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  • 1. Aguilera, Adriana Freites
    et al.
    Tolvanen, Pasi
    Heredia, Shuyana
    Muñoz, Marta González
    Samson, Tina
    Oger, Adrien
    Verove, Antoine
    Eränen, Kari
    Leveneur, Sebastien
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry & Reaction Engineering, Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Salmi, Tapio
    Epoxidation of fatty acids and vegetable oils assisted by microwaves catalyzed by a cation exchange resin2018In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 57, no 11, p. 3876-3886Article in journal (Refereed)
    Abstract [en]

    Epoxidation of oleic acid and cottonseed oil was conducted in a semibatch reactor with in-situ-formed percarboxylic acid (peracetic acid or perpropionic acid), using hydrogen peroxide as an oxidizing agent and carboxylic acid (acetic acid or propionic acid) as oxygen carriers. Amberlite IR-120 was implemented as the catalyst. The system was comprised of a loop reactor, where the mixture was pumped through a single-mode cavity in which microwave irradiation was introduced. A heat exchanger was integrated into the system to replace microwave heating, to compare the results obtained via microwave heating versus conventional heating. The catalyst loading effect was studied, as well as the influence of microwave irradiation and the implementation of the SpinChem rotating bed reactor (RBR), in hopes of decreasing the influence of the internal mass transfer. The application of microwave irradiation results in an improvement of the reaction yield in the absence of a catalyst.

  • 2.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ajaikumar, Samikannu
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, William
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    One-pot catalytic conversion of Nordic pulp media into green platform chemicals2013In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 454, p. 21-29Article in journal (Refereed)
    Abstract [en]

    In this paper, both sulphite and sulphate (Kraft) cellulose from Nordic pulp mills were used as raw materials in the catalytic one-pot synthesis of green platform chemicals, levulinic and formic acids, respectively. The catalyst of choice was a macro-porous, cationic ion-exchange resin, Amberlyst 70. The optimal reaction conditions were determined and the influence of various gas atmospheres was investigated. The maximum yields of 53% formic acid and 57% of levulinic acid were separately obtained in a straight-forward conversion system only containing cellulose, water and the heterogeneous catalyst. The concept introduces a one-pot procedure providing a feasible route to green platform chemicals obtained via conversion of coniferous soft wood pulp to levulinic and formic acids, respectively.

  • 3.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mäki-Arvela, Päivi
    Åbo Akademi.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Åbo Akademi University, Process Chemistry Centre, Åbo Akademi University, Industrial Chemistry & Reaction Engineering., Finland.
    Macro-molecules as a source of levulinic acid2014In: International Review of Chemical Engineering, ISSN 2035-1755, Vol. 16, no 1, p. 44-58Article in journal (Refereed)
    Abstract [en]

    The production of levulinic acid from biomass and macromolecules has been reviewed. It was concluded that the most important parameters in the one-pot hydrolysis of biomass, also including dehydration of glucose to hydroxymethylfurfural as well as its further rehydration to formic and levulinic acids, respectively, are the reaction temperature, initial reactant concentration, acid type as well as the raw material applied. The theoretical maximum yield can hardly be obtained due to formation of humins. Further, the optimum reaction conditions as well as the influence of the catalyst and biomass type are also discussed.

  • 4.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Samikannu, Ajaikumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, William
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wärnå, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo, Finland.
    Salmi, Tapio
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo, Finland.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo, Finland.
    Reaction Network upon One-pot Catalytic Conversion of Pulp2013In: / [ed] Sauro Pierucci, Jiří J. Klemeš, AIDIC - associazione italiana di ingegneria chimica, 2013, Vol. 32, p. 649-654Conference paper (Refereed)
    Abstract [en]

    Nordic sulphite and sulphate (Kraft) cellulose originating from Nordic pulp mills were used as raw materials in the catalytic synthesis of green platform chemicals, levulinic and formic acids, respectively. The catalyst of choice used in this study was a macro-porous, cationic ion-exchange resin Amberlyst 70 for which the optimal reaction conditions leading to best yields were determined. For this system, maximum yields of 53 mol-% and 57 mol-% were obtained for formic and levulinic acid, respectively. The reaction network of the various chemical species involved was investigated and a simple mechanistic approach involving first order reaction kinetics was developed. The prototype model was able to describe the behaviour of the system in a satisfactory manner.

  • 5.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Samikannu, Ajaikumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Catalytic conversion of lignocellulosic materials2010Conference paper (Other academic)
  • 6.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wärnå, Johan
    Åbo Akademi.
    Salmi, Tapio
    Åbo Akademi.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Experimental and Kinetic Modelling Studies upon Conversion of Nordic Pulp into Levulinic AcidManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, sulphite cellulose from a Swedish pulp mill was applied as the raw material upon catalytic, one-pot synthesis of green platform chemicals – levulinic and formic acids. Cationic ion-exchange resin, Amberlyst 70, was the catalyst of choice and the optimal reaction conditions leading to best yields were determined. The kinetic experiments were performed in a temperature range of 180–200 °C and an initial substrate concentration regime ranging from 0.7 to 6.0 wt %. For this system, maximum theoretical yields of around 59 mol % and 68 mol % were obtained for formic and levulinic acid, respectively. These yields were achieved at a reaction temperature of 180 °C and an initial cellulose intake of 0.7 wt %. A simplified reaction network of the various chemical species involved was investigated and a mechanistic approach involving first order reaction kinetics was developed. The model was able to describe the behaviour of the system in a satisfactory manner (degree of explanation 97.8 %). Since the solid catalyst proved to exhibit good mechanical strength under the experimental conditions applied here, the concept introduces a one-pot procedure providing a route to green platform chemicals from coniferous soft wood pulp to produce levulinic and formic acids, respectively.

  • 7.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wärnå, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University,Turku, Finland.
    Salmi, Tapio
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University,Turku, Finland.
    Heterogeneously catalyzed conversion of nordic pulp to levulinic and formic acids2016In: Reaction Kinetics, Mechanisms and Catalysis, ISSN 1878-5190, E-ISSN 1878-5204, Vol. 119, no 2, p. 415-427Article in journal (Refereed)
    Abstract [en]

    Herein, one-pot conversion of cellulose to platform chemicals, formic and levulinic acids was demonstrated. The catalyst selected was an affordable, acidic ion-exchange resin, Amberlyst 70, whereas the cellulose used was sulfite cellulose delivered by a Swedish pulp mill. Furthermore, in an attempt to better understand the complex hydrolysis network of the polysaccharide, kinetic experiments were carried out to pinpoint the optimal reaction conditions with an initial substrate concentration of 0.7–6.0 wt% and a temperature range of 180–200 °C. Higher temperatures could not be used due to the limitations in the thermal stability of the catalyst. Overall, maximum theoretical yields of 59 and 68 mol% were obtained for formic and levulinic acid, respectively. The parameters allowing for the best performance were reaction temperature of 180 °C and initial cellulose concentration of 0.7 wt%. After studying the behavior of the system, a simplified reaction network in line with a mechanistic approach was developed and found to follow first order reaction kinetics. A satisfactory fit of the model to the experimental data was achieved (97.8 % degree of explanation). The catalyst chosen exhibited good mechanical strength under the experimental conditions and thus, a route providing green platform chemicals from soft wood pulp from coniferous trees (mixture of Scots Pine and Norway Spruce) was demonstrated.

  • 8. Aid, T.
    et al.
    Hyvarinen, S.
    Vaher, M.
    Koel, M.
    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, Åbo-Turku, Finland.
    Saccharification of lignocellulosic biomasses via ionic liquid pretreatment2016In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 92, p. 336-341Article in journal (Refereed)
    Abstract [en]

    The current work focuses on the pretreatment efficiency of ILs combined with heat for woody biomass consisting of spruce, birch and pine as well as winter wheat straw. The latter was investigated as a comparison and with the aim to enhance its digestibility during enzymatic hydrolysis whereby the influence of IL-treatment to cellulose resistance for hydrolysis was investigated. Considering the wood species, the most common and industrially important wood species in Northern Europe were chosen in the present work and the goal was to obtain fermentable sugars and their degradation product, i.e. 5-hydroxymethylfurfural (5-HMF), which is known valuable platform chemical. Further, the differences in the yields of IL-obtainable carbohydrates between these species were studied. The highest sugar yields were obtained to glucose in the case of spruce and arabinose in the case of pine sapwood, 12.07 and 7.72 mmol/L, respectively. The highest 5-HMF yield was obtained for spruce heartwood (9.18 mmol/L) with longer treatment time, such as 100h. However, regarding woody biomass, the present work was focused more on the study and analysis of the IL-containing liquid part, wood hydrolysate, after IL-treatment aiming to answer the analysis challenges related to this fraction.

  • 9.
    Ajaikumar, Samikannu
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ahlkvist, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, William
    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.
    Kordas, K
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Highly active and selective bimetallic catalysts supported on transition metal oxides for the oxidation of α-pinene using molecular oxygen2010Conference paper (Other academic)
  • 10.
    Ajaikumar, Samikannu
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ahlkvist, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, William
    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.
    Kordas, K
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Synthesis and characterization of Cu and Cu-M (M=Co, Ni, Au and Zn) bimetallic catalysts supported on TiO2 modified SBA-152010Conference paper (Other academic)
  • 11.
    Ajaikumar, Samikannu
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ahlkvist, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, William
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kordas, K
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Piispankatu 8, FIN-20500, Turku/Åbo, Finland.
    Oxidation of α-pinene over gold containing bimetallic nanoparticles supported on reducible TiO2 by DPU method2011In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 392, no 1-2, p. 11-18Article in journal (Refereed)
    Abstract [en]

    A series of bimetallic catalysts Au–M (where M = Cu, Co and Ru) were supported on a reducible TiO2 oxide via deposition-precipitation (DP) method with a slow decomposition of urea as the precipitating agent. The characteristic structural features of the prepared materials were characterized by various physico-chemical techniques such as X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). XPS results indicated the formation of alloyed bimetallic particles on the TiO2 support. TEM results confirmed the fine dispersion of metal nanoparticles on the support with an average particle size in the range of 3–5 nm. An industrially important process, oxy-functionalization of α-pinene was carried out over the prepared bimetallic heterogeneous catalysts under liquid phase conditions. Reaction parameters such as the reaction time, temperature, and the effect of solvent were studied for optimal conversion of α-pinene into verbenone. The major products obtained were verbenone, verbenol, α-pinene oxide and alkyl-pinene peroxide. The activity of the catalysts followed the order; AuCu/TiO2 > AuCo/TiO2 > Cu/TiO2 > Au/TiO2 > AuRu/TiO2. Upon comparison of the various catalysts, AuCu/TiO2 was found to be an active and selective catalyst towards the formation of verbenone. The temperature, nature of the catalysts and the choice of solvents greatly influenced the reaction rate.

  • 12.
    Ajaikumar, Samikannu
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemistry, Anna University, Guindy, Chennai, India.
    Backiaraj, Muthaiah
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Turku/Åbo, Finland.
    Pandurangan, Arumugam
    Transesterification of diethyl malonate with n-butanol over HPWA/MCM-41 molecular sieves2013In: Journal of porous materials, ISSN 1380-2224, E-ISSN 1573-4854, Vol. 20, no 4, p. 951-959Article in journal (Refereed)
    Abstract [en]

    Mesoporous Si-MCM-41 and Al-MCM-41 (Si/Al = 100) materials were synthesized via a hydrothermal method. Three different ratios (10, 20 and 30 wt%) of heteropoly tungstic acid (HPWA) was loaded on Si-MCM-41 by wet impregnation techniques. The characteristic structural features of the prepared materials were studied by various physico-chemical techniques such as X-ray diffraction (XRD), Nitrogen physisorption (BET), temperature programmed desorption of ammonia (TPD) and transmission electron microscopy (TEM). Transesterification of diethyl malonate (DEM) with n-butanol under autogeneous conditions in a temperature range from 50 to 125 °C was selected as the test reaction for the as synthesized materials. The reactants were fed with various mole ratios in order to determine the optimal feed composition leading to maximum yields of transesterified products. The results indicated that the conversion of diethylmalonate depends on the HPWA concentration on the support, temperature, reaction time and mole ratio of the reactants. Further, the catalytic efficiency of HPWA/MCM-41 was compared with that of Al-MCM-41. The solid acid HPWA/MCM-41 catalysts have several advantages in comparison to conventional mineral acid catalysts which are heterogeneous, eco-friendly, highly active and selective in the formation of transesters.

  • 13. Aldea, Steliana
    et al.
    Snåre, Mathias
    Eränen, Kari
    Grenman, Henrik
    Rautio, Anne-Riika
    Kordás, Krisztian
    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, Biskopsgatan 8, 20500 Åbo-Turku, Finland.
    Salmi, Tapio
    Murzin, Dmitry Y.
    Crystallization of Nano-Calcium Carbonate: The Influence of Process Parameters2016In: Chemie Ingenieur Technik, ISSN 0009-286X, E-ISSN 1522-2640, Vol. 88, no 11, p. 1609-1616Article in journal (Refereed)
    Abstract [en]

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

  • 14. Anugwom, I
    et al.
    Mäki-Arvela, P
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Extraction of nitrogen and sulphur-compounds from heavy fuel oil by 1-ethyl-3-methyl-imidazolium chloride2010Conference paper (Other academic)
  • 15. Anugwom, I
    et al.
    Mäki-Arvela, P
    Salmi, T
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Turku, Finland.
    Ionic liquid assisted extraction of nitrogen and sulphur-containing air pollutants from model oil and regeneration of the spent ionic liquid2011In: Journal of Environmental Protection, ISSN 2152-2197, E-ISSN 2152-2219, Vol. 2, no 6, p. 796-802Article in journal (Refereed)
    Abstract [en]

    Removal of air pollutants, such as nitrogen and sulphur containing compounds from a model oil (dodecane) was studied. An ionic liquid (1-ethyl-3-methylimidazolium chloride [C2mim] [Cl]) was used as an extractant. Liquid-liquid extraction by using 1-ethyl-3-methylimidazolium chloride [C2mim] [Cl] was found to be a very promising method for the removal of N- and S-compounds. This was evaluated by using a model oil (dodecane) with indole as a neutral nitrogen compound and pyridine as a basic nitrogen compound. Dibenzothiophene (DBT) was used as a sulphur compound. An extraction capacity of up to 90 wt% was achieved for the model oil containing pyridine, while only 76 wt% of indole in the oil was extracted. The extraction capacity of a model sulphur compound DBT was found to be up to 99 wt%. Regeneration of the spent ionic liquid was carried out with toluene back-extraction. A 1:1 toluene-to-IL wt ratio was performed at room temperature. It was observed that, for the spent ionic liquid containing DBT as a model compound more than 85 wt% (corresponding 3852 mg/kg) could be removed from the oil. After the second regeneration cycle, 86 wt% of the DBT was recovered from the ionic liquid to toluene. In the case of indole as the nitrogen containing species, more than 99 wt%, (corresponding to 2993 mg/kg) of the original indole was transferred from the model oil to the ionic liquid. After the first-regeneration cycle of the spent ionic liquid, 54 wt% of the indole–in-IL was transferred to toluene. Thus, both extractions of nitrogen and sulphur model compounds were successfully carried out from model oil and the back-extraction of these compounds from the ionic liquids to toluene demonstrated the proved the concept of the regeneration point of view.

  • 16. Anugwom, I
    et al.
    Mäki-Arvela, P
    Virtanen, P
    Willför, S
    Sjöholm, R
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Selective Extraction of Hemicelluloses from Spruce using Switchable Ionic Liquids2012In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 87, no 3, p. 2005-2011Article in journal (Refereed)
    Abstract [en]

    Switchable Ionic Liquids (SILs) made from alcohols, either hexanol or butanol, and CO2 together with an amidine (1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)) were investigated as dissolution/fractionation solvents for wood material. Both native spruce (Picea abies), and pre-extracted spruce were treated with either butanol SIL (SIL1) or hexanol SIL (SIL 2) for 5 days at 55 °C under normal pressure. The SILs were formed by bubbling CO2 through an equimolar mixture of either 1-hexanol or 1-butanol and DBU. The viscosity of the mixture increased from 7.1 mPas to 2980 mPas for SIL 2 and 5.1 to 1600 mPas for SIL 1. Melting points of the SILs 1 and 2 were at 8 and 14 °C, respectively. After the treatment time (5 days), the undissolved fraction contained 38 wt % less hemicelluloses compared to native spruce. There was an increase in the glucose content of the milled spruce treated with both SILs, since the milling step reduced the cellulose crystallinity of the wood and facilitated an easier SIL access into the wood. The solvents were very neutral in terms of lignin removal. Consequently, only about 2% of the lignin was removed from native wood. Moreover, a priori removal of the wood extractives did not influence the lignin removal.

    Highlights► Switchable Ionic Liquids made from, either hexanol or butanol, and CO2 together with an amidine (DBU) were studies as dissolution/fractionation solvents for spruce wood. ► After the treatment undissolved fraction contained 38 wt-% less hemicelluloses. ► We conclude that Switchable ionic liquids are effective solvent for fractionation of wood material, and they are easily recycled and can be reused.

  • 17. Anugwom, Ikenna
    et al.
    Eta, Valeri
    Mäki-Arvela, Päivi
    Virtanen, Pasi
    Lahtinen, Manu
    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, Åbo-Turku, FI-20500, Finland.
    The effect of switchable ionic liquid (SIL) treatment on the composition and crystallinity of birch chips (Betula pendula) using a novel alkanol amine-organic superbase-derived SIL2014In: Green Processing and Synthesis, ISSN 2191-9542, E-ISSN 2191-9550, Vol. 3, no 2, p. 147-154Article in journal (Refereed)
    Abstract [en]

    Two-step treatment of birch chips (Betula pendula) was tested using diethanolamine (DEA)-1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)-CO2-switchable ionic liquid (SIL), resulting in a 23% weight reduction in 24 h. The weight of the chips was reduced to 32% of their initial weight upon the second treatment with fresh SIL. SIL to wood ratio of 5:1, at 100°C for 24 h, without stirring, was applied in both steps. The relative amount of wood lignin reduced from 24% to 14% after two treatment cycles. The relative amount of cellulose of the undissolved fraction after SIL treatment increased from 43% (native birch wood) to 68% after the second cycle. Also, the undissolved material was efficiently fibrillated. The dissolved materials recovered from spent SIL, after treatment, contained high xylan content, about 90% of the total hemicelluloses, which was 85% of the recovered material. The powder X-ray diffraction (XRD) results revealed that the crystallinity of the undissolved material increased slightly, indicating dissolution of the amorphous material. Moreover, transformation of cellulose form I to form II in the remaining undissolved chips was not observed.

  • 18. Anugwom, Ikenna
    et al.
    Eta, Valerie
    Virtanen, Pasi
    Mäki-Arvela, Paivi
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Yibo, Ma
    Hummel, Micheal
    Sixta, Herbert
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University.
    Towards optimal selective fractionation for Nordic woody biomass using novel amine–organic superbase derived switchable ionic liquids (SILs)2014In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 70, p. 373-381Article in journal (Refereed)
    Abstract [en]

    Abstract Improved fractionation process conditions for wood dissolution with switchable ionic liquids (SILs) were determined. The short time, high temperature (STHT) system was introduced as a selective and efficient way to extract components from lignocellulosic material. A SIL based on monoethanol amine (MEA) and 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) formed via coupling with SO2, was applied as a solvent in a 1:3 weight ratio with water. In essence, selective dissolution of mainly lignin was achieved by means of the aqueous SIL at 160 °C (∼6.1 bar corresponding to the vapor pressure of water) in 2 h and in a pressure vessel, for both hard- and soft-wood. About 95 wt-% of wood lignin was extracted. The dissolved components in the spent SIL were recovered by the addition of an anti-solvent whereupon over 70% of the dissolved components were recovered; the recovered fraction contained 19 wt-% hemicellulose while the rest of the material was in essence lignin. The non-dissolved, fluffy material contained ∼70 wt-% cellulose and ∼20 wt-% hemicellulose – a consistency resembling that of Kraft pulp.

  • 19. Anugwom, Ikenna
    et al.
    Eta, Valerie
    Virtanen, Pasi
    Mäki-Arvela, Päivi
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hummel, Michael
    Sixta, Herbert
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Switchable ionic liquids as delignification solvents for lignocellulosic materials2014In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 7, no 4, p. 1170-1176Article in journal (Refereed)
    Abstract [en]

    The transformation of lignocellulosic materials into potentially valuable resources is compromised by their complicated structure. Consequently, new economical and feasible conversion/fractionation techniques that render value-added products are intensely investigated. Herein an unorthodox and feasible fractionation method of birch chips (B. pendula) using a switchable ionic liquid (SIL) derived from an alkanol amine (monoethanol amine, MEA) and an organic super base (1,8-diazabicyclo-[5.4.0]-undec-7-ene, DBU) with two different trigger acid gases (CO2 and SO2 ) is studied. After SIL treatment, the dissolved fractions were selectively separated by a step-wise method using an antisolvent to induce precipitation. The SIL was recycled after concentration and evaporation of anti-solvent. The composition of undissolved wood after MEA-SO2 -SIL treatment resulted in 80 wt % cellulose, 10 wt % hemicelluloses, and 3 wt % lignin, whereas MEA-CO2 -SIL treatment resulted in 66 wt % cellulose, 12 wt % hemicelluloses and 11 wt % lignin. Thus, the MEA-SO2 -SIL proved more efficient than the MEA-CO2 -SIL, and a better solvent for lignin removal. All fractions were analyzed by gas chromatography (GC), Fourier transform infrared spectroscopy (FT-IR), (13) C nuclear magnetic resonance spectroscopy (NMR) and Gel permeation chromatography (GPC).

  • 20. Anugwom, Ikenna
    et al.
    Maki-Arvela, Paivi
    Virtanen, Pasi
    Willfor, Stefan
    Damlin, Pia
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Treating birch wood with a switchable 1,8-diazabicyclo-[5.4.0]-undec-7-ene-glycerol carbonate ionic liquid2012In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 66, no 7, p. 809-815Article in journal (Refereed)
    Abstract [en]

    The suitability of a new switchable ionic liquid (SIL) has been investigated as a solvent for fractionation of lignocellulosic materials. SIL was prepared from inexpensive chemicals, e. g., glycerol, CO2, and 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU). Fresh Nordic birch wood (B. pendula) was treated with the SIL for a time period of 1-5 days at 100 degrees C and under atmospheric pressure. Upon SIL treatment, at best, 57 % of the hemicelluloses were dissolved and 50 % of lignins were dissolved from the native birch. The slightly fibrillated SIL treated chips contained about 55 % cellulose. Up to 76 % of the recovered species removed from the spent SIL liquor was originating from hemicelluloses, mainly from xylan. The spent SILs were reused for fresh wood dissolution in four consecutive cycles and each time the wood dissolution efficiency was similar. SILs could offer affordable (easy-to-synthesize) solvent systems for partial elimination of hemicelluloses and lignin from wood. SILs can also be prepared in-situ and on-site.

  • 21. Anugwom, Ikenna
    et al.
    Mäki-Arvela, Päivi
    Virtanen, Pasi
    Damlin, Pia
    Sjöholm, Rainer
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Switchable ionic liquids (SILs) based on glycerol and acid gases 2011In: RSC Advances, ISSN 2046-2069, Vol. 1, no 3, p. 452-457Article in journal (Refereed)
    Abstract [en]

    New types of switchable ionic liquids (SILs), containing 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU), glycerol and an acid gas (CO2, SO2), were synthesized and characterized in this study. [DBU][Carbonate] or [sulfonate] were easily synthesized from a non-ionic mixture of molecular organic polyol and amidine base upon bubbling of an acid gas (CO2, SO2). Moreover, they were switched back to the original molecular solvents by flushing out the acid gas (CO2, SO2) by heating and/or bubbling an inert gas such as N2 through it. The structures of the SILs were confirmed by NMR and FTIR. The change from low polarity (molecular solvent) to high polarity (Switchable Ionic Liquid, SIL) was also indicated by the changes in properties, such as viscosity and miscibility with different organic solvents. The decomposition temperatures of the SILs were determined by means of Thermo Gravimetric Analysis (TGA) and gave values in the range of 50 °C and 120 °C for DBU-glycerol-CO2 (SIL1) and DBU-glycerol-SO2 (SIL2), respectively. Due to the reasonable decomposition temperatures, these novel SILs can be employed in multiple applications.

  • 22.
    Anugwom, Ikenna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku FI-20500, Finland.
    Rujana, L.
    Wärnå, J.
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku FI-20500, Finland.
    In quest for the optimal delignification of lignocellulosic biomass using hydrated, SO2 switched DBU MEASIL switchable ionic liquid2016In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 297, p. 256-264Article in journal (Refereed)
    Abstract [en]

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

  • 23. Asres, Georgies Alene
    et al.
    Baldoví, José J.
    Dombovari, Aron
    Järvinen, Topias
    Lorite, Gabriela Simone
    Mohl, Melinda
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Pérez Paz, Alejandro
    Xian, Lede
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry & Reaction Engineering, Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Spetz, Anita Lloyd
    Jantunen, Heli
    Rubio, Ángel
    Kordás, Krisztian
    Ultrasensitive H2S gas sensors based on p-type WS2 hybrid materials2018In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 11, no 8, p. 4215-4224Article in journal (Refereed)
    Abstract [en]

    Owing to their higher intrinsic electrical conductivity and chemical stability with respect to their oxide counterparts, nanostructured metal sulfides are expected to revive materials for resistive chemical sensor applications. Herein, we explore the gas sensing behavior of WS2 nanowire-nanoflake hybrid materials and demonstrate their excellent sensitivity (0.043 ppm-1) as well as high selectivity towards H2S relative to CO, NH3, H2, and NO (with corresponding sensitivities of 0.002, 0.0074, 0.0002, and 0.0046 ppm-1, respectively). Gas response measurements, complemented with the results of X-ray photoelectron spectroscopy analysis and first-principles calculations based on density functional theory, suggest that the intrinsic electronic properties of pristine WS2 alone are not sufficient to explain the observed high sensitivity towards H2S. A major role in this behavior is also played by O doping in the S sites of the WS2 lattice. The results of the present study open up new avenues for the use of transition metal disulfide nanomaterials as effective alternatives to metal oxides in future applications for industrial process control, security, and health and environmental safety.

  • 24. Bawuaha, Prince
    et al.
    Silfsten, Pertti
    Sarkar, Anjana
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kordas, Kristian
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Peiponen, Kai-Erik
    On the complex refractive index of N-doped TiO2 nanospheres and nanowires in the terahertz spectral region2013In: Vibrational Spectroscopy, ISSN 0924-2031, E-ISSN 1873-3697, Vol. 68, p. 241-245Article in journal (Refereed)
    Abstract [en]

    In this paper, the terahertz (THz) transmission measurement technique was applied to characterize titanium dioxide (TiO2) nanospheres and nanowires subjected to thermal treatments under various conditions. Differences in the spectral features of the nanospheres and nanowires were observed due to treatment and annealing of the samples in different gas atmospheres. The observations made can be explained based on the formation of new phonon bands and/or widening of the phonon bands due to polymorphism. A singly subtractive Kramers Kronig dispersion relation was utilized to estimate the frequency-dependent real refractive index of the various samples, having a priori unknown sample thickness, from the absorbance data.

  • 25. Behravesh, Erfan
    et al.
    Kumar, Narendra
    Balme, Quentin
    Roine, Jorma
    Salonen, Jarno
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Process Chemistry Centre, Åbo Akademi University, FI-20500 Turku/Åbo, Finland.
    Peurla, Markus
    Aho, Atte
    Eränen, Kari
    Murzin, Dmitry Yu.
    Salmi, Tapio
    Synthesis and characterization of Au nano particles supported catalysts for partial oxidation of ethanol: Influence of solution pH, Au nanoparticle size, support structure and acidity2017In: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 353, p. 223-238Article in journal (Refereed)
    Abstract [en]

    Partial oxidation of ethanol to acetaldehyde was carried out over gold catalysts supported on various oxides and zeolites by deposition precipitation. The special focus of this work was on the influence of H-Y zeolite surface charge on Au cluster size and loading linking it to activity and selectivity in ethanol oxidation and comparing with other studied catalysts. The catalysts were characterized by nitrogen physisorption, transmission electron microscopy (TEM), scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDXA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and zeta potential measurements. pH of the solution governed the Au NPs size within the range of 5.8–13.2 nm with less negatively charged surfaces leading to formation of smaller clusters. Au loading on H-Y zeolite with silica to alumina ratio of 80 was increased by raising the pH. In fact, H-Y-12 and H-Beta-25 were selective towards diethyl ether while acetaldehyde was the prevalent product on less acidic H-Y-80. The results demonstrated strong dependency of the catalytic activity on the Au cluster size. Namely turn over frequency (TOF) decreased with an increase in metal size from 6.3 to 9.3 nm on H-Y-80. Selectivity towards acetaldehyde and ethyl acetate did not change significantly on H-Y-80 within 6.3–9.3 nm Au particle size range. On Al2O3 support, however, selectivity towards acetaldehyde increased considerably upon diminishing Au average particle size from 3.7 to 2.1 nm.

  • 26. Berglund, Linn
    et al.
    Anugwom, Ikenna
    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, Finland.
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Aitomäki, Yvonne
    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, Finland.
    Oksman, Kristiina
    Switchable ionic liquids enable efficient nanofibrillation of wood pulp2017In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 8, p. 3265-3279Article in journal (Refereed)
    Abstract [en]

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

  • 27.
    Bernardini, A.
    et al.
    Padova, Italy.
    Gemo, N.
    Turku/Åbo, Finland; .
    Biasi, Paolo
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Canu, P.
    Padova, Italy.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Salmi, T.
    Turku/Åbo, Finland; .
    Lanza, R.
    Stockholm, Sweden.
    Direct synthesis of H2O2 over Pd supported on rare earths promoted zirconia2015In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 256, no 2, p. 294-301Article in journal (Refereed)
    Abstract [en]

    In this work Pd (0.3 or 0.6 wt.%) was supported on both ZrxM1-xO2 (M = La, Y, Ce) and on mechanical mixtures of CeO2 and ZrO2. The synthesized catalysts were characterized by XRD, TPR, AAS and CO chemisorption and tested for the direct synthesis of hydrogen peroxide in a high pressure semibatch apparatus. The reactants conversion was limited in order to avoid mass-transfer limitations. No selectivity enhancers of any kind were used and the all the materials were halide free. Small metal particles were obtained (1-2.6 nm). Supports with smaller pore diameters leaded to larger Pd particles, which in turn were found to preferentially support the formation of the peroxide. Moreover, supports with higher reducibility favored the production of H2O2, probably due to an easier reduction of the active metal, essential to achieve high selectivity. Notwithstanding the absence of enhancers, the specific activity and selectivity recorded were very high. (C) 2015 Elsevier B.V. All rights reserved.

  • 28. Bernas, Andreas
    et al.
    Salmi, Tapio
    Murzin, Dmitry Yu
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rintola, Mikko
    Catalytic transformation of abietic acid to hydrocarbons2012In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 55, no 7-10, p. 673-679Article in journal (Refereed)
    Abstract [en]

    Catalytic and thermal conversion of abietic acid was investigated in a laboratory scale high-pressure autoclave. Fractionation of crude tall oil produces rosin acids of which abietic acid is the main compound. Tall oil rosin acid, a forest product industry residue, is an abundant, inexpensive and chemically desirable feedstock for production of lighter hydrocarbons that can be used as diesel fuel additives. The carboxylic acid functionality of the main reactant, abietic acid, must first be removed, followed by double bond hydrogenation of the remaining aromatic rings. In this study, a number of catalytic and non-catalytic reaction steps in the conversion of abietic acid were investigated. The aim was to study hydrogenation and decarboxylation reactions of abietic acid in order to produce lighter hydrocarbons. The experiments were performed by using toluene as a solvent as well as with neat abietic acid, in the absence of any solvent. Hydrogenation of abietic acid to tetrahydroabietic acid in toluene was successfully performed over palladium on carbon catalyst at the temperature range of 100-200 A degrees C and at 30 bar hydrogen pressure. Thermal non-catalytic decarboxylation of abietic acid in toluene takes place at 200-300 A degrees C resulting in one main product. The hydrocarbon products were further hydrogenated under hydrogen pressure. Catalytic decarboxylation of abietic acid in toluene was achieved over 5 wt% Ru/C, giving a wider product distribution than thermal decarboxylation.

  • 29.
    Biasi, P.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Åbo Akad Univ, Dept Chem Engn, Lab Ind Chem & React Engn, Johan Gadolin Proc Chem Ctr PCC, Biskopsgatan 8, FI-20500 Turku, Finland.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Åbo Akad Univ, Dept Chem Engn, Lab Ind Chem & React Engn, Johan Gadolin Proc Chem Ctr PCC, Biskopsgatan 8, FI-20500 Turku, Finland.
    Sterchele, S.
    Salmi, T.
    Gemo, N.
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Centomo, P.
    Zecca, M.
    Canu, P.
    Rautio, A. -R
    Kordàs, K.
    Revealing the role of bromide in the H2O2 direct synthesis with the catalyst wet pretreatment method (CWPM)2017In: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 63, no 1, p. 32-42Article in journal (Refereed)
    Abstract [en]

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

  • 30. Biasi, Pierdomenico
    et al.
    Serna, Juan Garcia
    Salmi, Tapio O.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemical Engineering, Process Chemistry Centre (PCC), Laboratory of Industrial Chemistry and Reaction Engineering, Åbo Akademi University, ÅBO-TURKU, Finland.
    Hydrogen Peroxide Direct Synthesis: Enhancement of Selectivity and Production with non-Conventional Methods2013In: ICHEAP-11: 11TH INTERNATIONAL CONFERENCE ON CHEMICAL AND PROCESS ENGINEERING, PTS 1-4 / [ed] Pierucci, S, Klemes, JJ, AIDIC - associazione italiana di ingegneria chimica, 2013, p. 673-678Conference paper (Refereed)
    Abstract [en]

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

  • 31.
    Biasi, Pierdomenico
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry and Reaction Engineering, Process Chemistry Center (PCC), Department of Chemical Engineering, Åbo Akademi University,Turku/Åbo, Finland.
    Sterchele, Stefano
    Bizzotto, Francesco
    Manzoli, Maela
    Lindholm, Sten
    Ek, Paul
    Bobacka, Johan
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry and Reaction Engineering, Process Chemistry Center (PCC), Department of Chemical Engineering, Åbo Akademi University,Turku/Åbo, Finland.
    Salmi, Tapio
    Application of the Catalyst Wet Pretreatment Method (CWPM) for catalytic direct synthesis of H2O22015In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 246, no Special Issue, p. 207-215Article in journal (Refereed)
    Abstract [en]

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

  • 32. Borah, Raju Kumar
    et al.
    Raul, Prasanta Kumar
    Mahanta, Abhijit
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry & Reaction Engineering, Åbo Akademi University, Åbo-Turku, Finland.
    Thakur, Ashim Jyoti
    Copper Oxide Nanoparticles as a Mild and Efficient Catalyst for N-Arylation of Imidazole and Aniline with Boronic Acids at Room Temperature2017In: Synlett: Accounts and Rapid Communications in Synthetic Organic Chemistry, ISSN 0936-5214, E-ISSN 1437-2096, Vol. 28, no 10, p. 1177-1182Article in journal (Refereed)
    Abstract [en]

    The present work describes the excellent catalytic activity of copper(II) oxide nanoparticles (NPs) towards N-arylation of aniline and imidazole at room temperature. The copper(II) oxide NPs were synthesized by a thermal refluxing technique and characterized by FT-IR spectroscopy; powder XRD, SEM, EDX, TEM, TGA, XPS, BET surface area analysis, and particle size analysis. The size of the NPs was found to be around 12 nm having a surface area of 164.180 m(2) g(-1). The catalytic system was also found to be recyclable and could be reused in subsequent catalytic runs without a significant loss of activity.

  • 33.
    Bourajoini, Hasna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rautio, Anne-Riikka
    Kordas, Krisztian
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Calcium manganese oxide catalysts for water oxidation: Unravelling the influence of various synthesis strategies2016In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 79, p. 133-137Article in journal (Refereed)
    Abstract [en]

    Abstract Three different mixed oxide catalysts primarily consisting of calcium and manganese oxides targeting artificial photosynthesis were synthesized and studied. According to the results, their catalytic activity for water oxidation was enhanced by the presence of mixed valence states of Mnn+ ions (3.0 ≤ n ≪ 4.0), while the specific surface area had negligible effect.

  • 34.
    Bui, Thai Q.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Khokarale, Santosh G.
    Shukla, Shashi K.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry & Reaction Engineering, Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FI-20500 Åbo-Turku, Finland.
    Switchable Aqueous Pentaethylenehexamine System for CO2 Capture: an Alternative Technology with Industrial Potential2018In: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 6, no 8, p. 10395-10407Article in journal (Refereed)
    Abstract [en]

    Herein we report the application of polyamine pentaethylenehexamine (PEHA, 3,6,9,12-tetraazatetradecane-1,14-diamine) in CO2 absorption with both neat PEHA and aqueous solutions thereof. The absorption of molecular CO2 in pure PEHA and in PEHA-water systems resulted in the formation of two chemical species, namely, PEHA carbamate and bicarbonate. It was observed that, upon formation of these species, both the CO2 absorption capacity and CO2 absorption rate were controlled by the amount of water in the system. During the CO2 absorption, the neat PEHA and 92 wt % PEHA were capable of forming carbamate species only while other aqueous analogues with higher dilution allowed for the formation of both carbamate and bicarbonate species upon exceeding 8 wt % water in the mixture. The CO2 uptake steadily increased with an increase in the water concentration in the solvent mixture and reached the maximum value of 0.25 g of CO2/(g of solvent) in the case of 56 wt % PEHA in water. However, in the case of more dilute systems (i.e., <56 wt % PEHA in water), the trend reversed and the CO2 loading decreased linearly to 0.05 g of CO2/(g of solvent) for 11 wt % PEHA in water. Meanwhile, it usually took shorter time to achieve the full CO2 absorption capacity (equilibrium) with increasing water content in all cases. The C-13 NMR analysis was used to quantify the relative amount of PEHA carbamate and bicarbonate, respectively, in reaction mixtures. The Kamle-Taft parameters (alpha, beta, and pi*) of aqueous solutions for different concentrations of PEHA were also studied taking advantage of various solvatochromic dyes and correlated with the CO2 absorption capacity. The thermally induced switchable nature of CO2-saturated neat and aqueous PEHA solutions for transformation of ionic PEHA carbamate and bicarbonate moieties to molecular PEHA is also represented. A comparison between aqueous PEHA and aqueous monoethanolamine (industrial solvent) for CO2 capture is reported. Hence, most importantly, a switchable PEHA system is demonstrated for reversible CO2 absorption processes.

  • 35.
    Bukhanko, Natalia
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Samikannu, Ajaikumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, William
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Leino, Anne-Riikka
    Microelectronics and Materials Physics Laboratories, University of Oulu, Finland.
    Kordas, Krisztian
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Microelectronics and Materials Physics Laboratories, University of Oulu, Finland.
    Wärnå, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Finland.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Finland.
    Continuous gas phase synthesis of 1-ethyl chloride from ethyl alcohol and hydrochloric acid over Al2O3-based catalysts: the ‘green’ route2013In: ACS Sustainable Chemistry & Engineering, Vol. 1, no 8, p. 883-893Article in journal (Refereed)
    Abstract [en]

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

  • 36.
    Bukhanko, Natalia
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Forest Biomaterials Technology, Swedish University of Agricultural Science, Umeå, Sweden.
    Schwarz, Christopher
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Samikannu, Ajaikumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ngoc Pham, Tung
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemistry, The University of Danang - University of Science and Technology, Nguyen Luong Bang, Lien Chieu, Da Nang, Viet Nam.
    Siljebo, William
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wärnå, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rautio, Anne-Riikka
    Kordas, Krisztian
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gas phase synthesis of isopropyl chloride from isopropanol and HCl over alumina and flexible 3-D carbon foam supported catalysts2017In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 542, no 25, p. 212-225Article in journal (Refereed)
    Abstract [en]

    Isopropyl chloride synthesis from isopropanol and HCl in gas phase over ZnCl2 catalysts supported on Al2O3 as well as flexible carbon foam was studied in a continuous reactor. A series of catalytic materials were synthesised and characterised by BET, XPS, SEM, TEM, XRD and NH3-TPD methods. Catalytic activity tests (product selectivity and conversion of reactants) were performed for all materials and optimal reaction conditions (temperature and feedstock flow rates) were found. The results indicate that the highest yield of isopropyl chloride was obtained over 5 wt.% ZnCl2 on commercial Al2O3 (No. II) (95.3%). Determination of product mixture compositions and by-product identification were done using a GC-MS method. Carbon foam variant catalyst, 5 wt.% ZnCl2/C, was found to perform best out of the carbon-supported materials, achieving ∼75% yield of isopropyl chloride. The kinetic model describing the process in a continuous packed bed reactor was proposed and kinetic parameters were calculated. The activation energy for the formation of isopropyl chloride reaction directly from isopropanol and HCl was found to be ∼58 kJ/mol.

  • 37.
    Bukhanko, Natalia
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wärnå, Johan
    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, Biskopsgatan 8, FIN-20500, Turku/Åbo, Finland.
    Samikannu, Ajaikumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    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, Biskopsgatan 8, FIN-20500, Turku/Åbo, Finland.
    Kinetic modeling of gas phase synthesis of ethyl chloride from ethanol and HCl in fixed bed reactor2016In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 142, p. 310-317Article in journal (Refereed)
    Abstract [en]

    Kinetic modeling of gas-phase synthesis of ethyl chloride from ethanol and hydrochloric acid over high porous Al2O3 and 2 wt% ZnCl2/Al2O3 catalysts was studied in a continuous plug flow reactor in the temperature range of 200–325 °C. Two rival kinetic models were proposed that both describe the kinetics well. The kinetic parameters of the reaction were determined and activation energy values for ethyl chloride formation from ethyl alcohol and diethyl ether reactions were calculated.

  • 38. Cortinez, V
    et al.
    Hyvärinen, S
    Reunanen, M
    Hemming, J
    Lienqueo, M E
    Murzin, D Yu
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Evaluation of ionic liquid mediated pretreatment for the enzymatic hydrolysis of forest residues to obtain bioethanol2009Conference paper (Other academic)
  • 39. Cortinez, V
    et al.
    Hyvärinen, S
    Reunanen, M
    Hemming, J
    Murzin, D Yu
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lienqueo, ME
     Pretreatment with ionic líquids of Lenga (Nothofagus pumilio) and Eucalyptus (Eucalyptus nitens) residues for producción of second generation bioethanol2009Conference paper (Other academic)
  • 40. Damlin, P
    et al.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Salmi, T
    Characterization of softwood-derived carboxymethylcellulose by high-pH anion-exchange chromatography using pulsed amperometric detection2009Conference paper (Other academic)
  • 41.
    Damlin, Pia
    et al.
    Åbo Akademi University, Process Chemistry Centre, Laboratory of Industrial Chemistry and Reaction Engineering, FIN-20500 Turku/Åbo, Finland.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Salmi, Tapio
    Åbo Akademi University, Process Chemistry Centre, Laboratory of Industrial Chemistry and Reaction Engineering, FIN-20500 Turku/Åbo, Finland.
    Characterization of Hardwood-Derived Carboxymethylcellulose by High pH Anion Chromatography Using Pulsed Amperometric Detection2010In: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 44, no 1-3, p. 65-69Article in journal (Refereed)
    Abstract [en]

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

  • 42. Das, Vijay Kumar
    et al.
    Bharali, Pranjal
    Konwar, Bolin Kumar
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Shchukarev, Andrey
    Industrial Chemistry & Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University.
    Thakur, Ashim Jyoti
    A convenient 'NOSE' approach used towards the synthesis of 6-amino-1,3-dimethyl-5-indolyl-1H-pyrimidine-2,4-dione derivatives catalyzed by nano-Ag2016In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 40, no 3, p. 1935-1939Article in journal (Refereed)
    Abstract [en]

    An endeavour has been made towards the synthesis of uracil based compounds in good to high yield catalyzed by nano-Ag at 70 [degree]C upon reacting 6-amino-1,3-dimethyluracil and indole derivatives. The catalyst was potentially recyclable from fresh up to the third run.

  • 43. de Araujo Filho, Cesar A.
    et al.
    Eranen, Kari
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Salmi, Tapio
    Comparative Study of Reactive Flash Distillation vs Semibatch Reactor Technologies for the Glycerol Hydrochlorination with Gaseous HCl2016In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 55, no 19, p. 5500-5513Article in journal (Refereed)
    Abstract [en]

    The present work provides a systematic comparison of solvent-free glycerol hydrochlorination with semibatch and reactive flash distillation technologies. All the experiments were performed at atmospheric pressure and constant flow rate of gaseous HCl in the temperature range of 70 to 120 degrees C. Both acetic acid and adipic acid were used as homogeneous catalysts, separately, at a concentration of 12% by moles of each. In addition, a series of noncatalytic experiments was investigated. A comparative analysis between reactive flash distillation and semibatch operation suggested that reactive flash distillation only increases the production rate of the desired product 1,3-dichloropropan-2-ol (alpha gamma-DCP) for the highest temperature, i.e. 120 degrees C. Many aspects of the HCl liquid uptake were also exposed once water was allowed to leave the liquid phase, revealing that water also has a positive influence on the reaction rate because it promotes HCl solubility and hydrolysis. Such an important effect was not predicted by previous investigations, and it is hereby described for the first time. Additional semibatch experiments were conducted, in which different amounts of water and alpha gamma-DCP were initially added. It was found that, water exerts competing effects in the glycerol hydrochlorination; addition of alpha gamma-DCP showed an improvement of the reaction kinetics and decrease of HCl consumption. It is suggested that instead of using reactive distillation, a wiser choice to perform glycerol hydrochlorination would be to recycle large amounts of the product stream to achieve high conversion levels at milder temperatures and consuming less HCl gas.

  • 44. de Araujo Filho, Cesar A.
    et al.
    Eränen, Kari
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Salmi, Tapio
    A comprehensive study on the kinetics, mass transfer and reaction engineering aspects of solvent-free glycerol hydrochlorination2014In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 120, p. 88-104Article in journal (Refereed)
    Abstract [en]

    The thorough kinetic study of the solvent-free hydrochlorination of glycerol using gaseous hydrogen chloride in a laboratory-scale semibatch reactor was carried out. A wide set of experiments was performed where reaction temperature (70–120 °C), catalyst concentration (0–50% by moles) and partial pressure (0.25, 0.5, 0.75 and 1.0 atm) were varied. Acetic acid was used as a homogenous catalyst. A more accurate approach was given to the semibatch reactor modeling since it was demonstrated that the liquid volume significantly increased along the reaction. The concentration of HCl was determined experimentally and it was possible to observe the influence of the reaction parameters on the HCl uptake. It was also evidenced that a non-catalytic hydrochlorination takes place in the system and its effect is non-negligible, especially at high temperatures. A new kinetic model was proposed and tested in order to explain the experimental observations. Non-linear regression analysis was successfully applied on the experimental data and the modeling results showed a satisfactory agreement. The model was able to estimate the activation energies for both catalyzed and non-catalyzed experiments. A new concept named Catalyst Modulus was derived from the kinetic equations and then verified with experimental data; the fit of this parameter was very high, thus, pointing out the validity of the model.

  • 45. de Araujo Filho, Cesar A.
    et al.
    Mondal, Debanga
    Haase, Stefan
    Wärnå, Johan
    Eränen, Kari
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Laboratory of Industrial Chemistry and Reaction Engineering, Åbo Akademi University, FI-20500 Turku/Åbo, Finland.
    Salmi, Tapio
    Dynamic modelling of homogeneously catalysed glycerol hydrochlorination in bubble column reactor2016In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 149, p. 277-295Article in journal (Refereed)
    Abstract [en]

    The homogeneously catalysed glycerol hydrochlorination was thoroughly investigated in a continuous isothermal co-current bubble column reactor over a wide range of reaction parameters, such as temperature (70–120 °C), catalyst concentration (3–12%), liquid flow rate (6–12 mL/min) and gas flow rate (0.4–1.0 L/min). The flow patterns inside the reactor were studied by means of step response residence time distribution experiments and by high-speed camera images. The fluid dynamics of the system presented an unusual behaviour due to the extremely high solubility of HCl in the reaction mixture. Interestingly, the fluid dynamics imposed severe limitations to the reaction conversion. The axial dispersion model was applied for describing the dynamic changes in concentrations of compounds. Kinetic and solubility data were collected from previous work on glycerol hydrochlorination in semi-batch reactor conducted by our research group. The bubble column model was able to successfully describe the dynamic behaviour of 29 experiments, as well as estimate hydrodynamics and mass transfer parameters.

  • 46. de Araujo Filho, Cesar Augusto
    et al.
    Salmi, Tapio Olavi
    Bernas, Andreas
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kinetic model for homogeneously catalyzed halogenation of glycerol2013In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 52, no 4, p. 1523-1530Article in journal (Refereed)
    Abstract [en]

    A new kinetic model for the halogenation of polyalcohols, e.g. chlorination of glycerol with gaseous HCl in the presence of homogeneous acid catalysts was developed. The model is based on a reaction mechanism, which includes esterification and epoxidation steps followed by halogenation steps. The principle of quasi-steady state was applied to the ester and ionic intermediates appearing in the model and rate equations were derived. Furthermore, some simplified cases of the rate equations were considered, such as immediate water removal from the reaction mixture and analytical solutions for the simplified kinetic models were derived. The model was verified against experimental data obtained from laboratory-scale semibatch reactors. The conclusion is that the model worked very well, predicting correctly the glycerol conversion and the product distribution of α-, β-, α,β- and α,γ-chlorinated products. The kinetic model can be used for design of reactors for homogeneously catalyzed halogenation.

  • 47. Duan, Ran
    et al.
    Westerlind, Bo S.
    Norgren, Magnus
    Anugwom, Ikenna
    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, Finland.
    Virtanen, Pasi
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    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, Finland.
    Fibre Stress-Strain Response of High-Temperature Chemi-Thermomechanical Pulp Treated with Switchable Ionic Liquids2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 4, p. 8570-8588Article in journal (Refereed)
    Abstract [en]

    The removal of lignin from a high-temperature chemi-thermomechanical pulp (HT-CTMP) using a switchable ionic liquid prepared from an organic superbase (1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)), monoethanol amine (MEA), and SO2 was investigated. The objective was to measure the fibre properties before and after removal of the lignin to analyse the contributions from lignin in the HT-CTMP fibre to the tensile properties. It was found that the fibre displacement at break - measured in zero span, which is related to fibre strain at break - was not influenced by the lignin removal in this ionic liquid system when tested dry. There was a small increase in displacement at break and a reduction in tensile strength at zero span when tested after rewetting. At short span, the displacement at break decreased slightly when lignin was removed, while tensile strength was almost unaffected when tested dry. Under rewetted conditions, the displacement at break increased and tensile strength decreased after lignin removal. Nevertheless, no dramatic differences in the pulp properties could be observed. Under the experimental conditions, treatment with the ionic liquid reduced the lignin content from 37.4 to 15.5 wt%.

  • 48. Eta, Valerie
    et al.
    Anugwom, Ikenna
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Åbo akademi.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Åbo akademi.
    Catalysis for carbon dioxide activation2013In: Catalysis in Finland: an exciting pathway, Oulu: Finnish Catalysis Society , 2013, , p. 428Chapter in book (Other academic)
  • 49.
    Eta, Valerie
    et al.
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku FI-20500, Finland.
    Anugwom, Ikenna
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku FI-20500, Finland.
    Virtanen, Pasi
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku FI-20500, Finland.
    Eränen, Kari
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku FI-20500, Finland.
    Mäki-Arvela, P
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku FI-20500, Finland.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku FI-20500, Finland.
    Loop vs. batch reactor setups in the fractionation of birch chips using switchable ionic liquids2014In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 238, p. 242-248Article in journal (Refereed)
    Abstract [en]

    The fractionation of lignocellulosic feedstock into its major components with high purity represents an important commercialization milestone in the transformation of lignocellulosic forest derived products into fuels and commodity chemicals. A comparison between the traditionally used batch reactor and loop reactor systems demonstrates that improved dissolution of hemicelluloses and lignin are obtained using switchable ionic liquids in a loop reactor system which facilitates decreased heat and mass transfer restrictions. The treatment of birch chips using switchable ionic liquid (SIL) based on 1,8-diazabicyclo-[5.4.0]-undec-7-ene, CO2 and diethanolamine at 120 °C for 30 h in a loop reactor resulted in 24% loss of original weight of wood corresponding to dissolution of 52 wt.% of hemicelluloses and 42 wt.% of lignin, respectively, as opposed to 20% weight loss corresponding to 43 wt.% dissolution of hemicelluloses and 38 wt.% of lignin in the batch system. The non-dissolved material obtained from both reactors was efficiently fibrillated and softened cellulose fibres. The flow of switchable ionic liquid through the loop reactor and agitation of the chips enhanced the dissolution of hemicelluloses and lignin. The dissolved fractions recovered from spent SIL after treatment contained both hemicelluloses and lignin.

  • 50.
    Eta, Valerie
    et al.
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Finland.
    Anugwom, Ikenna
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Finland.
    Virtanen, Pasi
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Finland.
    Mäki-Arvela, P
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Finland.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Finland.
    Enhanced mass transfer upon switchable ionic liquid mediated wood fractionation2014In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 55, p. 109-115Article in journal (Refereed)
    Abstract [en]

    The fractionation of lignocellulosic biomass to its major components is the primary step towards the conversion of biomass-based biopolymers to commodity chemicals in the integrated biorefinery process. Wood chips encased in a SpinChem® device and attached to the stirrer of a batch autoclave were used together with switchable ionic liquids (SILs) for the selective fractionation of hemicelluloses and lignin. Stirring of the wood chips in the SpinChem® device facilitated the diffusion of SIL into the chips through forced recirculation and at the same time avoiding mechanical fibrillation. The treatment of birch chips (Betula pendula) with SILs comprising 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU), monoethanolamine (MEA) and CO2 at 120 °C in a SpinChem® device resulted in the fractionation of 82 wt.% hemicelluloses and 90 wt.% lignin, leaving the cellulose-rich non-dissolved material partially fibrillated and softened. The dissolved hemicelluloses and lignin were selectively precipitated using isopropanol and recovered from the spent SIL.

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