Innovative low temperature regenerable zinc based mixed oxide sorbents for synthesis gas desulfurization

FUEL

卷:140

Article

Girard, Vincent^1,2  Chiche, David¹  Baudot, Arnaud¹  Bazer-Bachi, Delphine¹  Clemencon, Isabelle¹  Moreau, Florent¹  Geantet, Christophe² 

[1] IFP Energies Nouvelles, Rond Point Echangeur Solaize, F-69360 Solaize, France

[2] Univ Lyon 1, CNRS UMR5256, Inst Rech Catalyse & Environm Lyon IRCELYON, F-69626 Villeurbanne, France

关键词: Desulfurization;    Synthesis gas;    Purification;    Sorbents regeneration;   

DOI  :  10.1016/j.fuel.2014.09.090

来源: Elsevier

【 摘 要 】

Zinc oxide-based materials are commonly used for the final desulfurization of synthesis gas in IGCC and Fischer-Tropsch based XTL processes. The formation of large amount of solid waste is the major issue of this process. In-situ oxidative regeneration is a promising way to reduce this waste formation and enhance desulfurization process efficiency and economics. However, previous studies showed that one of the major drawbacks of oxidative regeneration of sulfided oxides relies in the high operating temperature range required to overcome the formation of inhibitory sulfate phases. A preliminary work of the authors focused on single oxides identified that regeneration temperature of zinc oxide-based sorbent could be reduced through the addition of molybdenum oxide. Two composites oxides - a single oxides mixture (ZnO and MoO3) and a mixed oxide (ZnMoO4) - were synthesized and characterized. Their sulfidation and oxidative regeneration properties were investigated through thermogravimetry and in-situ characterizations. Sulfidation of the single oxides mixture was shown to be similar to the combination of the sulfidation of both independent single oxides. Mixed oxide sulfidation leads to ZnMoO4 phase demixing into ZnS, MoS2 and ZnMoO3. The oxidative regenerations of the sulfided single oxide mixtures and mixed oxide are initiated, respectively, at 350 degrees C and 300 degrees C. These temperatures are 250 degrees C and 300 degrees C lower than the regeneration temperature of a pure ZnS. For the sulfided mixed oxide regeneration is even complete at 500 degrees C under isothermal conditions. Regeneration of sulfided oxides mixture and mixed oxide was thus shown to exhibit synergetic effects, resulting from exothermic oxidative reactions of molybdenum phases. Heat energy released during these reactions is assumed to enhance ZnS oxidation kinetics at a temperature lower than the previously measured one. (C) 2014 Elsevier Ltd. All rights reserved.

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