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  • 1
    Electronic Resource
    Electronic Resource
    Remarks on "Effects of surface modification with silicon oxides on the photochemical properties of powdered titania" (1990)
    s.l. : American Chemical Society
    Langmuir 6 (1990), S. 1525-1526 
    Details
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/la00099a017
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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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  • 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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  • 4
    Electronic Resource
    Electronic Resource
    Influence of the nature of iron, aluminium and yttrium organometallic nanocluster precursors on the formation mechanism of ceramic ZrO2 obtained by sol-gel method (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 213-221 
    Details
    ISSN: 1573-4846
    Keywords: zirconia ; sol-gel method ; mixed oxides ; ceramic materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract To obtain new effective precursors for single phase ceramic zirconia materials by the alkoxide route, three heterometallic iron-yttrium acetylacetonate complexes were synthesized by electrochemical anodic dissolution in acetylacetone. The structure and properties of the synthesized complex oxides were studied by XRD, EXAFS, magnetic susceptibility and Mössbauer. It was shown that, for iron-containing gels and oxides, Fe3+ ions—interchangeably with Y3+—participate in the oxide formation mechanism. The sets of interatomic distances found by EXAFS in the iron-yttrium precursor and in the zirconia gel are practically equal. The presence of structure fragments formed by these interactions—and especially by direct Fe-Y bonds in the precursors—allows single-phase triple ceramic oxides to form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436843
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  • 5
    Electronic Resource
    Electronic Resource
    Bulk and surface characterization of powder iron-doped titania photocatalysts (1992)
    Springer
    Journal of materials science 27 (1992), S. 3036-3042 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Some additional contributions to structural and surface features of powder iron-doped titania photocatalysts have been investigated by applying a variety of complementary techniques: temperature programmed desorption-mass spectrometry analysis, non-isothermal thermogravimetric analysis, differential thermoanalysis, infrared spectroscopy, scanning electron microscopy and X-ray diffraction analysis. The effects of iron concentration and pretreatment temperature, over the polymorphic transformation anatase-rutile, were analysed. The results obtained were used in an attempt to correlate structural and surface aspects of catalysts, with their reported activity versus inactivity to photoreduce dinitrogen to ammonia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01154116
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  • 6
    Electronic Resource
    Electronic Resource
    Formation of zirconium titanate powder from a sol-gel prepared reactive precursor (1992)
    Springer
    Journal of materials science 27 (1992), S. 2463-2467 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A hydroxoperoxo compound of Zr and Ti (HXPZT) was prepared as a reactive powder by a sol-gel method. X-ray diffraction and SEM studies showed it to be formed from small (ca. 10–15 μm) amorphous particles. The effects of progressive thermal treatment were determined by differential thermal analysis, thermogravimetric analysis, temperature programmed desorption, X-ray diffraction, energy-dispersive spectrometry and SEM. The features observed have been attributed to the removal of physically and chemically bonded water and of some nitrogen-containing compound. Crystallization of zirconium titanate occurs at low temperature (650 °C), giving rise to spherical (ca. 2 μm dia.) regular particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01105059
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  • 7
    Electronic Resource
    Electronic Resource
    On the influence of chemical processing in the crystallization behaviour of zirconium titanate materials (1992)
    Springer
    Journal of materials science 11 (1992), S. 1570-1572 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00740835
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  • 8
    Electronic Resource
    Electronic Resource
    Kinetic study of zirconia crystallization from amorphous ZrO2-SiO2 composite precursors processed by sol-gel chemistry (1994)
    Springer
    Journal of sol gel science and technology 2 (1994), S. 353-357 
    Details
    ISSN: 1573-4846
    Keywords: ZrO2-SiO2 composite ; kinetics of crystallization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Powder precursor gels with composition xZrO2·(100−x)SiO2, with selected values of x=8, 24, 43 and 75 mol%, were processed by sol-gel chemistry. Differential thermal analysis (DTA) was used to study crystallization in (cubic/tetragonal)-ZrO2 during the heating of the reactive amorphous precursors. Kinetic parameters such as activation energy, Avrami's exponent and frequency factor have been simultaneously calculated from the computed DTA data using a previously reported kinetic model. The crystallization temperature decreases relative to the increase in the amount of ZrO2, the value of the kinetic parameter of the crystallization being related to the value of x.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00486269
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  • 9
    Electronic Resource
    Electronic Resource
    Photo-induced Transformation, upon UV Illumination in Air, of Hyponitrite SpeciesN2O22- Preadsorbed onTiO2 Surface (1996)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 24 (1996), S. 355-359 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Ultraviolet photo-excitation of hydroxylated TiO2 surfaces in the presence of a mixture of N2/O2 gas (air) produces some adsorbed nitrogen oxide species which were previously identified as hyponitrite, N2O22-. The present paper reports selected results relating to the photo-induced transformations, upon UV illumination in air, of N2O22- species preadsorbed on TiO2 surfaces. It provides some information about the mechanism by which dinitrogen is photofixed on TiO2 surface and of its phototransformation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 10
    Electronic Resource
    Electronic Resource
    Identification of the fixed nitrogen containing species during the photo-oxidative fixation of molecular nitrogen on UV-illuminated TiO2 surfaces (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 22 (1994), S. 417-420 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Ultraviolet photoexcitation of hydroxylated TiO2 surfaces in the presence of a mixture on N2/O2 gas (air) produces some adsorbed nitrogen oxide species which were previously assigned indirectly as probably N2O22-. Direct assignment is now reported here. From comparisons of the thermodesorption profiles and the XPS results from polycrystalline Na2N2O2 and from the corresponding data obtained from TiO2 surface upon which Na2N2O2 had been allowed to adsorb with the thermodesorption profile and XPS data obtained from the photo-induced fixation of nitrogen on TiO2, it can be concluded that the principal species formed during the photo-oxidative fixation of molecular nitrogen on TiO2 is hyponitrite anion, N2O22-.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740220190
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