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  • 2000-2004  (1)
  • 1995-1999  (4)
  • magnesia-silica mixed oxides  (2)
  • n-hexane conversion  (2)
  • Key words Thermoluminesence  (1)
Datenquelle
Materialart
Erscheinungszeitraum
  • 2000-2004  (1)
  • 1995-1999  (4)
Jahr
Schlagwörter
  • 1
    Digitale Medien
    Digitale Medien
    Thermo-luminescence induced by gamma irradiation in sol-gel prepared zirconia–silica materials (2000)
    Springer
    Materials research innovations 4 (2000), S. 32-35 
    Details
    ISSN: 1433-075X
    Schlagwort(e): Key words Thermoluminesence ; Gamma irradiation ; Zirconia–silica ; Sol-gel ; Dosimeter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract  Zirconia–silica materials prepared by the sol-gel method at different compositions were gamma irradiated with a dosage of 40 Krads for different irradiation periods. The thermoluminescent (TL) emission was studied as a function of the zirconia for temperatures from 100 to 300 °C. Pure zirconia produces a strong TL signal, followed by 50% zirconia sample, while pure silica and the 5% zirconia sample show a weak TL signal. This means that there exists a self-inhibited process possible due, on the one hand to the segregation effects of both components, and on the other to the stabilization of either tetragonal or monoclinic zirconia phases. This effect opens the possibility to control the TL signal in a wide range of dosages allowing to use this system as a wide range dosimeter.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100190000064
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Preparation of Magnesia-Silica Oxides: Effect of Mg/Si Ratio and Sulfate on Acidity (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 321-325 
    Details
    ISSN: 1573-4846
    Schlagwort(e): magnesia-silica mixed oxides ; sol-gel magnesia-silica ; magnesia-silica acidity ; sulfated magnesia-silica ; isopropanol decomposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Mg-Si binary oxides were prepared by the sol-gel method, using magnesium diethoxide and tetraethoxysilane as starting materials. Mg-Si mixed oxides were prepared at pH3 and 9 at nominal concentrations of 1.3, 4.0, and 6.7 mole% MgO. Density and strength of the acid sites were determined by pyridine thermal programmed desorption. Comparable Lewis acidity was found in pH3 and 9 preparations. However, when the samples were sulfated with sulfuric acid, strong Bronsted acidity was developed, reaching a maximum at 6.7 mole% MgO. The strong acidity of sulfated samples was corroborated using the isopropanol decomposition reaction as catalytic test. Similar conversions are obtained at 100°C on sulfated samples, whereas 260°C are required for non-sulfated ones.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1026487018502
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Effect of Tin Precursor on the Catalytic Properties of Pt-Sn/Al2O3 Sol-Gel Prepared Catalysts (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 847-849 
    Details
    ISSN: 1573-4846
    Schlagwort(e): platinum-tin catalysts ; Pt-Sn sol-gel catalysts ; cyclohexane dehydrogenation ; n-hexane conversion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Tin-alumina supports were prepared by cogelation of aluminum tri-sec-butoxide and tetrabutyltin or tin tetrachloride. Aqueous or acetone platinum solutions were used for impregnation. The results show that the specific surface area and the acidity of the catalysts were only slightly modified by the metal precursors used. On cyclohexane dehydrogenation and n-hexane conversion, high selectivity to olefins and low cracking products were detected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1018362813843
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Preparation of magnesia-silica oxides: Effect of Mg/Si ratio and sulfate on acidity (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 321-325 
    Details
    ISSN: 1573-4846
    Schlagwort(e): magnesia-silica mixed oxides ; sol-gel magnesia-silica ; magnesia-silica acidity ; sulfated magnesiasilica ; isopropanol decomposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Mg−Si binary oxides were prepared by the sol-gel method, using magnesium diethoxide and tetraethoxysilane as starting materials. Mg−Si mixed oxides were prepared at pH3 and 9 at nominal concentrations of 1.3, 4.0, and 6.7 mole% MgO. Density and strength of the acid sites were determined by pyridine thermal programmed desorption. Comparable Lewis acidity was found in pH3 and 9 preparations. However, when the samples were sulfated with sulfuric acid, strong Bronsted acidity was developed, reaching a maximum at 6.7 mole% MgO. The strong acidity of sulfated samples was corroborated using the isopropanol decomposition reaction as catalytic test. Similar conversions are obtained at 100°C on sulfated samples, whereas 260°C are required for non-sulfated ones.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02436859
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Effect of tin precursor on the catalytic properties of Pt-Sn/Al2O3 sol-gel prepared catalysts (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 847-849 
    Details
    ISSN: 1573-4846
    Schlagwort(e): platinum-tin catalysts ; Pt-Sn sol-gel catalysts ; cyclohexane dehydrogenation ; n-hexane conversion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Tin-alumina supports were prepared by cogelation of aluminum tri-sec-butoxide and tetrabutyltin or tin tetrachloride. Aqueous or acetone platinum solutions were used for impregnation. The results show that the specific surface area and the acidity of the catalysts were only slightly modified by the metal precursors used. On cyclohexane dehydrogenation andn-hexane conversion, high selectivity to olefins and low cracking products were detected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02436949
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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    Artikel (Nationallizenzen)
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