Enhanced Sulfur Tolerance of Ceria-Promoted NO x Storage Reduction (NSR) Catalysts: Sulfur Uptake, Thermal Regeneration and Reduction with H2(g) |
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Authors: | Zafer Say Evgeny I. Vovk Valerii I. Bukhtiyarov Emrah Ozensoy |
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Affiliation: | 1. Department of Chemistry, Bilkent University, Ankara, Turkey 2. Boreskov Institute of Catalysis, Novosibirsk, Russia
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Abstract: | SO x uptake, thermal regeneration and the reduction of SO x via H2(g) over ceria-promoted NSR catalysts were investigated. Sulfur poisoning and desulfation pathways of the complex BaO/Pt/CeO2/Al2O3 NSR system was investigated using a systematic approach where the functional sub-components such as Al2O3, CeO2/Al2O3, BaO/Al2O3, BaO/CeO2/Al2O3, and BaO/Pt/Al2O3 were studied in a comparative fashion. Incorporation of ceria significantly increases the S-uptake of Al2O3 and BaO/Al2O3 under both moderate and extreme S-poisoning conditions. Under moderate S-poisoning conditions, Pt sites seem to be the critical species for SO x oxidation and SO x storage, where BaO/Pt/Al2O3 and BaO/Pt/CeO2/Al2O3 catalysts reveal a comparable extent of sulfation. After extreme S-poisoning due to the deactivation of most of the Pt sites, ceria domains are the main SO x storage sites on the BaO/Pt/CeO2/Al2O3 surface. Thus, under these conditions, BaO/Pt/CeO2/Al2O3 surface stores more sulfur than that of BaO/Pt/Al2O3. BaO/Pt/CeO2/Al2O3 reveals a significantly improved thermal regeneration behavior in vacuum with respect to the conventional BaO/Pt/Al2O3 catalyst. Ceria promotion remarkably enhances the SO x reduction with H2(g). |
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