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Dispersion behaviors of molybdena on titania (rutile and/or anatase).

Authors
  • 1
  • 1 Key Laboratory of Mesoscopic Chemistry of MOE, College of Chemistry and Chemical Engineering, Center of Modern Analysis, Department of Physics, Nanjing University, Nanjing 210093, China. , (China)
Type
Published Article
Journal
The Journal of Physical Chemistry B
1520-5207
Publisher
American Chemical Society
Publication Date
Volume
109
Issue
23
Pages
11720–11726
Identifiers
PMID: 16852439
Source
Medline
License
Unknown

Abstract

Raman and FT-IR spectra were employed to investigate the dispersion of molybdena on mixed TiO2 (rutile and anatase, signed as R and A) with different BET surface ratios of rutile/TiO2(R + A). The results showed that (1) molybdena would preferentially disperse on the rutile surface in mixed TiO2; (2) for MoO3/rutile with low molybdena loading (e.g., 0.20 mmol/100 m2 rutile), a dispersed molybdena species existed on the rutile surface in an isolated tetrahedral coordination environment, while for MoO3/rutile with high molybdena loading (e.g. 0.82 mmol/100 m2 rutile), a polymeric molybdena species could be detected on the rutile surface; (3) for the MoO3/anatase sample, a dispersed molybdena species existed on the anatase surface in a polymeric coordination environment; and (4) the formation of the Bronsted acid site on the surface of rutile and anatase should be related to the polymeric molybdena species. All these results have been discussed via the interaction between OH groups of molybdena and OH groups of rutile and anatase, and it seems reasonable to suggest that, for the lower molybdena loading, the different states of the dispersed molybdena species should result from the different dehydration orders of OH groups of the molybdena and surface OH groups of rutile and anatase.

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