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  • 1.
    Ahlkvist, Johan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ajaikumar, Samikannu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    One-pot catalytic conversion of Nordic pulp media into green platform chemicals2013Inngår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 454, s. 21-29Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 2.
    Ahlkvist, Johan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wärnå, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. 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 universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo, Finland.
    Reaction Network upon One-pot Catalytic Conversion of Pulp2013Inngår i: / [ed] Sauro Pierucci, Jiří J. Klemeš, AIDIC - associazione italiana di ingegneria chimica, 2013, Vol. 32, s. 649-654Konferansepaper (Fagfellevurdert)
    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.

  • 3.
    Ahlkvist, Johan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Catalytic conversion of lignocellulosic materials2010Konferansepaper (Annet vitenskapelig)
  • 4.
    Ajaikumar, Samikannu
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ahlkvist, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Boström, Dan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Kordas, K
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Highly active and selective bimetallic catalysts supported on transition metal oxides for the oxidation of α-pinene using molecular oxygen2010Konferansepaper (Annet vitenskapelig)
  • 5.
    Ajaikumar, Samikannu
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ahlkvist, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Boström, Dan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Kordas, K
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Synthesis and characterization of Cu and Cu-M (M=Co, Ni, Au and Zn) bimetallic catalysts supported on TiO2 modified SBA-152010Konferansepaper (Annet vitenskapelig)
  • 6.
    Ajaikumar, Samikannu
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ahlkvist, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kordas, K
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. 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 method2011Inngår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 392, nr 1-2, s. 11-18Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 7.
    Ajaikumar, Samikannu
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Chemistry, Anna University, Guindy, Chennai, India.
    Backiaraj, Muthaiah
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. 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 sieves2013Inngår i: Journal of porous materials, ISSN 1380-2224, E-ISSN 1573-4854, Vol. 20, nr 4, s. 951-959Artikkel i tidsskrift (Fagfellevurdert)
    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.

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

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

  • 9.
    Bukhanko, Natalia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Forest Biomaterials Technology, Swedish University of Agricultural Science, Umeå, Sweden.
    Schwarz, Christopher
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ngoc Pham, Tung
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Chemistry, The University of Danang - University of Science and Technology, Nguyen Luong Bang, Lien Chieu, Da Nang, Viet Nam.
    Siljebo, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wärnå, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Rautio, Anne-Riikka
    Kordas, Krisztian
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Gas phase synthesis of isopropyl chloride from isopropanol and HCl over alumina and flexible 3-D carbon foam supported catalysts2017Inngår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 542, nr 25, s. 212-225Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 10.
    Bukhanko, Natalia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wärnå, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. 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 universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FIN-20500, Turku/Åbo, Finland.
    Kinetic modeling of gas phase synthesis of ethyl chloride from ethanol and HCl in fixed bed reactor2016Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 142, s. 310-317Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 11. Durgadevi, Ganesan
    et al.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Chandran, Muthaiah
    Kuppusamy, Muniyan Ramasamy
    Dinakaran, Kannaiyan
    Synthesis and characterization of CdS nanoparticle anchored Silica-Titania mixed Oxide mesoporous particles: Efficient photocatalyst for discoloration of textile effluent2019Inngår i: International Journal of Nano Dimension, ISSN 2008-8868, E-ISSN 2228-5059, Vol. 10, nr 3, s. 272-280Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient photocatalyst consisting of CdS nanoparticle dispersed mesoporous silica-titania was prepared using amphiphilic triblock copolymer P123 as template and silica-titania sol-gel precursors. The CdS nanoparticle was incorporated into silica-titania mesoporous nanosturctures by post impregnation method. The synthesized catalyst has been characterized by FTIR, TEM, SEM, and EDAX analysis. The CdS nanoparticles incorporated silica-titania mesoporous particles exhibited an enhanced light harvesting, large surface area and excellent photocatalytic activity. Photocatalytic degradation experiments on methyleneblue solution at different pH of the medium revealed that, the catalyst ST0.5CdS0.2 is more effective in basic medium with a degradation efficiency of 98%. In addition, the catalyst is also tested for dye degradation against a raw textile dye effluent containing multiple dye molecules, and their results indicated that the raw effluent can be decolorized within 90min using ST0.5CdS0.2 catalyst.

  • 12. Gemo, Nicola
    et al.
    Biasi, Pierdomenico
    Canu, Paolo
    Menegazzo, Federica
    Pinna, Francesco
    Ajaikumar, Samikannu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kordàs, Krisztián
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Electrical and Information Engineering, Microelectronics and Materials Physics Laboratories, University of Oulu, Oulu, Finland.
    Salmi, Tapio O.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Chemical Engineering, Process Chemistry Centre (PCC), Laboratory of Industrial Chemistry and Reaction Engineering, Åbo Akademi University, Åbo-turku, Finland.
    Reactivity aspects of SBA15-based doped supported catalysts: H2O2 direct synthesis and disproportionation reactions2013Inngår i: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 56, nr 9-10, s. 540-549Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pd and PdAu catalysts supported on SBA15 and SiO2 were prepared and investigated for H2O2 direct synthesis in a batch autoclave (10 °C and 17.5 bar) and in the absence of halides and acids. The SiO2 supported catalysts exhibited inferior performances compared to the mesoporous ordered SBA15. A good control of both the catalysts dispersion and nanoparticle stability was achieved using SBA15. Catalysts were doped with bromine, a promoter in the H2O2 direct synthesis. Productivity and selectivity decreased when bromine was incorporated in the catalysts, thus indicating a possible poisoning due to the grafting process. A synergetic effect between Pd and Au was observed both in presence and absence of bromopropylsilane grafting on the catalyst surface. Three modifiers of the SBA15 support (Al, CeO2 and Ti) were chosen to elucidate the influence of the surface properties on metal dispersion and catalytic performance. Higher productivity and selectivity were achieved incorporating Al into the SBA15 framework, whereas neither Ti nor CeO2 improved H2O2 yields. The enhanced performance observed for the Prau/Al–SBA15 catalysts was attributed to the increased number of Brønsted acid sites. A modification of this catalyst with bromine was confirmed to impair both productivity and selectivity, possibly due to the broader particle size distribution and the poor stability of the metal nanoparticles, as demonstrate by transmission electron microscopy (TEM) images. H2O2 disproportionation was also investigated. A much slower reaction rate was observed compared to the H2O2 production, suggesting that the major contributor in the process of H2O2 destruction must be connected to the hydrogenation reaction.

  • 13. Gemo, Nicola
    et al.
    Menegazzo, Federica
    Biasi, Pierdomenico
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo Akademi University, Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Turku/Åbo, Finland .
    Sarkar, Anjana
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Raut, Dilip G.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kordás, Krisztián
    Rautio, Anne-Riikka
    Mohl, Melinda
    Boström, Dan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo Akademi University, Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Turku/Åbo, Finland .
    TiO2 nanoparticles vs. TiO2 nanowires as support in hydrogen peroxide direct synthesis: the influence of N and Au doping2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 105, s. 103311-103319Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The performance of Pd on titania support were evaluated in the direct synthesis of hydrogen peroxide. The equipment used was a high pressure, semi-batch apparatus equipped with a special injection system. Pd (1 wt%) catalysts on TiO2 materials with different nature were prepared by wet impregnation method. Three aspects were investigated: (a) the structure of the support (nanoparticles vs. nanowires); (b) the addition of a second active metal (Au); (c) the influence of N-doping of the support. All samples were characterized by means of XPS, TEM and XRD analyses. TiO2 nanoparticle supported catalyst demonstrated higher H2O2 selectivity and higher turnover frequency (TOF) than the catalysts based on TiO2 nanowires. The addition of Au to the Pd TiO2 nanowire catalyst improved the H2O2 selectivity due to altered particle size and electronic effects. Both N-doped versions of the catalysts gave rise to higher H2O2 selectivity than the parent non-doped ones. The synthetic procedure was the source of this observation: larger mean Pd nanoparticles were present, thus favouring the formation of H2O2 as the primary product.

  • 14.
    Goets, Mikhail
    et al.
    Åbo-Turku, Finland.
    Ajaikumar, Samikannu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo-Turku, Finland.
    Catalytic Upgrading of Extractives to Chemicals: Monoterpenes to "EXICALS"2015Inngår i: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 115, nr 9, s. 3141-3169Artikkel, forskningsoversikt (Fagfellevurdert)
  • 15.
    Golets, Mikhail
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Blomberg, David
    Processum Biorefinery Initiative AB, SE-89186, Örnsköldsvik, Sweden.
    Grundberg, H
    Aditya Birla Domsjö Fabriker AB, SE-89186, Örnsköldsvik, Sweden.
    Wärnå, J
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Salmi, T
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Liquid phase acetoxylation of α-pinene over Amberlyst-70 ion-exchange resin2012Inngår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 435-436, s. 43-50Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Heterogeneously-catalyzed and solvent-catalyzed liquid phase acetoxylation of α-pinene with acetic acid acting as both a solvent and a reagent was studied. Both solvent-catalyzed and catalytic experiments were carried out and various reaction conditions were studied. The influence of temperature, pressure, solvent and gas milieu were taken into account. Bornyl, fenchyl, verbenyl as well as α-terpinyl acetates, limonene, camphene and γ-terpinene were found among reaction products. The addition of the catalyst allowed for maximization of the yield of bornyl acetate. The predominant products obtained were α-terpinyl, verbenyl and bornyl acetates. The reaction pathways were identified and evaluated.

    The aim of this work was to study of the feasibility of batch acetoxylation of alpha-pinene. The analysis of the complex product distribution is not trivial and, consequently, resolving the reaction network was important. The optimized reaction conditions were searched for aiming at an efficient conversion of α-pinene to a mixture of valuable products.

  • 16.
    Golets, Mikhail
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Blomberg, David
    Processum Biorefinery Initiative AB, 89186, Örnsköldsvik, Sweden.
    Grundberg, H
    Aditya Birla Domsjö Fabriker AB, 89186, Örnsköldsvik, Sweden .
    Wärnå, J
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Turku, Finland.
    Salmi, T
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Turku, Finland.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Turku, Finland.
    A kinetic study of the liquid phase acetoxylation of α-pinene2012Inngår i: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 55, nr 7-10, s. 649-656Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present study introduces kinetic modeling of liquid phase α-pinene acetoxylation with acetic acid over an ion-exchange resin catalyst. The reaction was carried out in a laboratory scale high-pressure autoclave. α-terpinyl (35 wt%) and bornyl (40 wt%) acetates were the primary products. The predominant reaction pathways were identified and evaluated.

  • 17.
    Golets, Mikhail
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mohln, M.
    University of Oulu, Oulu, Finland.
    Wärnå, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo Akademi University, Åbo-Turku, Finland.
    Rakesh, S.
    Department of Chemistry, Podhigai College of Engineering and Technology, Tamilnadu, India.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo Akademi University, Åbo-Turku, Finland.
    Continuous production of the renewable ρ-cymene from α-pinene2013Inngår i: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 307, s. 305-315Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this work was to demonstrate the feasibility to produce ρ-cymene, an important commodity chemical, in a continuous, one-pot reaction system from abundant α-pinene, available e.g. as a by-product of pulping industry. The isomerization reactions of α-pinene over bimetallic heterogeneous catalysts, 3 and 5 wt% Pd–Zn (1:1, 1:4, 4:1, 1:0, and 0:1), supported on Al-SBA15 were studied. The principal reaction products were identified as ρ- and m-cymenes, limonene, camphene, and ρ-menthene, respectively. The highest concentration of ρ-cymene reached 77 wt% under the optimized reaction conditions: 300 °C and α-pinene feed of 0.03 mL/min. Two main reaction pathways toward ρ- and m-cymenes were described, and a mechanistic kinetic model, based on a plausible reaction network in line with Langmuir–Hinshelwood approach, was developed. The catalyst characterization revealed the reduction in Pd(II) sites, catalyst coking, and decline of surface area over the course of time. The catalyst recovery and reuse was addressed.

  • 18. Horáček, Jan
    et al.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry & Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Ajaikumar, Samikannu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Šťávová, Gabriela
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Hora, Lukáš
    Kubička, David
    Studies on sodium lignosulfonate depolymerization over Al2O3 supported catalysts loaded with metals and metal oxides in a continuous flow reactor2013Inngår i: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 56, nr 9-10, s. 794-799Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this work was to study the how various heterogeneous catalysts perform upon lignosulfonate decomposition reactions. The main target of the study was to obtain extractable phenolic compounds as potential renewable chemicals for the production of fuel components and chemicals. The nature of the heterogeneous catalyst was found to have a great impact on the obtained product yields and the composition of the product mixture. Initially, a nickel–tungsten on alumina (NiW/Al2O3) reference catalyst was applied upon screening the influence of catalyst particle size and various reaction parameters. Significantly increasing product yields with decreasing catalyst particle size indicated that the lignosulfonate transformation takes place on the external catalyst surface due to large macromolecular structure of the feedstock. The contact time (space time velocity) and catalyst particle size were the most important factors influencing the selectivity profiles towards various products as well as the yields observed. The highest conversion to phenolics was obtained over in-house-prepared NiO/Al2O3 and NiMo/Al2O3 catalysts with various NiO and MoO3 loadings.

  • 19. Kocík, Jaroslav
    et al.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bourajoini, Hasna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Pham, Tung Ngoc
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Faculty of Science and Engineering, Industrial Chemistry & Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Hájek, Martin
    Čapek, Libor
    Screening of active solid catalysts for esterification of tall oil fatty acids with methanol2017Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 155, nr 1, s. 34-38Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The paper is focused on the description of the activity/selectivity of mesoporous silica based materials loaded with various types of active species in the esterification of tall oil free fatty acids. The metals such as aluminium, molybdenum, gallium and zinc, including their combinations were impregnated on the mesoporous silica, which was tested in esterification reaction. All these catalysts preserved its tall oil free fatty conversion in the first and the second catalytic cycles. However, while only insignificant amount of gallium or molybdenum was lost from the solid catalyst into the liquid phases, zinc leached from every studied solid catalyst. In contrast to impregnated gallium on mesoporous silica, which exhibited higher acidity and higher tall oil free fatty acids conversion in the first catalytic cycle, but its value was not preserved in the second catalytic test.

  • 20.
    Konwar, Lakhya Jyoti
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mäki-Arvela, Päivi
    Boström, Dan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Turku, FI-20500, Finland.
    Lignosulfonate-based macro/mesoporous solid protonic acids for acetalization of glycerol to bio-additives2018Inngår i: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 220, s. 314-323Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 21.
    Konwar, Lakhya Jyoti
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mäki-Arvela, Päivi
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Turku, Finland .
    Efficient C-C coupling of bio-based furanics and carbonyl compounds to liquid hydrocarbon precursors over lignosulfonate derived acidic carbocatalysts2018Inngår i: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 8, nr 9, s. 2449-2459Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper demonstrates the catalytic potential of novel Na-lignosulfonate (LS) derived meso/macroporous solid protonic acids upon C–C coupling of bio-based furanics and carbonyl compounds. The materials demonstrated catalytic activity for solventless hydroxyalkylation/alkylation (HAA) of 2-methylfuran with furfural, acetone, butanal, cyclohexanone, levulinic acid and α-angelica lactone under mild reaction conditions (50–60 °C) producing branched-chain C12–C16 hydrocarbon precursors in yields approaching 96%. Moreover, the carbon materials exhibiting high total acidity (6–6.4 mmol g−1) outperformed sulfonic acid resins (Amberlyst®70, Amberlite®IR120 and LS resin), zeolites and liquid acids (p-toluenesulfonic acid, acetic acid and phenol). In fact, the most active carbocatalyst (60LS40PS350H+) exhibited the same turnover frequency as p-toluenesulfonic acid (186 h−1) upon furfural conversion but with an improved HAA product yield (up to 88%) and reusability, maintaining 98% of its original activity up to seven reaction cycles. The observed catalytic activity and operational stability of the LS derived acidic carbocatalysts were attributed to the strongly Brønsted acidic –SO3H groups covalently incorporated into their structural carbon framework and the promotional effects of hydrophilic surface functional groups (–COOH and –OH) favoring adsorption of oxygenated reactant molecules.

  • 22. Leino, Ewelina
    et al.
    Mäki-Arvela, Päivi
    Eta, Valerie
    Kumar, Narendra
    Demoisson, Frédéric
    Ajaikumar, Samikannu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Leino, Anne-Riikka
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Murzin, Dmitry Yu
    Kordás, Krisztián
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    The influence of various synthesis methods on the catalytic activity of cerium oxide in one-pot synthesis of diethyl carbonate starting from CO2, ethanol and butylene oxide2013Inngår i: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 210, s. 47-54Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Different synthesis methods such as homogeneous precipitation at room temperature and supercritical water (T > 647 K and P > 22.1 MPa) were employed for cerium oxide preparation. Additionally, deposition of ceria on silica mesoporous material, SBA-15, was carried out. The obtained materials were characterized by means of X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen physisorption, X-ray photoelectron spectroscopy and CO2 temperature programmed desorption. Considerable variations in physico-chemical properties of the resulting materials were observed. The catalytic activities of pristine cerium oxide and ceria loaded on SBA-15 support were compared. The test reaction was synthesis of diethyl carbonate starting from carbon dioxide and ethanol using butylene oxide as the dehydrating agent.

  • 23. Lin, Jhih-Fong
    et al.
    Kukkola, Jarmo
    Sipola, Teemu
    Raut, Dilip
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo Akad Univ, Dept Chem Engn, Proc Chem Ctr, FI-20500 Turku, Finland.
    Mohl, Melinda
    Toth, Geza
    Su, Wei-Fang
    Laurila, Tomi
    Kordas, Krisztian
    Trifluoroacetylazobenzene for optical and electrochemical detection of amines2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 8, s. 4687-4694Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, we demonstrate the solution processing of optical and electrochemical dye sensors based on 4-(dioctylamino)-4'-(trifluoroacetyl) azobenzene and its application in sensing different amine compounds. Distinct optical response of the sensors exposed to ammonia, tetramethylammonium hydroxide, ethylamine, cadaverine and putrescine (typical compounds upon the decomposition of proteins) is observed. Incorporation of inkjet deposited thin films of the dye as sensors in food packages of ground meat and salmon is found as a feasible route to detect the appearance of biogenic amines produced by the degrading food products. Furthermore, we demonstrate an electrochemical amine sensor based on (trifluoroacetyl) azobenzene dye added in carbon nanotube-Nafion (R) composites. The electrochemical sensor exploits the reaction between the dye and amines to detect amines in electrolytes, while the carbon nanotubes provide large surface for adsorption and also provide a percolating electrical network for allowing efficient charge transfer at the electrode electrolyte interface.

  • 24.
    Ngoc Pham, Tung
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kukkola, Jarmo
    Rautio, Anne-Riikka
    Pitkänen, Olli
    Dombovari, Aron
    Lorite, Gabriela Simone
    Sipola, Teemu
    Toth, Geza
    Mohl, Melinda
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry & Reaction Engineering, Department of Chemical Engineering, Process Chemistry Centre, Åbo Akademi University, FI-20500, Åbo-Turku, Finland.
    Kordas, Krisztian Kordas
    Industrially benign super-compressible piezoresistive carbon foams with predefined wetting properties: from environmental to electrical applications2014Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 4, artikkel-id 6933Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present work electrically conductive, flexible, lightweight carbon sponge materials derived from open-pore structure melamine foams are studied and explored. Hydrophobic and hydrophilic surface properties - depending on the chosen treatment conditions - allow the separation and storage of liquid chemical compounds. Activation of the carbonaceous structures substantially increases the specific surface area from ,4 m2 g21 to ,345 m2 g21 , while retaining the original three-dimensional, open-pore structure suitable for hosting, for example, Ni catalyst nanoparticles. In turn the structure is rendered suitable for hydrogenating acetone to 2-propanol and methyl isobutyl ketone as well for growing hierarchical carbon nanotube structures used as electric double-layer capacitor electrodes with specific capacitance of ,40 F/g. Mechanical stress-strain analysis indicates the materials are super-compressible (.70% volume reduction) and viscoelastic with excellent damping behavior (loss of 0.69 6 0.07), while piezoresistive measurements show very high gauge factors (from ,20 to 50) over a large range of deformations. The cost-effective, robust and scalable synthesis - in conjunction with their fascinating multifunctional utility - makes the demonstrated carbon foams remarkable competitors with other three-dimensional carbon materials typically based on pyrolyzed biopolymers or on covalently bonded graphene and carbon nanotube frameworks.

  • 25.
    Ngoc Pham, Tung
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Chemistry, The University of Danang, Danang University of Science and Technology, 54 Nguyen Luong Bang, Da Nang, Lien Chieu, Vietnam.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Rautio, Anne-Riikka
    Juhasz, Koppany L.
    Konya, Zoltan
    Wärnå, Johan
    Kordas, Krisztian
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry & Reaction Engineering, Department of Chemical Engineering, Process Chemistry Centre, Åbo Akademi University, 20500 Åbo-Turku, Finland.
    Catalytic Hydrogenation of d-Xylose Over Ru Decorated Carbon Foam Catalyst in a SpinChem® Rotating Bed Reactor2016Inngår i: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 59, nr 13-14, s. 1165-1177Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work the activity of ruthenium decorated carbon foam (Ru/CF) catalyst was studied in three phase hydrogenation reaction of d-xylose to d-xylitol. The developed catalyst was characterized by using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, inductively coupled plasma optical emission spectrometry and nitrogen adsorption–desorption measurement. Kinetic measurements were carried out in a laboratory scale pressurized reactor (Parr®) assisted by SpinChem® rotating bed reactor (SRBR), at pre-defined conditions (40–60 bar H2 and 100–120 °C). The study on the influence of reaction conditions showed that the conversion rate and selectivity of hydrogenation reaction of d-xylose was significantly affected by temperature. These results have been proved by a competitive kinetics model which was found to describe the behavior of the novel system (Ru/CF catalyst used together with the SRBR) very well. Besides, it was revealed that the catalytic activity as well as the stability of our Ru/CF-SRBR is comparable with the commercial ruthenium decorated carbon catalyst (Ru/AC) under identical reaction conditions. Moreover, all steps from catalyst preparation and catalyst recycling as well as catalytic testing can be performed in an easy, fast and elegant manner without any loss of materials. Briefly, the developed Ru/CF catalyst used together with the SRBR could be used an excellent alternative for the conventional Raney nickel catalyst in a slurry batch reactor and offers an attractive concept with obvious industrial applicability.

  • 26. Rautio, Anne-Riikka
    et al.
    Pitkänen, Olli
    Järvinen, Topias
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Halonen, Niina
    Mohl, Melinda
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Department of Chemical Engineering, Process Chemistry Centre Åbo Akademi University, Åbo, Finland.
    Kordas, Krisztian
    Electric double-layer capacitors based on multiwalled carbon nanotubes: can nanostructuring of the nanotubes enhance performance?2015Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, nr 7, s. 3538-3544Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Supercapacitors prepared from chemically modified and vacuum filtered buckypapers were studied. The aim was to evaluate how its pore structure impacts the specific capacitance, energy, and power density in different electrolytes. The specific capacitance varies in a linear fashion with the specific surface area for nanotubes modified by the means of catalytic, low-temperature partial catalytic oxidation using cobalt oxide nanoparticles decorating the nanotubes. In contrast, electrodes composed of nanotubes preactivated in CO2 demonstrated only a minor increase in their specific capacitance, despite the observed significant increase in specific surface area. The radically improved surface area was a result of emergence and deposition of soot on the nanotubes during the activation process, as revealed by transmission electron microscopy. Among six different types of electrode materials, the CoOx decorated materials proved to have the highest specific capacitance (similar to 25 F/g in aqueous KOH and similar to 15 F/g in triethylsulfonium bis(trifluoromethylsulfonyl)imide ionic liquid). Thus, highly structured carbon nanotubes giving rise to energy and power storage densities comparable with commercial and other multiwalled carbon nanotube based electric double-layer capacitor devices were obtained.

  • 27.
    Samikannu, Ajaikumar
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Golets, MikhailUmeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.Larsson, WilliamUmeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.Shchukarev, AndreyUmeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.Kordas, KrisztianUmeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Microelectronics and Materials Physics Laboratories, University of Oulu, FIN-90570 Oulu, Finland.Leino, Anne-RiikkaMicroelectronics and Materials Physics Laboratories, University of Oulu, FIN-90570 Oulu, Finland.Mikkola, Jyri-PekkaUmeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo Akademi University, Åbo, Finland.
    Dehydroisomerization of α-pinene over metal supported Si-SBA-15 mesoporous molecular sieves2013Konferanseproceedings (Fagfellevurdert)
    Abstract [en]

    The effective dispersion of active metal species on mesoporous Si-SBA-15 is acquired by means of deposition-precipitation method.  In order to achieve this, the surface of Si-SBA-15 was first modified with TiO2 via grafting method, followed by deposition-precipitation method (DP) to obtain a fine dispersion of metallic nanoparticles over TiO2 modified Si-SBA-15. The structural features of the synthesized materials were characterized by means of X-ray diffraction (XRD), nitrogen sorption (BET), XPS and HR-TEM. A valuable platform chemical, p-cymene, was produced over the prepared catalyst by dehydroisomerization of α-pinene under vapour-phase conditions. A stable catalyst for one-spot synthesis of renewable p-cymene from α-pinene was developed.

  • 28.
    Samikannu, Ajaikumar
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Golets, Mikhail
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kordas, Krisztian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Microelectronics and Materials Physics Laboratories, University of Oulu, FIN-90570 Oulu, Finland.
    Leino, A-R
    Microelectronics and Materials Physics Laboratories, University of Oulu, FIN-90570 Oulu, Finland.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Effective dispersion of Au and Au-M (M = Co, Ni, Cu and Zn) bimetallic nanoparticles over TiO2 grafted SBA-15: their catalytic activity on dehydroisomerization of α-pinene2013Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 173, s. 99-111Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mesostructured siliceous SBA-15 was synthesized via direct hydrothermal crystallization from acidic solution of poly-(ethylene glycol)-block-poly(propylene glycol)-block poly(ethylene glycol)-copolymer and tetraethyl orthosilicate. The amorphous surface of the calcined Si-SBA-15 was modified with 20wt.% of TiO2 by chemical grafting method using titanium isopropoxide as the titanium source in ethanol solution. Various metal nanoparticles Au, Au-M (M = Co, Ni, Cu and Zn) were supported on TiO2/SBA-15 by deposition-precipitation method (DP) using urea as the precipitating agent. The structural features of the synthesized materials were characterized by various physico-chemical techniques such as X-ray diffraction, nitrogen sorption, XPS and HR-TEM. BET results of Si-SBA-15 revealed the formation of mesoporous structure with an average pore size of 5.9nm, pore volume of 1.12 cm3/g and the specific surface area of 846 m2/g. HR-TEM results demonstrated that metal nanoparticles were highly dispersed over TiO2/SBA-15 and long range ordering of hexagonal mesopores of Si-SBA-15 was well retained after loading of 20 wt.% TiO2 and 3 wt.% of bimetallic nanoparticles. The catalytic performances of the prepared catalysts were studied on dehydroisomerization of α-pinene under gas phase conditions using hydrogen atmosphere. The stability and catalytic activity of Au-M-TiO2/SBA-15 (DP) catalysts upon conversion of α-pinene in to p-cymene was explored in comparison with the catalysts prepared by conventional method. AuNi-TiO2/SBA-15 catalysts prepared via DP method were found to be stable upon longer reaction time as well as superior in terms of conversion and selective towards the formation of p-cymene.

  • 29.
    Samikannu, Ajaikumar
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Konwar, Lakhya Jyoti
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mäki-Arvela, Päivi
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Turku, FI-20500, Finland.
    Renewable N-doped active carbons as efficient catalysts for direct synthesis of cyclic carbonates from epoxides and CO22019Inngår i: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 241, s. 41-51Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the spirit of green chemistry and greenhouse gas mitigation, we explore herein the chemical utilization of CO2 upon synthesis of cyclic carbonates over N-doped activated carbons. The N-doped carbocatalysts were obtained from inexpensive N-rich bio-waste precursors and characterized by standard techniques (N2 physisorption, chemisorption, XPS, SEM, TEM, XRD, FT-IR and Micro-Raman spectroscopy). The materials exhibited excellent catalytic activity for direct carbonation of epoxides with CO2 to cyclic carbonates (yields upto 99%) under solvent free, moderate temperature (100–150 °C) and low CO2 pressure (5–50 bar) conditions. The observed catalytic activity of the N-doped carbocatalysts was attributed to the Lewis basic sites originating from pyridinic, pyridonic, and quaternary N-sites capable of activating the CO2 molecule. While control experiments with multiwalled carbon nanotubes (MWCNT) or commercial activated carbon, failed to produce cyclic carbonates due to lack of active (basic) sites. In terms of the catalytic performance, the N-doped carbocatalysts presenting a high porosity (634–1316 m2/g) and high levels of pyridinic (33%) and quaternary N-doping (30%), (i.e. CA500 and MA500), exhibited the highest activity and selectivity (TOF, conversion and cyclic carbonate yields upto 99% in 5–15 h). Most importantly, these materials demonstrated good operational stability and reusability.

  • 30.
    Samikannu, Rakesh
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shukla, Shashi Kant
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo Akademi University, Process Chemistry Centre, Laboratory of Industrial Chemistry and Reaction Engineering, FI-20500 Turku, Finland.
    Lutidinium-Based Ionic Liquids for Efficient Dissolution of Cellulose2019Inngår i: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 43, nr 5, s. 2299-2306Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Herein, we have studied the potential of lutidinium-based ILs (1-allyl-3,5-dimethylpyridinium chloride [3,5-ADMPy]Cl and 1-allyl-3,4-dimethylpyridinium chloride [3,4-ADMPy]Cl) in the dissolution of cellulose, and their structures were confirmed by 1H and 13C NMR spectra, respectively. [3,5-ADMPy]Cl exhibited the highest capacity in cellulose dissolution. In fact, it dissolved 20 wt% of cellulose within 12 min and 26 wt% of cellulose in 35 min at 118 °C. The crystallinity and morphology of native and regenerated cellulose were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and CP/MAS 13C NMR spectroscopy. These techniques clearly suggest that the crystallinity of cellulose is reduced upon treatment in lutidinium-based ILs. The thermogravimetric analysis (TGA) showed that regenerated cellulose had thermal stability close to that of native cellulose.

  • 31. Verziu, Marian
    et al.
    Tirsoaga, Alina
    Cojocaru, Bogdan
    Bucur, Cristina
    Tudora, Bogdan
    Richel, Aurore
    Aguedo, Mario
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, FI-20500, Finland.
    Hydrogenolysis of lignin over Ru-based catalysts: the role of the ruthenium in a lignin fragmentation process2018Inngår i: Molecular Catalysis, ISSN 2468-8231, Vol. 450, s. 65-76Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The catalytic performances of two different classes of catalysts containing nickel or/and ruthenium as the active sites were studied in the depolymerisation of lignin isolated from Miscanthus×giganteus. The catalysts were prepared either by coprecipitation (ie, (RuNiMgAlO)x, (RuNiAlO)x, (NiAlO)x, (NiMgAlO)x) or by wet impregnation (ie, Ru/Al2O3) and characterized by nitrogen physisorption (BET), XRD, XPS, NH3-TPD, Raman and H2-TPR techniques. The experimental results indicate that the presence of ruthenium led to dimers as dominant products.

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