Ag-incorporated macroporous CeO2 catalysts for soot oxidation: Effects of Ag amount on the generation of active oxygen species

Jae Hwan Lee, Seong Ho Lee, Jin Woo Choung, Chang Hwan Kim, Kwan Young Lee

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

A series of CeO2-based catalysts were investigated for soot oxidation with O2. The macroporous CeO2 catalyst (M-CeO2) showed higher soot oxidation activity than mesoporous CeO2 due to the enhanced contact between catalyst and soot caused by the large pore size of M-CeO2. Moreover, various amounts of Ag (2–20 wt.%) were introduced to M-CeO2 to increase the activity, and the Ag-incorporated macroporous CeO2 catalysts (Ag(x)_M-CeO2) were characterized. Raman spectra showed that the ratio of active oxygen species (Ox n−) were different according to amount of Ag. The ratio of highly reactive superoxide (O2 ) was largest for the Ag(5)_M-CeO2 catalyst, and then it was decreased as the Ag amount increased further. In addition, XPS analysis showed that the difference in Ox n− generation could be attributed to diverse surface oxygen vacancies in the catalysts. Hence, the amount of loaded Ag affected the surface oxygen vacancies of Ag(x)_M-CeO2 and consequently the ratio of Ox n− was different according to the surface oxygen vacancies of the catalysts. Ag(5)_M-CeO2 with the appropriate surface oxygen vacancies induced the promotion of O2 generation, resulting in the best soot oxidation activity. It was concluded that the amount of Ag on CeO2 has a great influence on the catalytic soot oxidation activity, and proper surface oxygen vacancies facilitated O2 generation, whereas excessive surface oxygen vacancies hindered the formation of highly reactive Ox n−.

Original languageEnglish
Pages (from-to)356-366
Number of pages11
JournalApplied Catalysis B: Environmental
Volume246
DOIs
Publication statusPublished - 2019 Jun 5

Keywords

  • Active oxygen species
  • Ag-loaded CeO
  • Macroporous structure
  • Soot oxidation
  • Surface oxygen vacancies

ASJC Scopus subject areas

  • Catalysis
  • Environmental Science(all)
  • Process Chemistry and Technology

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