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Wärnå, Johan
Publications (10 of 11) Show all publications
Ahlkvist, J., Wärnå, J., Salmi, T. & Mikkola, J.-P. (2016). Heterogeneously catalyzed conversion of nordic pulp to levulinic and formic acids. Reaction Kinetics, Mechanisms and Catalysis, 119(2), 415-427
Open this publication in new window or tab >>Heterogeneously catalyzed conversion of nordic pulp to levulinic and formic acids
2016 (English)In: Reaction Kinetics, Mechanisms and Catalysis, ISSN 1878-5190, E-ISSN 1878-5204, Vol. 119, no 2, p. 415-427Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Springer, 2016
Keywords
Heterogeneous acid catalysis, Amberlyst 70, Levulinic and formic acids
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-124987 (URN)10.1007/s11144-016-1069-7 (DOI)000388189000004 ()
Projects
Bio4Energy
Available from: 2016-09-01 Created: 2016-09-01 Last updated: 2019-08-29Bibliographically approved
Bukhanko, N., Wärnå, J., Samikannu, A. & Mikkola, J.-P. (2016). Kinetic modeling of gas phase synthesis of ethyl chloride from ethanol and HCl in fixed bed reactor. Chemical Engineering Science, 142, 310-317
Open this publication in new window or tab >>Kinetic modeling of gas phase synthesis of ethyl chloride from ethanol and HCl in fixed bed reactor
2016 (English)In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 142, p. 310-317Article in journal (Refereed) Published
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.

Keywords
Ethyl chloride, Kinetic modeling, Gas-phase reaction, Heterogeneous catalysis
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-114093 (URN)10.1016/j.ces.2015.12.005 (DOI)000369068500027 ()
Projects
Bio4Energy
Available from: 2016-01-13 Created: 2016-01-13 Last updated: 2019-08-29Bibliographically approved
Konwar, L. J., Wärnå, J., Mäki-Arvela, P., Kumar, N. & Mikkola, J.-P. (2016). Reaction kinetics with catalyst deactivation in simultaneous esterification and transesterification of acid oils to biodiesel (FAME) over a mesoporous sulphonated carbon catalyst. Fuel, 166, 1-11
Open this publication in new window or tab >>Reaction kinetics with catalyst deactivation in simultaneous esterification and transesterification of acid oils to biodiesel (FAME) over a mesoporous sulphonated carbon catalyst
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2016 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 166, p. 1-11Article in journal (Refereed) Published
Abstract [en]

In this work, a careful analysis of the reaction kinetics upon simultaneous esterification and transesterification of acidic oils over a mesoporous sulphonated carbon catalyst is discussed. A batch reactor system was used and the synthesized carbon catalyst were characterized by N2-physisorption, transmission electron microscopy, elemental analysis and NH3-TPD. A second order pseudo-homogeneous kinetic model was proposed which explained the experimental results obtained for three different feedstock oils with ⩾98% accuracy. The rate constants (k), activation energies (Ea) and equilibrium constants (Keq) of the individual reactions were determined by regression analysis which confirmed that the reaction steps were kinetically controlled and not limited by inter-particle diffusion or external mass transfer limitations (Ea > 25 kJ mol−1). Furthermore, the composition feedstock was found to have a distinct effect on the solubility of methanol and oil phase which influenced k, Keq and Ea values, eventually determining the final biodiesel (FAME) yield. To account for the loss of activity upon catalyst reuse, a deactivation model was also proposed which explained our results with ∼94% accuracy. In fact, the loss of activity was accounted for by incorporating a concentration-independent ‘deactivation constant’ kd in the reaction rate equations. Moreover, under optimized reaction conditions (120 °C and 20:1 methanol-to-FFA molar ratio), FAME yields up to 79–91 wt% could be obtained in one step process from oils containing 21–41 wt% FFA.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Biodiesel, Sulfonated carbon, Heterogeneous catalysis, Kinetics
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-111645 (URN)10.1016/j.fuel.2015.10.102 (DOI)000365627700001 ()
Projects
Bio4Energy
Available from: 2015-11-19 Created: 2015-11-19 Last updated: 2019-08-30Bibliographically approved
Murzin, D. Y., Kusema, B., Murzina, E. V., Aho, A., Tokarev, A., Boymirzaev, A. S., . . . Salmi, T. (2015). Hemicellulose arabinogalactan hydrolytic hydrogenation over Ru-modified H-USY zeolites. Journal of Catalysis, 330, 93-105
Open this publication in new window or tab >>Hemicellulose arabinogalactan hydrolytic hydrogenation over Ru-modified H-USY zeolites
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2015 (English)In: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 330, p. 93-105Article in journal (Refereed) Published
Abstract [en]

The hydrolytic hydrogenation of hemicellulose arabinogalactan was investigated in the presence of protonic and Ru (1-5 wt.%)-modified USY zeolites (Si/Al ratio = 15 and 30). The use of the purely acidic materials was effective in depolymerizing the macromolecule into free sugars. While the latter partly dehydrated into 5-hydroxymethylfurfural and furfural, the generation of high molecular-weight compounds (aggregates of sugars and humins) was not favored, in contrast to previous evidences over beta zeolites. Application of the bifunctional Ru/USY catalyst, comprising well-dispersed metallic nanopartides on the aluminosilicate support, resulted in the formation of galactitol and arabitol, in the suppression of dehydration side products, and further inhibition of polymerization reactions, which only yielded low molecular-weight oligomers. Detailed analysis of the reaction pathways as well as kinetic modeling of hydrolytic hydrogenation was performed with an advanced reaction mechanism.

Keywords
Arabinogalactan, Bifunctional catalysis, Biomass upgrading, Ru/USY zeolites, Hydrolysis
National Category
Organic Chemistry
Identifiers
urn:nbn:se:umu:diva-111008 (URN)10.1016/j.jcat.2015.06.022 (DOI)000362603200009 ()
Available from: 2015-11-11 Created: 2015-11-02 Last updated: 2018-06-07Bibliographically approved
Rozmyslowicz, B., Kirilin, A., Aho, A., Manyar, H., Hardacre, C., Wärnå, J., . . . Murzin, D. Y. (2015). Selective hydrogenation of fatty acids to alcohols over highly dispersed ReOx/TiO2 catalyst. Journal of Catalysis, 328, 197-207
Open this publication in new window or tab >>Selective hydrogenation of fatty acids to alcohols over highly dispersed ReOx/TiO2 catalyst
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2015 (English)In: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 328, p. 197-207Article in journal (Refereed) Published
Abstract [en]

Production of fatty alcohols through selective hydrogenation of fatty acids was studied over a 4% ReOx/TiO2 catalyst. Stearic acid was hydrogenated to octadecanol at temperatures and pressures between 180-200 degrees C and 2-4 MPa, with selectivity reaching 93%. A high yield of octadecanol was attributed to a strong adsorption of the acid compared to alcohol on the catalyst, which inhibits further alcohol transformation to alkanes. Low amounts (<7%) of alkanes (mainly octadecane) were formed during the conversion of stearic acid. However, it was found that the catalyst could be tuned for the production of alkanes. The reaction intermediates were octadecanal and stearyl stearate. Based on the reaction products analysis and catalyst characterization, a reaction mechanism and possible pathways were proposed.

Keywords
Fatty acids, Fatty alcohols, Rhenium, Selective hydrogenation, Hydrocarbons
National Category
Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-106553 (URN)10.1016/j.jcat.2015.01.003 (DOI)000356748300023 ()
Available from: 2015-07-20 Created: 2015-07-20 Last updated: 2018-06-07Bibliographically approved
Riittonen, T., Salmi, T., Mikkola, J.-P. & Wärnå, J. (2014). Direct Synthesis of 1-Butanol from Ethanol in a Plug Flow Reactor: Reactor and Reaction Kinetics Modeling. Topics in catalysis, 57(17-20), 1425-1429
Open this publication in new window or tab >>Direct Synthesis of 1-Butanol from Ethanol in a Plug Flow Reactor: Reactor and Reaction Kinetics Modeling
2014 (English)In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 57, no 17-20, p. 1425-1429Article in journal (Refereed) Published
Abstract [en]

Bio-ethanol is well known for its use as a gasoline additive. However, it can be blended in low portions to traditional gasoline although it has a corrosive nature. By taking advantage of modern continuous reactor technology and heterogeneous alumina catalysts, ethanol can be upgraded to 1-butanol in fixed beds. Butanol has more feasible properties as fuel component in comparison to ethanol. Mathematical modeling of reaction kinetics revealed a simple kinetic model could be used to describe the complex reaction process on a Cu/alumina catalyst. The reaction kinetics model is based on five parallel reactions in which ethanol reacts to 1-butanol, acetealdehyde, ethyl acetate, diethyl ether and diethoxyethane, respectively.

Keywords
Bio-ethanol, Bi-butanol, Heterogeneous catalyst, Reaction kinetics, Fixed bed
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-96944 (URN)10.1007/s11244-014-0314-4 (DOI)000344158300018 ()
Available from: 2015-01-30 Created: 2014-12-05 Last updated: 2018-06-07Bibliographically approved
Leveneur, S., Zheng, J., Taouk, B., Burel, F., Wärnå, J. & Salmi, T. (2014). Interaction of thermal and kinetic parameters for a liquid-liquid reaction system: Application to vegetable oils epoxidation by peroxycarboxylic acid. Journal of the Taiwan Institute of Chemical Engineers / Elsevier, 45(4), 1449-1458
Open this publication in new window or tab >>Interaction of thermal and kinetic parameters for a liquid-liquid reaction system: Application to vegetable oils epoxidation by peroxycarboxylic acid
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2014 (English)In: Journal of the Taiwan Institute of Chemical Engineers / Elsevier, ISSN 1876-1070, E-ISSN 1876-1089, Vol. 45, no 4, p. 1449-1458Article in journal (Refereed) Published
Abstract [en]

A mathematical model was developed to analyze an exothermic liquid-liquid reaction system using epoxidation of oleic acid by peroxyformic acid formed in situ as an example. Kinetic and thermal parameters were included, mass transfer parameters were eliminated from the model and evaporation/condensation was taken into account. A calorimetric semi-batch reactor under isoperibolic mode was used in the experimental work. Different initial aqueous-phase concentrations of H2O2 [6.5-8.8 mol/l], water [44-45 mol/l], molar flow rate of formic acid [0.02-0.54 mol/min], initial reaction temperature [50-70 degrees C] and amount of organic phase [34-46 wt.%] were studied. A non-linear regression method was used to estimate kinetic (e.g., rate constant at average temperature and activation energy) and thermal parameters (e.g., reaction enthalpy) of the epoxidation and ring-opening reactions. The standard reaction enthalpy changes were estimated to be -116 kJ/mol for epoxidation reaction and -50 kJ/mol for the ring opening. (C) 2014 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Keywords
Kinetic modeling, Calorimetry, Liquid-liquid reaction system, Epoxidation of vegetable oils
National Category
Organic Chemistry
Identifiers
urn:nbn:se:umu:diva-93236 (URN)10.1016/j.jtice.2014.01.015 (DOI)000340352000041 ()
Available from: 2014-12-22 Created: 2014-09-15 Last updated: 2018-06-07Bibliographically approved
Salmi, T., Murzin, D. Y., Mäki-Arvela, P., Kusema, B., Holmbom, B., Willfor, S. & Wärnå, J. (2014). Kinetic modeling of hemicellulose hydrolysis in the presence of homogeneous and heterogeneous catalysts. AIChE Journal, 60(3), 1066-1077
Open this publication in new window or tab >>Kinetic modeling of hemicellulose hydrolysis in the presence of homogeneous and heterogeneous catalysts
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2014 (English)In: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 60, no 3, p. 1066-1077Article in journal (Refereed) Published
Abstract [en]

Kinetic models were developed for the hydrolysis of O-acetyl-galactoglucomannan (GGM), a hemicellulose appearing in coniferous trees. Homogeneous and heterogeneous acid catalysts hydrolyze GGM at about 90°C to the monomeric sugars galactose, glucose, and mannose. In the presence of homogeneous catalysts, such as HCl, H2SO4, oxalic acid, and trifluoroacetic acid, the hydrolysis process shows a regular kinetic behavior, while a prominent autocatalytic effect was observed in the presence of heterogeneous cation-exchange catalysts, Amberlyst 15 and Smopex 101. The kinetic models proposed were based on the reactivities of the nonhydrolyzed sugar units and the increase of the rate constant (for heterogeneous catalysts) as the reaction progresses and the degree of polymerization decreases. General kinetic models were derived and special cases of them were considered in detail, by deriving analytical solutions for product distributions. The kinetic parameters, describing the autocatalytic effect were determined by nonlinear regression analysis. The kinetic model described very well the overall kinetics, as well as the product distribution in the hydrolysis of water soluble GGM by homogeneous and heterogeneous catalysts. The modelling principles developed in the work can be in principle applied to hydrolysis of similar hemicelluloses as well as starch and cellulose.

© 2014 American Institute of Chemical Engineers AIChE J, 60: 1066–1077, 2014

Place, publisher, year, edition, pages
John Wiley & Sons, 2014
Keywords
hemicellulose hydrolysis; kinetics; mechanism; autocatalysis; homogeneous catalyst; heterogeneous catalyst
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-87150 (URN)10.1002/aic.14311 (DOI)000331338600020 ()
Available from: 2014-04-11 Created: 2014-03-24 Last updated: 2018-06-08Bibliographically 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
Golets, M., Samikannu, A., Mohln, M., Wärnå, J., Rakesh, S. & Mikkola, J.-P. (2013). Continuous production of the renewable ρ-cymene from α-pinene. Journal of Catalysis, 307, 305-315
Open this publication in new window or tab >>Continuous production of the renewable ρ-cymene from α-pinene
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2013 (English)In: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 307, p. 305-315Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2013
Keywords
q-Cymene, a-Pinene isomerization, Heterogeneous catalyst, Flow-through reactor
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-80681 (URN)10.1016/j.jcat.2013.08.007 (DOI)000327903900033 ()
Funder
Bio4Energy
Note

Continuous production of the renewable rho-cymene from alpha-pinene

Available from: 2013-09-23 Created: 2013-09-23 Last updated: 2018-06-08Bibliographically approved
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