, the content is much higher; from being about 0.3 – 0.5% (wt) in stem wood, it can amount to between 2 and 10 %(wt) in agricultural biomass. In addition, the composition of the ash forming matter is different. Shortly, the main difference is due to a much higher content of phosphorus (occasionally also silicon) which has major consequences on the ash-transformation reactions. In many crops, the concentration of phosphorus and silicon is equivalent, which (depending on the concentration levels of basic oxides) may result in a phosphate dominated ash. The properties of this ash are in several aspects different from the silicate dominated woody biomass ash and will consequently behave differently in various types of energy conversion systems. The knowledge about phosphate dominated ash systems has so far been scarce. We have been working with these systems, both with basic and applied research, for about a decade know. Some general experiences and conclusions as well as some specific examples of our research will be presented.

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  • 27.
    Boström, Dan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Grimm, Alejandro
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Björnbom, Emilia
    Chemical Engineering and Technology, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
    Öhman, Marcus
    Division of Energy Engineering, Luleå University of Technology, SE- 971 87 Luleå, Sweden.
    Influence of kaolin and calcite additives on ash transformations in small-scale combustion of oat2009Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, nr 10, s. 5184-5190Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A growing interest has been observed for the use of cereal grains in small- and medium-scale heating. Previous studies have been performed to determine the fuel quality of various cereal grains for combustion purposes. The present investigation was undertaken in order to elucidate the potential abatement of low-temperature corrosion and deposits formation by using fuel additives (calcite and kaolin) during combustion of oat. Special emphasis was put on understanding the role of slag and bottom ash composition on the volatilization of species responsible for fouling and emission of fine particles and acid gases. The ash fractions were analyzed with scanning electron micro scopy/energy dispersive spectroscopy (SEM/EDS), for elemental composition, and with X-ray diffraction (XRD) for identification of crystalline phases. The previously reported K and Si capturing effects of kaolin additive were observed also in the present study using P-rich biomass fuels. That is, the prerequisites for the formation of low melting K-rich silicates were reduced. The result of using kaolin additive on the bottom ash was that no slag was formed. The effect of the kaolin additive on the formation of submicrometer flue gas particles was an increased share of condensed K-phosphates at the expense of K-sulfate and KCl. The latter phase was almost completely absent in the particulate matter. Consequently, the levels of HCl and SO2 in the flue gases increased somewhat. The addition of both calcite assortments increased the amount of farmed slag, although to a considerably higher extent for the precipitated calcite. P was captured to a higher degree in the bottom ash, compared to the combustion of pure oat. The effect of the calcite additives on the fine particle emissions in the flue gases was that the share of K-phosphate decreased considerably, while the content of K-sulfate and KCl increased. Consequently, also the flue-gas levels of acidic HCl and SO2 decreased. This implies that the low-temperature corrosion observed in small-scale combustion of oat possibly can be abated by employing calcite additives. Alternatively, if problems with slagging and deposition of corrosive matter at heat convection surfaces are to be avoided, kaolin additive can be utilized, on the condition that the higher concentrations of acidic gases can be tolerated.

  • 28.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Effects of alkali chlorides in biomass and waste-fired boilers2009Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 29.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Integrated thermal treatment of acid sulfate soils2020Patent (Annet (populærvitenskap, debatt, mm))
  • 30.
    Broström, Markus
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Andersson, Christer
    Axner, Ove
    Nordin, Anders
    IACM - In situ alkali chloride monitor2004Inngår i: 2nd World Conference for Energy, Industry and Climate Protection, Rome, Italy, 2004Konferansepaper (Annet vitenskapelig)
  • 31.
    Broström, Markus
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Enestam, Sonja
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Mäkelä, Kari
    Condensation in the KCl–NaCl system2013Inngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 105, s. 142-148Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Condensation of gaseous KCl and NaCl is known to participate in deposit formation and high temperature corrosion processes in heat and power plants. Little is known about interaction between the two salts, which is of interest for the overall understanding of deposit and corrosion problems. Within this study, condensation at different material surface temperatures and salt mixtures was investigated.

    Salt vapors were prepared by temperature controlled evaporation. A cooled condensation probe with a temperature gradient was inserted in the hot gas. After exposure, the probe surface was visually inspected and analyzed with SEM/EDS and XRD for elemental and phase composition. TGA/DTA was used to provide complementary information on vaporization and sintering.

    The results indicated that a mixture of KCl and NaCl probably condenses as separate phases at concentrations and temperatures below the melting points of the salts. Condensation was possibly followed by a secondary sintering process. It was verified by TGA/DTA that a mixture of solid KCl and NaCl particles sinters and melts rapidly at temperatures above the melting temperature of a corresponding solution. It was also seen that sintering took place at lower temperatures with slow solid-gas interactions, possibly with the formation of solid solutions.

  • 32.
    Broström, Markus
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Holmgren, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Ash fractionation and slag formation during entrained flow biomass gasification2018Konferansepaper (Annet vitenskapelig)
  • 33.
    Broström, Markus
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Kassman, Håkan
    Helgesson, Anna
    Berg, Magnus
    Andersson, Christer
    Backman, Rainer
    Nordin, Anders
    Sulphation of Corrosive Alkali Chlorides by Ammonium Sulphate in a Biomass Fired CFB Boiler2006Inngår i: Impacts of Fuel Quality on Power Production, Snowbird, Utah, USA, 2006Konferansepaper (Annet vitenskapelig)
  • 34.
    Bui, Thai Q.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Development of nitrogen-containing materials for capture and catalytic conversion of carbon dioxide to value-added chemicals2021Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Anthropogenic carbon dioxide (CO2) emissions have become a critical environmental issue because a large amount of CO2 releasing into the atmosphere, particularly from the massive use of fossil fuels, is the major factor promoting the global warming and climate change. To mitigate the CO2 emissions, Carbon Capture, Utilization and Storage (CCUS) can be one of important solutions. Inspired by the CCUS approach, the aims of this thesis are to develop materials for CO2 capture (Papers I, II) and conversion of CO2 to value-added chemicals (Papers III, IV) such as dimethyl carbonate (DMC) and cyclic carbonates (CCs). The main idea is to focus on nitrogen-containing materials because basic nitrogen sites can increase the chemical affinity towards CO2, which is a weak Lewis acid gas.

    In practice, aqueous monoethanolamine (aq MEA) is widely used to capture CO2 from flue gases in CCUS projects. However, this solvent suffers from several major drawbacks such as high energy consumption for regeneration of MEA, degradation and evaporation. In Paper I, aq pentaethylenehexamine (PEHA) was proposed as an alternative solvent for chemical absorption of CO2. A comprehensive study was performed, including the influence of water content on CO2 capacity, chemical composition of absorption products, viscosities before and after absorption, regeneration of PEHA, correlation between CO2 capacity with Kamlet-Taft parameters, comparison with aq MEA. In Paper II, aq PEHA was further studied for CO2 capture from bio-syngas resulting from pilot-scale gasification of biomass to investigate the influence of other compositions on the capture performance. Additionally, this solvent was simultaneously used as a reagent for chemical pretreatment of biomass to investigate the influence of pretreatment on biomass gasification and CO2 capture.

    The conversion of captured CO2 to value-added chemicals gains increasing attentions in both academia and industry because CO2 represents a renewable, virtually inexhaustible, and nontoxic building block. In addition, this approach can provide economic incentives for CO2 capture facilities by selling their captured CO2 to other interested users or by benefiting from their own additional facilities using the CO2. In Paper III, 1,8-diazabicyclo[2.2.2]undec-7-ene (DBU) was used to capture and subsequent conversion of CO2 to DMC at ambient conditions. In Paper IV, mesoporous melamine-formaldehyde resins were prepared, characterized and studied as heterogeneous catalysts for synthesis of CCs from epoxides and CO2. These low-cost polymeric catalysts were reusable and demonstrated excellent performance in a flow reactor under industrially relevant conditions (120 °C, 13 bar, solvent-free/co-catalyst-free).

    Applications of ionic liquids (ILs) in capture and conversion of CO2 to organic carbonates were briefly reviewed in Paper V (mini review). The viscosity of ILs for CO2 capture and the mechanism involved in the CO2 binding were also discussed.

    In conclusion, this thesis will hopefully contribute to the sustainable development of society in the fields of reducing anthropogenic CO2 emissions and production of chemicals.

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  • 35.
    Bui, Thai Q.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Konwar, Lakhya Jyoti
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Nikjoo, Dariush
    Division of Materials Science, Luleå University of Technology, Luleå, Sweden.
    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.
    Mesoporous Melamine-Formaldehyde Resins as Efficient Heterogeneous Catalyst for Continuous Synthesis of Cyclic Carbonates from Epoxides and gaseous CO22020Inngår i: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 8, nr 34, s. 12852-12869Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Herein we report the application of inexpensive mesoporous melamine-formaldehyde resins (MMFR and MMFR250) obtained by a novel template-free and organosolvent-free hydrothermal method as efficient heterogeneous catalysts for direct synthesis of cyclic carbonates from CO2 and epoxides (epichlorohydrin, butylene oxide and styrene oxide). The catalytic activity of the melamine resins was attributed to the abundant Lewis basic N-sites capable of activating CO2 molecules. Based on CO2-Temperature programmed desorption, the concentration of surface basic sites for MMFR and MMFR250 were estimated to be 172 and 56 µmol/g, while the activation energy of CO2 desorption (strength of basic sites) were calculated to be 92.1 and 64.5 kJ/mol. We also observed considerable differences in the catalytic activity and stability of polymeric catalysts in batch and in continuous-flow mode; due to the existence of a synergism between adsorption of CO2 and cyclic carbonates (poison). Our experiments also revealed important role of catalyst surface chemistry and CO2 partial pressure upon catalyst poisoning. Nevertheless, owing to their unique properties (large specific surface area, large mesoporous and CO2 basicity) melamine resins presented excellent activity (turnover frequency 207-2147 h-1), selectivity (>99%) for carbonation of epoxides with CO2 (20 bar initial CO2 or CO2:epoxide mole ratio ~1.5) under solvent-free and co-catalyst-free conditions at 100-120 oC. Most importantly, these low-cost polymeric catalysts were reusable and demonstrated exceptional stability in a flow reactor (tested upto 13 days time on stream, weight hourly space velocity 0.26-1.91 h-1) for continuous cyclic carbonate production from gaseous CO2 with different epoxides (conversion 76-100% and selectivity >99%) under industrially relevant conditions (120 oC, 13 bar, solvent-free/co-catalyst-free) confirming their superiority over the previously reported catalytic materials.

  • 36.
    Bukhanko, Natalia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Leino, Anne-Riikka
    Microelectronics and Materials Physics Laboratories, University of Oulu, Finland.
    Kordas, Krisztian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Microelectronics and Materials Physics Laboratories, University of Oulu, Finland.
    Wärnå, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Finland.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Finland.
    Continuous gas phase synthesis of 1-ethyl chloride from ethyl alcohol and hydrochloric acid over Al2O3-based catalysts: the ‘green’ route2013Inngår i: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 1, nr 8, s. 883-893Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The synthesis of 1-ethyl chloride in the gas-phase mixture of ethanol and hydrochloric acid over ZnCl2/Al2O3 catalysts was studied in a continuous reactor using both commercial and tailor-made supports. The catalytic materials were characterized by the means of structural (XPS, TEM, XRD, and BET) and catalytic activity (selectivity and conversion) measurements. The reaction parameters such as temperature, pressure, and feedstock flow rates were optimized for the conversion of ethanol to ethyl chloride. The new tailor-made highly porous Al2O3-based catalyst outperformed its commercial counterpart by exhibiting high conversion and selectivity (98%) at the temperature of 325 °C. Long-term stability tests (240 h) confirmed the excellent durability of the tailor-made alumina catalysts. The process demonstrated here poses an efficient and economic “green” large-scale on-site synthesis of this industrially important reactant in industry, where bioethanol is produced and 1-ethyl chloride is necessary, e.g., for ethylation of cellulose and synthetic polymer products. On-site in situ production of ethyl chloride avoids the problems associated with the transportation and storage of toxic and flammable 1-ethyl chloride.

  • 37. Buss, Wolfram
    et al.
    Jansson, Stina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wurzer, Christian
    Masek, Ondrej
    Synergies between BECCS and Biochar-Maximizing Carbon Sequestration Potential by Recycling Wood Ash2019Inngår i: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 7, nr 4, s. 4204-4209Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bioenergy carbon capture and storage (BECCS) and biochar are key carbon-negative technologies. In this study, synergies between these technologies were explored by using ash from wood combustion, a byproduct from BECCS, as an additive (0, 5, 10, 20, and 50 wt %) in biochar production (wood pyrolysis at 450 degrees C). The addition of wood ash catalyzed biochar formation and increased the yield of fixed carbon (FC) (per dry, ash-free feedstock), i.e., the sequestrable carbon per spruce wood input. At the highest ash addition (50%), 45% less wood was needed to yield the same amount of FC. Since the land area available for growing biomass is becoming scarcer, our approach significantly increases biochar's potential to sequester carbon. However, increasing the feedstock ash content results in less feedstock carbon available for conversion into FC. Consequently, the yield of FC per pyrolysis run (based on dry feedstock) in the 50% ash-amended material was lower than in the control. An economic analysis showed that the 20% ash-amended biochar brings the biggest cost savings over the control with a 15% decrease in CO2-abatement costs. Biochar-ash composites increase the carbon sequestration potential of biochar significantly, reduce the CO2-abatement costs, and recycle nutrients which can result in increased plant growth in turn and more biomass for BECCS, bringing synergies for BECCS and biochar deployment.

  • 38. Capablo, Joaquin
    et al.
    Arendt Jensen, Peter
    Hougaard Pedersen, Kim
    Hjuler, Klaus
    Nikolaisen, Lars
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Frandsen, Flemming
    Ash properties of alternative biomass2009Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, s. 1965-1976Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ash behavior during suspension firing of 12 alternative solid biofuels, such as pectin waste, mash from a beer brewery, or waste from cigarette production have been studied and compared to wood and straw ash behavior. Laboratory suspension firing tests were performed on an entrained flow reactor and a swirl burner test rig, with special emphasis on the formation of fly ash and ash deposit. Thermodynamic equilibrium calculations were performed to support the interpretation of the experiments. To generalize the results of the combustion tests, the fuels are classified according to fuel ash analysis into three main groups depending upon their ash content of silica, alkali metal, and calcium and magnesium. To further detail the biomass classification, the relative molar ratio of Cl, S, and P to alkali were included. The study has led to knowledge on biomass fuel ash composition influence on ash transformation, ash deposit flux, and deposit chlorine content when biomass fuels are applied for suspension combustion.

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

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

  • 40.
    Conte, Ricardo Pezoa
    et al.
    Industrial Chemistry and Reaction Engineering Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Ravanal, M. Cristina
    Centre for Biochemical Engineering and Biotechnology, Department of Chemical Engineering and Biotechnology, University of Chile, Santiago, Chile.
    Mäki-Arvela, Päivi
    Industrial Chemistry and Reaction Engineering Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Willför, Stefan
    Wood and Paper Chemistry Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Lienqueo, M. Elena
    Centre for Biochemical Engineering and Biotechnology, Department of Chemical Engineering and Biotechnology, University of Chile, Santiago, Chile.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry and Reaction Engineering Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Bioethanol production from the green alga ulva rigida and the brown algae macrocystis pyrifera2015Inngår i: NWBC 2015: the 6th Nordic Wood Biorefinery Conference, VTT Technical Research Centre of Finland , 2015, s. 319-325Konferansepaper (Fagfellevurdert)
    Abstract [en]

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

  • 41.
    Cwik, Katarzyna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Backlund, Krister
    Fjäder, Kenneth
    Hiljanen, Emil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Eriksson, Matias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Swedish Mineral Processing Research Association MinFo, Stockholm, Sweden.
    Thermal decrepitation and thermally-induced cracking of limestone used in quicklime production2022Inngår i: Minerals, E-ISSN 2075-163X, Vol. 12, nr 10, artikkel-id 1197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To produce quicklime, high calcium carbonate rocks, including limestone, are burned in industrial kilns at 1100–1450 °C. As a consequence of the high temperatures, the carbonate rock can break and decrepitate into fine material, causing operational problems and material losses. In the present paper, an industrial case study on thermal decrepitation was performed on Boda Limestone from the Jutjärn quarry in Dalarna, Sweden. We analyzed 80 limestone samples for thermal decrepitation; furthermore, the correlation with chemical composition was statistically analyzed. The experiments were complemented by a detailed analysis of thermally-induced cracking at a range of temperatures (ambient, 500 °C, 800 °C, and 1150 °C) for two limestone samples with similar chemical compositions but with very different decrepitation behaviors. Decrepitation was analyzed by an in-house method, the chemical composition by XRF, and the thermally-induced cracking was investigated by SEM and image analysis. No strong correlation was found between thermal decrepitation and the chemical composition of the limestone. For the sample with low thermal decrepitation, a dense narrow network of fractures was found after full calcination; however, this network was not observed in the sample with high thermal decrepitation. A plausible explanation for the different decrepitation behaviors is that this fracture network releases internal stress and stabilizes the calcined rock. The obtained results can help in predicting limestone thermal decrepitation, enabling increased resource efficiency in quicklime production.

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  • 42.
    Cwik, Katarzyna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Ma, Charlie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Eriksson, Matias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Electrifying quicklime production to enable carbon capture: how to avoid product carbonation?2023Konferansepaper (Annet vitenskapelig)
  • 43.
    Damlin, Pia
    et al.
    Åbo Akademi University, Process Chemistry Centre, Laboratory of Industrial Chemistry and Reaction Engineering, FIN-20500 Turku/Åbo, Finland.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Salmi, Tapio
    Åbo Akademi University, Process Chemistry Centre, Laboratory of Industrial Chemistry and Reaction Engineering, FIN-20500 Turku/Åbo, Finland.
    Characterization of Hardwood-Derived Carboxymethylcellulose by High pH Anion Chromatography Using Pulsed Amperometric Detection2010Inngår i: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 44, nr 1-3, s. 65-69Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An approach for the quantitative analysis of substituent distribution in carboxymethylcellulose (CMC) is presented. In short, the high-pH anion-exchange chromatography method, coupled to pulsed amperometric detection (PAD), is introduced. Each of the seven derivatives in CMC is presented by a single peak on the PAD trace, thus enabling an easy quantification. New inside information on monomer composition is obtained by this novel method, which is essential for understanding the structure versus property relationships in the CMC samples.

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  • 44.
    Dannelind, Filip
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Hydrogen on demand for vessels: Using ammonia for hydrogen storage2022Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

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

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

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

    Fulltekst tilgjengelig fra 2025-05-25 13:00
  • 45.
    Decker, Daniel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    UDP-sugar metabolizing pyrophosphorylases in plants: formation of precursors for essential glycosylation-reactions2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    UDP-sugar metabolizing pyrophosphorylases provide the primary mechanism for de novo synthesis of UDP-sugars, which can then be used for myriads of glycosyltranferase reactions, producing cell wall carbohydrates, sucrose, glycoproteins and glycolipids, as well as many other glycosylated compounds. The pyrophosphorylases can be divided into three families: UDP-Glc pyrophosphorylase (UGPase), UDP-sugar pyrophosphorylase (USPase) and UDP-N-acety lglucosamine pyrophosphorylase (UAGPase), which can be discriminated both by differences in accepted substrate range and amino acid sequences.

    This thesis focuses both on experimental examination (and re-examination) of some enzymatic/ biochemical properties of selected members of the UGPases and USPases and UAGPase families and on the design and implementation of a strategy to study in vivo roles of these pyrophosphorylases using specific inhibitors. In the first part, substrate specificities of members of the Arabidopsis UGPase, USPase and UAGPase families were comprehensively surveyed and kinetically analyzed, with barley UGPase also further studied with regard to itspH dependency, regulation by oligomerization, etc. Whereas all the enzymes preferentially used UTP as nucleotide donor, they differed in their specificity for sugar-1-P. UGPases had high activity with D-Glc-1-P, but could also react with Frc-1-P, whereas USPase reacted with arange of sugar-1-phosphates, including D-Glc-1-P, D-Gal-1-P, D-GalA-1-P, β-L-Ara-1-P and α-D-Fuc-1-P. In contrast, UAGPase2 reacted only with D-GlcNAc-1-P, D-GalNAc-1-P and, to some extent, with D-Glc-1-P. A structure activity relationship was established to connect enzyme activity, the examined sugar-1-phosphates and the three pyrophosphorylases. The UGPase/USPase/UAGPase active sites were subsequently compared in an attempt to identify amino acids which may contribute to the experimentally determined differences in substrate specificities.

    The second part of the thesis deals with identification and characterization of inhibitors of the pyrophosphorylases and with studies on in vivo effects of those inhibitors in Arabidopsis-based systems. A novel luminescence-based high-throughput assay system was designed, which allowed for quantitative measurement of UGPase and USPase activities, down to a pmol per min level. The assay was then used to screen a chemical library (which contained 17,500 potential inhibitors) to identify several compounds affecting UGPase and USPase. Hit-optimization on one of the compounds revealed even stronger inhibitors of UGPase and USPase which also strongly inhibited Arabidopsis pollen germination, by disturbing UDP-sugar metabolism. The inhibitors may represent useful tools to study in vivo roles of the pyrophosphorylases, as a complement to previous genetics-based studies.

    The thesis also includes two review papers on mechanisms of synthesis of NDP-sugars. The first review covered the characterization of USPase from both prokaryotic and eukaryotic organisms, whereas the second review was a comprehensive survey of NDP-sugar producing enzymes (not only UDP-sugar producing and not only pyrophosphorylases). All these enzymes were discussed with respect to their substrate specificities and structural features (if known) and their proposed in vivo functions.

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  • 46.
    Dodda, Jagan Mohan
    et al.
    New Technologies – Research Centre (NTC), University of West Bohemia, Plzeň, Czech Republic.
    Azar, Mina Ghafouri
    New Technologies – Research Centre (NTC), University of West Bohemia, Plzeň, Czech Republic.
    Bělský, Petr
    New Technologies – Research Centre (NTC), University of West Bohemia, Plzeň, Czech Republic.
    Šlouf, Miroslav
    Institute of Macromolecular Chemistry CAS, Prague, Czech Republic.
    Gajdošová, Veronika
    Institute of Macromolecular Chemistry CAS, Prague, Czech Republic.
    Kasi, Phanindra Babu
    Department of Medical Chemistry and Biochemistry, Faculty of Medicine in Pilsen, Charles University, Plzeň, Czech Republic.
    Anerillas, Luis Oliveros
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Kovářík, Tomáš
    New Technologies – Research Centre (NTC), University of West Bohemia, Plzeň, Czech Republic.
    Bioresorbable films of polycaprolactone blended with poly(lactic acid) or poly(lactic-co-glycolic acid)2023Inngår i: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 248, artikkel-id 126654Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent complications on the use of polypropylene meshes for hernia repair has led to the development of meshes or films, which were based on resorbable polymers such as polycaprolactone (PCL), polylactic acid (PLA) and poly(lactic-co-glycolic acid) (PLGA). These materials are able to create suitable bioactive environment for the growth and development of cells. In this research, we mainly focused on the relations among structure, mechanical performance and biocompatiblity of PCL/PLA and PCL/PLGA and blends prepared by solution casting. The films were characterized regarding the chemical structure, morphology, physicochemical properties, cytotoxicity, biocompatibility and cell growth. All the films showed high tensile strength ranging from 9.5 to 11.8 MPa. SAXS showed that the lamellar stack structure typical for PCL was present even in the blend films while the morphological parameters of the stacks varied slightly with the content of PLGA or PLA in the blends. WAXS indicated preferential orientation of crystallites (and thus, also the lamellar stacks) in the blend films. In vitro studies revealed that PCL/PLGA films displayed better cell adhesion, spreading and proliferation than PCL/PLA and PCL films. Further the effect of blending on the degradation was investigated, to understand the significant variable within the process that could provide further control of cell adhesion. The results showed that the investigated blend films are promising materials for biomedical applications.

  • 47.
    Eklund, Patrik
    et al.
    Department of Computer Science, Åbo Akademi, Åbo, Finland.
    Forsström, Jari
    University of Turku, Department of Clinical Chemistry, Central Laboratory, Turku University Central Hospital, SF-20520 Turku, Finland.
    Diagnosis of nephropathia epidemica by adaptation through Lukasiewicz inference1990Inngår i: Computational Intelligence, III: Proceedings of the International Symposium "Computational Intelligence 90", Milan, Italy, 24-28 September, 1990. / [ed] Nick Cerone, Francesco Gardin, co-editor, George Valle, Amsterdam, The Netherlands: Elsevier, 1990, s. 237-246Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    This paper describes a method how to arrive at a medical expert system (as a knowledge based system) to support physicians in classifying patients in diagnosis of Nephropathia epidemica (NE). We thereby present a link between Lukasiewicz inference and learning in neural nets, as a formal connection between uncertainty in logical implication and synaptic weights. The system presented uses clinical findings and laboratory investigations to arrive at predictions whether or not patients suffer from NE. Although we are willing to call our system a medical expert system, it could equally well be called a decision support system, this being more in spirit to what such a system really offers a physician.

  • 48.
    Ekspong, Joakim
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Sharifi, Tiva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Klechikov, Alexey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Gracia-Espino, Eduardo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Stabilizing Active Edge Sites in Semicrystalline Molybdenum Sulfide by Anchorage on Nitrogen-Doped Carbon Nanotubes for Hydrogen Evolution Reaction2016Inngår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, nr 37, s. 6766-6776Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Finding an abundant and cost-effective electrocatalyst for the hydrogen evolu-tion reaction (HER) is crucial for a global production of hydrogen from water electrolysis. This work reports an exceptionally large surface area hybrid catalyst electrode comprising semicrystalline molybdenum sulfi de (MoS 2+ x) catalystattached on a substrate based on nitrogen-doped carbon nanotubes (N-CNTs), which are directly grown on carbon fiber paper (CP). It is shown here that nitrogen-doping of the carbon nanotubes improves the anchoring of MoS 2+ xcatalyst compared to undoped carbon nanotubes and concurrently stabilizes a semicrystalline structure of MoS 2+ x with a high exposure of active sites for HER. The well-connected constituents of the hybrid catalyst are shown to facilitate electron transport and as a result of the good attributes, the MoS 2+ x/N-CNT/CPelectrode exhibits an onset potential of −135 mV for HER in 0.5 M H2SO4, a Tafel slope of 36 mV dec −1, and high stability at a current density of −10 mA cm −2.

  • 49.
    Ekspong, Joakim
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Stainless Steel as A Bi-Functional Electrocatalyst – A Top-Down Approach2019Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, nr 13, artikkel-id 2128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For a hydrogen economy to be viable, clean and economical hydrogen production methods are vital. Electrolysis of water is a promising hydrogen production technique with zero emissions, but suffer from relatively high production costs. In order to make electrolysis of water sustainable, abundant, and efficient materials has to replace expensive and scarce noble metals as electrocatalysts in the reaction cells. Herein, we study activated stainless steel as a bi-functional electrocatalyst for the full water splitting reaction by taking advantage of nickel and iron suppressed within the bulk. The final electrocatalyst consists of a stainless steel mesh with a modified surface of layered NiFe nanosheets. By using a top down approach, the nanosheets stay well anchored to the surface and maintain an excellent electrical connection to the bulk structure. At ambient temperature, the activated stainless steel electrodes produce 10 mA/cm(2) at a cell voltage of 1.78 V and display an onset for water splitting at 1.68 V in 1M KOH, which is close to benchmarking nanosized catalysts. Furthermore, we use a scalable activation method using no externally added electrocatalyst, which could be a practical and cheap alternative to traditionally catalyst-coated electrodes.

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  • 50. Enestam, Sonja
    et al.
    Mäkelä, Kari
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Hupa, Miko
    Occurrence of Zinc and Lead in Aerosols and Deposits in the Fluidized-Bed Combustion of Recovered Waste Wood. Part 2: Thermodynamic Considerations2011Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, nr 4, s. 1970-1977Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present work, which is the second part in a series of two, multi-phase, multi-component equilibrium calculations were used to study the chemistry and deposition behavior of lead and zinc in the combustion of recovered waste wood (RWW). Particular attention was paid to the deposition behavior in different parts of the boiler under varying flue gas and material temperature conditions. In addition, the influence of fuel composition was considered by studying three different fuel compositions. The results from the calculations were compared to experimental results from two measurement campaigns, whose goal was to experimentally determine the distribution and speciation of zinc and lead compounds in aerosol particles and deposits in the fluidized-bed combustion of RWW. The results from the experimental work are presented in part 1 (10.1021/ef101478n) of this work.

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