Conditions Extrêmes et Matériaux : Haute Température et Irradiation

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Joris Kadok, Nicolas Bost, Antoine Coulon, Mohamed-Ramzi Ammar, Séverine Brassamin, Cécile Genevois, Auriane Etienne, Aurélien Canizarès, Jacques Poirier, 'Inhibiting the sp2 carbon deposition by adjunction of sulphurous species in refractory ceramics subjected to CO and H2 reducing atmosphere', J. Eur. Ceram. Soc. 39 2960-2972 (2019) doi:10.1016/j.jeurceramsoc.2019.03.008

The formation of sp2 carbon by the Boudouard reaction significantly damages the refractory ceramics. Sulphur is an efficient way to prevent the carbon deposition catalysed by Fe3C, in the presence of H2. Thermogravimetric analysis was carried out on Fe2O3 samples exposed to a CO/H2 gas mixture at 600 °C. Solid sulphur was mixed with Fe2O3 powder or continually added in the form of gas into the CO/H2 reducing gas. The samples were characterised by X-ray diffraction, Raman spectroscopy, SEM and TEM. The addition of 100 ppm of sulphur species in the gas prevents the formation of carbon. The mechanism that governs the inhibition of the reaction is proposed, in which the formation of a thin protective FeS layer (0.5–1 nm) is involved. This study paves the way to an effective solution to inhibit the sp2 carbon deposition in the refractories by poisoning the Fe3C catalyst with sulphur.