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  • CRTA  (1)
  • TPD-MS method  (1)
  • hexamethyldisilazane  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Comparative study of the kinetics of the thermal decomposition of synthetic and natural siderite samples (2000)
    Springer
    Physics and chemistry of minerals 27 (2000), S. 495-503 
    Details
    ISSN: 1432-2021
    Keywords: Key words Thermal decomposition ; Kinetics ; Siderite ; CRTA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The mechanism of the thermal decomposition of two siderites (a pure synthetic and a natural Mg-containing sample) has been determined from comparison of the results obtained from linear heating rate (TG) and constant rate thermal analysis (CRTA) experiments in high vacuum. The thermal decomposition of the synthetic siderite takes place approximately 200 K below the decomposition temperature of the natural sample. The mechanism and the product of the thermal decomposition are different for the siderite samples. In fact, an A2 kinetic model describes the thermal decomposition of the synthetic siderite, whereas the thermal decomposition of the natural sample obeys an F1 kinetic law. Decomposition products of the synthetic siderite are iron and magnetite, those of the natural siderite are wüstite and minor magnetite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002690000093
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Fluoride treatment of AlPO4-Al2O3 catalysts. II. Poisoning experiments by bases for cyclohexene conversion and cumene cracking (1994)
    Springer
    Catalysis letters 24 (1994), S. 293-301 
    Details
    ISSN: 1572-879X
    Keywords: AlPO4-Al2O3 ; fluoride ion loading ; surface acidity ; cyclohexene conversion ; cumene cracking ; poisoning by bases ; pyridine ; 2,6-dimethylpyridine ; hexamethyldisilazane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Brønsted acid sites on fluoride-modified AlPO4-Al2O3 (2.5 wt% F; APAl-P-2.5F) catalyst are poisoned by the presence of 2,6-dimethylpyridine (DMPY) and hexamethyldisilazane (HMDS), thus decreasing the catalytic activity for cyclohexene and cumene reaction processes, while the effect of pyridine (PY) was scarce. Besides, the drop in activity for cyclohexene conversion was accompanied by a change in reaction selectivity so that hydrogen transfer sites are much more sensitive to base poisoning (getting greater as the poisoning effect increased) than isomerization sites. Moreover, surface trimethylsilyl (TMS) complexes (formed by covalent reaction of HMDS with surface hydroxyls) decomposed and thus, the activity progressively increased at increasing time intervals, thus reaching greater values (at ca. 4 h) than the unpoisoned APAl-P-2.5F catalyst. So, DMPY was more suitable than PY and HMDS for the poisoning of Brønsted acid sites on APAl-P-F catalyst.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00811802
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Thermal decomposition of sodium nitrite and sodium nitrate pre-adsorbed on TiO2 surfaces (1992)
    Springer
    Journal of thermal analysis and calorimetry 38 (1992), S. 673-682 
    Details
    ISSN: 1572-8943
    Keywords: DTA ; pre-adsorbed sodium nitrite/nitrate ; solid state chemical reaction ; TPD-MS method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Mittels verschiedenen Techniken, wie z.B. IR-Spektroskopie oder temperaturprogrammierte Desorption in Verbindung mit massenspektrometrischer Analyse wurde die thermische Zersetzung von Natriumnitrit oder Natriumnitrat, welches zuvor an der Oberfläche von TiO2 absorbiert wurde, untersucht, um die Eigenschaften bei dieser thermischen Zersetzung zu beobachten. DTA in Verbindung mit Röntgendiffraktions-analyse wurde eingesetzt, um die Möglichkeit einer chemischen Feststoffreaktion zwischen den bei der thermischen Zersetzung der voradsorbierten Proben entstehenden Produkten und TiO2 zu untersuchen. Anhand der Ergebnisse werden zahlreiche verschiedene charakteristische Wesenszüge dieser thermischen Zersetzung diskutiert.
    Notes: Abstract The thermal decomposition of sodium nitrite or nitrate pre-adsorbed upon TiO2 surfaces has been investigated by employing several techniques as infrared spectroscopy (IR) and temperature programmed desorption in conjunction with mass spectrometry analysis (TPD-MS) to study the features observed during these thermal decompositions. Differential thermal analysis (DTA) in combination with X-ray diffraction analysis (XRD) were used to investigate the possibility of a solid state chemical reaction between the solid products originated from the thermal decomposition of the pre-adsorbed species and the TiO2. On the basis of our results, various characteristic features of these thermal decomposition reactions will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01979396
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    Paper (German National Licenses)
    Fulltext
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