CO oxidation on palladium. 1. A combined kinetic-infrared reflection absorption spectroscopic study of Pd(100)
- Texas A M Univ., College Station, TX (United States)
The oxidation of carbon monoxide on a Pd(100) single-crystal catalyst was studied using an elevated-pressure IR cell/ultrahigh vacuum surface analysis system. The kinetics of the reaction was followed by monitoring the total pressure change during the course of the reaction. Simultaneously, the surface concentration of adsorbed CO was measured using IR reflection absorption spectroscopy. An activation energy of 29.4 [+-] 0.3 kcal/mol was found between 500 and 575 K at a total pressure of 1.50 Torr and CO/O[sub 2] = 2. The IR data obtained under reaction conditions show the CO coverage to vary between 0.45 and 0.55 monolayers (ML). For this coverage regime, the CO heat of adsorption was determined to be 29 [+-] 2 kcal/mol, corresponding closely to the apparent activation energy. Between 0.5 and 10.0 Torr, negative first-order CO and positive first-order oxygen pressure dependencies were measured, yielding a zero-order total pressure dependence of the reaction rate. No change in CO coverage was observed with a change in the oxygen pressure, while the CO coverage increased from 0.50 ML at P[sub CO] = 0.50 Torr to 0.55 ML at P[sub CO] = 8.0 Torr. 40 refs., 10 figs.
- OSTI ID:
- 7019722
- Journal Information:
- Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 98:11; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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360102 -- Metals & Alloys-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
54 ENVIRONMENTAL SCIENCES
540120 -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ABSORPTION SPECTRA
ACTIVATION ENERGY
ADSORPTION
AIR POLLUTION CONTROL
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CONTROL
CRYSTALS
ELEMENTS
ENERGY
INFRARED SPECTRA
KINETICS
METALS
MONITORING
MONOCRYSTALS
NONMETALS
OXIDATION
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PALLADIUM
PLATINUM METALS
POLLUTION CONTROL
PRESSURE DEPENDENCE
REACTION KINETICS
SORPTION
SPECTRA
SURFACE PROPERTIES
TRANSITION ELEMENTS