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KMID : 1024520080170080933
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Journal of the Environmental Sciences
2008 Volume.17 No. 8 p.933 ~ p.941
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The Formation of CoOx/TiO₂ Compounds in ConTion+2 Catalysts and Their Activity for Low-Temperature CO Oxidation
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Kim Moon-Hyeon
Ham Sung-Won
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Abstract
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The formation of compounds, i.e., and , in a 5wt% catalyst after calcination at different temperatures has been characterized via scanning electron microscopy (SEM), Raman and X-ray photoelectron spectroscopy (XPS) measurements to verify our earlier model associated with nanoparticles present in the catalyst, and laboratory-synthesized chemicals have been employed to directly measure their activity profiles for CO oxidation at . SEM measurements with the synthetic and gave the respective tetragonal and rhombohedral morphology structures, in good agreement with the earlier XRD results. Weak Raman peaks at 239, 267 and 336 appeared on 5wt% after calcination at but not on the catalyst calcined at , and these peaks were observed for the compounds, particularly . All samples of the two cobalt titanate possessed O ls XPS spectra comprised of strong peaks at eV with a shoulder at a 532.2-eV binding energy. The O ls structure at binding energies near 530.0 eV was shown for a sample of 5 wt% , irrespective to calcination temperature. The noticeable difference between the catalyst calcined at 450 and is the 532.2 eV shoulder which was indicative of the formation of the compounds in the catalyst. No long-life activity maintenance of the synthetic compounds for CO oxidation at was a good vehicle to strongly sup port the reason why the supported catalyst after calcination at had been practically inactive for the oxidation reaction in our previous study; consequently, the earlier proposed model for the nanoparticles existing with the catalyst following calcination at different temperatures is very consistent with the characterization results and activity measurements with the cobalt titanates.
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KEYWORD
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CO oxidation, Cobalt titanates, Raman, X-ray photoelectron spectroscopy, Titania-supported cobalt oxides, Nanoparticles
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