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  • 1
    Electronic Resource
    Electronic Resource
    Tg/dta, Xrd and NH3-TPD Characterization of Layered VOPO4·2H2O and its Fe3+-Substituted Compound (1998)
    Springer
    Journal of thermal analysis and calorimetry 52 (1998), S. 615-630 
    Details
    ISSN: 1572-8943
    Keywords: Fe3+-vanadyl phosphate ; NH3-TPD ; surface acidity ; TG/DTA ; vanadyl phosphate ; XRD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Iron(III)-substituted vanadyl phosphate, [Fe(H2O)]0.20VO0.80PO4·2.25H2O (FeVOP), has been prepared and characterized by XRD and TG/DTA analyses. The new compound is isomorphous with layered tetragonal VOPO4·2H2O (VOP), but it possesses a lower interlayer distance. Information on the reactivity and surface acidity of both VOP and FeVOP has been obtained by NH3-TPD experiments. The hydrated materials adsorb high amounts of NH3 (up to 2 mmol g-1). Different ammonia-containing phases are formed, characterized by lower interlayer distances in comparison with the NH3-free parent compounds. NH3 is intercalated between the layers without displacement of water. The materials dehydrated by heat treatment at 450°C retain the layered structure but adsorb NH3 only on the external surface. A wide variety of acid sites, from weak to strong, was observed. A mechanism is proposed for the NH3- acid sites interaction. SEM micrographs of VOP and FeVOP are shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010136126445
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  • 2
    Electronic Resource
    Electronic Resource
    Thermal, structural and acidic characterization of some vanadyl phosphate materials modified with trivalent metal cations (1997)
    Springer
    Journal of thermal analysis and calorimetry 50 (1997), S. 355-364 
    Details
    ISSN: 1572-8943
    Keywords: 1-butene isomerization ; M3+-substituted vanadyl phosphates ; structural characterization ; thermal characterization ; vanadyl phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A set of new materials with general formula [M(H2O)]X(VO)1−XPO4·2H2O (M 3+=Al, Cr, Ga, Mn), isomorphous with layered tetragonal VOPO4·2H2O and having potential catalytic properties, have been characterized by TG and DTA, X-ray diffraction and surface acid strength. During heating the compounds transform in the monohydrated and anhydrous phases, all maintaining a layered structure, with a proper interlayer spacing. Catalytic tests performed with 1-butene show that theM 3+-vanadyl phosphates greatly improve the conversion of the olefine with respect to pure vanadyl phosphate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01980496
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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