CO oxidation over Pd and Cu catalysts. V. Al sub 2 O sub 3 -supported bimetallic Pd-Cu particles
- Pennsylvania State Univ., University Park (United States)
Bimetallic Cu-rich (91% Cu) particles dispersed on {delta}-Al{sub 2}O{sub 3} were characterized by chemisorption, in situ IR spectroscopy, and catalytic behavior in the oxidation of CO by O{sub 2}. On fresh reduced catalysts hydrogen chemisorption was near zero, and irreversible Co adsorption was low at 300 K but substantially higher at 195 K. Shorter reduction times (3 h) at 573 K produced a strong IR peak near 2,120 cm{sup {minus}1} in the presence of gas-phase CO, while longer reduction times (18 h) at 573 K shifted the peak to 2,105 cm{sup {minus}1}. On the reduced bimetallic surface Co bands that could be attributed to multiple coordination Pd sites, i.e., ensembles of two or more Pd atoms, were extremely weak, and the 2,070 cm{sup {minus}1} peak attributable to Co adsorption on singlet Pd sites was either absent or difficult to resolve from the overlap of the 2,105 cm{sup {minus}1} band for CO on the Cu atoms. However, under reaction conditions, CO adsorbed on Cu gave a peak between 2,115 and 2,120 cm{sup {minus}1}, and a weaker broadband developed between 1,850 and 2,000 cm{sup {minus}1} which was attributed to CO multiply coordinated on ensembles of Pd atoms. This behavior clearly showed an interaction between Cu and Pd and demonstrated bimetallic particle formation. The kinetic behavior established that Pd not only was present at the surface but also dominated the reaction at low CO pressures and gave a {minus}0.5 rate dependence on CO. In contrast, the catalytic activity was similar to the Cu-only catalyst at higher CO pressures and the rate dependence on CO shifted to 0.7. Thus, the contribution to the overall rate from each metal component was approximately additive and each was similar to that observed on the single metal catalysts.
- OSTI ID:
- 5636397
- Journal Information:
- Journal of Catalysis; (United States), Vol. 131:1; ISSN 0021-9517
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
33 ADVANCED PROPULSION SYSTEMS
CARBON MONOXIDE
OXIDATION
COPPER
CATALYTIC EFFECTS
PALLADIUM
ADSORPTION
AIR POLLUTION CONTROL
ALUMINIUM OXIDES
BIMETALS
CATALYSIS
CATALYST SUPPORTS
CATALYSTS
CATALYTIC CONVERTERS
CHEMICAL PREPARATION
CHEMICAL REACTION KINETICS
CHEMISORPTION
COMBUSTORS
INFRARED RADIATION
INFRARED SPECTRA
REDUCTION
SPECTROSCOPY
SURFACE PROPERTIES
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
ALUMINIUM COMPOUNDS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CONTROL
ELECTROMAGNETIC RADIATION
ELEMENTS
EQUIPMENT
KINETICS
METALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
POLLUTION CONTROL
POLLUTION CONTROL EQUIPMENT
RADIATIONS
REACTION KINETICS
SEPARATION PROCESSES
SORPTION
SPECTRA
SYNTHESIS
TEMPERATURE RANGE
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties
540120 - Environment
Atmospheric- Chemicals Monitoring & Transport- (1990-)
330702 - Emission Control- Carbon Monoxide