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  • 1
    Electronic Resource
    Electronic Resource
    Selective catalytic reduction of nitric oxide over vanadia grafted on titania. Influence of vanadia loading on structural and catalytic properties of catalysts (1992)
    Springer
    Catalysis letters 14 (1992), S. 89-99 
    Details
    ISSN: 1572-879X
    Keywords: Reduction of nitric oxide ; ammonia ; vanadia/titania ; vanadyl alkoxides ; selective immobilization ; structure sensitivity ; structure of vanadia ; Raman spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The selective catalytic reduction (SCR) of NO by NH3 has been studied over vanadia/ titania catalysts prepared by selective immobilization of vanadyl alkoxide species on two structurally different titania supports. The loading of vanadia was varied from 1.8 to 7.5 μ,mol V5+ per m2 surface area. Comparative kinetic measurements at 150 °C show that the NO turnover frequencies increase by more than an order of magnitude when the vanadia loading is increased from 1.8 to ≈ 3 μmol V5+/m2. In the region of lower SCR activity, i.e. at lower coverages (≈ 2 μmol V5+/m2), small clusters and ribbons of vanadia are detected in the Raman spectra, whereas at loadings where maximum NO turnovers are achieved (≈ 3 μmol V5+/m2) the prevalent vanadia species are well-developed two-dimensional vanadia layers bound to titania.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00764222
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Vanadia layers supported on TiO2/SiO2 mixed oxides — An ESR and Raman investigation (1990)
    Springer
    Catalysis letters 4 (1990), S. 327-338 
    Details
    ISSN: 1572-879X
    Keywords: Vanadium oxide catalyst ; mixed oxide supports ; ESR spectroscopy ; Raman spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract ESR and Raman spectroscopy have been used to characterize monolayers of vanadia, which had been immobilized on titania and on a 20% TiO2/80% SiO2 mixed oxide support from a vanadyl alkoxide precursor. Characteristic vibrations observed in the Raman spectrum, as well as UV-visible reflection data, indicate that the most abundant vanadia species on the surface consists of disordered polymeric arrays: the central vanadium ion is surrounded by the tightly bound vanadyl oxygen, four oxygen ions in the basal plane, and a distant sixth oxygen ligand in bridging position to the support. From the ESR spectra the principal values ofg andA tensors are obtained, and their dependence on the support material and on the vanadia loading is investigated. Comparison with TPR measurements indicates that for structurally and chemically similar catalysts, the ESR-derived deviationΔg⊥ = g⊥ − g e from the free electrong value provides a useful measure of the V=O bond strength.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00765318
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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