Selective catalytic reduction of NO(x) with CH3OH, C2H5OH and C3H6 in the presence of O2 over Ag/Al2O3 catalyst: Role of surface nitrate species

Satoshi Kameoka, Yuji Ukisu, Tatsuo Miyadera

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Abstract

The involvement of the reaction of surface nitrate [NO3 -(ads)] species with different reductants (C3H6, C2H5OH and CH3OH) in the selective catalytic reduction of nitrogen oxides (NO(x)) over a Ag/Al2O3 catalyst has been studied by in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and temperature-programmed desorption (TPD). When an NO/O2 mixture was exposed to a Ag/Al2O3 catalyst at 150°C, three kinds of nitrate species (bridging, monodentate and bidentate) were observed by DRIFT. The thermal stability of the monodentate NO3 -(ads) species was higher than that of the bridging and bidentate NO3 -(ads) species, which was confirmed by DRIFT and TPD measurements. The monodentate NO3 -(ads) species reacted effectively with C2H5OH and CH3 OH in the presence of O2 to form surface isocyanate [NCO(ads)] species at 250°C, whereas the bridging and bidentate NO3 -(ads) species reacted minimally. All NO3 -(ads) species were largely unreactive with C3H6 in the presence of O2 at temperatures below 250°C. On the other hand, the order of reactivity in the reduction of NO(x) at temperatures below 350°C was in good agreement with that of both the reactivity of the monodentate NO3 -(ads) species and the ease of NCO(a) formation (C2H5OH > CH3OH > C3H6). Based on these findings, the involvement of the reactivity of NO3 -(ads) species and the formation of NCO(ads) species in the selective reduction of NO(x) are discussed.

Original languageEnglish
Pages (from-to)367-372
Number of pages6
JournalPhysical Chemistry Chemical Physics
Volume2
Issue number3
DOIs
Publication statusPublished - 2000 Feb 1
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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