Optical spectroscopy of Rh3+ ions in the lanthanum-aluminum oxide systems
| Parent link: | Journal of Luminescence Vol. 204.— 2018.— [P. 609-617] |
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| Other Authors: | , , , , , , |
| Summary: | Title screen A series of the Rh-containing samples supported on pure γ-Al2O3, La-doped γ-Al2O3, LaAl11O18 and LaAlO3 was prepared and characterized. Diffusion of Rh3+ ions from the surface of the support into its bulk causing the rapid deactivation of the catalyst in a model reaction of CO oxidation under the prompt thermal aging <https://www.sciencedirect.com/topics/chemistry/thermal-aging> conditions was shown to be accelerated by a presence of lanthanum <https://www.sciencedirect.com/topics/chemistry/lanthanum>. The amount of rhodium <https://www.sciencedirect.com/topics/chemistry/rhodium> disappeared from the surface during the high temperature treatment was estimated by a testing reaction of ethane <https://www.sciencedirect.com/topics/chemistry/ethanes>hydrogenolysis <https://www.sciencedirect.com/topics/chemistry/hydrogenolysis> and an electron paramagnetic resonance spectroscopy with spin probe <https://www.sciencedirect.com/topics/chemistry/spin-probe>. In order to characterize rhodium ions diffused into the bulk of the support at different calcination <https://www.sciencedirect.com/topics/materials-science/calcination>temperatures, the optical spectroscopic methods (diffuse reflectance UV-vis and photoluminescence <https://www.sciencedirect.com/topics/materials-science/photoluminescence> spectroscopies) were applied. Rh3+ ions were shown to be applicable as a luminescence <https://www.sciencedirect.com/topics/materials-science/luminescence> probe to follow the process of their bulk diffusion and localization within the matrix of the support, as well as for the structure identification of the La-containing sites responsible for the alumina <https://www.sciencedirect.com/topics/chemistry/aluminum-oxide> thermal stabilization. The obtained data on luminescence of Rh3+ ions indicate that already at 800 °C the oxygen octahedrons <https://www.sciencedirect.com/topics/chemistry/octahedral-crystal> corresponding to LaAl11O18 structure are being formed in the local coordination surroundings of isolated La ion in the 4%La2O3-Al2O3 support. It is important to notice that the structures of such kind can be formed in La-doped aluminas only. There are no octahedron positions with sufficient values of the crystal field <https://www.sciencedirect.com/topics/chemistry/crystal-field> for the formation of luminescence centers of Rh3+ ions in pure γ-Al2O3. Режим доступа: по договору с организацией-держателем ресурса |
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2018
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| Subjects: | |
| Online Access: | https://doi.org/10.1016/j.jlumin.2018.08.070 |
| Format: | Electronic Book Chapter |
| KOHA link: | https://koha.lib.tpu.ru/cgi-bin/koha/opac-detail.pl?biblionumber=658269 |