| 1. |
- Anugwom, Ikenna, et al.
(författare)
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Treating birch wood with a switchable 1,8-diazabicyclo-[5.4.0]-undec-7-ene-glycerol carbonate ionic liquid
- 2012
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 66:7, s. 809-815
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Tidskriftsartikel (refereegranskat)abstract
- The suitability of a new switchable ionic liquid (SIL) has been investigated as a solvent for fractionation of lignocellulosic materials. SIL was prepared from inexpensive chemicals, e. g., glycerol, CO2, and 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU). Fresh Nordic birch wood (B. pendula) was treated with the SIL for a time period of 1-5 days at 100 degrees C and under atmospheric pressure. Upon SIL treatment, at best, 57 % of the hemicelluloses were dissolved and 50 % of lignins were dissolved from the native birch. The slightly fibrillated SIL treated chips contained about 55 % cellulose. Up to 76 % of the recovered species removed from the spent SIL liquor was originating from hemicelluloses, mainly from xylan. The spent SILs were reused for fresh wood dissolution in four consecutive cycles and each time the wood dissolution efficiency was similar. SILs could offer affordable (easy-to-synthesize) solvent systems for partial elimination of hemicelluloses and lignin from wood. SILs can also be prepared in-situ and on-site.
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| 2. |
- Eta, Valerie, et al.
(författare)
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The Effect of Alkoxide Ionic Liquids on the Synthesis of Dimethyl Carbonate from CO2 and Methanol over ZrO2-MgO
- 2011
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Ingår i: Catalysis Letters. - : Springer Science and Business Media LLC. - 1011-372X .- 1572-879X. ; 141:9, s. 1254-1261
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Tidskriftsartikel (refereegranskat)abstract
- The use of carbon dioxide in the synthesis of chemicals, such as dimethyl carbonate (DMC), constitutes an environmentally attractive alternative to hazardous and toxic reagents. However, the direct synthesis of DMC from methanol and CO2 is characterized by low yields due to the reaction equilibrium and the thermodynamic limitations (Delta G(298K)(0) = + 26.3 kj/mol). Alkoxide ionic liquids possessing alkylimidazolium and benzalkonium cations were prepared, characterised and tested together with ZrO2-MgO catalyst for the synthesis of DMC from methanol and CO2. By using the novel ionic liquid as additives, ca. 12% conversion of methanol, and 90% selectivity to DMC was obtained at 120 A degrees C and 7.5 MPa. The water abstracting potential of the ionic liquids influenced the conversion of methanol and the selectivity to DMC. The alkoxide ionic liquids were recovered and reused in DMC synthesis without loss in activity and selectivity.
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| 3. |
- Konwar, Lakhya Jyoti, et al.
(författare)
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Towards carbon efficient biorefining : Multifunctional mesoporous solid acids obtained from biodiesel production wastes for biomass conversion
- 2015
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Ingår i: Applied Catalysis B. - : Elsevier. - 0926-3373 .- 1873-3883. ; 176, s. 20-35
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Tidskriftsartikel (refereegranskat)abstract
- Multifunctional mesoporous solid acids were prepared by the sulfonation of carbonized de-oiled seed waste cake (DOWC), a solid waste from biodiesel production. Detailed structural characterization of the materials by elemental analysis, FT-IR, Raman, XRD, XPS, TGA, NH3-TPD and N-2-physisorption showed that they were structurally different from the carbohydrate and resin based sulfonated carbon catalysts. In addition to the typical -OH, -COOH and -SO3H groups they contain several N species (pyridinic, pyrrolic etc.) incorporated in their carbon frameworks. The basic structural unit of these materials is a flexible carbon nitride sheet which is extensively functionalized with acidic groups. Our results show distinct effects of raw material composition and preparation methods (activation, sulfonating agent etc.) on structure, stability, surface acidity and textural properties. Here, catalyst -SO3H density and porosity (pore size, pore volume and surface area) had a direct effect on activity. Also, H2SO4 was less useful than 4-BDS (4-benzenediazoniumsulfoante) as a sulfonating agent. The best catalysts with mesoporous structure (average pore diameter 3.9-4.8 nm, pore volume 0.28-0.46 cm(3) g(-1)) and -SO3H density (0.70-0.84 mmol/g(cat)) were obtained by 4-BDS sulfonation of chemically activated DOWCs. In contrast, hydrothermal H2SO4 sulfonation of DOWC produced a non-porous catalyst with high -SO3H density while those obtained by H2SO4 treatment of activated biomass (AC) had a porous structure with low -SO3H density (0.19 mmol/gcat). Furthermore, the reported catalysts show excellent activity in two reactions of interest in biomass conversion: cellulose saccharification (glucose yield 35-53%) and fatty acid esterification (conversion upto 97%) outperforming H2SO4, conventional solid acids (zeolites, ion-exchange resins etc.) as well as sulfonated carbons reported earlier works, confirming their potential as alternative environmentally benign solid catalysts for sustainable, carbon efficient biorefining.
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| 4. |
- Leino, Ewelina, et al.
(författare)
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Influence of the synthesis parameters on the physico-chemical and catalytic properties of cerium oxide for application in the synthesis of diethyl carbonate
- 2013
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Ingår i: Materials Chemistry and Physics. - : Elsevier. - 0254-0584 .- 1879-3312. ; 143:1, s. 65-75
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Tidskriftsartikel (refereegranskat)abstract
- Synthesis of cerium (IV) oxide by means of room temperature precipitation method was carried out. The effect of preparation variables such as synthesis time, calcination temperature and pH of the solution on resulting CeO2 properties was discussed. Moreover, the comparison of CeO2 samples prepared in a static and rotation mode of synthesis is presented. The solid catalysts were characterized by means of X-ray powder diffraction, scanning electron microscopy, transmission electron microscope, nitrogen physisorption, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy using pyridine as a probe molecule and temperature programmed desorption of CO2. Significant variations in physicochemical properties of CeO2 by varying the preparation conditions were observed. Furthermore, the catalytic performances of CeO2 catalysts were compared in the synthesis of diethyl carbonate starting from ethanol and CeO2 using butylene oxide as a dehydrating agent. The dependence of CeO2 properties on its catalytic activity is evaluated in detail. (C) 2013 Elsevier B.V. All rights reserved.
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| 5. |
- Privalova, Elena I., et al.
(författare)
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Imidazolium-Based Poly(ionic liquid)s as New Alternatives for CO2 Capture
- 2013
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Ingår i: ChemSusChem. - : Wiley-VCH Verlagsgesellschaft. - 1864-5631 .- 1864-564X. ; 6:8, s. 1500-1509
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Tidskriftsartikel (refereegranskat)abstract
- Solid imidazolium-based poly(ionic liquid)s with variable molecular weights that contain the poly[2-(1-butylimidazolium-3-yl)ethyl methacrylate] (BIEMA) cation and different counter anions were evaluated in terms of CO2 capture and compared with classical ionic liquids with similar counter anions. In addition to poly(ionic liquid)s with often-applied ions such as BF4-, PF6-, NTf2-, trifluoromethanesulfonate (OTf-) and Br-, for the first time [BIEMA][acetate] was synthesised, which revealed a remarkably high CO2 sorption performance that exceeded the poly(ionic liquid)s studied previously on average by a factor of four (12.46mgg(PIL)(-1)). This study provides an understanding of the factors that affect CO2 sorption and a comparison of the CO2 capture efficiency with the frequently used sorbents. Moreover, all the studied sorbents were reusable if regenerated under carefully selected conditions and can be considered as suitable candidates for CO2 sorption.
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| 6. |
- Salminen, Eero, et al.
(författare)
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Etherification of 5-Hydroxymethylfurfural to a Biodiesel Component Over Ionic Liquid Modified Zeolites
- 2013
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Ingår i: Topics in catalysis. - : Springer. - 1022-5528 .- 1572-9028. ; 56:9-10, s. 765-769
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Tidskriftsartikel (refereegranskat)abstract
- In this work, ionic liquid (IL) modified H-Beta zeolites were prepared and the physicochemical properties of the catalysts were investigated. IL modified zeolites were applied in 5-hydroxymethylfurfural (HMF) etherification to tert-butoxymethylfurfural (tBMF) which is a potential (bio)diesel component. The best catalyst, IL-H-Beta-25, yielded at BMF selectivity of 76 % corresponding to a HMF conversion of 46 %.
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