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  • Articles: DFG German National Licenses  (3)
  • 1990-1994  (3)
  • temperature  (2)
  • 27.40.+z  (1)
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  • Articles: DFG German National Licenses  (3)
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Years
  • 1990-1994  (3)
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Keywords
  • 1
    Electronic Resource
    Electronic Resource
    In situ high temperature and high pressure exafs studie of Pt/Al2O3 catalysts. Part I: Reduction and deactivation (1991)
    Springer
    Catalysis letters 8 (1991), S. 283-295 
    Details
    ISSN: 1572-879X
    Keywords: EXAFS ; Pt/Al2O3 catalysts ; chlorine ; temperature ; pressure ; reduction ; deactivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract EXAFS has been used to follow in situ the structural evolution of a chlorinated and non-chlorinated Pt/Al2O3 catalyst during reduction in the temperature range of 300–500 °C. Smaller metal clusters are formed from the hydrogen reduction of the chlorinated catalyst, in contrast to the larger cluster formed from the non-chlorinated one. At 460 °C, the total hydrogen pressure was raised to 5 atm. and n-heptane was injected over the samples. EXAFS measurements at the Pt edge were carried out while hydrocarbon conversion was monitored with a gas Chromatograph. We observe the rapid formation of a carbon-platinum bond. This is unmodified while turnover rates and selectivities indicate evidence for deactivation. From this structural information supplied by EXAFS, correlated with the data obtained from gas chromatography, we find that our results are consistent with a model proposed by others where deactivation is due to the build-up of a multilayer of carbon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00764190
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The decay modes of proton drip-line nuclei with A between 42 and 47 (1992)
    Springer
    The European physical journal 344 (1992), S. 135-144 
    Details
    ISSN: 1434-601X
    Keywords: 21.10.Dr ; 23.90.+w ; 27.40.+z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Neutron-deficient isotopes with Z=21 to 26 have been produced as projectile-like fragments of an intense58Ni GANIL beam of 69 MeV/nucleon. The nuclei selected by the upgraded LISE3 spectrometer were identified and implanted in a silicon detector telescope. The43Cr,47Fe and46Fe isotopes were identified for the first time whereas45Fe,45Mn,44Mn and42V were not observed, indicating probable instability of these nuclei against particle emission. Measurements of the half-lives of43Cr and46Mn have been performed and the analysis of their measured beta-delayed proton spectra has given, through the isobaric multiplet mass equation, an empirical estimation of their masses. Half-lives of44Cr,43V,47Fe and46Fe have also been measured. A discussion of various mass predictions for nuclei at the proton drip-line is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01291696
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    In situ high temperature and high pressure exafs studies of Pt/Al2O3 Catalysts. Part II: Carbon removal (1991)
    Springer
    Catalysis letters 8 (1991), S. 297-304 
    Details
    ISSN: 1572-879X
    Keywords: EXAFS ; Pt/Al2O3 catalyst ; temperature ; pressure ; carbon deposition ; carbon removal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract EXAFS has been used to follow in situ the structural evolution of a Pt/Al2O3 catalyst during removal of carbon by hydrogenation, after reduction and carbon deposition. After reduction at 350 °C, the total hydrogen pressure was raised to 3 atm. and n-heptane was injected over the sample. EXAFS measurements at the Pt edge were carried out with simultaneous on-line EXAFS analysis of the spectra. After observing the rapid formation of a carbon-platinum bond which is unmodified with time, we stopped the heptane flow, raised the temperature to 450 °C, and maintained hydrogen flow at 3 atm. The disappearance of the platinum-carbon bond during heat treatment in hydrogen was monitored via on-line analysis. No sintering of the metal particles was observed. EXAFS is thus proven to be an efficient tool to study not just structural changes of a catalyst during a hydrocarbon reaction [1], but also to use it as a technique to study other catalytic phenomena as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00764191
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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