Abstract:
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[EN] Me-containing V2O5 materials (Me =Ag, Cu, Ca and Na) were prepared hydrothermally (from aqueous
gels containing V2O5/H2O2/MeClx mixtures, with Me/V ratios of 0.17). The samples were finally heattreated
in air or in ...[+]
[EN] Me-containing V2O5 materials (Me =Ag, Cu, Ca and Na) were prepared hydrothermally (from aqueous
gels containing V2O5/H2O2/MeClx mixtures, with Me/V ratios of 0.17). The samples were finally heattreated
in air or in N2 atmosphere. The heat-treated samples have been characterized by several physicochemical
techniques and tested in the partial oxidation of hydrogen sulfide. According to XRD, electron
paramagnetic resonance and 51V NMR results, Ag0.35V2O5 and Na0.33V2O5 (or NaV6O15) bronzes with
a minority presence of V2O5 were mainly obtained in the case of Ag- and Na-containing materials in
samples both heat-treated in air or in N2 atmosphere. In the case of Cu- and Ca-containing samples, V2O5
was mainly observed in samples calcined in air. However, Cu0.26V2O5 and Ca0.17V2O5 bronzes, with the
minority presence of V2O5, have been observed in Cu- and Ca-containing samples heat-treated in N2. On
the other hand, the catalytic behavior strongly depends on the metal promoter. Thus catalysts presenting
vanadium oxide bronzes, i.e. samples presenting Ag0.35V2O5, NaV6O15, Cu0.26V2O5 or Ca0.17V2O5 shows
a catalytic activity during the partial oxidation of H2S to sulfur higher than that observed over pure
V2O5 or over promoted catalysts presenting mainly V2O5 (i.e. Cu- or Ca-containing samples calcined in
air). Moreover, some differences in the selectivity to sulfur were observed. A higher formation of SO2 at
high reaction temperature has been favored over Ag0.35V2O5-containing catalyst. This different behavior
between samples could be explained by the presence of metallic Ag on the surface of Ag0.35V2O5, which
was detected by XRD. Also, higher formation of SO2 is favored in the case of catalyst heat-treated in N2,
in which the presence of VO2, as minority, could have a role in combustion of sulfur. Accordingly, this
work should be considered as a first approach to relate catalytic activity of the Me-containing vanadium
oxide bronze (containing Ag, Cu, Ca and Na) for the selective oxidation of hydrogen sulfide.
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