Diffuse Reflectance Infrared Spectroscopy Study of Co<sub>2</sub>(CO)<sub>8</sub> Supported on Alumina

Kurhinen, Maria; Pakkanen, Tapani A.

doi:10.1021/la9803326

Cited by 15 publications

(20 citation statements)

References 38 publications

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“…Typical carbonyl bands of CO adsorption on the activated cobalt surface were observed at 1737 cm À1 (CO absorbed in bridged mode) [17] and at 1439-1215 cm À1 (assigned to the CO of carbonate), while the terminal CO stretching lies under the free CO band at around 2180-2115 cm À1 . [17] The band at 750 cm À1 is typical of bridged CO carbonate. [18] Interestingly, these nanoparticles, whether they are dispersed in the ionic liquid (BMI·NTf 2 ) or isolated, are effective catalysts for the FTS.…”

Section: Dedicated To Prof Martin Schmal On the Occasion Of His 70thmentioning

confidence: 98%

“…[17] The band at 750 cm À1 is typical of bridged CO carbonate. [18] Interestingly, these nanoparticles, whether they are dispersed in the ionic liquid (BMI·NTf 2 ) or isolated, are effective catalysts for the FTS.…”

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confidence: 99%

“…[15,16] The IR spectra of the isolated Co nanoparticles ((7.7 AE 1.2) nm) in a diffuse-reflectance infrared Fourier transform (DRIFT) cell and in the presence of CO (20 atm) at room temperature for 15 h are presented in Figure 4. Typical carbonyl bands of CO adsorption on the activated cobalt surface were observed at 1737 cm À1 (CO absorbed in bridged mode) [17] and at 1439-1215 cm À1 (assigned to the CO of carbonate), while the terminal CO stretching lies under the free CO band at around 2180-2115 cm…”

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Catalytic Gas‐to‐Liquid Processing Using Cobalt Nanoparticles Dispersed in Imidazolium Ionic Liquids

et al. 2008

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FT special report: Cobalt nanoparticles with a size of around 7.7 nm prepared in 1‐alkyl‐3‐methylimidazolium bis(trifluoromethanesulfonyl)imidate ionic liquids are effective catalysts for the Fischer–Tropsch (FT) synthesis, yielding olefins, oxygenates, and paraffins (C7–C30). The nanoparticles are easily prepared by the decomposition of [Co(CO)8] in the ionic liquid at 150 °C and can be reused at least three times if they are not exposed to air.

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Section: Dedicated To Prof Martin Schmal On the Occasion Of His 70thmentioning

confidence: 98%

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confidence: 99%

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confidence: 99%

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Catalytic Gas‐to‐Liquid Processing Using Cobalt Nanoparticles Dispersed in Imidazolium Ionic Liquids

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“…As a typical experiment to better evaluate the properties of the metallic surface, CO adsorption (20 atm at 25 °C for 20 h) was performed with the isolated cobalt MNPs (prepared in [DMI][NTf 2 ]) in a DRIFT cell (DRIFT=diffuse reflectance infrared Fourier transform; Figure S5 in the Supporting Information). Typical bands for CO adsorbed on the activated cobalt surface were observed around 2210–2050 cm −1 (terminal CO stretching), at 1732 cm −1 (CO adsorbed in a bridged mode),38 1367 cm −1 , and 1213 cm −1 (assigned to the CO group of carbonate),39 while the band at 750 cm −1 is typical of a bridged CO carbonate 39…”

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Cobalt Nanocubes in Ionic Liquids: Synthesis and Properties

et al. 2008

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The magnetic, optical, and catalytic properties of soluble metal nanoparticles (MNPs) depend primarily on their size, shape, and type, and on the nature of the stabilizer. [1][2][3][4][5][6] The generation of MNPs of controlled size and shape has been achieved by using a variety of methods that are mainly based on the use of ligands. [7,8] Indeed, the vast majority of stable and soluble MNPs formed from transition metals have a ligand and/or oxide environment that has a substantial effect on the metal-surface properties of the nanoparticles. [7,9] The synthesis of stable, soluble, naked, and ligand-free MNPs of controlled size and shape still remains a challenge. Although these MNPs can be produced in organic solvents (e.g., alcohols or tetrahydrofuran) by the simple decomposition of organometallic precursors, [10] the properties of these nanoparticles cannot be investigated in solution because of their poor stability and the volatility of the solvents.[11] Since imidazolium ionic liquids (ILs) possess preorganized structures that can adapt or are adaptable to many species-as they provide hydrophobic or hydrophilic regions with high directionality-they are emerging as alternative liquid templates for the generation of a plethora of size-and shapecontrolled nanostructures. [12][13][14][15][16][17][18] In particular, the size of "soluble" MNPs is apparently directly related to IL selforganization, [19] and can thus, in principle, be tuned by modulating the length of the N-alkyl imidazolium side chains, [20] reaction temperature, [21] anion volume, [22,23] or anion coordination ability. [24,25] Moreover, the advent of imidazolium ILs that possess very low vapor pressure [26,27] and high thermal stability has opened the way for the investigation of processes in solution using physical methods, for example, transmission electron microscopy (TEM) [28] and X-ray photoelectron spectroscopy, [29] which require special conditions such as high vacuum. We report herein that, with the proper combination of N-alkyl imidazolium side chain, anion, and reaction conditions, ligand-free cobalt MNPs with either cubic or spherical shapes can be prepared. Moreover, we present the magnetic and catalytic properties of these naked ligand-free MNPs in 1-alkyl-3-methylimidazolium ILs.The (Figure 1 and Figure S1 in the Supporting Information). These cobalt particles show a bimodal size distribution with a mean diameter of (79 AE 17) nm for the larger particles (cubic shape) and (11 AE 3) nm for the smaller particles (mainly spherical in shape; Figure 1). However, nanoparticles with an exclusively cubic shape ((53 AE 22) nm) were obtained by decomposition of [Co 2 (CO) 8 ] in 1-n-decyl-3-methylimidazolium trifluoro-tris-(pentafluoroethane) phosphate ([DMI][FAP]) after 5 min at 150 8C (Figure 2). Interestingly, MNPs with an irregular shape were obtained from reactions in 1-n-butyl-3-methylimidazolium (BMI) ILs associated with NTf 2 À , FAP À , and BF 4 À ions under similar reaction conditions. Therefore, the formation of cubic-shaped cobalt ...

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“…Typical bands for CO adsorbed on the activated cobalt surface were observed around 2210-2050 cm À1 (terminal CO stretching), at 1732 cm À1 (CO adsorbed in a bridged mode), [38] 1367 cm À1 , and 1213 cm À1 (assigned to the CO group of carbonate), [39] while the band at 750 cm À1 is typical of a bridged CO carbonate. [39] The isolated [Co 0 ] n NPs prepared in [DMI][NTf 2 ] were tested as catalysts in the Fischer-Tropsch synthesis (FTS).…”

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Cobalt Nanocubes in Ionic Liquids: Synthesis and Properties

et al. 2008

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The magnetic, optical, and catalytic properties of soluble metal nanoparticles (MNPs) depend primarily on their size, shape, and type, and on the nature of the stabilizer. [1][2][3][4][5][6] The generation of MNPs of controlled size and shape has been achieved by using a variety of methods that are mainly based on the use of ligands. [7,8] Indeed, the vast majority of stable and soluble MNPs formed from transition metals have a ligand and/or oxide environment that has a substantial effect on the metal-surface properties of the nanoparticles. [7,9] The synthesis of stable, soluble, naked, and ligand-free MNPs of controlled size and shape still remains a challenge. Although these MNPs can be produced in organic solvents (e.g., alcohols or tetrahydrofuran) by the simple decomposition of organometallic precursors, [10] the properties of these nanoparticles cannot be investigated in solution because of their poor stability and the volatility of the solvents. [11] Since imidazolium ionic liquids (ILs) possess preorganized structures that can adapt or are adaptable to many species-as they provide hydrophobic or hydrophilic regions with high directionality-they are emerging as alternative liquid templates for the generation of a plethora of size-and shapecontrolled nanostructures. [12][13][14][15][16][17][18] In particular, the size of "soluble" MNPs is apparently directly related to IL selforganization, [19] and can thus, in principle, be tuned by modulating the length of the N-alkyl imidazolium side chains, [20] reaction temperature, [21] anion volume, [22,23] or anion coordination ability. [24,25] Moreover, the advent of imidazolium ILs that possess very low vapor pressure [26,27] and high thermal stability has opened the way for the investigation of processes in solution using physical methods, for example, transmission electron microscopy (TEM) [28] and X-ray photoelectron spectroscopy, [29] which require special conditions such as high vacuum. We report herein that, with the proper combination of N-alkyl imidazolium side chain, anion, and reaction conditions, ligand-free cobalt MNPs with either cubic or spherical shapes can be prepared. Moreover, we present the magnetic and catalytic properties of these naked ligand-free MNPs in 1-alkyl-3-methylimidazolium ILs.The in situ decomposition of [Co 2 (CO) 8 ] dispersed in 1-ndecyl-3-methylimidazolium N-bis(trifluoromethanesulfonyl)imidate ([DMI][NTf 2 ]) at 150 8C over 1 h afforded a black solution containing [Co 0 ] n NPs with a cubic shape, together with MNPs with an irregular shape (Figure 1 and Figure S1 in the Supporting Information). These cobalt particles show a bimodal size distribution with a mean diameter of (79 AE 17) nm for the larger particles (cubic shape) and (11 AE 3) nm for the smaller particles (mainly spherical in shape; Figure 1). However, nanoparticles with an exclusively cubic shape ((53 AE 22) nm) were obtained by decomposition of [Co 2 (CO) 8 ] in 1-n-decyl-3-methylimidazolium trifluoro-tris-(pentafluoroethane) phosphate ([DMI][FAP]) after 5 min a...

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Diffuse Reflectance Infrared Spectroscopy Study of Co₂(CO)₈ Supported on Alumina

Cited by 15 publications

References 38 publications

Catalytic Gas‐to‐Liquid Processing Using Cobalt Nanoparticles Dispersed in Imidazolium Ionic Liquids

Catalytic Gas‐to‐Liquid Processing Using Cobalt Nanoparticles Dispersed in Imidazolium Ionic Liquids

Cobalt Nanocubes in Ionic Liquids: Synthesis and Properties

Cobalt Nanocubes in Ionic Liquids: Synthesis and Properties

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Diffuse Reflectance Infrared Spectroscopy Study of Co2(CO)8 Supported on Alumina

Cited by 15 publications

References 38 publications

Catalytic Gas‐to‐Liquid Processing Using Cobalt Nanoparticles Dispersed in Imidazolium Ionic Liquids

Catalytic Gas‐to‐Liquid Processing Using Cobalt Nanoparticles Dispersed in Imidazolium Ionic Liquids

Cobalt Nanocubes in Ionic Liquids: Synthesis and Properties

Cobalt Nanocubes in Ionic Liquids: Synthesis and Properties

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Diffuse Reflectance Infrared Spectroscopy Study of Co₂(CO)₈ Supported on Alumina