Role of nascent oxygen transients in N2O decomposition and selective catalytic reduction of N2O

Takeshi Nobukawa, Masanori Yoshida, Satoshi Kameoka, Shin Ichi Ito, Keiichi Tomishige, Kimio Kunimori

Research output: Contribution to journalConference articlepeer-review

33 Citations (Scopus)

Abstract

Pulsed N2O decomposition on an 18O treated Rh/USY catalyst has been carried out to study the mechanism of O2 desorption using isotopic tracer technique. The results show that O2 desorption proceeds at 220°C via the Langmuir-Hinshelwood (LH) mechanism, although O2-TPD measurement showed that desorption of oxygen in He gas from Rh catalyst occurred at much higher temperatures. Therefore, it was proposed that reaction-assisted desorption of O2 occurs during N2O decomposition. Reaction between N2O and CH4 over an Fe-BEA catalyst was also studied. In the pulse studies, N2O readily reacted with CH4 in the exposure of N2O+CH4 mixture above 200°C. In the O2-TPD studies, a new O2 desorption peak appeared at the lower temperatures (300-600°C) after N 2O treatment. However, CH4 was not reactive with the new O(a) species even at 300°C. In the FT-IR studies, the peak of Fe-OH was not changed in the exposure of CH4 only, but decreased in the exposure of N2O+CH4 mixture, accompanied with the formation of methoxy and formate species. A possible mechanism is discussed in terms of nascent oxygen transients (O*(a)), which may play an important role in the activation/oxidation of CH4 at initial steps.

Original languageEnglish
Pages (from-to)791-796
Number of pages6
JournalCatalysis Today
Volume93-95
DOIs
Publication statusPublished - 2004 Sep 1
Externally publishedYes
EventSelections from the Presentations of the 3rd Asia-Pacific Congress - Dalian, China
Duration: 2003 Oct 122003 Oct 12

Keywords

  • Catalytic reduction
  • NO decomposition
  • Nascent oxygen transients

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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