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  • 51. Jonsson, Carrie Y. C.
    et al.
    Stjernberg, Jesper
    Wiinikka, Henrik
    Lindblom, Bo
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Energy Technology and Thermal Process Chemistry (ETPC).
    Ohman, Marcus
    Deposit Formation in a Grate-Kiln Plant for Iron-Ore Pellet Production. Part 1: Characterization of Process Gas Particles2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 10, p. 6159-6170Article in journal (Refereed)
    Abstract [en]

    Slag formation in the grate-kiln process is a major problem for iron-ore pellet producers. It is therefore important to understand the slag formation mechanism in the grate-kiln production plant. This study initiated the investigation by in situ sampling and identifying particles in the flue gas from a full-scale 40 MW grate-kiln production plant for iron-ore pelletizing. Particles were sampled from two cases of combustion with pulverized coal and heavy fuel oil. The sampling location was at the transfer chute that was situated between the traveling grate and the rotary kiln. The particle-sampling system was set up with a water-cooled particle probe equipped with nitrogen gas dilution, cyclone, and low-pressure impactor. Sub-micrometer and fine particles were size-segregated in the impactor, while coarse particles (>6 mu m) were separated with a cyclone before the impactor. Characterization of these particles was carried out with environmental scanning electron microscopy (ESEM), and the morphology of sub-micrometer particles was studied with transmission electron microscopy (TEM). The results showed that particles in the flue gas consisted principally of fragments from iron-ore pellets and secondarily of ashes from pulverized coal and heavy fuel oil combustions. Three categories of particle modes were identified: (1) sub-micrometer mode, (2) first fragmentation mode, and (3) second fragmentation mode. The sub-micrometer mode consisted of vaporized and condensed species; relatively high concentrations of Na and K were observed for both combustion cases, with higher concentrations of Cl and S from heavy fuel oil combustion but higher concentrations of Si and Fe and minor P, Ca, and Al from coal combustion. The first fragmentation mode consisted of both iron-ore pellet fines and fly ash particles; a significant increment of Fe (>65 wt %) was observed, with higher concentrations of Ca and Si during heavy fuel oil combustion but higher concentrations of Si and Al during coal combustion. The second fragmentation mode consisted almost entirely of coarse iron-ore pellet fines, predominantly of Fe (similar to 90 wt %). The particles in the flue gas were dominantly iron-ore fines because the second fragmentation mode contributed >96 wt % of the total mass of collected particles.

  • 52.
    Kaplun, Marina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sandström, Malin
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Persson, Per
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Crystal structures and spectroscopic properties of palladium complexes isolated from Pd–EDTA solutions2005In: Inorganica Chimica Acta, ISSN 0020-1693, E-ISSN 1873-3255, Vol. 358, no 3, p. 527-534Article in journal (Refereed)
    Abstract [en]

    Two complexes were isolated from aqueous Pd(NO3)2–Na2H2EDTA solutions and studied by single crystal X-ray diffraction, IR/Raman spectroscopy, and photoelectron spectroscopy. The first complex, Pd(Hkpda)2 (kpda = ketopiperazinediacetate dianion, C8H10N2O5), forms yellow parallelepipeds during slow evaporation of Pd(NO3)2–Na2H2EDTA solution at 25 °C, and is a result of EDTA oxidation. The second one, [Pd(μ-H2EDTA)]2 · 2NaNO3 · 7.5H2O, with two EDTA molecules acting as bridges between two palladium atoms, forms yellow bipyramides during fast evaporation at 60 °C. In both complexes, the palladium atoms adopt a planar trans-geometry by bonding to two nitrogen and two oxygen atoms of two ligand molecules.

  • 53. Kirilin, A
    et al.
    Mäki-Arvela, P
    Kordas, K
    Leino, A-R
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Process Chemistry Centre, Laboratory of Industrial Chemistry and Reaction Engineering, Åbo Akademi University, Turku/Åbo, Finland .
    Kustov, L M
    Salmi, T O
    Murzin, D Yu
    Chemo-Bio Catalyzed Synthesis of R-1-Phenylethyl Acetate over Bimetallic PdZn Catalysts, Lipase, and Ru/Al2O3: part II2011In: Kinetics and catalysis, ISSN 0023-1584, E-ISSN 1608-3210, Vol. 52, no 1, p. 77-81Article in journal (Refereed)
    Abstract [en]

    One-pot synthesis of R-1-phenyethylacetate at 70 degrees C was investigated using three different catalysts simultaneously, namely a bimetallic PdZn/Al2O3 as a hydrogenation catalyst, an immobilized lipase as an acylation catalyst and Ru/Al2O3 as a racemization catalyst. The most active bimetallic catalyst was PdZn/Al2O3 calcined at 300 degrees C and reduced at 400 degrees C, whereas the most selective although less active catalyst was the one being calcined and reduced at 500 degrees C. The highest selectivity to R-1-phenylethyl acetate over this catalyst was 32 at 48% conversion. Ru/Al2O3 was confirmed to have a positive effect on the formation of the desired product, although it was not very active in the racemization during one-pot synthesis.

  • 54. Kirilin, A
    et al.
    Mäki-Arvela, P
    Kordas, K
    Leino, A-R
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kustov, L M
    Salmi, T O
    Murzin, D Yu
    Chemo-bio catalyzed synthesis of R-1-phenylethyl acetateover bimetallic PdZn catalysts, lipase and Ru/Al2o3. Part I2011In: Kinetics and catalysis, ISSN 0023-1584, E-ISSN 1608-3210, Vol. 52, no 1, p. 72-76Article in journal (Refereed)
    Abstract [en]

    The effect of calcination and reduction temperature on the physical properties of PdZn/Al2O3 catalysts, prepared by coprecipitation deposition technique and characterized by XPS, XRD and TEM methods are reported. The temperatures were varied in a range of 300–500°C. The catalyst calcined at 300°C and reducedat 400°C exhibited the metal particle size of 2–6 nm and contained the highest surface concentrations of Pd and Zn according to XPS measurements. The size and the fraction of large particles (above 10 nm) increased with increasing the calcinations and reduction temperatures.

  • 55. Kirilin, A
    et al.
    Mäki-Arvela, P
    Kordas, K
    Leino, A-R
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kustov, L M
    Salmi, T O
    Murzin, D Yu
    Chemo-bio catalyzed synthesis of R-1-phenylethyl acetateover bimetallic PdZn catalysts, lipase and Ru/Al2o3: part II2011In: Kinetika i kataliz, ISSN 0453-8811, Vol. 52, no 1, p. 78-82Article in journal (Refereed)
    Abstract [en]

    Onepot synthesis of R1phenyethylacetate at 70°C was investigated using three different catalysts simultaneously, namely a bimetallic PdZn/Al2O3 as a hydrogenation catalyst, an immobilized lipase as an acylation catalyst and Ru/Al2O3 as a racemization catalyst. The most active bimetallic catalyst was PdZn/Al2O3 calcined at 300°C and reduced at 400°C, whereas the most selective although less active catalyst was the one being calcined and reduced at 500°C. The highest selectivity to R1phenylethyl acetate over this catalyst was 32% at 48% conversion. Ru/Al2O3 was confirmed to have a positive effect on the formation of the desired product, although it was not very active in the racemization during onepot synthesis.

  • 56.
    Konwar, Lakhya Jyoti
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Samikannu, Ajaikumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mäki-Arvela, Päivi
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Turku, FI-20500, Finland.
    Lignosulfonate-based macro/mesoporous solid protonic acids for acetalization of glycerol to bio-additives2018In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 220, p. 314-323Article in journal (Refereed)
    Abstract [en]

    The enclosed paper introduces a novel, scalable and environmentally benign process for making strongly acidic solid meso/macroporous carbon catalysts from Na-lignosulfonate (LS), a byproduct from sulfite pulping. Ice-templated LS was converted to strongly acidic macro/mesoporous solid protonic acids via mild pyrolysis (350–450 °C) and ion/H+ exchanging technique. The synthesized materials were extensively characterized by FT-IR, Raman, XRD, XPS, TGA, FE-SEM, TEM and N2-physisorption methods. These LS derived materials exhibited a macro/mesoporous and highly functionalized heteroatom doped (O, S) carbon structure with large amounts of surface OH, COOH and SO3H groups similar to the sulfonated carbon materials. Further, these carbon materials showed excellent potential as solid acid catalysts upon acetalization of glycerol with various bio-based aldehydes and ketones (acetone, methyl levulinate and furfural), easily outperforming the commercial acid exchange resins (Amberlite® IR120 and Amberlyst® 70). Most importantly, the optimum LS catalyst exhibiting a large specific surface area demonstrated exceptional potential for continuous solketal production (liquid phase atmospheric pressure operation) maintaining its activity (glycerol conversion ≥ 91%) and structural features even after 90 h time on stream.

  • 57. Kuba, Matthias
    et al.
    He, Hanbing
    Kirnbauer, Friedrich
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ohman, Marcus
    Hofbauer, Hermann
    Deposit build-up and ash behavior in dual fluid bed steam gasification of logging residues in an industrial power plant2015In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 139, p. 33-41Article in journal (Refereed)
    Abstract [en]

    A promising way to substitute fossil fuels for production of electricity, heat, fuels for transportation and synthetic chemicals is biomass steam gasification in a dual fluidized bed (DFB). Using lower-cost feedstock, such as logging residues, instead of stemwood, improves the economic operation. In Senden, near Ulm in Germany, the first plant using logging residues is successfully operated by Stadtwerke Ulm. The major difficulties are slagging and deposit build-up. This paper characterizes inorganic components of ash forming matter and draws conclusions regarding mechanisms of deposit build-up. Olivine is used as bed material. Impurities, e.g., quartz, brought into the fluidized bed with the feedstock play a critical role. Interaction with biomass ash leads to formation of potassium silicates, decreasing the melting temperature. Recirculation of coarse ash back into combustion leads to enrichment of critical fragments. Improving the management of inorganic streams and controlling temperature levels is essential for operation with logging residues. (C) 2015 Elsevier B.V. All rights reserved.

  • 58.
    Kuba, Matthias
    et al.
    Technische Universität Wien, Institute of Chemical Engineering.
    He, Hanbing
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Kirnbauer, Friedrich
    Technische Universität Wien, Institute of Chemical Engineering.
    Skoglund, Nils
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Hofbauer, Hermann
    Technische Universität Wien, Institute of Chemical Engineering.
    Mechanism of Layer Formation on Olivine Bed Particles in Industrial-Scale Dual Fluid Bed Gasification of Wood2016In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 30, no 9, p. 7410-7418Article in journal (Refereed)
    Abstract [en]

    Utilization of biomass as feedstock in dual fluidized bed steam gasification is a promising technology for the substitution of fossil energy carriers. Experience from industrial-scale power plants showed an alteration of the olivine bed material due to interaction with biomass ash components. This change results mainly in the formation of Ca-rich layers on the bed particles. In this paper, a mechanism for layer formation is proposed and compared to the better understood mechanism for layer formation on quartz bed particles. Olivine bed material was sampled at an industrial-scale power plant before the start of operation and at predefined times after the operation had commenced. Therefore, time-dependent layer formation under industrial-scale conditions could be investigated. The proposed mechanism suggests that the interaction between wood biomass ash and olivine bed particles is based on a solid–solid substitution reaction, where Ca2+ is incorporated into the crystal structure. As a consequence, Fe2+/3+ and Mg2+ ions are expelled as oxides. This substitution results in the formation of cracks in the particle layer due to a volume expansion in the crystal structure once Ca2+ is incorporated. The results of this work are compared to relevant published results, including those related to quartz bed particles.

  • 59.
    Kuba, Matthias
    et al.
    Technische Universität Wien, Institute of Chemical Engineering.
    He, Hanbing
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Kirnbauer, Friedrich
    Technische Universität Wien, Institute of Chemical Engineering.
    Skoglund, Nils
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Hofbauer, Hermann
    Technische Universität Wien, Institute of Chemical Engineering.
    Thermal stability of bed particle layers on naturally occurring minerals from dual fluid bed gasification of woody biomass2016In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 30, no 10, p. 8277-8285Article in journal (Refereed)
    Abstract [en]

    The use of biomass as feedstock for gasification is a promising way of producing not only electricity and heat but also fuels for transportation and synthetic chemicals. Dual fluid bed steam gasification has proven to be suitable for this purpose. Olivine is currently the most commonly used bed material in this process due to its good agglomeration performance and its catalytic effectiveness in the reduction of biomass tars. However, as olivine contains heavy metals such as nickel and chromium, no further usage of the nutrient-rich ash is possible, and additional operational costs arise due to necessary disposal of the ash fractions. This paper investigates possible alternative bed materials and their suitability for dual fluid bed gasification systems focusing on the behavior of the naturally occurring minerals olivine, quartz, and K-feldspar in terms of agglomeration and fracturing at typical temperatures. To this end, samples of bed materials with layer formation on their particles were collected at the industrial biomass combined heat and power (CHP) plant in Senden, Germany, which uses olivine as the bed material and woody biomass as feedstock. The low cost logging residue feedstock contains mineral impurities such as quartz and K-feldspar, which become mixed into the fluidized bed during operation. Using experimental and thermochemical analysis, it was found that the layers on olivine and K-feldspar showed a significantly lower agglomeration tendency than quartz. Significant fracturing of particles or their layers could be detected for olivine and quartz, whereas K-feldspar layers were characterized by a higher stability. High catalytic activity is predicted for all three minerals once Ca-rich particle layers are fully developed. However, quartz may be less active during the buildup of the layers due to lower amounts of Ca in the initial layer formation.

  • 60.
    Lind, Per
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Carlsson, Marcus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Eriksson, Anders
    Glimsdal, Eirik
    Lindgren, Mikael
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Structural, photophysical, and nonlinear absorption properties of trans-di-arylalkynyl Platinum(II) Complexes with Phenyl and Thiophenyl Groups2007In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 111, no 9, p. 1598-1609Article in journal (Refereed)
    Abstract [en]

    Optical power limiting and luminescence properties of two Pt(II) complexes with thiophenyl and phenyl groups in the ligands, trans-Pt(P(n-Bu)3)2(C[triple bond]C-Ar)2, where Ar = -C4H2S-C[triple bond]C-p-C6H4-n-C5H11 (1) and -p-C6H4-C[triple bond]C-C4H3S (2), have been investigated. The fluorescence lifetimes were found to be on the sub-nanosecond time scale, and the quantum yields were low, in accord with fast intersystem crossing from the excited singlet to triplet manifold. The phosphorescence lifetimes of 1 and 2 were shorter than that of a Pt(II) complex having two phenyl groups in the ligands. In order to elucidate the C-Pt bonding nature in the ground state, the 13C NMR chemical shift of the carbon directly bonded to Pt, the coupling constants 1JPtC, 2JPtC, and 1JPtP, and IR νC[triple bond]C wavenumbers were obtained for 1, 2, and three other trans-diarylalkynyl Pt(II) complexes. X-ray diffraction data of 1 and 2 and density functional theory calculated geometries of models of 1, 2, and trans-Pt(P(n-Bu)3)2(C[triple bond]C-p-C6H4-C[triple bond]C-C6H5)2 (3) show that 1 preferably exists in a different conformation from that of 2 and 3. The variations in photophysical, NMR, and IR data can be rationalized by differences in geometry and pi-backbonding from Pt to the alkynyl ligand.

  • 61.
    Lindberg, Gustav
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Larsson, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Råberg, Mathias
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Determination of thermodynamic properties of Na2S using solid-state EMF measurements2007In: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 39, no 1, p. 44-48Article in journal (Refereed)
    Abstract [en]

    To obtain reliable thermodynamic data for Na2S(s), solid-state EMF measurements of the cell Pd(s)|O2(g)|Na2S(s), Na2SO4(s)|YSZ| Fe(s), FeO(s)|O2(g)ref| Pd(s) were carried out in the temperature range 870 < T/K < 1000 with yttria stabilized zirconia as the solid electrolyte. The measured EMF values were fitted according to the equation Efit/V (±0.00047) = 0.63650 − 0.00584732(T/K) + 0.00073190(T/K) ln (T/K). From the experimental results and the available literature data on Na2SO4(s), the equilibrium constant of formation for Na2S(s) was determined to be lg Kf(Na2S(s)) (±0.05) = 216.28 − 4750(T/K)−1 − 28.28878 ln (T/K). Gibbs energy of formation for Na2S(s) was obtained as ΔfG(Na2S(s))/(kJ · mol−1) (±1.0) = 90.9 − 4.1407(T/K) + 0.5415849(T/K) ln (T/K). By applying third law analysis of the experimental data, the standard enthalpy of formation of Na2S(s) was evaluated to be ΔfH(Na2S(s), 298.15 K)/(kJ · mol−1) (±1.0) = −369.0. Using the literature data for Cp and the calculated ΔfH, the standard entropy was evaluated to S(Na2S(s), 298.15 K)/(J · mol−1 · K−1) (±2.0) = 97.0.

  • 62.
    Lindström, Erica
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Larsson, Sylvia H
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Slagging tendencies during combustion of woody biomass pellets made from  a range of different forestry assortments2010In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 24, no 6, p. 3456-3461Article in journal (Refereed)
    Abstract [en]

    In this study, multivariate methods were used to select representative raw materials of the pellet assortments prior to combustion. The fuels were selected to form a range of expected slagging tendencies. During combustion, temperatures and O2, CO, NO, and SO2 were measured continuously. The deposits (i.e., slag and bottom ash) were quantified after every experiment and collected for analysis to identify the crystalline phases and to study the morphology and elemental composition respectively. As expected, the slagging was most severe for the whole-tree assortments because of their content of branches, foliage, and twigs. In the most severe case over three-quarters of the total amount of ash melted to form slag. This study indicates that certain concentrations of silicon, inherent in the fuel but also as silicates from contamination, together with alkali metals, mainly potassium, are prerequisites for the initiation of and progress of slag formation. Generally the concentrations of silicon and potassium are low in stemwood but higher in bark, foliage, and living tissues of the tree. Also, the contamination from sand and/or soil is present in the bark and foliage.

  • 63.
    Lindström, Erica
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Sandström, Malin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Luleå tekniska universitet.
    Slagging characteristics during combustion of cereal grains rich in phosphorous2007In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 21, no 2, p. 710-717Article in journal (Refereed)
    Abstract [en]

    A residential cereal burner (20 kW) was used to study the slagging characteristics of cereal grains with and without lime addition. The deposited bottom ash and slag were analyzed using X-ray diffraction (XRD), to identify the crystalline phases, and environmental scanning electron microscopy, coupled with energy-dispersive X-ray spectroscopy (ESEM/EDS), to study the morphology and elemental composition. Phase-diagram information was utilized to extract qualitative information about the behavior of cereal grain ashes under combustion conditions. Chemical equilibrium model calculations were used to interpret the experimental results. In addition, investigations of the melting behavior of the produced slags were conducted. The results showed significant differences in slagging characteristics between the fuels that were used. The slags consisted of high-temperature melting crystalline phases (calcium/magnesium potassium phosphates) and a potassium-rich phosphate melt for all cereal grains. For oat and barley, cristobalite was also identified in the slag. Furthermore, in these cases, the slags most probably contained a potassium-rich silica melt. The differences in the melting behaviors of the slags had a considerable effect on the performance of the burner. The addition of lime reduced the formation of slag for barley and totally eliminated it for rye and wheat. This occurs because lime contributes to the formation of high-temperature melting calcium potassium phosphates.

  • 64.
    Lou, B
    et al.
    Luleå tekniska universitet.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Velaga, Sitaram P
    Luleå tekniska universitet.
    Hydrogen-bonding interactions in the 4-aminobenzoic acid salt of atenolol monohydrate2007In: Acta Crystallographica Section C: Crystal Structure Communications, ISSN 0108-2701, E-ISSN 1600-5759, Vol. 63, no 12, p. 714-716Article in journal (Refereed)
    Abstract [en]

    Atenolol {or 4-[2-hydroxy-3-(isopropylamino)propoxy]phenylacetamide} crystallizes with 4-aminobenzoic acid to give the salt {3-[4-(aminocarbonylmethyl)phenoxy]-2-hydroxypropyl}isopropylammonium 4-aminobenzoate monohydrate, C14H23N2O3+·C7H6NO2-·H2O. In the crystal structure, the water molecule, the carboxylate group of 4-aminobenzoate, and the hydroxy and ether O atoms of atenolol form a supramolecular R33(11) heterosynthon. Three other types of supramolecular synthons link the asymmetric unit into a two-dimensional structure.

  • 65. Lou, Benyong
    et al.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Velaga, Sitaram P
    1-Ethyl-6-fluoro-7-(4-formylpiperazin-1-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid2007In: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 63, no 11, p. o4281-Article in journal (Refereed)
    Abstract [en]

    The formylation reaction of norfloxacin with N,N-dimethylformamide (DMF) gives the title compound, C17H18FN3O4. In the structure, molecules are connected via weak C-HO, C-H and - interactions [perpendicular distance 3.423 Å and centroid-centroid distance 3.8141 Å].

  • 66. Lou, Benyong
    et al.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Velaga, Sitaram P.
    Polymorph control of felodipine form II in an attempted cocrystallization2009In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 9, no 3, p. 1254-1257Article in journal (Refereed)
    Abstract [en]

    The metastable form II of racentic felodipine was obtained in an attempted cocrystallization with isonicotinamide. Its low temperature crystal structure was characterized by a ID hydrogen-bonded chain consisting of four independent felodipine molecules.

  • 67.
    Lundholm, Karin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Shchukarev, Andrei
    Fate of Cu, Cr and As during combustion of impregnated wood with and without peat additive2007In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 41, no 18, p. 6534-6540Article in journal (Refereed)
    Abstract [en]

    The EU Directive on incineration of waste regulates the harmful emissions of particles and twelve toxic elements, including copper, chromium, and arsenic. More information is critically needed on the speciation and behavior of these trace elements during combustion, including the effects of different process variables, as well as of different fuels and fuel mixtures. Using a 15 kW pellets-fueled grate burner, experiments were performed to determine the fate of copper, chromium, and arsenic during combustion of chromate copper arsenate (CCA) preservative wood. The effects of co-combustion of CCA-wood with peat were also studied since peat fuels previously have proved to generally reduce ash related problems. The fate and speciation of copper, chromium, and arsenic were determined from analysis of the flue gas particles and the bottom ash using SEM-EDS, XRD, XPS, and ICP-AES. In addition, chemical equilibrium model calculations were performed to interpret the experimental findings. The results revealed that about 5% copper, 15% chromium, and 60% arsenic were volatilized during combustion of pure CCA-wood, which is lower than predicted volatilization from the individual arsenic, chromium, and copper oxides. This is explained by the formation of more stable refractory complex oxide phases for which the stability trends and patterns are presented. When co-combusted with peat, an additional stabilization of these phases was obtained and thus a small but noteworthy decrease in volatilization of all three elements was observed. The major identified phases for all fuels were CuCrO2(s), (Fe,Mg,Cu)(Cr,Fe,Al)O4(s), Cr2O3(s), and Ca3(AsO4)2(s). Arsenic was also identified in the fine particles as KH2AsO4(s) and As2O3(s). A strong indication of hexavalent chromium in the form of K2CrO4 or as a solid solution between K3Na(CrO4)2 and K3Na(SO4)2 was found in the fine particles. Good qualitative agreement was observed between experimental data and chemical equilibrium model calculations.

  • 68. Ma, Charlie
    et al.
    Weiland, Fredrik
    Hedman, Henry
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ohman, Marcus
    Characterization of Reactor Ash Deposits from Pilot-Scale Pressurized Entrained-Flow Gasification of Woody Biomass2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 11, p. 6801-6814Article in journal (Refereed)
    Abstract [en]

    Pressurized entrained-flow gasification of renewable forest residues has the potential to produce high-quality syngas suitable for the synthesis of transport fuels and chemicals. The ash transformation behavior during gasification is critical to the overall production process and necessitates a level of understanding to implement appropriate control measures. Toward this end, ash deposits were collected from inside the reactor of a pilot-scale O-2-blown pressurized entrained-flow gasifier firing stem wood, bark, and pulp mill debarking residue (PMDR) in separate campaigns. These deposits were characterized with environmental scanning electron microscopy equipped with energy-dispersive X-ray spectrometry and X-ray diffractometry. The stem wood deposit contained high levels of calcium and was comparatively insubstantial. The bark and PMDR fuels contained contaminant sand and feldspar particles that were subsequently evident in each respective deposit. The bark deposit consisted of lightly sintered ash aggregates comprising presumably a silicate melt that enveloped particles of quartz and, to a lesser degree, feldspars. Discontinuous layers likely to be composed of alkaline-earth metal silicates were found upon the aggregate peripheries. The PMDR deposit consisted of a continuous slag that contained quartz and feldspar particles dispersed within a silicate melt. Significant levels of alkaline-earth and alkali metals constituted the silicate melts of both the bark and PMDR deposits. Overall, the results suggest that fuel contaminants (i.e., quartz and feldspars) play a significant role in the slag formation process during pressurized entrained-flow gasification of these woody biomasses.

  • 69. Nazelius, Ida-Linn
    et al.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Hedman, Henry
    Samuelsson, Robert
    Ohman, Marcus
    Influence of Peat Addition to Woody Biomass Pellets on Slagging Characteristics during Combustion2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 7, p. 3997-4006Article in journal (Refereed)
    Abstract [en]

    Upgraded biofuels such as pellets, briquettes, and powder are today commonly used in small as well as large scale appliances. In order to cover an increasing fuel demand new materials such as bark, whole tree assortments, and peat are introduced. These materials have higher ash content which is why they are potentially more problematic compared with stem wood. In general, few studies can be found regarding cocombustion of peat and biomass and in particular where the slagging tendencies are discussed. The overall objective of this study was therefore to determine the influence of peat addition to woody biomass pellets on slagging characteristics. Two different peat assortments (peat A and B) were copelletized separately in four different dry matter levels (0-5-15-30 wt %) into stem wood and energy wood, respectively. Peat A was a traditional Scandinavian fuel peat, with a high ash and Si content (carex), and peat B had a low ash content and relatively high Ca/Si ratio (sphagnum) chosen for its special characteristics. The produced pellets were combusted in a commercial underfed pellet burner (15 kW) installed in a reference boiler. The collected deposits (bottom ash and slag) from the combustion experiments were chemically characterized by scanning electron microscopy (SEM) combined with energy-dispersive X-ray analysis (EDS) and X-ray diffraction (XRD) regarding the elemental distribution and morphology and phase composition, respectively. In addition, the bottom ashes were characterized according to inductively coupled plasma atomic emission spectroscopy (ICP-AES). To interpret the experimental findings chemical equilibrium model calculations were performed. The slagging tendency increased when adding peat into the woody biomasses. Especially sawdust with its relatively low ash and Ca content was generally more sensitive for the different peat assortments. Cofiring with the relatively Si and ash rich peat A resulted in the most severe slagging tendency. A significant increment of the Si, Al, and Fe content and a significant decrement of the Ca content in the slag could be seen when increasing the content of peat A in both woody biomasses. The slagging tendency increased when adding peat A because high temperature melting Ca-Mg oxides react to form more low temperature melting Ca/Mg-Al-K silicates. The slagging tendency was significantly lower when adding the more ash poor peat B, with relatively high Ca/Si ratio, into the woody biomass fuels compared with the peat A mixtures. The slag from the peat B mixings had a slightly higher Ca content compared with the Si content and a clearly higher content of Ca compared with the peat A mixtures. There were still Ca-Mg oxides left in the bottom ash i.e. a less amount of sticky low temperature melting K-silicate rich melt was formed when peat B was added to the woody biomasses.

  • 70. Nazelius, Ida-Linn
    et al.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Rebbling, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Fuel indices for estimation of slagging of phosphorus-poor biomass in fixed bed combustion2017In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 1, p. 904-915Article in journal (Refereed)
    Abstract [en]

    The market for solid biofuels will grow rapidly during the coming years, and there will be a great demand for raw materials. This will force the existing fuel base to also cover wooden materials of lower qualities as well as agricultural raw materials and residues, which often show unfavorable ash-melting temperatures. This may lead to combustion-related problems. Thus, for the utilization of lower quality fuels, it is important to be able to predict potential fuel ash-related problems such as slagging. In light of this, the first objective of the present paper was to evaluate the applicability of previously defined indices for slagging of biomass fuels (phosphorus-poor) in fixed bed combustion. The evaluation showed that none of the previously suggested indices in the literature are suitable for qualitative (nor quantitative) prediction of slagging during fixed bed combustion of P-poor biomass fuels. Hence, a second objective was to develop improved novel fuel indices that can be applied to estimate the slagging of phosphorus-poor biomass in fixed bed combustion. The novel fuel indices give a qualitative prediction of the slagging tendency in biomass fixed bed combustion but still needs additional work to further extend the compositional range as well as to fine tune the indices' boundaries.

  • 71. Neuschutz, Clara
    et al.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Greger, Maria
    Root growth into sealing layers of fly ash2010In: Journal of Plant Interactions, ISSN 1742-9145, Vol. 5, no 2, p. 75-85Article in journal (Refereed)
    Abstract [en]

    Fly ash can be used as sealing material on mine waste disposal sites. Our aim was to determine the penetration resistance necessary to prevent root penetration of ash sealing layers, and investigate whether plants can affect the layer strength. We analyzed the root penetration, pH, EC and penetration resistance of layers on which Phalaris arundinacea, Salix myrsinifolia, Epilobium angustifolium, and Pinus sylvestris had been growing for 4-8 months in a greenhouse. Fly ashes obtained from the incineration of biofuel or municipal solid waste were used. A penetration resistance of similar to 1.5 MPa generally prevented root penetration, but roots of P. arundinacea could grow into the surface of layers with similar to 5 MPa penetration resistance. We examined the loosening ability of agents found in root exudates and the mineralogy of rhizosphere ash. The roots increased the weathering of the ash, including dissolution of secondary calcium minerals, possibly related to saccharide exudation.

  • 72. Nordgren, Daniel
    et al.
    Hedman, Henry
    Padban, Nader
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Ash transformations in pulverised fuel co-combustion of straw and woody biomass2013In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 105, p. 52-58Article in journal (Refereed)
    Abstract [en]

    Ash transformation processes have been studied during co-firing of wheat straw and pine stem wood and softwood bark. Pilot-scale trials in a 150 kW pulverised-fuel-fired burner were performed. Thermodynamic equilibrium calculations were made to support the interpretation of the results. The results show that reactions involving condensed phases are kinetically limited compared to reactions between gaseous ash compounds. Accordingly, the conditions promote gas phase reactions resulting in the formation of chlorides, sulphates and carbonates whereas reactions involving condensed reactants are suppressed. Both the slagging and fouling propensities of all co-firing mixes were reduced compared to that for pure straw. For the wood/straw mixes this was mainly due to a dilution of the ash forming elements of straw whereas for straw/bark, an additional effect from interaction between the fuel ash components was observed to reduce slagging. In general it can be concluded that under powder combustion conditions equilibrium is approached selectively and that the ash matter is strongly fractionated. The general results in this paper are useful for straw-fired power stations looking for alternative co-firing fuels.

  • 73.
    Näzelius, Ida-Linn
    et al.
    Luleå, Sweden.
    Fagerström, Jonathan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Luleå, Sweden.
    Slagging in fixed-bed combustion of phosphorus-poor biomass: critical ash-forming processes and compositions2015In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 29, no 2, p. 894-908Article in journal (Refereed)
    Abstract [en]

    Slagging in combustion facilities is not welcomed, because it may cause technical and operational problems, as well as extra costs. Increased understanding of the critical slagging subprocesses makes it easier to suggest semiempirical models and fuel indexes for predicting the slagging tendencies of different fuels. That could open the biomass market for potentially more troublesome raw materials. The objective of this work was to determine critical ash-forming processes and compositions in the fixed-bed combustion of phosphorus-poor biomass fuels. This was achieved by performing a systematic review of data and experience gathered from combustion experiments in a small grate burner of 36 different biomasses, as well as chemical analysis of their bottom ashes and slags. The paper presents a discussion of the slagging tendency in phosphorus-poor biomass by combining three different slagging classifications, culminating in a proposed starting point for a new slagging index. The slag (ash particles >3.15 mm in size) formed during the combustion experiments has been described according to the fraction of fuel ash that forms slag (expressed in terms of weight percent), the visual sintering category (1-4), and the viscosity predictions. The results explain that both the fraction of melt and its viscosity are critical for the slag formation process in phosphorus-poor biomasses. In addition, fuels with low Si/K ratio along with a higher Ca concentration may form a low viscous carbonate melt that is not prone to form slag. Increased Si and lowered Ca concentration will increase the amount of formed silicate melt formed, as well as its viscosity, thus resulting in a more sticky melt.

  • 74. Olwa, Joseph
    et al.
    Öhman, Marcus
    Esbjörn, Pettersson
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Okure, Mackay
    Kjellström, Björn
    Potassium Retention in Updraft Gasification of Wood2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 11, p. 6718-6724Article in journal (Refereed)
    Abstract [en]

    The release of compounds of K with producer gas during biomass gasification is known to play significant roles in fouling and high-temperature corrosion in boilers and high-temperature heat exchangers as well as blades in gas turbines that use producer gas as fuel. These phenomena are a major setback in the application of biomass fuel in combination with advanced process conditions. Updraft gasification provides gas filtering by the fuel bed with a gas cooling effect, conditions anticipated to create an avenue for K retention in the gasifier. The objective of this study was to determine the K retention potential of such gasifiers during wood gasification. Samples for the determination of the fate of K compounds included in the feedstock were collected from the generated producer gas using Teflon filters and gas wash bottles and also from wall deposits and ash residues. Analyses of samples were carried out using inductively coupled plasma atomic emission spectrometry/mass spectrometry and Xray diffraction methods. The finding was that about 99% of K was retained in the gasifier. K was found in the ash samples as a crystalline phase of K2Ca(CO3)(2)(s) (fairchildite). A possible reaction mechanism leading to the formation of K2Ca(CO3)(2) is discussed in the paper. The 1% K understood as released, equivalent to 1200 ppbw content of K entrained in the producer gas stream, exceeds a known limit for application of the gas in conventional gas turbines. This would suggest application of the gas in an externally fired gas turbine system, where some limited K and other depositions in the heat exchanger can be relatively easy to handle.

  • 75.
    Pemberton, Nils
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Emtenäs, Hans
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Domaille, Peter J
    Greenberg, William A
    Levin, Michael D
    Zhu, Zuolin
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Cycloaddition of 2-thiazolines and acyl ketenes under acidic conditions results in bicyclic 1,3-oxazinones and not 6-acylpenams as earlier reported2005In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 7, no 6, p. 1019-1021Article in journal (Refereed)
    Abstract [en]

    Optically active 2-thiazolines 4 were previously reported to react with acyl Meldrum's acid derivatives 5 under acidic conditions (HCl (g) in benzene) to stereoselectively give 6-acylpenams 1. Recently we have discovered that the structure elucidation of these compounds was incorrect. Thus, we report new data showing that instead of acyl -lactams, the optically active isomers 3R,9R-1,3-oxazinones 3a-g are obtained stereoselectively in 38-93% yields.

  • 76.
    Pettersson, Esbjörn
    et al.
    Luleå tekniska universitet och ETC Piteå.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Westerholm, Roger
    Stockholms universitet, Analytisk kemi.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Stove performance and emission characteristics in residential wood log and pellet combustion: Part 2: Wood stove2011In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, no 1, p. 315-323Article in journal (Refereed)
    Abstract [en]

    The characteristics and quantities of a large number of gaseous and particulate emission components during combustion in a residential wood log stove with variations in fuel, appliance and operational conditions were determined experimentally. The measurement campaign included CO, NOx, organic gaseous carbon (OGC), volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), total particulate matter (PMtot) as well as particle mass and number concentrations, size distributions, and inorganic composition. CO varied in the range of 1100 to 7200 mg/MJfuel, while OGC varied from 210 to 3300 mg/MJfuel. Dominating VOCs were methane, followed by ethene, acetylene, and benzene. Methane varied from 9 to 1600 mg/MJfuel. The nonmethane volatile organic compound (NMVOC) emissions were in the range of 20−2300 mg/MJfuel. The PAHtot emissions varied from 1.3 to 220 mg/MJfuel, in most cases dominated by phenantrene, fluoranthene, and pyrene. PMtot were in all cases dominated by fine particles and varied in the range 38−350 mg/MJfuel. The mass median particle diameters and the peak mobility diameters of the fine particles varied in the range 200−320 and 220−330 nm, respectively, and number concentrations in the range of 1−4 × 1013 particles/MJfuel. Air starved conditions, at high firing intensity, gave the highest emissions, especially for hydrocarbons. This type of condition is seldom considered, though it may occur occasionally. The emissions from Swedish wood stoves, comparing a Swedish field study, are covered fairly well with the applied methodology, but other field studies report considerably higher emissions especially for diluted particle sampling.

  • 77.
    Piotrowska, Patrycja
    et al.
    Åbo Akad Univ, Proc Chem Ctr, Inorgan Chem Lab, Turku, Finland.
    Grimm, Alejandro
    Luleå Univ Technol, Dept Engn Sci & Math, S-95187 Luleå, Sweden.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Luleå Univ Technol, Dept Engn Sci & Math, S-95187 Luleå, Sweden.
    Zevenhoven, Maria
    Åbo Akad Univ, Proc Chem Ctr, Inorgan Chem Lab, Turku, Finland.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Hupa, Mikko
    Åbo Akad Univ, Proc Chem Ctr, Inorgan Chem Lab, Turku, Finland.
    Fluidized-Bed Combustion of Mixtures of Rapeseed Cake and Bark: The Resulting Bed Agglomeration Characteristics2012In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 26, no 4, p. 2028-2037Article in journal (Refereed)
    Abstract [en]

    The bed agglomeration characteristics resulting from the combustion of 11 mixtures of rapeseed cake and spruce bark were studied in a bench-scale bubbling fluidized-bed reactor (5 kW). The objective was to determine the defluidization temperatures and the prevailing bed agglomeration mechanism as functions of the fuel mixture. Controlled fluidized-bed agglomeration tests were performed for each mixture with quartz sand as the bed material. The total defluidization temperatures and the initial defluidization temperatures were determined based on the measured pressure and temperature profiles in the bed. After combustion, bottom ash samples, agglomerates, and fly ash samples were analyzed by means of scanning electron microscope combined with energy dispersive X-ray detector (SEM-EDX). The composition of the ash-forming matter produced by the combustion of rapeseed cake is significantly different from that produced by the combustion of bark, resulting in different bed agglomeration tendencies. Bark contains ash-forming matter dominated by calcium, with some silicon and potassium, whereas rapeseed cake is rich in phosphorus, potassium, and sodium. The total defluidization temperature for pure bark was above 1045 degrees C, whereas, for rapeseed cake, defluidization occurred during combustion (800 degrees C). During the combustion of bark, the formation of a potassium-rich layer on the silica-bed grains was found to be a crucial for the formation of agglomerates. The low defluidization temperature for the rapeseed cake can be attributed to the formation of sticky ash, which is dominated by phosphates. Two main phosphate forms were observed in the neck between the silica grains: calcium-potassium/sodium phosphates, and magnesium potassium phosphates. As the proportion of bark increased, the Ca/P ratio increased in the fuel mixture, and the formation of high-temperature melting phosphates in the ash was favored. However, the addition of bark also favored the formation of a potassium-rich layer on the silica bed material, leading to the coexistence of both bed agglomeration mechanisms. In the present work, mixtures with a minimum of 60 wt % bark resulted in significantly increased defluidization temperatures and reduced bed agglomeration tendencies, compared to what occurs in rapeseed cake monocombustion.

  • 78.
    Piotrowska, Patrycja
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Rebbling, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Lindberg, Daniel
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Waste gypsum board and ash-related problems during combustion of biomass: 1. Fluidized bed2015In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 29, no 2, p. 877-893Article in journal (Refereed)
    Abstract [en]

    This paper is the first in a series of two describing the use of waste gypsum boards as an additive during combustion of biomass. This paper focuses on experiments performed in a bench-scale bubbling fluidized-bed reactor (5 kW). Three biomass fuels were used, i.e., wheat straw (WS), reed canary grass (RC), and spruce bark (SB), with and without addition of shredded waste gypsum board (SWGB). The objective of this work was to determine the effect of SWGB addition on biomass ash transformation reactions during fluidized bed combustion. The combustion was carried out in a bed of quartz sand at 800 or 700 degrees C for 8 h. After the combustion stage, a controlled fluidizedbed agglomeration test was carried out to determine the defluidization temperature. During combustion experiments, outlet gas composition was continuously measured by means of Fourier transform infrared spectroscopy. At the same place in the flue gas channel, particulate matter was collected with a 13-stage Dekati low-pressure impactor. Bottom and cyclone fly ash samples were collected after the combustion tests. In addition, during the combustion tests a 6-h deposit sample was collected with an air-cooled (430 degrees C) probe. All ash samples were analyzed by means of scanning electron microscopy combined with energy dispersive X-ray spectrometry for elemental composition and with X-ray powder diffraction for the detection of crystalline phases. Decomposition of CaSO4 originating from SWGB was mainly observed during combustion of reed canary grass at 800 degrees C. The decomposition was observed as doubled SO2 emissions. No significant increase of SO2 during combustion of SB and WS was observed. However, the interaction of SWGB particles with WS and SB ash forming matter, mainly potassium containing compounds, led to the formation of K2Ca2(SO4)(3).

  • 79. Piotrowska, Patrycja
    et al.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Grimm, Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Zevenhoven, Maria
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Hupa, Mikko
    Agglomeration Tendency in Fluidized-Bed Combustion of Rapeseed Cake and Bark Mixtures2011Conference paper (Other academic)
  • 80. Piotrowska, Patrycja
    et al.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Grimm, Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Zevenhoven, Maria
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Hupa, Mikko
    Systematic Studies of Ash Composition During the Co-Combustion of Rapeseed Cake and Bark2012In: Proceedings of the 21st International Conference on Fluidized Bed Combustion, Naples, Italy, June 3-6, 2012, 2012, p. 219-226Conference paper (Refereed)
    Abstract [en]

    Agglomeration occurring during the firing of phosphorus-rich biomass is not fully understood. It has become clear that the ash-forming matter in agricultural biomass (e.g., rapeseed cake) is phosphorus dominated and that phosphate species are involved in agglomeration. Understanding the agglomeration mechanisms would provide valuable insight into possible strategies for preventing defluidization. The objective of this work was to study the ash composition resulting from the combustion of a phosphorus-rich fuel, in particular, the phosphorus compounds formed; the focus was the effect of ash composition on the formation of sticky ash particles, which cause defluidization. Eleven mixtures of rapeseed cake and bark with varying Ca/P molar ratio were studied. Using a 5 kW quartz BFB reactor operated at approximately 800 °C, eight‐hour combustion tests were performed prior to each agglomeration experiment. Fly ash and bottom ash samples were extensively analyzed with SEM/EDX, and the fuel properties were also determined. Rapeseed cake ash consists of particles containing different K/Na-Ca/Mg-P compounds. The ash composition responsible for low defluidization temperatures was found to lie in the region of the ternary diagram containing 30-40 mol% P2O5, 20-40 mol% (CaO+MgO), and 30-50 mol% (K2O+Na2O). Sodium probably formed CaNaPO4, but it was also found in mixtures with other phosphates. The addition of bark favoured the formation of orthophosphates containing 40-50 mol% (CaO+MgO), which increased the first melting temperature of the ash.

  • 81.
    Pommer, Linda
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Burvall, Jan
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Olofsson, Ingemar
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Mechanisms behind the positive effects on bed agglomeration and deposit formation combusting forest residue with peat additives in fluidized beds2009In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, no 9, p. 4245-4253Article in journal (Refereed)
    Abstract [en]

    A compilation was made of the composition of peat from different areas in Sweden, or which a selected But was characterized anal co-combusted with forest residue ill controlled fludized-bed agglomeration tests with extensive particle sampling, The variation in ash-forming elements in the different peat samples was large; thus, eight peat samples were selected from the compilation to represent the variation in peat composition in Sweden. These samples were characterized in terms of botanical composition, analyzed for ash-forming elements, and oxidized using a low-temperature ashing procedure, followed by characterization using scanning electron microscopy/electron-dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD). The selected peat samples had in common the presence of Et small fraction of crystalline phases, such as quartz, microcline, albite, and calcium sulfate. The controlled fluidized-bed agglomeration tests that co-combusted forest residue with peat resulted ill a significant increase it) agglomeration temperatures compared to combusting forest residue alone. Plausible explanations for this were in increase of calcium, iron, Or aluminum in the bed particle layers and/or the reaction of potassium with clay minerals, which prevented the formation of low molting bed particle layers, The effects oil particle and deposit formation during co-combustion were reduced amounts of rule particles and all increased number of coarse particles, The mechanisms for the positive effects were a transfer and/or removal of potassium ill the gas phase to it loss reactive particular form via sorption and/or it reaction with the reactive peat ash (SiO2 and CaO), which in most cases formed larger particles (> 1 mu m) containing calcium silicon and Potassium.

  • 82.
    Ramstedt, Madeleine
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Norgren, Caroline
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sheals, Julia
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sjöberg, Staffan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Persson, Per
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Thermodynamic and spectroscopic studies of cadmium(II)–N-(phosphonomethyl)glycine (PMG) complexes2004In: Inorganica Chimica Acta, ISSN 0020-1693, E-ISSN 1873-3255, Vol. 357, no 4, p. 1185-1192Article in journal (Refereed)
    Abstract [en]

    Speciation and equilibria in the H+–Cd2+N-(phosphonomethyl)glycine (PMG, H3L) system have been studied in 0.1 M Na(Cl) medium at 25.0 °C. Formation constants for a series of mononuclear complexes, CdHL, CdL, CdL2 4− and CdL(OH)2− were determined from potentiometric titrations. The structures of the predominating species CdL, and CdL2 4− in solution were investigated using EXAFS and IR spectroscopic techniques. In the 1:1 complex bonds are formed between the Cd(II) ion and all three donor groups (amino, carboxylate, phosphonate) of the PMG molecule resulting in two 5-membered chelate rings. At the remaining three of the corners of the distorted Cd(II) octahedra oxygens were found which are replaced by donor groups of a second PMG molecule in the 1:2 complex. Furthermore, a solid phase consisting of Cd9(PMG)6(H2O)12 · 6H2O crystals was synthesized and the crystal structure was determined. The structure consists of six CdL octahedra connected through a seventh Cd–O octahedron in the centre of the entity, with two additional Cd–O octahedra located at the apices of the unit formed.

    Speciation and equilibria in the H+–Cd2+N-(phosphonomethyl)glycine (PMG, H3L) system have been studied using potentiometry, and formation constants for CdHL, CdL, CdL2 4− and CdL(OH)2− were determined. The structures of CdL, and CdL2 4− in solution were investigated using EXAFS and IR spectroscopic techniques. The results indicated chelating PMG molecules forming two 5-membered chelate rings.

  • 83.
    Rebbling, Anders
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Luleå University of Technology, Department of Engineering Sciences & Mathematics, Energy Engineering.
    Understanding reactivity using fuel design - phosphorus vs kaolin in combustion of stem wood2016Conference paper (Other academic)
    Abstract [en]

    The fate of various ash-forming elements determine how well a fuel will perform in a given thermochemical energy conversion process. In order understand ash-related process problems it is particularly important in which compounds alkali metal ions, for biomass this primarily means K+ and Na+, are bonded. Their low charge and relatively large ionic radii leads to poor bond strengths in compounds where they provide the only Lewis acid component, i.e. electron acceptor. This can be remedied by trying to bond alkali metal ions to stronger, predominantly molecular Lewis bases which is the case in for instance arkanite, K2SO4 – the targeted reaction product when (NH4)2SO4 is added in the flue gas to reduce KCl formation. Another approach is to bond alkali in bottom or bed ash, by including Lewis base forming elements such as phosphorus or the additive kaolin which is dominated by kaolinite. This route attempts to promote formation of high-temperature melting compounds with at least one alkali metal ion per phosphate or other starting molecule.

    While the understanding of how phosphorus reacts in combustion process is increasing it is valuable to understand how it will react in presence of other elements or molecules that play an important role for alkali capture. This will be of interest in situations where the base fuels may be combusted with addition of sulphur or kaolin, for instance. If the base fuels has a high concentration of phosphorus the amount of additive may need to be adjusted according to what phosphates will form, and if they will form even in the presence of the amending additives. Using the inherent composition of the fuel to decide suitable strategies for additive choice or possibly co-combustion is a key component of fuel design.

    The aim of this study is to investigate the relative Lewis base potential for capture of alkali metal ions between phosphates and kaolin. This is made by adding highly available phosphorus in the form of di-ammonium hydrogen phosphate, (NH4)2HPO4, and kaolin, a mineral where kaolinite is the main constituent for capturing alkali to the fuel blend. The fuel chosen is stem wood where the amount of Lewis acid forming elements greatly surpass that of Lewis base forming elements found in the ash forming matter.

  • 84.
    Rebbling, Anders
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Näzelius, Ida-Linn
    Piotrowska, Patrycja
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ohman, Marcus
    Waste Gypsum Board and Ash-Related Problems during Combustion of Biomass. 2. Fixed Bed2016In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 30, no 12, p. 10705-10713Article in journal (Refereed)
    Abstract [en]

    This paper is the second of two describing the use of shredded waste gypsum board (SWGB) as an additive during combustion of biomass. The focus of this paper is to determine whether SWGB can be used as a fuel additive providing CaO and SO2/SO3 for mitigation of ash-related operational problems during combustion of biomass and waste derived fuels in grate fired fixed bed applications. The former study in this series was performed in a fluidized bed and thus allow for comparison of results. Gypsum may decompose at elevated temperatures and forms solid CaO and gaseous SO2/SO3 which have been shown to reduce problems with slagging on the fixed bed and alkali chloride deposit formation. Three different biomasses, spruce bark (SB), reed canary grass (RG), and wheat straw (WS), were combusted with and without addition of SWGB in a residential pellet burner (20 kWth). Waste derived fuel with and without the addition of SWGB was combusted in a large scale grate-fired boiler (25 MWth). The amount of added SWGB varied between 1 and 4 wt %. Ash, slag, and particulate matter (PM) were sampled and subsequently analyzed with scanning electron microscopy/ energy dispersive spectroscopy and X-ray diffraction. Decomposition of CaSO4 originating from SWGB was observed as elevated SO2 emissions in both the large scale and small scale facilities and significantly higher than was observed in the fluidized bed study. Slag formation was significantly reduced due to formation of calcium-silicates in small scale application, but no conclusive observations regarding calcium reactivity could be made in the large scale application. In the small scale study the formation of K2SO4 was favored over KC1 in PM, while in the large scale study K3Na(SO4)(2) and K2Zn2(SO4)(3) increased. It is concluded that SWGB can be used as a source of CaO and SO2/SO3 to mitigate slag formation on the grate and chloride-induced high temperature corrosion and that fixed bed applications are likely more suitable than bubbling fluidized beds when using SWGB as an additive.

  • 85. Reinik, Janek
    et al.
    Heinmaa, Ivo
    Kirso, Uuve
    Kallaste, Toivo
    Ritamäki, Johannes
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Pongrácz, Eva
    Huuhtanen, Mika
    Larsson, William
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Keiski, Riitta
    Kordás, Krisztián
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Alkaline modified oil shale fly ash: Optimal synthesis conditions and preliminary tests on CO(2) adsorption2011In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 196, p. 180-186Article in journal (Refereed)
    Abstract [en]

    Environmentally friendly product, calcium-silica-aluminum hydrate, was synthesized from oil shale fly ash, which is rendered so far partly as an industrial waste. Reaction conditions were: temperature 130 and 160°C, NaOH concentrations 1, 3, 5 and 8M and synthesis time 24h. Optimal conditions were found to be 5M at 130°C at given parameter range. Original and activated ash samples were characterized by XRD, XRF, SEM, EFTEM, (29)Si MAS-NMR, BET and TGA. Semi-quantitative XRD and MAS-NMR showed that mainly tobermorites and katoite are formed during alkaline hydrothermal treatment. Physical adsorption of CO(2) on the surface of the original and activated ash samples was measured with thermo-gravimetric analysis. TGA showed that the physical adsorption of CO(2) on the oil shale fly ash sample increases from 0.06 to 3-4mass% after alkaline hydrothermal activation with NaOH. The activated product has a potential to be used in industrial processes for physical adsorption of CO(2) emissions.

  • 86. Reinik, Janek
    et al.
    Heinmaa, Ivo
    Ritamäki, Johannes
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Pongracz, Eva
    Huuhtanen, Mika
    Larsson, William
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Keiski, Riitta
    Kordas, Krisztian
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    DIRECT CO2 SEQUESTRATION ONTO ALKALINE MODIFIED OIL SHALE FLY ASH2014In: Gorûcie slancy, ISSN 0208-189X, E-ISSN 1736-7492, Vol. 31, no 1, p. 79-90Article in journal (Refereed)
    Abstract [en]

    The present study focuses on the direct chemical adsorption of CO2 onto alkaline hydrothermally activated oil shale fly ash (OSFA). The CO2 chemisorption experiments were conducted in a high-pressure reactor at a temperature of 150 degrees C and CO2 partial pressure of 100 bar during a 24-hour period. Original, activated and chemisorbed OSFA samples were characterized by means of X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) coupled with energy-dispersive X-ray spectroscopy (EDS), specific surface area (BETN2) and high-resolution Si-29 magic angle spinning nuclear magnetic resonance (MAS-NMR). The results indicated moderate weight increase (max 5 wt%) and according to XRD and MAS-NMR analysis tobermorites had reacted with CO2, leading to calcite formation. The results also show that the alkaline hydrothermally activated OSFA has a potential to be used in industrial processes for direct chemical adsorption of CO2 from flue gases.

  • 87.
    Råberg, Mathias
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Rosén, Erik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Warnqvist, Björn
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Improvement of the binary phase diagram Na2CO3 -Na2S2003In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 17, no 6, p. 1591-1594Article in journal (Refereed)
    Abstract [en]

    Gasification of black liquor is an attractive alternative to the traditional recovery boiler. However, in process modeling of gasification, thermodynamic data for the key components are quite uncertain, which will reduce the reliability of the modeling of the chemical processes in a gasifier. The objective of this work was to experimentally re-determine and improve data on the binary phase diagram Na2CO3−Na2S, especially on the Na2CO3 side of the system, which is the region of interest concerning black liquor combustion and gasification, and also the region with the most significant uncertainties. Measurements were carried out in a dry inert atmosphere at temperatures from 25 to 1200 °C, using high-temperature microscopy (HTM) and high-temperature X-ray powder diffraction (HT-XRD). To examine the influence of pure CO2 atmosphere on the melting behavior, HTM experiments in the same temperature interval were made. This paper presents new data complementary to earlier published data on the binary phase diagram Na2CO3−Na2S. These include re-determination of liquidus curves, in the Na2CO3-rich area, melting points of the pure components, as well as determination of the extent of the solid solution, Na2CO3(ss), area.

  • 88.
    Rönnbäck, Marie
    et al.
    SP Sveriges Tekniska Forskningsinstitut.
    Gustavsson, Lennart
    SP Sveriges Tekniska Forskningsinstitut.
    Hermansson, Sven
    SP Sveriges Tekniska Forskningsinstitut.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Fagerström, Jonathan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Näzelius, Ida-Linn
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Grimm, Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Öhman, Marcus
    Förbränningskaraktärisering och förbränningsteknisk utvärdering av olika pelletsbränslen - syntes av projektet2011Report (Other academic)
  • 89.
    Saitton, Stina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Del Tredici, Andria L.
    Mohell, Nina
    Vollinga, Roeland C.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kihlberg, Jan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Luthman, Kristina
    Design, synthesis and evaluation of a PLG tripeptidomimetic based on a pyridine scaffold2004In: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 47, no 26, p. 6595-6602Article in journal (Refereed)
    Abstract [en]

    A 2,3,4-substituted pyridine derivative has been identified as a potential tripeptidomimetic scaffold. The design of the scaffold was based on conformational and electrostatic comparisons with a natural tripeptide. The scaffold has been used in the synthesis of a Pro-Leu-Gly-NH2 (PLG) mimetic. The different substituents in the 2-, 3-, and 4-positions of the pyridine ring were introduced via an aromatic nucleophilic substitution reaction, a "halogen-dancing" reaction, and a Grignard coupling of a Boc-protected amino aldehyde, respectively. The synthetic route involves eight steps and provides the mimetic in 20% overall yield. The pyridine based PLG-mimetic was evaluated for its ability to enhance the maximum response of the dopamine agonist N-propylapomorphine (NPA) at human D2 receptors using a cell based assay (the R-SAT assay). The dose-response curve of the mimetic was found to exhibit a down-turn phase, similar to that of PLG. In addition, the mimetic was more potent than PLG to enhance the NPA response; the maximum response was found to be 146% at 10 nM concentration, as compared to 115% for PLG at the same concentration. Interestingly, conformational analysis by molecular modeling showed that the pyridine mimetic cannot adopt a type II -turn conformation that previously has been suggested to be the bioactive conformation of PLG.

  • 90.
    Salehi, Shahrbanoo
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Energy Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Investigation of phase diagram with relevance for thermal conversion of biomass2014In: KBC-days, Umeå university, 2014Conference paper (Other academic)
  • 91.
    Sandström, Malin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Ca10K(PO4)7 from single-crystal data2006In: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 62, no 12, p. 253-255Article in journal (Refereed)
    Abstract [en]

     Crystals of decacalcium potassium heptakis(orthophosphate), Ca10K(PO4)7, were obtained from a melt. The structure of Ca10K(PO4)7 is isostructural with β-Ca3(PO4)2 and has been determined previously [Morozov, Presnyakov, Belik, Khasanov & Lazoryak (2000). Crystallogr. Rep. 45, 19-26]. The present investigation confirms the previous study, but with higher precision and with all displacement parameters refined anisotropically. The structure contains four Ca, one K, three P and ten unique O atoms, of which the K, one Ca, one P and one O atom are located on threefold rotation axes.

  • 92.
    Sandström, Malin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Calcium potassium cyclo-triphosphate2004In: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. E60, no 2, p. i15-i17Article in journal (Refereed)
    Abstract [en]

    Crystals of calcium potassium cyclo-triphosphate, CaKP3O9, have been synthesized from a melt and structurally characterized using single-crystal X-ray diffraction. The compound is isostructural with the mineral benitoite (BaTiSi3O9).

  • 93.
    Sandström, Malin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fischer, Andreas
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    CaK2P2O72003In: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. E59, no part 11, p. i139-i141Article in journal (Refereed)
    Abstract [en]

    Crystals of the title compound, calcium dipotassium diphosphate, have been synthesized from a melt and structurally characterized using single-crystal X-ray diffraction. The CaK2P2O7 structure can be described as a layer structure, with alternating [K2P2O72-] and [Ca2+] layers parallel to the ab plane. Ca2+ is coordinated by six O atoms in a distorted octahedron. K+ is coordinated by nine O atoms in two different polyhedra.

  • 94.
    Sandström, Malin Hannah
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Rosén, Erik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Determination of standard Gibbs free energy of formation for Ca2P2O7 and Ca(PO3)2 from solid state EMF measurements using yttria stabilised zirconia as solid electrolyte2006In: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 38, no 11, p. 1371-1376Article in journal (Refereed)
    Abstract [en]

    The equilibrium reactions: 3Ca2P2O7(s) + 6Ni(s) reversible arrow 2Ca3(PO4)2(s) + 2Ni3P(s) + 5/O-2(g) and 2Ca(PO3)2(s) + 6Ni(s) reversible arrow Ca2P2O7(s) + 2Ni3P(s) +/- 5/2O2(g) were studied in the temperature range 890 K to 1140 K. The oxygen equilibrium pressures were determined using galvanic cells incorporating yttria stabilized zirconia as solid electrolyte. From the measured data and using the literature values of standard Gibbs free energy of formation for Ca3(PO4)2 and Ni3P, the following relationship of the standard Gibbs free energy of formation for Ca2P2O7 and Ca(PO3)(2) were calculated:

    ΔfG° (Ca2P2O7) +/- 11/(kJ · mol-1)=-3475.9 + 1.5441 (T/K) -0.1051 (T/K) · 1n(T/K) and

    ΔfG° (Ca(PO3)2) +/- 12/(kJ · mol-1)= -3334.8 + 6.1561 (T/K) -0.6950(T/K) · 1n(T/K).

  • 95. Shimpi, Manishkumar R.
    et al.
    Childs, Scott L.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Velaga, Sitaram P.
    New cocrystals of ezetimibe with L-proline and imidazole2014In: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 16, no 38, p. 8984-8993Article in journal (Refereed)
    Abstract [en]

    The objectives of the study were to screen and prepare cocrystals of anti-cholesterol drug ezetimibe (EZT) with the aim of increasing its solubility and dissolution rate. Thermodynamic phase diagram based high throughput screening was performed using wet milling/grinding or solution crystallization methods. A large number of coformers were tested and the resulting solids were preliminarily characterized using X-ray powder diffraction (PXRD) and Raman spectroscopy. Potential cocrystals of EZT with L-proline and imidazole and a solvate formamide were identified in the screening experiments. The cocrystal hits were further characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), solution Proton nuclear magnetic resonance spectroscopy (H-1-NMR) and single crystal XRD. The dissolution properties and stability of cocrystals were determined. Single-crystal X-ray diffraction data were obtained for EZT, EZT-IMI cocrystal and formamide solvate of ezetimibe. All three systems were crystallized in non-centrosymmetric orthorhombic space group P2(1)2(1)2(1) with Z = 4. Robust O-H center dot center dot center dot O, O-H center dot center dot center dot N, N-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds played an important role in all these crystal structures. EZT-PRO cocrystal showed improved apparent solubility and solid state stability.

  • 96.
    Skoglund, Nils
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Grimm, Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Öhman, Marcus
    Återvinning av fosfor och energi ur avloppsslam genom termiskbehandling i fluidiserad bädd: Utvärdering och optimering av prestandaför slutprodukten2012Report (Other academic)
    Abstract [en]

    Combustion of pelletized sewage sludge in a fluidized bed allows the production of ash pellets with high P availability for plants. Co-combustion with biofuels, e.g. agricultural residues, is a suitable approach to raise the levels of K and Ca. The bed temperature used should be as high as possible without putting plant availability at risk in order to volatilize potentially harmful elements. Residence time for the ash pellet in the bed should be made as short as possible to improve ash recovery.

  • 97.
    Skoglund, Nils
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Brännvall, Evelina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Waste Science & Technology.
    Grimm, Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Waste Science & Technology.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Combustion of Biosolids in a Bubbling Fluidized Bed Part 2: Environmental Aspects of Ash from Combustion of Biosolids for Application as FertilizerManuscript (preprint) (Other academic)
  • 98.
    Skoglund, Nils
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Grimm, Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Combustion of biosolids in a bubbling fluidized bed part 1: main ash forming elements and ash distribution with a focus on phosphorus2014In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, no 2, p. 1183-1190Article in journal (Refereed)
    Abstract [en]

    This is the first in a series of three papers describing combustion of biosolids in a 5-kW bubbling fluidized bed, the ash chemistry, and possible application of the ash produced as a fertilizing agent. This part of the study aims to clarify whether the distribution of main ash forming elements from biosolids can be changed by modifying the fuel matrix, the crystalline compounds of which can be identified in the raw materials and what role the total composition may play for which compounds are formed during combustion. The biosolids were subjected to low-temperature ashing to investigate which crystalline compounds that were present in the raw materials. Combustion experiments of two different types of biosolids were conducted in a 5-kW benchscale bubbling fluidized bed at two different bed temperatures and with two different additives. The additives were chosen to investigate whether the addition of alkali (K2CO3) and alkaline-earth metal (CaCO3) would affect the speciation of phosphorus, so the molar ratios targeted in modified fuels were P:K = 1:1 and P:K:Ca = 1:1:1, respectively. After combustion the ash fractions were collected, the ash distribution was determined and the ash fractions were analyzed with regards to elemental composition (ICP-AES and SEM-EDS) and part of the bed ash was also analyzed qualitatively using XRD. There was no evidence of zeolites in the unmodified fuels, based on low-temperature ashing. During combustion, the biosolid pellets formed large bed ash particles, ash pellets, which contained most of the total ash content (54%–95% (w/w)). This ash fraction contained most of the phosphorus found in the ash and the only phosphate that was identified was a whitlockite, Ca9(K,Mg,Fe)(PO4)7, for all fuels and fuel mixtures. With the addition of potassium, cristobalite (SiO2) could no longer be identified via X-ray diffraction (XRD) in the bed ash particles and leucite (KAlSi2O6) was formed. Most of the alkaline-earth metals calcium and magnesium were also found in the bed ash. Both the formation of aluminum-containing alkali silicates and inclusion of calcium and magnesium in bed ash could assist in preventing bed agglomeration during co-combustion of biosolids with other renewable fuels in a full-scale bubbling fluidized bed.

  • 99.
    Skoglund, Nils
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Grimm, Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Öhman, Marcus
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Effects on ash chemistry when co-firing municipal sewage sludge and wheat straw in a fluidised bed: Influence on the ash chemistry by fuel mixing2012Conference paper (Refereed)
    Abstract [en]

    Municipal sewage sludge (MSS) is of interest for co-combustion with problematic fuels, such as agricultural residues, due to its high content of inorganic elements which may improve combustion properties of such problematic fuels. Ash transformation when co-combusting MSS with the agricultural residue wheat straw was examined using a bench-scale bubbling fluidised bed (5 kW). Wheat straw pellets were combusted with MSS both in a co-pelletized form and co-firing of separate fuel particles. This was done to examine whether there is any advantage to either approach of introducing MSS together with a problematic fuel.

    Co-combusting wheat straw with MSS changed the bed agglomeration characteristics from being caused by the formation of low-temperature melting potassium silicates in the fuel ash to being caused by a higher-temperature melting bed ash. This shift in ash chemistry had a significant positive effect on the initial defluidisation temperature. The cyclone ash and fine particulate matter changed from being dominated by alkali in general and alkali chlorides in specific to an increased phosphate and sulphate formation which reduces the risk of alkali-related fouling and corrosion. The influence of aluminosilicates may also play a role in the improvement of fuel ash behaviour.

  • 100.
    Skoglund, Nils
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Grimm, Alejandro
    Energy Engineering, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, Sweden.
    Öhman, Marcus
    Energy Engineering, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, Sweden.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Effects on Ash Chemistry when Co-firing Municipal Sewage Sludge and Wheat Straw in a Fluidized Bed: Influence on the Ash Chemistry by Fuel Mixing2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 10, p. 5725-5732Article in journal (Refereed)
    Abstract [en]

    Municipal sewage sludge (MSS) is of interest for co-combustion with problematic fuels, such as agricultural residues, because of its high content of inorganic elements, which may improve combustion properties of such problematic fuels. Ash transformation when co-combusting MSS with the agricultural residue wheat straw was examined using a bench-scale bubbling fluidized bed (5 kW). Wheat straw pellets were combusted with MSS in both a co-pelletized form and co-firing of separate fuel particles. This was performed to examine whether there is any advantage to either approach of introducing MSS together with a problematic fuel. Co-combusting wheat straw with MSS changed the bed agglomeration characteristics from being caused by the formation of low-temperature melting potassium silicates in the fuel ash to being caused by a higher temperature melting bed ash. This shift in ash chemistry had a significant positive effect on the initial defluidization temperature. The cyclone ash and fine particulate matter changed from being dominated by alkali in general and alkali chlorides in specific to an increased phosphate and sulfate formation, which reduces the risk of alkali-related fouling and corrosion. The influence of aluminosilicates may also play a role in the improvement of fuel ash behavior.

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