| 초록 |
Characterization of CoOx/TiO2 catalysts for continuous wet TCE decomposition by acquiring XPS spectra of both fresh and used Co surfaces has given different surface spectral features of CoOx. Co 2p3/2 binding energy of Co species exposed predominantly onto the outermost surface of the fresh catalyst appeared at 781.3 eV, which is very similar to chemical states of CoTiOx such as Co2TiO4 and CoTiO3. The used catalyst exhibited a 780.3-eV main peak with a satellite structure at 795.8 eV. Based on XPS spectra of reference Co compounds and their energy separation and spin-orbit splitting values, the TCE-exposed Co surfaces could be assigned to be in the form of mainly Co3O4. XRD patterns for 5% CoOx/TiO2 catalyst indicate that the bulk structure of Co species in the catalyst even before reaction was quite comparable to the diffraction lines of external Co3O4 standard. Regardless, the both instrumental results propose a model structure, of CoOx present on titania surfaces, consistent with transient behavior of 5% CoOx/TiO2 catalyst in the wet oxidation with respect to time on-stream. It would be Co3O4, encapsulated in thin-film CoTiOx species consisting Co2TiO4 and CoTiO3, which may be active for the decomposition of aqueous phase TCE in a flow of air. |
