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Effects of alkaline earth metals on the surface, structure, and reactivity of α-alumina

Abstract : A series of strontium- and barium-doped alumina samples were prepared by hydrolysis, in neutral medium, starting from commercial Al2O3, SrCO3, and BaCO3 materials. The precursors thus obtained were calcined under air at 700 °C; then, the bulk and surface properties of the resulting mixed oxides were characterized by nitrogen physisorption, X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H2-TPR), thermogravimetry (TGA), and differential thermal analysis (DTA). Contrary to SrCO3, an addition of BaCO3 to α-Al2O3 increases slightly the specific surface area. XRD patterns essentially reveal the characteristic reflections assigned to α-Al2O3. In agreement with TGA and XRD analysis, strontium and barium carbonates remain after calcination at 700 °C, their decomposition starting above 800 °C. Let us note that this decomposition occurs more readily on AlSr-100 than on AlBa-100 with no apparent relationship with the evolution observed on the specific surface areas. H2-TPR experiments underline a significant bulk reduction of barium and strontium carbonates taking place significantly above 900 °C with similar trend noticed during TGA regarding their thermal decomposition. However, the most relevant observation is related to a sharp enhancement of the reducibility of AlSr-y with the appearance two reduction ranges highlighting the existence of different types of interactions with strontium and the alumina substrate.
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https://hal.univ-lille.fr/hal-03154848
Contributeur : Lilloa Université de Lille <>
Soumis le : lundi 1 mars 2021 - 12:45:34
Dernière modification le : mardi 2 mars 2021 - 03:16:54

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Madani Ghelamallah, Soufi Kacimi, Pascal Granger. Effects of alkaline earth metals on the surface, structure, and reactivity of α-alumina. Arabian Journal of Geosciences, 2018, Arabian Journal of Geosciences, 11, pp.221. ⟨10.1007/s12517-018-3578-3⟩. ⟨hal-03154848⟩

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