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  • Fischer-Tropsch synthesis  (2)
  • CuO  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Nickel-iron catalysts prepared by homogeneous deposition-precipitation of cyanide complexes on a titania support (1995)
    Springer
    Topics in catalysis 2 (1995), S. 29-43 
    Details
    ISSN: 1572-9028
    Keywords: Fischer-Tropsch synthesis ; bimetallic nickel-iron ; cyanide complex ; potassium ; catalysts preparation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Nickel-iron catalysts have been prepared by homogeneous deposition-precipitation of complex nickel-iron cyanides on a titania support. The nickel-iron alloys obtained after calcination and reduction of the cyanide precursors were characterized by Mössbauer spectroscopy, high-temperature X-ray diffraction, and magnetic measurements. Fischer-Tropsch experiments show remarkable results. Catalysts prepared from K3Fe(CN)6 and Na2Fe(CN)5NO cyanide precursors exhibit a high activity and selectivity, whereas catalysts prepared from K4Fe(CN)6 do not show any activity. This lack of activity is caused by the presence of potassium in catalysts prepared from K4Fe(CN)6. Potassium or iron titanate inhibits the adsorption of CO on the nickel-iron surface. Deactivation of active nickel-iron catalysts was caused by the deposition of inactive carbon during Fischer-Tropsch synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01491953
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of steam treatment on MeO/Al2O3 model catalysts (Me = Ni, Co, Cu, Fe) (1996)
    Springer
    Catalysis letters 39 (1996), S. 233-240 
    Details
    ISSN: 1572-879X
    Keywords: volatilization ; steam ; transition metal hydroxides ; NiO ; Co3O4 ; CuO ; Al2O3 ; Rutherford backscattering spectrometry (RBS) ; solid state reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract To study the influence of steam on the solid state reaction between MeO (Me = Ni, Co, Cu or Fe) and Al2O3, MeO/α-Al2O3 and MeO/γ-Al2O3 model catalysts were kept in either N2/20% O2 or N2/O2/30% H2O at 500–1000°C. The samples were subsequently analyzed with RBS and FTIR. Surprisingly, nickel, cobalt and copper volatilized when MeO/α-Al2O3 or MeAl2U4/α-Al2O3 samples were annealed in the presence of 0.3 atm steam at 1000°C. Especially copper was found to volatilize very rapidly in the presence of steam, even at a temperature as low as 800°C. FTIR spectra of steam-treated NiO/α-Al2O3 samples showed the incorporation of hydroxyl groups in the nickel oxide layer. This observation and an excellent agreement with thermochemical calculations support our conclusion that the volatile species are metal hydroxides. The solid state reaction of MeO withγ-Al2O3 was found to proceed at a much higher rate in the presence of 0.3 atm steam at 500–800°C, presumably as a result of an enhanced surface mobility of Me and Al ions along the grain boundaries and the surfaces of the internal pores of theγ-Al2O3 support, when steam is present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00805588
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Metal-support interaction: titania-supported nickel-iron catalysts (1996)
    Springer
    Catalysis letters 41 (1996), S. 27-34 
    Details
    ISSN: 1572-879X
    Keywords: Fischer-Tropsch synthesis ; nickel-iron ; particle size ; metal-support interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The influence of the titania support and metal particle size on the performance of nickel-iron catalysts in the Fischer-Tropsch synthesis has been studied by varying the nickel-iron loading and, consequently, varying the nickel-iron particle size. Low-loaded titania-supported nickel-iron catalysts (2 wt%) turned out to be more selective towards higher hydrocarbons than high-loaded nickel-iron catalysts (20 wt%), which produce much more methane. From temperature-programmed hydrogenation experiments, magnetic measurements and Mössbauer spectroscopy it followed that different types of carbon are present on the catalysts depending on the metal loading. These types of carbon could be related to the selectivity in Fischer-Tropsch synthesis and to the deactivation of the catalysts with time on stream. These differences in catalytic behaviour are most likely due to the presence of TiO x species on the surface of the active phase, which species decrease the CO and H2 adsorption properties of the catalyst, but increase the dissociation of CO.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00811708
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    Paper (German National Licenses)
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