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  • 1
    Electronic Resource
    Electronic Resource
    Coke formation on an industrial reforming Pt–Sn/γ‐Al2O3 catalyst (2000)
    Springer
    Catalysis letters 65 (2000), S. 209-216 
    Details
    ISSN: 1572-879X
    Keywords: coke formation ; industrial reforming catalyst ; Pt–Sn/γ‐Al2O3 ; coke characterization ; coke burning off
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The characterization of the coke deposited on an industrial Pt–Sn/γ‐Al2O3 catalyst, used in a continuous reforming process, was performed with AFM, XRD, FTIR, EPR, NMR, TG‐DTG and DTA techniques. Composition, structure and location of the coke on the catalyst were investigated. The coke was predominantly deposited on the catalyst surface and in the interstices between the catalyst particles. Its content increased along the reactor from top to bottom. Coke was deposited in the form of uniform films and clusters of three‐dimensional disks with diameters between 0.12 and 0.18 μm. It had a pseudo‐graphite structure produced by the dehydrogenation and polymerization of the aromatic precursor compounds. The coked catalyst showed a good combustion behavior; it was regenerated below 550°C. These results are important to elucidate the coke formation mechanism, to generate new continuous reforming catalysts, and to optimize the reactor operation parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019042027077
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  • 2
    Electronic Resource
    Electronic Resource
    Pt-Sn/Al2O3 sol-gel catalysts: Metallic phase characterization (1993)
    Springer
    Catalysis letters 21 (1993), S. 309-320 
    Details
    ISSN: 1572-879X
    Keywords: Sol-gel catalysts ; platinum-tin catalysts ; platinum dispersion ; X-ray diffraction ; energy dispersive X-ray analysis ; EDX analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Highly dispersed platinum was found in Pt-Sn/Al2O3 catalysts prepared by the sol-gel method, i.e., cogelation of aluminum tri-sec-butoxide and tetrabutyltin and subsequent impregnation with hexachloroplatinic acid. X-ray diffraction studies showed that the cell parameter of pure platinum is not modified in bimetallic Pt-Sn samples. Moreover, energy dispersive X-ray analysis studies (EDX) showed that platinum, but not tin, was detected in the catalysts where tin was incorporated by the sol-gel coprecipitation of tin and aluminum. Incorporation of tin into the alumina network is suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00769483
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  • 3
    Electronic Resource
    Electronic Resource
    A Raman Scattering Study of PbTiO3 and TiO2 Obtained by Sol-Gel (1998)
    Springer
    Journal of sol gel science and technology 13 (1998), S. 849-853 
    Details
    ISSN: 1573-4846
    Keywords: Raman ; TiO2 ; PbTiO3-nanocrystals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The mechanisms that give rise to the broadening and the shifts of the Raman peaks of titanium dioxide and lead titanate nanocrystals prepared by sol-gel are discussed. Phonon confinement and oxygen deficiency are competitive mechanisms in TiO2 obtained by different sol-gel preparations whereas pressure effects on the nanocrystals predominate in ferroelectric PbTiO3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008602718987
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  • 4
    Electronic Resource
    Electronic Resource
    Dehydroxylation and the Crystalline Phases in Sol-Gel Zirconia (1998)
    Springer
    Journal of sol gel science and technology 11 (1998), S. 309-319 
    Details
    ISSN: 1573-4846
    Keywords: dehydroxilation in sol-gel ZrO2 ; paramagnetic point defects ; tetragonal zirconia stabilization ; nanocrystalline tetragonal ZrO2 ; nanocrystalline monoclinic ZrO2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The formation and evolution with temperature of the crystalline phases in sol-gel ZrO2 was analyzed by using X-ray powder diffraction, refinement of the crystalline structures, ESR, and UV-Vis spectroscopy. The precursor phase of crystalline zirconia was amorphous Zr(OH)4 with the same local order as the tetragonal crystalline phase. This amorphous phase dehydroxylated with temperature, generating nanocrystalline tetragonal zirconia, and producing point defects that stabilized the tetragonal structure, generated a paramagetic ESR signal with g values like the free electron, and had a light absorption band at 310 nm. When the sample was annealed at higher temperatures, it continued dehydroxilating, and the point defects disappeared, causing the transformation of the nanocrystalline tetragonal phase into nanocrystalline monoclinic zirconia. The two crystalline nanophases coexisted since the beginning of crystallization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008666531404
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  • 5
    Electronic Resource
    Electronic Resource
    Thermal Stability of Sol-Gel Hydrotalcites (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 437-442 
    Details
    ISSN: 1573-4846
    Keywords: sol-gel hydrotalcites ; X-ray diffraction ; aluminum precursors ; hydrotalcites Mg/Al ratio ; mixed metal hydroxides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sol-Gel Hydrotalcites were synthesized using magnesium ethoxide and variable aluminum sources: aluminum acetilacetonate, aluminum chloride, aluminum nitrate and aluminum sulfate; in all cases, the gelation was done at pH 10. X-ray diffraction studies show that the crystallinity depends on the aluminum precursor used. The crystallinity was found in the order aluminum acetylcetonate 〉 aluminum chloride 〉 aluminum nitrate 〉 aluminum sulfate. The precursor determines the sintering behavior as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018309420745
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  • 6
    Electronic Resource
    Electronic Resource
    Sorption of131I− by hydrotalcites (1997)
    Springer
    Journal of radioanalytical and nuclear chemistry 221 (1997), S. 63-66 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In this work, hydrotalcites were used to remove131I− from aqueous solutions. It was found that131I− sorption by hydrotalcites depends greatly on the thermal treatment of the solid and does not take place by ion exchange as I− is not capable of removing CO 3 −2 or other ions in the hydrotalcite. The anions have to be removed from the solid in order to permit I− to be sorbed in the hydrotalcite. The radionuclide content was determined by γ-spectrometry and X-ray diffraction was used to identify the compounds and to estimate cell parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02035243
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  • 7
    Electronic Resource
    Electronic Resource
    Application of sol-gel process to H-zeolite synthesis over amorphous aluminosilicate materials (1991)
    Springer
    Reaction kinetics and catalysis letters 43 (1991), S. 461-466 
    Details
    ISSN: 1588-2837
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Получение H-цеолитов импрегнированием на аморфных алюмосиликатных порошках (катализаторы крекинга) сравнивали с новыми методами синтеза, основанными на процессе соль-гель. Исходя из полученных результатов видно, что H-цеолиты реагируют с промежуточными продуктами аморфных алюмосиликатов.
    Notes: Abstract The impregnation preparation of H-zeolite over amorphous aluminosilicate solids (cracking catalysts) is compared with new synthesis procedures based on sol-gel process. The characterization results show that the H-zeolite reacts with the intermediates of the amorphous aluminosilicate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02064713
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of hydrolysis catalyst and thermal treatment on titania synthesis via sol-gel (1992)
    Springer
    Reaction kinetics and catalysis letters 48 (1992), S. 295-300 
    Details
    ISSN: 1588-2837
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Исследовали влияние кислых и основных катализаторов, а также их термической обработки в приготовлении TiO2 с помощью твердо-гелеобразного метода. Полученные твердые образцы характеризовали с помощью УФ и видимой спектроскопии. При использовании кислых катализаторов наблюдали смещение полосы Фундаментальных переходов в область более низких энергий.
    Notes: Abstract The effect of acidic and basic catalysts and of thermal treatment on the preparation of TiO2 by the sol-gel method has been studied. The resultant solids were characterized by UV-Vis spectroscopy. A displacement of the band due to a fundamental transition to lower energies was observed when acid catalysts were used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02070099
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  • 9
    Electronic Resource
    Electronic Resource
    Phenylacetylene hydrogenation on Pt/TiO2 sol-gel catalysts (1993)
    Springer
    Reaction kinetics and catalysis letters 49 (1993), S. 95-101 
    Details
    ISSN: 1588-2837
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Comparative results on sol-gel and impregnated Pt/TiO2 catalysts are presented. Important differences between the two preparations were found, especially the high resistivity of sol-gel materials to deactivation during phenylacetylene hydrogenation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02084034
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  • 10
    Electronic Resource
    Electronic Resource
    Pore size controlled Pt/SiO2 catalysts (1994)
    Springer
    Reaction kinetics and catalysis letters 52 (1994), S. 65-71 
    Details
    ISSN: 1588-2837
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Pt/SiO2 catalysts have been prepared by the sol-gol and impregnation methods. The platinum complex interacts with the silanol groups during the gelation step. At acidic pH the pore size distribution is monomodal. At basic pH no small pores are observed. Impregnated catalyst porosity is less sensitive to pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02129851
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