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  • Artikel: DFG Deutsche Nationallizenzen  (4)
  • methane activation  (2)
  • deuterium isotope effect  (1)
  • rare earth orthovanadates  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Methane activation over unsupported and La2O3-supported copper and nickel catalysts (1996)
    Springer
    Catalysis letters 36 (1996), S. 159-163 
    Details
    ISSN: 1572-879X
    Schlagwort(e): methane activation ; Cu/La2O3 and Ni/La2O3 catalysts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Methane was pulsed over pure CuO and NiO as well as Cu/La2O3 and Ni/La2O3 catalysts at 600° C. Results indicate that the mechanisms for methane activation over copper and nickel are quite different. Over CuO, methane is converted to CO2 and H2O, most likely via the combustion mechanism; whereas metallic copper does not activate methane. Over NiO in the presence of metallic nickel sites, methane activation follows the pyrolysis mechanism to give CO, CO2, H2 and H2O. Similar results were obtained over the Cu/La2O3 and Ni/La2O3 catalysts. XRD investigations indicate that copper and nickel existed as CuLa2O4 and LaNiO3 respectively in the La2O3-supported catalysts. The effect of La2O3 on the activation of methane is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00807613
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  • 2
    Digitale Medien
    Digitale Medien
    Preparation and characterization of rare earth orthovanadates for propane oxidative dehydrogenation (1996)
    Springer
    Catalysis letters 37 (1996), S. 241-246 
    Details
    ISSN: 1572-879X
    Schlagwort(e): rare earth orthovanadates ; citrate method ; propane oxidative dehydrogenation ; redox property
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract High purity rare earth orthovanadates (REVO4), YVO4, LaVO4, CeVO4, NdVO4, SmVO4 and EuVO4, were prepared by the citrate method. XRD, FT-IR, LRS and TPR techniques were employed to characterize these orthovanadates. The catalytic performance of SmVO4, LaVO4 and YVO4 in the oxidative dehydrogenation of propane can compete with that of Mg3V2O8. The selectivity of propene over CeVO4, NdVO4 and EuVO4 was relatively lower. The correlation between the reducibility and the selectivity of the catalysts implied that the V4+/V3+ couple might be involved in the dehydrogenation process.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00807761
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  • 3
    Digitale Medien
    Digitale Medien
    Pulse study of methane partial oxidation to syngas over SiO2-supported nickel catalysts (1996)
    Springer
    Catalysis letters 41 (1996), S. 159-163 
    Details
    ISSN: 1572-879X
    Schlagwort(e): methane oxidation ; syngas ; SiO2-supported nickel (Ni/SiO2) ; deuterium isotope effect
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The reaction behaviors of CH4/O2 (2/1) with unreduced and reduced SiO2-supported nickel (10 wt% metal) catalysts were investigated in a pulse micro-reactor at temperatures ranging from 600 to 800° C. In the interaction of CH4/O2 with unreduced NiO/SiO2, the products are exclusively CO2 and H2O at or below 700°C. At 800° C, besides CO2 and H2O, CO and H2 are formed. The reactivity at 800°C can be ascribed to the net generation of metallic nickel site at this temperature. In the reaction of CH4/O2 over reduced Ni/SiO2, the main products are CO and H2 with CO2 and H2O being the minor ones. The results indicate metallic nickel is the active site for methane partial oxidation to syngas. Normal deuterium isotope effects of similar magnitude were observed on the overall, as well as on the CO and CO2 formation reactions with insignificant change in the product selectivities when CD4 was used instead of CH4, indicating that methane dissociation is a key step and that CO and CO2 are formed via some common intermediates which are subject to kinetic deuterium isotope effect. The results of deuterium isotope effects can be reasonably explained based on the methane pyrolysis mechanism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00811484
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  • 4
    Digitale Medien
    Digitale Medien
    Pulse studies of CH4 interaction with NiO/Al2O3 catalysts (1994)
    Springer
    Catalysis letters 27 (1994), S. 199-206 
    Details
    ISSN: 1572-879X
    Schlagwort(e): pulse reaction ; NiO/Al2O3 catalysts ; methane activation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Pulse studies of the interaction of CH4 and NiO/Al2O3 catalysts at 500°C indicate that CH4 adsorption on reduced nickel sites is a key step for CH4 oxidative conversion. On an oxygen-rich surface, CH4 conversion is low and the selectivity of CO2 is higher than that of CO. With the consumption of surface oxygen, CO selectivity increases while the CO2 selectivity falls. The conversion of CH4 is small at 500°C when a pulse of CH4/O2 (CH4∶O2=2∶1) is introduced to the partially reduced catalyst, indicating that CH4 and O2 adsorption are competitive steps and the adsorption of O2 is more favorable than CH4 adsorption
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00806993
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    Artikel (Nationallizenzen)
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