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  • 1‐butene skeletal isomerization  (1)
  • Polymer and Materials Science  (1)
  • acid strength  (1)
Materialart
Erscheinungszeitraum
  • 1
    ISSN: 1572-879X
    Schlagwort(e): 1‐butene skeletal isomerization ; synthetic clinoptilolite ; carbonaceous deposits ; spatial constraints
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract A pure, highly crystalline clinoptilolite (CLI) zeolite with a Si/Al ratio of 5.8 has been synthesized using a small amount (1%) of seed crystals and tested as a catalyst for the skeletal isomerization of 1‐butene at 623–723 K at atmospheric pressure. The catalytic results are compared to those obtained from a ferrierite (FER) zeolite with a Si/Al ratio of 7.6. It is found that selectivity for isobutene is very high on CLI zeolite, but conversion was lower than for FER zeolite. The simulated distribution and calculated potential profile of 1‐butene molecules in CLI zeolite pore 10‐ring channels show that the spatial constraints imposed by the pores are very severe. The exceptional selectivity and the low conversion of CLI zeolite results from the strict restriction of adsorption to very specific sites, inhibiting dimerization, as well as from the high potential barrier which reduces mass transfer.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Catalysis letters 28 (1994), S. 41-52 
    ISSN: 1572-879X
    Schlagwort(e): nickel ; Y-zeolite ; ion exchange ; hydrogenation of carbon dioxide ; methane ; hydrogen ; carbon monoxide ; acid strength ; electrostatic field
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Nickel metal introduced into Y-zeolite exhibited a high catalytic activity in the dehydro-genation of methane and in the hydrogenation of carbon dioxide with methane to obtain hydrogen and CO at about 850 K. The activity strongly depended on the nickel amount in NaY, and the catalytic properties were influenced by the kind of cations in the Y-zeolite. The higher CO2 conversion was obtained over Ni supported on non-acidic zeolites.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 1343-1348 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Flat-type poly(ether sulfone) (PES) membranes for ultrafiltration were prepared by the traditional phase-inversion technique. The effects of the concentration of PES and the combination of two solvents, dichloromethane (DCM) and N-methyl-2-pyrrolidone (NMP), with differences in volatility and solvating power on membrane performance were examined in terms of pure water flux (PWF) and solute rejection (SR) against poly(ethylene glycol) (PEG, MW 20,000). Changing the thermodynamic quality of PES/NMP casting solution by combining DCM, a volatile and weak solvent, affected the PWF of the resulting membrane. The SR of PES/DCM-NMP membrane, however, was more likely dependent upon the effect of evaporating the volatile solvent from the casting solution/air interface rather than the effect of changing the thermodynamic quality of the casting solution. Combining DCM in PES/NMP casting solution transformed the fingerlike macrovoids of PES/NMP membrane prepared without DCM into the isolated macrovoids. PES/DCM-NMP membrane prepared with PVP, a water soluble poreforming agent, showed an increased PWF while maintaining SR of over 90%, even under the reduced feeding pressure of 1 kg/cm2. It is necessary to measure molecular weight cutoff of membrane for demonstrating the potential of PVP for improving the membrane permeability without losing the selectivity.© 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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