High-Surface-Area Synthesis of Iron-Doped CaTiO 3 at Low Temperatures: New Insights into Oxygen Activation, Iron States, and the Impact on Methane Oxidation - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Inorganic Chemistry Année : 2022

High-Surface-Area Synthesis of Iron-Doped CaTiO 3 at Low Temperatures: New Insights into Oxygen Activation, Iron States, and the Impact on Methane Oxidation

Résumé

In the present work, a series of CaTi1-xFexO3-delta (0 < x < 0.5) materials are prepared using a modified Pechini method based on citric acid and a polyol as chelating agents. The synthesis conditions are optimized with respect to the specific surface area and phase purity by varying polyols (ethylene glycol, glycerol, and 1.6-hexanediol) and the ratio between citric acid, polyols, and cations. The impact of the polyols and the iron content (up to 40 mol % on the B site) is studied with respect to the oxygen exchange rate, reducibility using H2- TPR, and catalytic performance for methane total oxidation. A correlation between the oxygen exchange rate studied using 18O exchange in powdered samples of CaTi1-xFexO3-delta (0 < x < 0.5) and ferric sites determined using Mo''ssbauer spectroscopy and H2-TPR is established. The oxygen activation and diffusion in CaTi1-xFexO3-delta (0 < x < 0.5) continuously increase in the studied range of Ti substitution. The methane oxidation performance does not increase above x = 0.3, showing that methane oxidation is not limited by surface oxygen activation and CH4 is activated by specific iron sites in Fe-doped perovskites.

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Chimie
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Dates et versions

hal-03827342 , version 1 (24-10-2022)

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Maxime Delporte, Julie Cavailles, Michaël Martin Romo y Morales, Nicolas Bion, Luca Nodari, et al.. High-Surface-Area Synthesis of Iron-Doped CaTiO 3 at Low Temperatures: New Insights into Oxygen Activation, Iron States, and the Impact on Methane Oxidation. Inorganic Chemistry, 2022, 61 (39), pp.15432-15443. ⟨10.1021/acs.inorgchem.2c01966⟩. ⟨hal-03827342⟩
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