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- Title
Laser-induced luminescence of model Fe/Al<sub>2</sub>O<sub>3</sub> and Cr/Al<sub>2</sub>O<sub>3</sub> catalysts.
- Authors
Snytnikov, V.; Stoyanovskii, V.; Larina, T.; Krivoruchko, O.; Ushakov, V.; Parmon, V.
- Abstract
The laser-induced luminescence of Cr3+ impurity ions in model Fe/Al2O3 and Cr/Al2O3 catalysts with different calcination temperatures was studied. It was found that an additional luminescence band at 770 nm appeared in the luminescence spectra of low-temperature samples as a result of the interaction of octahedrally coordinated Cr3+ ions with Fe3+ impurity ions. In the θ-Al2O3 phase with a concentration of Cr3+ ions higher than 0.1 wt %, the interaction of the Cr3+-Cr3+ ion pairs in the immediate surroundings resulted in the appearance of N θ lines due to the splitting of R θ lines. The differences of these lines from the N α lines of α-Al2O3 were related to the individuality of the crystal lattice of the θ phase and the coordination of Cr3+ impurity ions in the immediate surroundings, which is different from that in the α phase. Based on the laser-induced luminescence spectroscopic data, it was found that regions with a local Cr3+ concentration higher than the average Cr3+ concentration in the bulk of a catalyst by one order of magnitude were formed in the α-Al2O3-Fe2O3 system with the bulk Fe and Cr concentrations of 2.5 and 0.04 wt %, respectively, which was calcined at 1220°C, as a result of the diffusion of chromium and iron ions.
- Subjects
LASER photochemistry; LUMINESCENCE; CATALYSTS; CHROMIUM; IRON ions
- Publication
Kinetics & Catalysis, 2008, Vol 49, Issue 2, p291
- ISSN
0023-1584
- Publication type
Article
- DOI
10.1134/S0023158408020183