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1.	Hao, Liqing, et al. (författare) Combined effects of boundary layer dynamics and atmospheric chemistry on aerosol composition during new particle formation periods 2018 Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 18:23, s. 17705-17716 Tidskriftsartikel (refereegranskat)abstract Characterizing aerosol chemical composition in response to meteorological changes and atmospheric chemistry is important to gain insights into new particle formation mechanisms. A BAECC (Biogenic Aerosols - Effects on Clouds and Climate) campaign was conducted during the spring 2014 at the SMEAR II station (Station for Measuring Forest Ecosystem-Aerosol Relations) in Finland. The particles were characterized by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). A PBL (planetary boundary layer) dilution model was developed to assist interpreting the measurement results. Right before nucleation events, the mass concentrations of organic and sulfate aerosol species were both decreased rapidly along with the growth of PBL heights. However, the mass fraction of sulfate aerosol of the total aerosol mass was increased, in contrast to a decrease for the organic mass fraction. Meanwhile, an increase in LVOOA (low-volatility oxygenated organic aerosol) mass fraction of the total organic mass was observed, in distinct comparison to a reduction of SVOOA (semi-volatile OOA) mass fraction. Our results demonstrate that, at the beginning of nucleation events, the observed sulfate aerosol mass was mainly driven by vertical turbulent mixing of sulfate-rich aerosols between the residual layer and the newly formed boundary layer, while the condensation of sulfuric acid (SA) played a minor role in interpreting the measured sulfate mass concentration. For the measured organic aerosols, their temporal profiles were mainly driven by dilution from PBL development, organic aerosol mixing in different boundary layers and/or partitioning of organic vapors, but accurate measurements of organic vapor concentrations and characterization on the spatial aerosol chemical composition are required. In general, the observed aerosol particles by AMS are subjected to joint effects of PBL dilution, atmospheric chemistry and aerosol mixing in different boundary layers. During aerosol growth periods in the nighttime, the mass concentrations of organic aerosols and organic nitrate aerosols were both increased. The increase in SVOOA mass correlated well with the calculated increase in condensed HOMs' (highly oxygenated organic molecules) mass. To our knowledge, our results are the first atmospheric observations showing a connection between increase in SVOOA and condensed HOMs during the nighttime.
2.	Anugwom, Ikenna, et al. (författare) Switchable ionic liquids as delignification solvents for lignocellulosic materials 2014 Ingår i: ChemSusChem. - : John Wiley & Sons. - 1864-5631 .- 1864-564X. ; 7:4, s. 1170-1176 Tidskriftsartikel (refereegranskat)abstract The transformation of lignocellulosic materials into potentially valuable resources is compromised by their complicated structure. Consequently, new economical and feasible conversion/fractionation techniques that render value-added products are intensely investigated. Herein an unorthodox and feasible fractionation method of birch chips (B. pendula) using a switchable ionic liquid (SIL) derived from an alkanol amine (monoethanol amine, MEA) and an organic super base (1,8-diazabicyclo-[5.4.0]-undec-7-ene, DBU) with two different trigger acid gases (CO2 and SO2 ) is studied. After SIL treatment, the dissolved fractions were selectively separated by a step-wise method using an antisolvent to induce precipitation. The SIL was recycled after concentration and evaporation of anti-solvent. The composition of undissolved wood after MEA-SO2 -SIL treatment resulted in 80 wt % cellulose, 10 wt % hemicelluloses, and 3 wt % lignin, whereas MEA-CO2 -SIL treatment resulted in 66 wt % cellulose, 12 wt % hemicelluloses and 11 wt % lignin. Thus, the MEA-SO2 -SIL proved more efficient than the MEA-CO2 -SIL, and a better solvent for lignin removal. All fractions were analyzed by gas chromatography (GC), Fourier transform infrared spectroscopy (FT-IR), (13) C nuclear magnetic resonance spectroscopy (NMR) and Gel permeation chromatography (GPC).
3.	Anugwom, Ikenna, et al. (författare) Switchable ionic liquids (SILs) based on glycerol and acid gases 2011 Ingår i: RSC Advances. - : The Royal Society of Chemistry. - 2046-2069. ; 1:3, s. 452-457 Tidskriftsartikel (refereegranskat)abstract New types of switchable ionic liquids (SILs), containing 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU), glycerol and an acid gas (CO2, SO2), were synthesized and characterized in this study. [DBU][Carbonate] or [sulfonate] were easily synthesized from a non-ionic mixture of molecular organic polyol and amidine base upon bubbling of an acid gas (CO2, SO2). Moreover, they were switched back to the original molecular solvents by flushing out the acid gas (CO2, SO2) by heating and/or bubbling an inert gas such as N2 through it. The structures of the SILs were confirmed by NMR and FTIR. The change from low polarity (molecular solvent) to high polarity (Switchable Ionic Liquid, SIL) was also indicated by the changes in properties, such as viscosity and miscibility with different organic solvents. The decomposition temperatures of the SILs were determined by means of Thermo Gravimetric Analysis (TGA) and gave values in the range of 50 °C and 120 °C for DBU-glycerol-CO2 (SIL1) and DBU-glycerol-SO2 (SIL2), respectively. Due to the reasonable decomposition temperatures, these novel SILs can be employed in multiple applications.
4.	Anugwom, Ikenna, et al. (författare) The effect of switchable ionic liquid (SIL) treatment on the composition and crystallinity of birch chips (Betula pendula) using a novel alkanol amine-organic superbase-derived SIL 2014 Ingår i: Green Processing and Synthesis. - : Walter de Gruyter GmbH. - 2191-9542 .- 2191-9550. ; 3:2, s. 147-154 Tidskriftsartikel (refereegranskat)abstract Two-step treatment of birch chips (Betula pendula) was tested using diethanolamine (DEA)-1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)-CO2-switchable ionic liquid (SIL), resulting in a 23% weight reduction in 24 h. The weight of the chips was reduced to 32% of their initial weight upon the second treatment with fresh SIL. SIL to wood ratio of 5:1, at 100°C for 24 h, without stirring, was applied in both steps. The relative amount of wood lignin reduced from 24% to 14% after two treatment cycles. The relative amount of cellulose of the undissolved fraction after SIL treatment increased from 43% (native birch wood) to 68% after the second cycle. Also, the undissolved material was efficiently fibrillated. The dissolved materials recovered from spent SIL, after treatment, contained high xylan content, about 90% of the total hemicelluloses, which was 85% of the recovered material. The powder X-ray diffraction (XRD) results revealed that the crystallinity of the undissolved material increased slightly, indicating dissolution of the amorphous material. Moreover, transformation of cellulose form I to form II in the remaining undissolved chips was not observed.
5.	Anugwom, Ikenna, et al. (författare) Towards optimal selective fractionation for Nordic woody biomass using novel amine–organic superbase derived switchable ionic liquids (SILs) 2014 Ingår i: Biomass and Bioenergy. - : Elsevier. - 0961-9534 .- 1873-2909. ; 70, s. 373-381 Tidskriftsartikel (refereegranskat)abstract Abstract Improved fractionation process conditions for wood dissolution with switchable ionic liquids (SILs) were determined. The short time, high temperature (STHT) system was introduced as a selective and efficient way to extract components from lignocellulosic material. A SIL based on monoethanol amine (MEA) and 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) formed via coupling with SO2, was applied as a solvent in a 1:3 weight ratio with water. In essence, selective dissolution of mainly lignin was achieved by means of the aqueous SIL at 160 °C (∼6.1 bar corresponding to the vapor pressure of water) in 2 h and in a pressure vessel, for both hard- and soft-wood. About 95 wt-% of wood lignin was extracted. The dissolved components in the spent SIL were recovered by the addition of an anti-solvent whereupon over 70% of the dissolved components were recovered; the recovered fraction contained 19 wt-% hemicellulose while the rest of the material was in essence lignin. The non-dissolved, fluffy material contained ∼70 wt-% cellulose and ∼20 wt-% hemicellulose – a consistency resembling that of Kraft pulp.
6.	Anugwom, Ikenna, et al. (författare) Treating birch wood with a switchable 1,8-diazabicyclo-[5.4.0]-undec-7-ene-glycerol carbonate ionic liquid 2012 Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 66:7, s. 809-815 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.
7.	Duan, Ran, et al. (författare) Fibre Stress-Strain Response of High-Temperature Chemi-Thermomechanical Pulp Treated with Switchable Ionic Liquids 2016 Ingår i: BioResources. - : BioResources. - 1930-2126. ; 11:4, s. 8570-8588 Tidskriftsartikel (refereegranskat)abstract The removal of lignin from a high-temperature chemi-thermomechanical pulp (HT-CTMP) using a switchable ionic liquid prepared from an organic superbase (1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)), monoethanol amine (MEA), and SO2 was investigated. The objective was to measure the fibre properties before and after removal of the lignin to analyse the contributions from lignin in the HT-CTMP fibre to the tensile properties. It was found that the fibre displacement at break - measured in zero span, which is related to fibre strain at break - was not influenced by the lignin removal in this ionic liquid system when tested dry. There was a small increase in displacement at break and a reduction in tensile strength at zero span when tested after rewetting. At short span, the displacement at break decreased slightly when lignin was removed, while tensile strength was almost unaffected when tested dry. Under rewetted conditions, the displacement at break increased and tensile strength decreased after lignin removal. Nevertheless, no dramatic differences in the pulp properties could be observed. Under the experimental conditions, treatment with the ionic liquid reduced the lignin content from 37.4 to 15.5 wt%.
8.	Ekman, Jörgen, et al. (författare) Retention of Pb isotopes in glass surfaces for retrospective assessment of radon exposure 2006 Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier. - 0168-583X .- 1872-9584. ; 249:1-2, s. 544-547 Tidskriftsartikel (refereegranskat)abstract In recent years there has been increasing interest in radio-epidemiological techniques to retrospectively measure the radon dose exposure by determining the activity of 210Pb, the longest-lived 222Rn progeny, in glass surface layers. In this study the diffusion of 39 keV 209Pb+ ions implanted into glass using the IGISOL facility has been studied under conditions that mimic the recoil implantation of 210Pb from 222Rn. The resulting depth distributions of 209Pb were then measured after heat treatment in vacuum at different temperatures by a sputter erosion technique. The diffusion coefficient could be described by an Arrhenius equation D = D0exp(−H/kT) where and H = 2.81 ± 0.11 eV. No statistically significant loss of 209Pb from the sample was observed for annealing between 470 and 600 °C.
9.	Eta, Valerie, et al. (författare) Enhanced mass transfer upon switchable ionic liquid mediated wood fractionation 2014 Ingår i: Industrial crops and products (Print). - : Elsevier. - 0926-6690 .- 1872-633X. ; 55, s. 109-115 Tidskriftsartikel (refereegranskat)abstract The fractionation of lignocellulosic biomass to its major components is the primary step towards the conversion of biomass-based biopolymers to commodity chemicals in the integrated biorefinery process. Wood chips encased in a SpinChem® device and attached to the stirrer of a batch autoclave were used together with switchable ionic liquids (SILs) for the selective fractionation of hemicelluloses and lignin. Stirring of the wood chips in the SpinChem® device facilitated the diffusion of SIL into the chips through forced recirculation and at the same time avoiding mechanical fibrillation. The treatment of birch chips (Betula pendula) with SILs comprising 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU), monoethanolamine (MEA) and CO2 at 120 °C in a SpinChem® device resulted in the fractionation of 82 wt.% hemicelluloses and 90 wt.% lignin, leaving the cellulose-rich non-dissolved material partially fibrillated and softened. The dissolved hemicelluloses and lignin were selectively precipitated using isopropanol and recovered from the spent SIL.
10.	Eta, Valerie, et al. (författare) Loop vs. batch reactor setups in the fractionation of birch chips using switchable ionic liquids 2014 Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 238, s. 242-248 Tidskriftsartikel (refereegranskat)abstract The fractionation of lignocellulosic feedstock into its major components with high purity represents an important commercialization milestone in the transformation of lignocellulosic forest derived products into fuels and commodity chemicals. A comparison between the traditionally used batch reactor and loop reactor systems demonstrates that improved dissolution of hemicelluloses and lignin are obtained using switchable ionic liquids in a loop reactor system which facilitates decreased heat and mass transfer restrictions. The treatment of birch chips using switchable ionic liquid (SIL) based on 1,8-diazabicyclo-[5.4.0]-undec-7-ene, CO2 and diethanolamine at 120 °C for 30 h in a loop reactor resulted in 24% loss of original weight of wood corresponding to dissolution of 52 wt.% of hemicelluloses and 42 wt.% of lignin, respectively, as opposed to 20% weight loss corresponding to 43 wt.% dissolution of hemicelluloses and 38 wt.% of lignin in the batch system. The non-dissolved material obtained from both reactors was efficiently fibrillated and softened cellulose fibres. The flow of switchable ionic liquid through the loop reactor and agitation of the chips enhanced the dissolution of hemicelluloses and lignin. The dissolved fractions recovered from spent SIL after treatment contained both hemicelluloses and lignin.
11.	Jogi, Ramakrishna, et al. (författare) Biocrude production through hydro‐liquefaction of wood biomass in supercritical ethanol using iron silica and iron Beta zeolite catalysts 2019 Ingår i: Journal of chemical technology and biotechnology (1986). - : John Wiley & Sons. - 0268-2575 .- 1097-4660. ; 94:11, s. 3736-3744 Tidskriftsartikel (refereegranskat)abstract BACKGROUND: In the production of biofuels from lignocellulosic material, biocrude plays a key role. The present work deals with the biocrude production through hydrothermal liquefaction (HTL) of birch wood in supercritical ethanol over 5 wt. % Fe‐H‐Beta‐150 (SiO2 to Al2O3 ratio of 150) or 5 wt. % Fe‐SiO2 catalyst.RESULTS: The liquid and solid products were characterized with various analytical techniques such as GC‐MS, GC‐FID, SEC, ICP‐MS, p‐XRD, SEM, and solid‐state 13C MAS NMR respectively. The results revealed that 5 wt. % Fe‐H‐Beta‐150, a strongly Brønsted acidic catalyst, enhanced the biocrude formation when compared with a non‐acidic 5 wt. % Fe‐SiO2 catalyst. Hemicellulose and lignin degradation occurred resulting in formation of mainly sugars, acids‐esters and phenolic compounds in liquid phase. The gaseous atmosphere of hydrogen also enhanced the degradation of biomass. The biocrude yield from birch was 25 wt. % over 5 wt. % Fe‐H‐Beta‐150. The Brønsted acidic catalyst gave higher dissolution efficiency and its clear catalytic effect was observed in comparison to non‐acidic 5 wt. % Fe‐SiO2. The degradation level of lignin in presence of 5 wt. % Fe‐H‐Beta‐150 was high 68 wt. % aromatic products were formed, while only 38 wt. % was obtained with 5 wt. % Fe‐SiO2.CONCLUSIONS: Hydrogen atmosphere enhances the fractionation of birch wood when compared to argon atmosphere. 5 wt. % Fe‐H‐Beta‐150 catalyst enhanced very strongly the degradation of hemicellulose and lignin in biomass to sugars and acid‐esters as well as phenolic compounds, respectively compared to the non‐acidic 5 wt. % Fe‐SiO2 catalyst.
12.	Jogi, Ramakrishna, et al. (författare) Liquefaction of Lignocellulosic Biomass into Phenolic Monomers and Dimers Over Multifunctional Pd/Nbopo4 Catalyst 2022 Ingår i: SSRN Electronic Journal. - : Elsevier BV. - 1556-5068. Annan publikation (övrigt vetenskapligt/konstnärligt)abstract For the first time, a tandem catalytic material namely 5 wt. % Pd/NbOPO 4 was utilized in the depolymerization of wood in supercritical-ethanol under low initial-hydrogen pressure. The experiments were conducted under various experimental conditions, wood fractionation was executed with fresh, and acetone extracted birch. A comprehensive analysis was performed to elucidate the dissolution efficiency and achieved product distribution. The results indicated fresh birch, 34 wt. % of lignin monomer yield with 84 wt. % delignification efficiency were obtained while extracted wood, 35 wt. % of lignin monomer yield with 78 wt. % delignification efficiency was achieved. The total lignin monomer content extracted from the fresh birch is composed of 76.9 wt. % of dimethoxyphenols and 16.5 wt. % of monomers with the guaiacol structure. Among the dimethoxyphenols, major homosyringaldehyde (61.9 wt. %). Where extracted wood, 93.2 wt. % of dimethoxyphenols (63.6 wt. % homosyringaldehyde) and guaiacol-monomers (6.8 wt. %). It was concluded that the depolymerization occurred via breaking of the ether bonds in lignin, including ether hydrolysis by Lewis acid sites over the solid acid catalyst and with subsequent deoxygenation of monophenols over Pd. In addition, an extraction process was proposed to extract the aromatic fraction from the obtained biocrude.
13.	Jogi, Ramakrishna, et al. (författare) Liquefaction of lignocellulosic biomass into phenolic monomers and dimers over multifunctional Pd/NbOPO4 catalyst 2024 Ingår i: Renewable energy. - : Elsevier. - 0960-1481 .- 1879-0682. ; 233 Tidskriftsartikel (refereegranskat)abstract For the first time, a tandem catalytic material, 5 wt. % Pd/NbOPO4, was utilized in the depolymerization of wood in supercritical ethanol under hydrogen atmosphere. The experiments were conducted under various conditions, with fresh, and acetone extracted birch. A comprehensive analysis was performed to elucidate the dissolution efficiency and achieved product distribution. The results indicated that with fresh birch, 34 wt. % of lignin monomer yield with 84 wt. % delignification efficiency were obtained while with extracted wood, 35 wt. % of lignin monomer yield with 78 wt. % delignification efficiency were achieved. The total lignin monomer content extracted from the fresh birch is composed of 76.9 wt. % of dimethoxyphenols and 16.5 wt. % with the guaiacol structure. Major lignin monomer product was homosyringaldehyde (61.9 wt. %). With extracted wood, 93.2 wt. % of dimethoxyphenols (63.6 wt. % homosyringaldehyde) and 6.8 wt. % of guaiacol-monomers were achieved. It was concluded that the depolymerization occurred via breaking of the ether bonds in lignin, including ether hydrolysis by Lewis acid sites over the solid acid catalyst and with subsequent deoxygenation of monophenols over Pd. In addition, an extraction process was proposed to extract the aromatic fraction from the obtained biocrude.
14.	Jogi, Ramakrishna, et al. (författare) Understanding the formation of phenolic monomers during fractionation of birch wood under supercritical ethanol over iron based catalysts 2020 Ingår i: Journal of the Energy Institute. - : Elsevier. - 1743-9671 .- 1746-0220. ; 93:5, s. 2055-2062 Tidskriftsartikel (refereegranskat)abstract The liquefaction of biomass in ethanol, at the critical point, has high potential due to low temperature and pressure (243 °C, 63 bar) when compared with water (374 °C, 220 bar). The current study deals with the fractionation of birch wood powder which was liquefied under supercritical ethanol over acidic or non-acidic catalysts, 5 wt % Fe-Beta-H-150 and 5 wt % Fe–SiO2, respectively. Based on the results, the reaction mechanism for the formation of lignin degradation products was proposed. The main phenolic product was isoeugenol over 5 wt % Fe-Beta-H-150 while intermediate products, i.e. such as coniferyl, and sinapyl alcohol, 4-propenyl syringol, syringaresinol, as well as syringyldehyde reacted rapidly further. The thermodynamic analysis was performed by Joback approach and using Gibbs-Helmholtz equation supporting the obtained results.
15.	Mikkola, Jyri-Pekka, et al. (författare) The biorefinery and green chemistry 2016 Ingår i: Ionic liquids in the biorefinery concept. - Cambridge : RSC Publishing. - 9781849739764 - 9781782622598 - 9781782627241 ; , s. 1-37 Bokkapitel (refereegranskat)abstract If the living standards of western societies are to be maintained while those of the developing world change at their current tempo, then, because of the depletion of fossil resources and concerns about the environment, the concept of biorefining, following the principles of green chemistry as well as sustainability, will surely become more and more important in the future. This chapter introduces the concept of what biorefineries are and discusses their sustainability, taking into account green chemistry and engineering aspects. As well as a brief history, today's situation in the biorefining industry is covered with several examples. Also, the directions for the future biorefineries are considered.
16.	Mukesh, Chandrakant, et al. (författare) Rapid desorption of CO2 from deep eutectic solvents based on polyamines at lower temperatures : an alternative technology with industrial potential 2019 Ingår i: Sustainable Energy & Fuels. - : Royal Society of Chemistry. - 2398-4902. ; 3:8, s. 2125-2134 Tidskriftsartikel (refereegranskat)abstract Herein we developed a new family of polyamine-based deep eutectic solvents (DESs) dedicated to reduce the energy consumption, avoiding the formation of hazardous molecules, aiming at low solvent losses and robust desorption efficiency for carbon dioxide (CO 2) capture technology. The strategy developed for economical, thermally stable and low viscous absorbents for CO 2 capture by functionalized neoteric media of azolide anion and secondary amine is presented. The prepared anion functionalized ionic liquids (ILs) and the derived DESs with ethylene glycol (EG) have a low viscosity which promotes high uptake of CO 2 (17-22% w/w) at 298.15 K and 1 atm. The absorption capacity of DESs was determined by a gravimetric technique. 13 C NMR was used for examine the desorption efficiency (DE) of CO 2. It was found that rapid desorption of CO 2 in TEPA polyamine based DESs occurs compared to monoethanolamine at 80 °C. However, the desorption rate of CO 2 was observed to be higher at higher temperatures and, as a result, under nitrogen flow complete desorption of CO 2 took place at 100 and 110 °C after 30 and 20 minutes, respectively. Consequently, comparative regeneration of CO 2 was studied in the absence of nitrogen flow at different temperatures. Excellent reversible uptake of CO 2 was observed without significant loss of absorption capacity under four consecutive cycles at 100 °C. The chemisorption of CO 2 was verified by 13 C NMR, 2D-NMR and FT-IR spectroscopy. The solvent loss study demonstrated the low volatility of polyamines based DESs at 100 °C and 120 °C after 50 hrs. The proposed DESs are thermally stable, cheap and give rise to negligible amounts of hazardous degradation components. Further, they exhibit low solvent losses, low viscosities and rapid CO 2 desorption capability. Therefore they are promising candidates when aiming at improving amine based conventional CO 2 capture technology.
17.	Mäki-Arvela, Päivi, et al. (författare) The challenge of efficient synthesis of biofuels from lignocellulose for future renewable transportation fuels 2012 Ingår i: International Journal of Chemical Engineering. - : Hindawi Publishing Corporation. - 1687-806X .- 1687-8078. ; , s. 674761- Forskningsöversikt (refereegranskat)abstract Dehydration of sugars to 5-hydroxymethylfurfural (HMF) has recently been under intensive study by a multitude of research groups. On the other hand, when lignocellulosic biomass is applied as the starting material, very few studies can be found in the open literature. The direct synthesis of HMF, in line with the idea of “one-pot” synthesis strategy from lignocellulose, is demanding since the overall process should encompass dissolution, hydrolysis, and dehydration steps in a single processing unit. Ionic liquid-assisted methods to produce hydroxymethyl-furfural directly from lignocellulosic biomass are reported here together with a short overview of the most important biofuels. In reality, HMF is not suitable to be used as a single-component fuel as such, and, consequently, methods to produce HMF derivatives suitable as liquid fuels are reported.
18.	Männistö, Elisa, et al. (författare) Emissions of biogenic volatile organic compounds from adjacent boreal fen and bog as impacted by vegetation composition 2023 Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 858 Tidskriftsartikel (refereegranskat)abstract Peatland ecosystems emit biogenic volatile organic compounds (BVOC), which have a net cooling impact on the climate. However, the quality and quantity of BVOC emissions, and how they are regulated by vegetation and peatland type remain poorly understood. Here we measured BVOC emissions with dynamic enclosures from two major boreal peatland types, a minerotrophic fen and an ombrotrophic bog situated in Siikaneva, southern Finland and experimentally assessed the role of vegetation by removing vascular vegetation with or without the moss layer. Our measurements from four campaigns during growing seasons in 2017 and 2018 identified emissions of 59 compounds from nine different chemical groups. Isoprene accounted for 81 % of BVOC emissions. Measurements also revealed uptake of dichloromethane. Total BVOC emissions and the emissions of isoprene, monoterpenoids, sesquiterpenes, homoterpenes, and green leaf volatiles were tightly connected to vascular plants. Isoprene and sesquiterpene emissions were associated with sedges, whereas monoterpenoids and homoterpenes were associated with shrubs. Additionally, isoprene and alkane emissions were higher in the fen than in the bog and they significantly contributed to the higher BVOC emissions from intact vegetation in the fen. During an extreme drought event in 2018, emissions of organic halides were absent. Our results indicate that climate change with an increase in shrub cover and increased frequency of extreme weather events may have a negative impact on total BVOC emissions that otherwise are predicted to increase in warmer temperatures. However, these changes also accompanied a change in BVOC emission quality. As different compounds differ in their capacity to form secondary organic aerosols, the ultimate climate impact of peatland BVOC emissions may be altered.
19.	Nieminen, Tuomo, et al. (författare) Global analysis of continental boundary layer new particle formation based on long-term measurements 2018 Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 18:19, s. 14737-14756 Tidskriftsartikel (refereegranskat)abstract Atmospheric new particle formation (NPF) is an important phenomenon in terms of global particle number concentrations. Here we investigated the frequency of NPF, formation rates of 10 nm particles, and growth rates in the size range of 10-25 nm using at least 1 year of aerosol number size-distribution observations at 36 different locations around the world. The majority of these measurement sites are in the Northern Hemisphere. We found that the NPF frequency has a strong seasonal variability. At the measurement sites analyzed in this study, NPF occurs most frequently in March-May (on about 30 % of the days) and least frequently in December-February (about 10 % of the days). The median formation rate of 10 nm particles varies by about 3 orders of magnitude (0.01-10 cm(-3) s(-1)) and the growth rate by about an order of magnitude (1-10 nm h(-1)). The smallest values of both formation and growth rates were observed at polar sites and the largest ones in urban environments or anthropogenically influenced rural sites. The correlation between the NPF event frequency and the particle formation and growth rate was at best moderate among the different measurement sites, as well as among the sites belonging to a certain environmental regime. For a better understanding of atmospheric NPF and its regional importance, we would need more observational data from different urban areas in practically all parts of the world, from additional remote and rural locations in North America, Asia, and most of the Southern Hemisphere (especially Australia), from polar areas, and from at least a few locations over the oceans.
20.	Putkiranta, Pauli, et al. (författare) The value of hyperspectral UAV imagery in characterizing tundra vegetation 2024 Ingår i: Remote Sensing of Environment. - 0034-4257 .- 1879-0704. ; 308 Tidskriftsartikel (refereegranskat)abstract The fine-scale spatial heterogeneity of low-growth Arctic tundra landscapes necessitates the use of high-spatial-resolution remote sensing data for accurate detection of vegetation patterns. While multispectral satellite and aerial imaging, including the use of uncrewed aerial vehicles (UAVs), are common approaches, hyperspectral UAV imaging has not been thoroughly explored in these ecosystems. Here, we assess the added value of hyperspectral UAV imaging relative to multispectral UAV imaging in modelling plant communities in low-growth oroarctic tundra heaths in Saariselkä, northern Finland. We compare three different spectral compositions: 4-channel broadband aerial images, 5-channel broadband UAV images and 112-channel narrowband UAV images. Based on field vegetation plot data, we estimate vascular plant aboveground biomass, leaf area index, species richness, Shannon's diversity index, and community composition. We use spectral and topographic information to compile 12 explanatory datasets for random forest regression and classification.For aboveground biomass and leaf area index, the highest R2 values were 0.60 and 0.65, respectively, and broadband variables were most important. In the best models for biodiversity metrics species richness and Shannon's index R2 values were 0.53 and 0.46, respectively, with hyperspectral, topographic, and multispectral variables having high importance. For 4 floristically determined community clusters, both random forest classifications and fuzzy cluster membership regressions were conducted. Overall accuracy (OA) for classification was 0.67 at best, while cluster membership was estimated with an R2 of 0.29–0.53. Variable importance was heavily dependent on community composition, but topographic, multispectral, and hyperspectral data were all selected for these community composition models. Hyperspectral models generally outperformed multispectral ones when topographic data were excluded. With topographic data, this difference was diminished, and performance improvements from added hyperspectral data were limited to 0–10 percentage point increases in R2, the largest occurring in the metrics with lowest R2. These results suggest that while hyperspectral can outperform multispectral imaging, multispectral and topographic data are mostly sufficient in practical applications in tundra heaths.
21.	Raut, Dilip G., et al. (författare) A morpholinium ionic liquid for cellulose dissolution 2015 Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 130, s. 18-25 Tidskriftsartikel (refereegranskat)abstract A series of substituted morpholinium ionic salts and allyl ammonium acetates were prepared. Amongst those, N-allyl-N-methylmorpholinium acetate ([AMMorp][OAc]) was found to dissolve cellulose readily without any pre-processing of native cellulose. At 120 degrees C, [AMMorp][OAc] could dissolve 30 wt%, 28 wt% and 25 wt% of cellulose with degree of polymerization (DPn) - 789, 1644 and 2082 respectively, in 20 min. Importantly, SEC analysis indicated that no discernible changes occurred in terms of the degree of polymerization of the different celluloses after regeneration. Furthermore, when comparing the cellulose dissolution capability of these newly synthesized ionic liquids, it is evident that the combination of all three constituents - the morpholinium cation, the existence of an allyl group and choosing the acetate anion are essential for efficient cellulose dissolution. The structure and morphology of the regenerated cellulosic materials were characterized by SEM, XRD, TGA, CP/MAS C-13 NMR and FTIR, respectively.
22.	Salminen, Eero, et al. (författare) Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal 2014 Ingår i: Frontiers in Chemistry. - : Frontiers Media SA. - 2296-2646. ; 2 Tidskriftsartikel (refereegranskat)abstract The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes, or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70% molar yield toward citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide.
23.	Salminen, Eero, et al. (författare) Alkaline modifiers as performance boosters in citral hydrogenation over supported ionic liquid catalysts (SILCAs) 2012 Ingår i: Catalysis Today. - : Elsevier. - 0920-5861 .- 1873-4308. ; 196:1, s. 126-131 Tidskriftsartikel (refereegranskat)abstract Supported ionic liquid catalysts (SILCAs) consist of nano-scale catalytic species immobilized in an ionic liquid layer which, in turn, is immobilized on a solid support. In this work, novel SILCAs containing various inorganic alkaline modifiers (e.g. potassium hydroxide) were prepared and applied in citral hydrogenation reactions. The supported ionic liquid catalyst systems demonstrated enhanced reaction rates and improved selectivities toward citronellal in citral hydrogenation. With the addition of an alkaline modifier into ionic liquid layer, the catalyst selectivity increased from 16% to 74%. In fact, a highly selective reaction route toward citronellal was accomplished.
24.	Salminen, Eero, et al. (författare) Biomass to value added chemicals : Isomerisation of β-pinene oxide over supported ionic liquid catalysts (SILCAs) containing Lewis acids 2015 Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861 .- 1873-4308. ; 257, s. 318-321 Tidskriftsartikel (refereegranskat)abstract The isomerisation of β-pinene oxide was studied over supported ionic liquid catalysts (SILCAs) consisting of Lewis acids in immobilized ionic liquid. SILCAs were demonstrated as efficient catalysts for the transformation of β-pinene oxide to myrtanal with the product distribution and activity being depend-ent on the nature of the ionic liquid and Lewis acid strength of catalytic species. With the catalystZnCl2/[N(3-OH-Pr)Py][NTf2]/ACC, the highest myrtanal molar yield obtained was 68%.
25.	Salminen, Eero, et al. (författare) Etherification of 5-Hydroxymethylfurfural to a Biodiesel Component Over Ionic Liquid Modified Zeolites 2013 Ingår i: Topics in catalysis. - : Springer. - 1022-5528 .- 1572-9028. ; 56:9-10, s. 765-769 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 %.
26.	Salminen, Eero, et al. (författare) Isomerisation of a-Pinene Oxide to Campholenic Aldehyde OverSupported Ionic Liquid Catalysts (SILCAs) 2014 Ingår i: Topics in catalysis. - : Springer Science+Business Media B.V.. - 1022-5528 .- 1572-9028. ; 57:17-20, s. 1533-1538 Tidskriftsartikel (refereegranskat)abstract The isomerisation of α-pinene oxide to campholenic aldehyde, an expensive ingredient utilized by e.g. flavor industry, was studied over Supported Ionic Liquid Catalysts (SILCAs) consisting of catalytically active species residing in ionic liquid. The ionic liquid, in turn, was immobilized on a solid support material. SILCAs were demonstrated as efficient catalysts for the transformation of α-pinene oxide into campholenic aldehyde, with the product distribution and activity being dependent on the nature of the ionic liquid.
27.	Salminen, Eero, et al. (författare) Kinetics upon Isomerization of α,β-Pinene Oxides over Supported Ionic Liquid Catalysts Containing Lewis Acids 2014 Ingår i: Journal of Industrial and Engineering Chemistry. - : American Chemical Society (ACS). - 1226-086X .- 1876-794X .- 0888-5885 .- 1520-5045. ; 53:52, s. 20107-20115 Tidskriftsartikel (refereegranskat)abstract Wood extractives such as α-pinene oxide and β-pinene oxide are important renewable chemicals for the synthesis of fine chemicals, pharmaceuticals, and value-added intermediates. In this work, catalytic transformations of biomass derived extractives, isomerization of α,β-pinene oxides were studied over supported ionic liquid catalysts (SILCAs). SILCAs consist of catalytic species (e.g., metal nanoparticles or metal complexes) in a thin layer of ionic liquid which is immobilized on a solid support material (e.g., active carbon cloth). The reaction kinetics of the isomerization reactions over supported ionic liquid catalysts were studied and modeled. Mechanistic kinetic models describing the differences in selectivity and activity of the catalysts containing different ionic liquids were developed, and the models described the reaction rates and product distributions very well.
28.	Samikannu, Ajaikumar, et al. (författare) Highly dispersed NbOPO4/SBA-15 as a versatile acid catalyst upon production of renewable jet-fuel from bio-based furanics via hydroxyalkylation-alkylation (HAA) and hydrodeoxygenation (HDO) reactions 2020 Ingår i: Applied Catalysis B. - : Elsevier. - 0926-3373 .- 1873-3883. ; 272 Tidskriftsartikel (refereegranskat)abstract Herein, we report the synthesis of a highly active and mesoporous Brønsted acidic NbOPO4/SBA-15 catalyst. The prepared catalysts were thoroughly characterized by means of analytical techniques such as XRD, FT-IR, XPS, NH3-TPD, SEM-EDS, TEM, TGA, 31P-MAS-NMR and N2-physisorption. The H3PO4 free deposition method was found to be effective for preserving the structure of Silica based carrier. In terms of catalytic performance, these materials demonstrated high activity upon C-C coupling of 2-methyl furan with carbonyl compounds and outperforming bulk NbOPO4, Nb2O5/SBA-15 and traditional solid acid catalysts (Al-MCM-41, Si/Al and H-ZSM-5). The NbOPO4/SBA-15 catalysts were stable and maintained high activity upon reuse and continuous operation (∼65 h). Furthermore, the Pd loaded counterparts (Pd/NbOPO4/SBA-15 and Pd/Nb2O5/SBA-15) also functioned as bifunctional catalysts and exhibited excellent activity upon subsequent hydrodeoxygenation of C-C coupling products. Most importantly, in terms of jet-fuel range hydrocarbons selectivity, these catalysts outperformed monofunctional Pd/carbon and aluminosilicate based bifunctional catalysts.
29.	Tröstl, Jasmin, et al. (författare) The role of low-volatility organic compounds in initial particle growth in the atmosphere 2016 Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 533:7604, s. 527-531 Tidskriftsartikel (refereegranskat)abstract About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst of new particles near midday(1). Atmospheric observations show that the growth rate of new particles often accelerates when the diameter of the particles is between one and ten nanometres(2,3). In this critical size range, new particles are most likely to be lost by coagulation with pre-existing particles(4), thereby failing to form new cloud condensation nuclei that are typically 50 to 100 nanometres across. Sulfuric acid vapour is often involved in nucleation but is too scarce to explain most subsequent growth(5,6), leaving organic vapours as the most plausible alternative, at least in the planetary boundary layer(7-10). Although recent studies(11-13) predict that low-volatility organic vapours contribute during initial growth, direct evidence has been lacking. The accelerating growth may result from increased photolytic production of condensable organic species in the afternoon(2), and the presence of a possible Kelvin (curvature) effect, which inhibits organic vapour condensation on the smallest particles (the nano-Kohler theory)(2,14), has so far remained ambiguous. Here we present experiments performed in a large chamber under atmospheric conditions that investigate the role of organic vapours in the initial growth of nucleated organic particles in the absence of inorganic acids and bases such as sulfuric acid or ammonia and amines, respectively. Using data from the same set of experiments, it has been shown(15) that organic vapours alone can drive nucleation. We focus on the growth of nucleated particles and find that the organic vapours that drive initial growth have extremely low volatilities (saturation concentration less than 10(-4.5) micrograms per cubic metre). As the particles increase in size and the Kelvin barrier falls, subsequent growth is primarily due to more abundant organic vapours of slightly higher volatility (saturation concentrations of 10(-4.5) to 10(-0.5) micrograms per cubic metre). We present a particle growth model that quantitatively reproduces our measurements. Furthermore, we implement a parameterization of the first steps of growth in a global aerosol model and find that concentrations of atmospheric cloud concentration nuclei can change substantially in response, that is, by up to 50 per cent in comparison with previously assumed growth rate parameterizations.
30.	Virtanen, Annele, et al. (författare) An amorphous solid state of biogenic secondary organic aerosol particles 2010 Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 467:7317, s. 824-827 Tidskriftsartikel (refereegranskat)abstract Secondary organic aerosol (SOA) particles are formed in the atmosphere from condensable oxidation products of anthropogenic and biogenic volatile organic compounds (VOCs)(1-7). On a global scale, biogenic VOCs account for about 90% of VOC emissions(1,8) and of SOA formation (90 billion kilograms of carbon per year)(1-4). SOA particles can scatter radiation and act as cloud condensation or ice nuclei, and thereby influence the Earth's radiation balance and climate(1,2,5,9,10). They consist of a myriad of different compounds with varying physicochemical properties, and little information is available on the phase state of SOA particles. Gas-particle partitioning models usually assume that SOA particles are liquid(1,5,11), but here we present experimental evidence that they can be solid under ambient conditions. We investigated biogenic SOA particles formed from oxidation products of VOCs in plant chamber experiments and in boreal forests within a few hours after atmospheric nucleation events. On the basis of observed particle bouncing in an aerosol impactor and of electron microscopy we conclude that biogenic SOA particles can adopt an amorphous solid-most probably glassy-state. This amorphous solid state should provoke a rethinking of SOA processes because it may influence the partitioning of semi-volatile compounds, reduce the rate of heterogeneous chemical reactions, affect the particles' ability to accommodate water and act as cloud condensation or ice nuclei, and change the atmospheric lifetime of the particles(12-15). Thus, the results of this study challenge traditional views of the kinetics and thermodynamics of SOA formation and transformation in the atmosphere and their implications for air quality and climate.
31.	Virtanen, Pasi, et al. (författare) Kinetics of cinnamaldehyde hydrogenation by supported ionic liquid catalysts (SILCA) 2009 Ingår i: Industrial & Engineering Chemistry Research. - Washington : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 48:23, s. 10335-10342 Tidskriftsartikel (refereegranskat)abstract The research of ionic liquids and their applications in catalysis are attracting increasing attention in chemistry and chemical engineering. A supported ionic liquid catalyst (SILCA) consists of immobilized catalytic species (e.g., transition-metal particles, metal complexes, or enzymes) residing in an ionic liquid layer immobilized on a porous solid support. The kinetics of cinnamaldehyde hydrogenation over SILCAs that contained palladium nanoparticles in ionic liquid, which, in turn, was immobilized oil active carbon cloth (ACC), was studied and modeled in detail. A mechanistic kinetic model, which describes the differences of the activity and selectivity of the catalysts consisting of different ionic liquids, was developed. The model explained the experimental results well.
32.	Virtanen, Pasi, et al. (författare) Miljövänliga katalysatorer av joniska vätskor 2010 Ingår i: Kemia. - Finland : Kemian Kustannus Oy. - 0355-1628. ; :6, s. 32-34 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
33.	Virtanen, Pasi, et al. (författare) Modeling of Supported Ionic Liquid Catalysts Systems : From Idea to Applications 2017 Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 56:45, s. 12852-12862 Tidskriftsartikel (refereegranskat)abstract The modeling of chemical reactions studied in small scale, often carried out in Academia, is very important since it gives more information about the system and better possibilities to scale-up the processes in the future. Supported ionic liquid catalysts (SILCAs) have been studied in a number of different processes. However, the modeling of these processes have been studied only in a few cases. In this paper the sample cases are reviewed. These processes include hydrogenation of unsaturated aldehydes as well as isomerization of terpenes, α- and β-pinene oxides.
34.	Virtanen, Pasi, et al. (författare) Selective hydrogenation for fine chemical synthesis 2014 Ingår i: Supported ionic liquids. - Weinheim, Germany : Wiley-VCH Verlagsgesellschaft. - 9783527324293 - 9783527654819 - 9783527654802 - 9783527654796 - 9783527654789 ; , s. 251-262 Bokkapitel (refereegranskat)abstract Hydrogenation is an important and widely applied reaction in chemical industry. Supported ionic liquid (IL) type catalysts have shown good performance in various hydrogenation reactions. This chapter introduces a few case studies where supported IL catalysis has been applied in hydrogenation reactions. The case studies highlight the novelty of supported IL catalyst (SILCA) catalysts. Selective hydrogenation of α,ß-unsaturated aldehydes, ketones, and esters, in general, is a versatile pathway to obtain many interesting products that can be used in perfumes, hardening of fats, preparation of pharmaceuticals, and synthesis of organic intermediates. SILCAs have been successfully demonstrated to act as catalysts in chemoselective hydrogenations, and thus an analogous concept has been applied for the synthesis of chiral metal complexes in ILs supported on heterogeneous catalysts.
35.	Virtanen, Pasi, et al. (författare) Supported ionic liquid catalysts (SILCA) for preparation of organic chemicals 2010 Ingår i: Topics in catalysis. - : SpringerLink. - 1022-5528 .- 1572-9028. ; 53:15-18, s. 1096-1103 Tidskriftsartikel (refereegranskat)abstract Supported Ionic Liquid Catalysts (SILCA) designed by immobilization of catalytic species residing in an ionic liquid layer, which in turn was immobilized on a solid support, were applied on the selective hydrogenation of citral in a batch reactor and in a continuous reactor. Different ionic liquids with and without addition of acid modificators were studied in terms of the catalyst activity and product selectivity. Consequently, mechanistic kinetic models describing the differences in the activity and selectivity of the catalysts consisting different ionic liquids, were developed.
36.	Virtanen, Pasi, et al. (författare) Towards one-pot synthesis of menthols from citral : Modifying Supported Ionic Liquid Catalysts (SILCAs) with Lewis and Brønsted acids 2009 Ingår i: Journal of Catalysis. - : Elsevier Inc. - 0021-9517. ; 263:2, s. 209-19 Tidskriftsartikel (refereegranskat)abstract The use of ionic liquids in catalysis is attracting ever more attention in chemical engineering. In line with this research we have studied Supported Ionic Liquid Catalysts (SILCAs) which consist of immobilized catalytic species, e.g. transition metal particles residing in an ionic liquid layer immobilized on a solid support. We found out that dissolution of Lewis or Brønsted acids into the ionic liquid layer of SILCA has major effects to the activity as well as the product distribution of the catalyst in citral transformation reactions. In fact, one-pot synthesis of menthols from citral was accomplished. The effects of different amounts of added Lewis and/or Brønsted acids to SILCA (one of them or both) were studied in this work. Graphical abstract Supported Ionic Liquid Catalyst (SILCA) was modified with different Lewis and Brønsted acids and the effects of different acids to the catalyst activity and product selectivity in a reaction of menthols from citral was evaluated. Full-size image (20K)High-quality image (101K)
37.	Virtanen, Pasi, et al. (författare) Why SPI Initiative Failed: Contextual Factors and Changing Software Development Environment 2013 Ingår i: Proceedings of the 46th Annual Hawaii International Conference on System Sciences. - : IEEE Communications Society. - 9781467359337 - 9780769548920 ; , s. 4606-4615 Konferensbidrag (refereegranskat)abstract For today’s software business and its productivity, software process improvement (SPI) plays a significant role. Organizations that produce software face challenges with the productivity and effectiveness of their operation. The literature lists numerous methods to make the operation better. Critical success factors are defined in order to make the successful improvement procedures more certain. However, these methodologies need to be adjusted to match the organizational context. All organizations and their environments aredifferent, and thus the solution that is the most suitable for individual needs must be modified or localized to fit the case-specific contextual demands. This paper studies the importance of these contextual demands in SPI. In the paper, a framework is presented through which the software improvement process can be better understood and studied. The framework offers a view to understanding the change process describing eight change paths that may be observed when software process improvement is regarded.
38.	Vucetic, Nemanja, et al. (författare) Competing commercial catalysts: Unprecedented catalyst activity and stability of Mizoroki-Heck reaction in a continuous packed bed reactor 2022 Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 433 Tidskriftsartikel (refereegranskat)abstract Main obstacle for adopting continuous processes as a standard technology for Mizoroki-Heck reaction usually lies in its specific reaction mechanism. Here we present an important step forward answering the challenges unraveled through a comprehensive study that provides deeper understanding on the Mizoroki-Heck reaction, in particular the case when iodobenzene and butyl acrylate react in a continuous packed bed reactor in the presence of a Pd Supported Ionic Liquid Catalyst (SILCA). On-line UV–VIS spectrometry supported by ICP-OES, TEM and XPS measurements were carried out and the catalyst leaching was minimized. Finally, simple continuous flow process was proposed resulting in a high catalytic activity (up to 1470 molArI molPd−1h−1) and reaching productivity in the range of 12,000 to 16,000 molArI molPd−1 thus competing with the performance of commercial catalysts.
39.	Vucetic, Nemanja, et al. (författare) Preparation and characterization of a new bis-layered supported ionic liquid catalyst (SILCA) with an unprecedented activity in the Heck reaction 2019 Ingår i: Journal of Catalysis. - : Elsevier. - 0021-9517 .- 1090-2694. ; 371, s. 35-46 Tidskriftsartikel (refereegranskat)abstract A new bis-layered supported ionic liquid catalyst (SILCA) loaded with palladium was designed and successfully applied for the Heck reaction of iodobenzene and methyl acrylate. The silica modified catalyst consisting of the first ionic liquid layer - covalently anchored imidazolium bromide - on which the second layer, made of pyridine-carboxylic acid balanced with tetramethylguanidinium cation was attached, resulted in a catalyst with high activity. High turnover frequencies of 22,000 h(-1) were achieved in reactions with a low palladium loading as 0.009 mol %. Lower TOFs, indicating on palladium dimerization was detected when higher amounts were used. The TMG cation had a purpose to recapture and stabilize the Pd nanoparticles thus followed a release and catch mechanism. In order to get a full understanding of the catalyst structure and behaviour, the catalyst was characterized by means of nitrogen physisorption, thermal gravimetric analysis, infrared spectroscopy, scanning electron and transmission electron microscopes, solid-state NMR, X-ray photoelectron spectroscopy and inductively coupled plasma spectroscopy. The catalyst preserved good activity in five cycles.
40.	Vucetic, Nemanja, et al. (författare) Tuned Bis-Layered Supported Ionic Liquid Catalyst (SILCA) for Competitive Activity in the Heck Reaction of Iodobenzene and Butyl Acrylate 2020 Ingår i: Catalysts. - : MDPI. - 2073-4344. ; 10:9 Tidskriftsartikel (refereegranskat)abstract A thorough experimental optimization of supported ionic liquid catalyst (SILCA) was performed in order to obtain a stable and efficient catalyst for the Heck reaction. Out of fifteen proposed structures, propyl imidazolium bromide-tetramethylguanidinium pentanoate modified SiO2 loaded with PdCl2 appeared to be the most stable and to have a good activity in the reaction between butylacrylate and iodobezene, resulting in a complete conversion in 40 min at 100 °C, in four consecutive experiments. This study elucidated on the stability of the catalytic system with an ionic liquid layer during the catalyst synthesis but also under reaction conditions. In the bis-layered catalyst, the imidazolium moiety as a part of internal layer, brought rigidity to the structure, while in external layer pentanoic acid gave sufficiently acidic carboxylic group capable to coordinate 1,1,3,3-tetramethylguanidine (TMG) and thus, allow good dispersion of Pd nanoparticles. The catalyst was characterized by means of XPS, FT-IR, TEM, ICP-OES, ζ-potential, EDX, TGA, and 13C NMR. The release and catch mechanism was observed, whereas Pd re-deposition can be hindered by catalyst poisoning and eventual loss of palladium.

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