CO oxidation over Pd and Cu catalysts. IV. Prereduced Al sub 2 O sub 3 -supported copper

Journal Article · Sun Sep 01 04:00:00 EDT 1991 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(91)90320-4· OSTI ID:5536248

Choi, K I; Vannice, M A ^[1]

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1. Pennsylvania State Univ., University Park (United States)

A study of the kinetics for CO oxidation over supported, prereduced Cu crystallites showed that it is close to first order in CO and near zero order in O{sub 2} at temperatures around 400 K. In situ IR measurements under reaction conditions revealed a clear first-order dependence on chemisorbed CO and an absence of activity when no adsorbed CO was detected; thus an Eley-Rideal mechanism is eliminated and a Langmuir-Hinshelwood surface reaction between adsorbed CO molecules and chemisorbed oxygen is strongly supported. These Cu/Al{sub 2}O{sub 3} catalysts were more active than Pd/Al{sub 2}O{sub 3} catalysts, and the average turnover frequency of 0.016 s{sup {minus}1} at 400 K and 26 Torr CO was about four times higher than the average value on Pd. An invariant IR band at 2,118 cm{sup {minus}1} for Co was very near that of 2,115 cm{sup {minus}1} reported for CO adsorbed on an oxidized Cu(111) surface and therefore was consistent with the near-saturation oxygen coverage indicated from the kinetic behavior. Analysis of the Ir spectra at various temperatures allowed a heat of adsorption of 7.2 kcal/mol to be determined under reaction conditions. An activation energy of 22-27 kcal/mol was estimated for the rate-determining step, i.e., the surface reaction, which is somewhat higher than that reported for adsorbed CO and submonolayer coverages of oxygen on Cu single crystals.

• OSTI ID: 5536248
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 131:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

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ACTIVATION ENERGY
ADSORPTION HEAT
AIR POLLUTION CONTROL
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC CONVERTERS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
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CHEMISORPTION
COMBUSTORS
COMPARATIVE EVALUATIONS
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ELEMENTS
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EQUATIONS
EQUIPMENT
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KINETIC EQUATIONS
KINETICS
METALS
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OXYGEN COMPOUNDS
PALLADIUM
PHYSICAL PROPERTIES
PLATINUM METALS
POLLUTION CONTROL
POLLUTION CONTROL EQUIPMENT
RADIATIONS
REACTION KINETICS
SEPARATION PROCESSES
SORPTION
SPECTRA
SPECTROSCOPY
SURFACE PROPERTIES
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
THERMODYNAMIC PROPERTIES
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