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Siljebo, William
Alternative names
Publications (10 of 24) Show all publications
Bukhanko, N., Schwarz, C., Samikannu, A., Ngoc Pham, T., Siljebo, W., Wärnå, J., . . . Mikkola, J.-P. (2017). Gas phase synthesis of isopropyl chloride from isopropanol and HCl over alumina and flexible 3-D carbon foam supported catalysts. Applied Catalysis A: General, 542(25), 212-225
Open this publication in new window or tab >>Gas phase synthesis of isopropyl chloride from isopropanol and HCl over alumina and flexible 3-D carbon foam supported catalysts
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2017 (English)In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 542, no 25, p. 212-225Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Isopropyl chloride; Heterogeneous catalysis; Isopropanol; Hydrochlorination; Zinc chloride; Alumina oxide; Carbon foam; Highly porous catalyst
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-127043 (URN)10.1016/j.apcata.2017.05.013 (DOI)000405765200019 ()
Projects
Bio4Energy
Available from: 2016-10-26 Created: 2016-10-26 Last updated: 2019-09-02Bibliographically approved
Ngoc Pham, T., Sharifi, T., Sandström, R., Siljebo, W., Shchukarev, A., Kordas, K., . . . Mikkola, J.-P. (2017). Robust hierarchical 3D carbon foam electrode for efficient water electrolysis. Scientific Reports, 7, Article ID 6112.
Open this publication in new window or tab >>Robust hierarchical 3D carbon foam electrode for efficient water electrolysis
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2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 6112Article in journal (Refereed) Published
Abstract [en]

Herein we report a 3D heterostructure comprising a hierarchical macroporous carbon foam that incorporates mesoporous carbon nanotubes decorated with cobalt oxide nanoparticles as an unique and highly efficient electrode material for the oxygen evolution reaction (OER) in electrocatalytic water splitting. The best performing electrode material showed high stability after 10 h, at constant potential of 1.7 V vs. RHE (reversible hydrogen electrode) in a 0.1 M KOH solution and high electrocatalytic activity in OER with low overpotential (0.38 V vs RHE at 10 mA cm(-2)). The excellent electrocatalytic performance of the electrode is rationalized by the overall 3D macroporous structure and with the firmly integrated CNTs directly grown on the foam, resulting in a large specific surface area, good electrical conductivity, as well as an efficient electrolyte transport into the whole electrode matrix concurrent with an ability to quickly dispose oxygen bubbles into the electrolyte. The eminent properties of the three-dimensional structured carbon matrix, which can be synthesized through a simple, scalable and cost effective pyrolysis process show that it has potential to be implemented in large-scale water electrolysis systems.

National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:umu:diva-127042 (URN)10.1038/s41598-017-05215-1 (DOI)000406285700020 ()28733585 (PubMedID)
Projects
Bio4Energy
Available from: 2016-10-26 Created: 2016-10-26 Last updated: 2019-08-30Bibliographically approved
Huang, Y., Siljebo, W. & Westlund, P.-O. (2015). Water proton and deuterium spin-lattice relaxation in Zeolite ZSM-5 by fast field-cycling NMR relaxometry.
Open this publication in new window or tab >>Water proton and deuterium spin-lattice relaxation in Zeolite ZSM-5 by fast field-cycling NMR relaxometry
2015 (English)Manuscript (preprint) (Other academic)
Abstract [en]

The water dynamics in the confined space of the zeolite ZSM-5 has bee ninvestigated by means of the field dependence of 1H- and 2H- spin-lattice relaxation rates using a 1T Stelar FFC2000 fast field-cycling instrument. The NMRD analysis of  the experimental results indicates that the characteristic time dependence ( 50 ns to 1-2.4 μs) is due to water translational diffusion in narrow pores. The temperature dependence of the spin-lattice relaxation rates is weak.Zeolites with different counter ions( H+, NH4+ change the water hydration and the water translational diffusion in the pores drastically. The Zeolite-NH4+ slow down the water motion with a factor of 2.The NMRD profiles show somewhat stretched character and is described by two Lorenzian which indicates that the distribution of pore sizes is broaden.The water 1H and 2H spin lattice relaxation profiles give qualitatively information about water hydration in zeolites with different counter ions and is expected also to indicate structural changes of the zeolites. 

Keywords
proton, deuterium, spin lattice, relaxation, ZSM-5, zeolite
National Category
Theoretical Chemistry
Research subject
Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-110716 (URN)
Note

2015, in manuscript

Available from: 2015-10-26 Created: 2015-10-26 Last updated: 2018-06-07
Reinik, J., Heinmaa, I., Ritamäki, J., Boström, D., Pongracz, E., Huuhtanen, M., . . . Mikkola, J.-P. (2014). DIRECT CO2 SEQUESTRATION ONTO ALKALINE MODIFIED OIL SHALE FLY ASH. Gorûcie slancy, 31(1), 79-90
Open this publication in new window or tab >>DIRECT CO2 SEQUESTRATION ONTO ALKALINE MODIFIED OIL SHALE FLY ASH
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2014 (English)In: Gorûcie slancy, ISSN 0208-189X, E-ISSN 1736-7492, Vol. 31, no 1, p. 79-90Article in journal (Refereed) Published
Abstract [en]

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

Keywords
tobermorites, direct CO2 sequestration, oil shale fly ash
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-88297 (URN)10.3176/oil.2014.1.08 (DOI)000333225900008 ()
Available from: 2014-05-08 Created: 2014-04-29 Last updated: 2018-06-07Bibliographically approved
Bukhanko, N., Samikannu, A., Larsson, W., Shchukarev, A., Leino, A.-R., Kordas, K., . . . Mikkola, J.-P. (2013). Continuous gas phase synthesis of 1-ethyl chloride from ethyl alcohol and hydrochloric acid over Al2O3-based catalysts: the ‘green’ route. ACS Sustainable Chemistry & Engineering, 1(8), 883-893
Open this publication in new window or tab >>Continuous gas phase synthesis of 1-ethyl chloride from ethyl alcohol and hydrochloric acid over Al2O3-based catalysts: the ‘green’ route
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2013 (English)In: ACS Sustainable Chemistry & Engineering, Vol. 1, no 8, p. 883-893Article in journal (Refereed) Published
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.

Keywords
ethyl chloride, ethanol, heterogeneous catalysis, zinc chloride, high-porosity aluminum oxide
National Category
Chemical Sciences Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-71424 (URN)10.1021/sc300171m (DOI)000322863100004 ()
Available from: 2013-05-29 Created: 2013-05-29 Last updated: 2018-06-08Bibliographically approved
Samikannu, A., Golets, M., Larsson, W., Shchukarev, A., Kordas, K., Leino, A.-R. & Mikkola, J.-P. (Eds.). (2013). Dehydroisomerization of α-pinene over metal supported Si-SBA-15 mesoporous molecular sieves. Paper presented at 11th European Congress on Catalysis – EuropaCat-XI, Lyon, France.. 11th European Congress on Catalysis – EuropaCat-XI
Open this publication in new window or tab >>Dehydroisomerization of α-pinene over metal supported Si-SBA-15 mesoporous molecular sieves
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2013 (English)Conference proceedings (editor) (Refereed)
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.

Place, publisher, year, edition, pages
11th European Congress on Catalysis – EuropaCat-XI, 2013
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-79824 (URN)
Conference
11th European Congress on Catalysis – EuropaCat-XI, Lyon, France.
Available from: 2013-09-03 Created: 2013-09-03 Last updated: 2018-06-08Bibliographically approved
Samikannu, A., Golets, M., Larsson, W., Shchukarev, A., Kordas, K., Leino, A.-R. & Mikkola, J.-P. (2013). 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-pinene. Microporous and Mesoporous Materials, 173, 99-111
Open this publication in new window or tab >>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-pinene
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2013 (English)In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 173, p. 99-111Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Amsterdam: Elsevier, 2013
Keywords
Supported bimetal catalysts, TiO2/SBA-15, Dehydroisomerization, α-Pinene, p-Cymene
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-65772 (URN)10.1016/j.micromeso.2013.02.015 (DOI)000318210100015 ()
Available from: 2013-02-11 Created: 2013-02-11 Last updated: 2018-06-08Bibliographically approved
Ahlkvist, J., Ajaikumar, S., Larsson, W. & Mikkola, J.-P. (2013). One-pot catalytic conversion of Nordic pulp media into green platform chemicals. Applied Catalysis A: General, 454, 21-29
Open this publication in new window or tab >>One-pot catalytic conversion of Nordic pulp media into green platform chemicals
2013 (English)In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 454, p. 21-29Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2013
Keywords
Wood pulp, Solid acid catalysis, Amberlyst 70, Levulinic acid, Formic acid
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:umu:diva-64221 (URN)10.1016/j.apcata.2013.01.004 (DOI)000317870000004 ()
Available from: 2013-01-21 Created: 2013-01-21 Last updated: 2018-06-08Bibliographically approved
Wu, M.-C., Liao, H.-C., Cho, Y.-C., Hsu, C.-P., Lin, T.-H., Su, W.-F., . . . Kordas, K. (2013). Photocatalytic activity of nitrogen-doped TiO2-based nanowires: a photo-assisted Kelvin probe force microscopy study. Journal of nanoparticle research, 16(1), Article Number: UNSP 2143
Open this publication in new window or tab >>Photocatalytic activity of nitrogen-doped TiO2-based nanowires: a photo-assisted Kelvin probe force microscopy study
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2013 (English)In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 16, no 1, p. Article Number: UNSP 2143-Article in journal (Refereed) Published
Abstract [en]

In this study, a set of nitrogen-doped TiO2-based nanomaterials demonstrating photocatalytic activity was developed by combining the efforts of lattice doping and metal nanoparticle decoration and tested for photo-degradation of methylene blue dye by applying solar simulator irradiation. The surface potential shifts of these TiO2-based photocatalytic nanomaterials measured by Kelvin probe force microscope have been used to study the degree of electron generation of the photocatalysts after irradiation and were well correlated with the photocatalytic activity. The nitrogen-doped TiO2 nanowires decorated with Pt nanoparticles can induce obvious electron accumulation and result in a large shift of surface potential. The analysis shows a clear correlation between the surface potential shift and the photodegradation activity. Furthermore, a thorough comparative photocatalytic activity study combined with X-ray photoelectron spectroscopy analysis of the materials-doped with nitrogen under various conditions-reveals that the photocatalytic efficiency of the catalysts is maintained even if the lattice doping is leached e.g., by thermal treatments after doping. By monitoring the surface potential shifts of various TiO2-based photocatalysts by photo-assisted Kelvin probe force microscopy, we obtain a useful tool for developing novel materials with high photocatalytic activity.

Place, publisher, year, edition, pages
Springer, 2013
Keywords
Kelvin probe force microscopy, Photocatalyst, TiO2, Surface potential, Nanostructured catalyst, Photodegradation
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-85288 (URN)10.1007/s11051-013-2143-y (DOI)000328228700001 ()
Funder
EU, FP7, Seventh Framework ProgrammeBio4Energy
Available from: 2014-02-05 Created: 2014-01-31 Last updated: 2018-06-08Bibliographically approved
Ahlkvist, J., Samikannu, A., Larsson, W., Wärnå, J., Salmi, T. & Mikkola, J.-P. (2013). Reaction Network upon One-pot Catalytic Conversion of Pulp. In: Sauro Pierucci, Jiří J. Klemeš (Ed.), : . Paper presented at 11th International Conference on Chemical and Process Engineering (ICheaP),Milan, ITALY, JUN 02-05, 2013 (pp. 649-654). AIDIC - associazione italiana di ingegneria chimica, 32
Open this publication in new window or tab >>Reaction Network upon One-pot Catalytic Conversion of Pulp
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2013 (English)In: / [ed] Sauro Pierucci, Jiří J. Klemeš, AIDIC - associazione italiana di ingegneria chimica, 2013, Vol. 32, p. 649-654Conference paper, Published 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.

Place, publisher, year, edition, pages
AIDIC - associazione italiana di ingegneria chimica, 2013
Series
Chemical Engineering Transactions, ISSN 1974-9791 ; 32
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-72681 (URN)10.3303/CET1332109 (DOI)000335952100109 ()978-88-95608-23-5 (ISBN)
Conference
11th International Conference on Chemical and Process Engineering (ICheaP),Milan, ITALY, JUN 02-05, 2013
Available from: 2013-06-10 Created: 2013-06-10 Last updated: 2018-06-08Bibliographically approved
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