Extended X-ray absorption fine structure (EXAFS) was used, in combination with electron microscopy, NMR, and X-ray diffraction, to probe environments of Co atoms at every elementary step of the preparation procedure for TiO2supported Co catalyst. Special emphasis was placed on the relationship between the particle size and the methods, and conditions, of the catalyst preparation. The species which are formed during the course of the preparation were clearly identified, and it was found that a cluster size as small as about 8 Å can be estimated from the analysis of EXAFS spectra. It was also found that bulklike Co3O4, very tiny Co3O4clusters, and complex oxide CoTiO3are formed by the calcination, depending on the preparation method and temperature. It is concluded that the precedent species of oxide and their sizes before reduction have strong effects on the size of metal particles in the resultant catalyst.
ASJC Scopus subject areas
- Colloid and Surface Chemistry