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CoOx/TiO₂ 촉매상에 ConTiOn+₂ 화합물의 생성과 저온 CO 산화반응에 대한 촉매활성 KCI 등재

The Formation of ConTiOn+₂ Compounds in CoOx/TiO₂ Catalysts and Their Activity for Low-Temperature CO Oxidation

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한국환경과학회지 (Journal of Environmental Science International)
한국환경과학회 (The Korean Environmental Sciences Society)
초록

The formation of ConTiOn+₂ compounds, i.e., CoTiO₃ and Co2TiO₄, in a 5 wt% CoOx/TiO2 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 Co3O4 nanoparticles present in the catalyst, and laboratory-synthesized ConTiOn+₂ chemicals have been employed to directly measure their activity profiles for CO oxidation at 100˚C. SEM measurements with the synthetic CoTiO₃ and Co2TiO₄ gave the respective tetragonal and rhombohedral morphology structures, in good agreement with the earlier XRD results. Weak Raman peaks at 239, 267 and 336 cm-1 appeared on 5 wt% CoOx/TiO₂ after calcination at 570oC but not on the catalyst calcined at 450˚C, and these peaks were observed for the ConTiOn+₂ compounds, particularly CoTiO3. All samples of the two cobalt titanate possessed O 1s XPS spectra comprised of strong peaks at 530.0±0.1 eV with a shoulder at a 532.2-eV binding energy. The O 1s structure at binding energies near 530.0 eV was shown for a sample of 5 wt% CoOx/TiO₂, irrespective to calcination temperature. The noticeable difference between the catalyst calcined at 450 and 570˚C is the 532.2 eV shoulder which was indicative of the formation of the ConTiOn+₂ compounds in the catalyst. No long-life activity maintenance of the synthetic ConTiOn+₂ compounds for CO oxidation at 100˚C was a good vehicle to strongly support the reason why the supported CoOx catalyst after calcination at 570˚C had been practically inactive for the oxidation reaction in our previous study; consequently, the earlier proposed model for the Co₃O₄ nanoparticles existing with the catalyst following calcination at different temperatures is very consistent with the characterization results and activity measurements with the cobalt titanates.

저자
  • 김문현(대구대학교 환경공학과) | Moon Hyeon Kim Corresponding Author
  • 함성원(경일대학교 디스플레이화학공학과) | Sung-Won Ham