Role of adsorbed surface oxygen in the adsorption of NO on alkaline earth oxides and Pt-promoted CaO surfaces
- Chalmers Univ. of Technology and Goeteborg Univ. (Sweden). Dept. of Inorganic Chemistry
- Chalmers Univ. of Technology, Goeteborg (Sweden). Competence Centre for Catalysis
An understanding of the interaction between NO and metal-oxide surfaces is of interest for the development of catalysts reducing the nitrogen oxide emissions. Adsorbed surface oxygens are formed on CaO, SrO, and BaO during exposure to N{sub 2}O 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 -NO{sub 2} and/or -NO{sub 3} species. NO adsorption as -NO{sub 2} and/or -NO{sub 3} species finds evidence in the corresponding O{sub 2} desorption. Only one NO desorption peak is found for BaO. This NO desorption peak disappears in the absence of preadsorbed surface oxygens. O{sub 2} 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.
- OSTI ID:
- 332702
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Vol. 103, Issue 6; Other Information: PBD: 11 Feb 1999
- Country of Publication:
- United States
- Language:
- English
Similar Records
Roles of Fe2+, Fe3+, and Cr3+ Surface Sites in the Oxidation of NO on the (Fe,Cr)3O4(1 1 1) Surface Termination of an α-(Fe,Cr)2O3(0 0 0 1) Mixed Oxide
Alumina-supported manganese oxide catalysts. II. Surface characterization and adsorption of ammonia and nitric oxide