Enhanced sulfur tolerance of ceria-promoted NO x storage reduction (NSR) catalysts: Sulfur uptake, thermal regeneration and reduction with H2(g)

摘要

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 Al 2O3, CeO2/Al2O3, BaO/Al2O3, BaO/CeO2/Al2O 3, 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/Al 2O3 surface stores more sulfur than that of BaO/Pt/Al 2O3. 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 H 2(g). © 2013 Springer Science+Business Media New York.