A series of vanadium-doped CoCr2-xVxO4(x=0-0.20) catalysts were prepared via citric acid method andinvestigated for methane combustion. A significant improvement of the catalytic activity was observed overCoCr1.95V0.05O4catalyst, and the catalytic activity reached 90%of methane conversion at 438oC, which was 76oClower than that of the undoped catalyst. Vanadium doping caused disorder in the spinel structure and variouschanges in physicochemical properties. The higher concentration of suprafacial, weakly chemisorbed oxygen andthe active cobalt species, especially Co3+, could play a major role in the oxidation reaction. Results of XRD,Raman and XPS suggested that excess vanadium probably formed separate catalytically inactive VOxspecies,which would explain the decline of catalytic activity for samples with higher substitution degree.
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