Step and pulse transient studies of IR-observable adsorbates during NO and CO reaction on Rh/SiO{sub 2}
- Tesa Tape Inc., Charlotte, NC (United States)
- Univ. of Akron, OH (United States)
- United Catalysts Inc., Louisville, KY (United States)
The dynamics and reactivity of infrared-observable adsorbates for the reaction of NO with CO over a 44% Rh/SiO{sub 2} catalyst have been studied by in situ infrared spectroscopy combined with steady-state isotopic and pulse NO-CO transient techniques. Steady-state isotopic transient results reveal that (i) a rapid exchange between the gaseous CO and adsorbed CO occurs on the Rh surface; (ii) Rh+({sup 12}CO)({sup 13}CO) is an intermediate for the exchange between Rh{sup +}({sup 12}CO){sub 2} and gaseous {sup 13} CO; (iii) the adsorbed NCO species is not directly involved in the formation of CO{sub 2}; (iv) the residence time of the intermediate for CO{sub 2} formation decreases with an increase in temperature from 473 to 573 K. At 573 K, rapid NO dissociation led to the high availability of surface oxygen, which results in CO{sub 2} response leading the CO response during steady-state isotopic transient studies. Pulse NO-CO transients further confirm that the NCO species is not a reaction intermediate in the formation of CO{sub 2}- Pulse NO-CO studies show that Rh-NO{sup -}, Rh-NCO, and CO{sub 2} are formed prior to gem-dicarbonyl; CO{sub 2} can be produced without involving the gem-dicarbonyl as an intermediate. Steady-state isotopic transient and pulse studies were excellent complementary techniques that provided an insight into the reactivity and dynamics of adsorbates under reaction condition. 40 refs., 7 figs., 2 tabs.
- OSTI ID:
- 224020
- Journal Information:
- Journal of Catalysis, Vol. 157, Issue 2; Other Information: PBD: Dec 1995
- Country of Publication:
- United States
- Language:
- English
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