Intermediates in the selective reduction of NO by propene over Cu-Al{sub 2}O{sub 3} catalysts: Transient in-situ FTIR study
The mechanism of the selective catalytic reduction (SCR) of NO by C{sub 3}H{sub 6} on Cu-Al{sub 2}O{sub 3} catalysts, which consist of highly dispersed Cu{sup 2+} ions in the surface aluminate phase, are investigated by in-situ FTIR spectroscopy. During NO + C{sub 3}H{sub 6} + O{sub 2} reaction, the acetate is produced via the partial oxidation of C{sub 3}H{sub 6} and becomes the predominant adspecies in the steady-state condition at 473--623 K. The acetate, which is stable in NO, is quite reactive with NO + O{sub 2}, leading to the formation of isocyanate species (Cu-NCO) on the surface and N{sub 2} and CO{sub 2} in the gas phase. The rate of acetate reaction in NO + O{sub 2} is close to the steady-state rate of NO reduction over wide range of temperature, indicating that the acetate is an intermediate in the SCR and takes part in the rate-determining stage. A mechanism is proposed; the acetate and nitrates, formed by NO + O{sub 2}, react to generate the Cu-NCO species, then Cu-NCO reacts with nitrates or NO to produce N{sub 2} and CO{sub 2}. This mechanism explains the role of oxygen in facilitating SCR. Cu{sup 2} ion is the principal active component in Cu-Al{sub 2}O{sub 3} catalysts; it plays crucial roles in all the important steps, including the reaction of the acetate with nitrates.
- Research Organization:
- Nagoya Univ. (JP)
- OSTI ID:
- 20030669
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical Journal Issue: 13 Vol. 104; ISSN 1089-5647; ISSN JPCBFK
- Country of Publication:
- United States
- Language:
- English
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