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Mechanistic studies of the CO-oxidation reaction on catalysts for use in long-life CO2 lasers

Author
Riley, Brian W.
Published
Jun 1, 1990.
Physical Description
1 electronic document
Additional Creators
Dawood, Talat and Richmond, John R.
Online Version

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Summary
The catalytic recombination of carbon monoxide and oxygen was studied under conditions expected to be present in a sealed E-beam CO2 laser system. These conditions are typically a gas inlet temperature of 60 C, a substoichiometric CO/O2 ratio of ca. 2.5/1 with an oxygen feed rate of ca. 5 micromoles/s, a carrier gas comprising He, N2 and CO2 in the ratio of 3:2:1, near atmospheric pressure and a gas velocity of 4 m/s. Heterogeneous catalysts, based on precious metal supported on tin oxide, have been coated onto ceramic monoliths and tested for catalytic activity and stability after a reduction/passivation step. Two catalyst systems have been chosen. These are Pt/Pd/SnO2 and Pt/Ru/SnO2. Under the conditions described above, a characteristic decline in catalytic activity is apparent for both systems, and exit gas temperature has been recognized as a sensitive parameter by which to monitor the activity changes. A semilogarithmic plot of exit temperature as a function of time has revealed two distinct processes connected with the decline in activity: one process is associated with reduction of the oxidized precious metal (at Site A), whilst the other is related to the formation and approach to steady-state of an active site at the metal/support interface (Site B).
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Collection
NASA Technical Reports Server (NTRS) Collection.
Note
Document ID: 19900015280.
Accession ID: 90N24596.
NASA, Langley Research Center, Low-Temperature CO-Oxidation Catalysts for Long-Life CO2 Lasers; p 157-180.
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