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Role of adsorbed surface oxygen in the adsorption of NO on alkaline earth oxides and Pt-promoted CaO surfaces

Filip Acke (Institutionen för oorganisk miljökemi ; Kompetenscentrum katalys (KCK)) ; Magnus Skoglundh (Institutionen för teknisk ytkemi ; Kompetenscentrum katalys (KCK))
Journal of Physical Chemistry B (1089-5647). Vol. 103 (1999), 6, p. 972-978.
[Artikel, refereegranskad vetenskaplig]

Adsorbed surface oxygens are formed on CaO, SrO, and BaO during exposure to N2O, and their presence is shown to affect the room-temperature NO adsorption. Information about the adsorbed intermediates is contained in the desorption products and in the desorption temperatures during the subsequent heating ramp in Ar. The presence of adsorbed oxygen species increases the total amount of adsorbed NO for CaO and BaO substrates, whereas for SrO the adsorbed intermediate is stabilized. Two NO desorption peaks are found for CaO and SrO, one at low and one at high temperature. The former is assigned to adsorbed NO, whereas the latter is assigned to adsorbed -NO2 and/or -NO3 species. NO adsorption as -NO2 and/or -NO3 species finds evidence in the corresponding O2 desorption. Only one NO desorption peak is found for BaO. This NO desorption peak disappears in the absence of preadsorbed surface oxygens. O2 desorption is observed, even in the absence of any preadsorbed surface oxygens, for CaO and SrO substrates. This suggests NO bond dissociation upon NO adsorption. The effect of the promotion of CaO by Pt has also been investigated. The respective desorption profiles are similar to those for the unpromoted CaO with preadsorbed surface oxygens, although the amounts are significantly increased.

Nyckelord: MAGNESIUM-OXIDE; NITRIC-OXIDE; DECOMPOSITION; REDUCTION; ENGINE; N2O



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Denna post skapades 2012-01-27. Senast ändrad 2017-09-14.
CPL Pubid: 154474

 

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Institutioner (Chalmers)

Institutionen för oorganisk miljökemi (1900-2004)
Kompetenscentrum katalys (KCK)
Institutionen för teknisk ytkemi (1999-2003)

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