Oxidation of carbon monoxide on polycrystalline platinum

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1978

OSTI ID:6856759

Golchet, A

The oxidation of carbon monoxide on polycrystalline platinum was studied kinetically under steady-state and transient conditions at 375/sup 0/-1000/sup 0/K and 0.000001-0.001 Pa. The oxidation predominantly followed an Eley-Rideal mechanism when the oxygen pressure was much greater than the carbon monoxide pressure, and a Langmuir-Hinshelwood mechanism when the reverse was true. In the intermediate region, it had contributions from both reaction paths. Above 750/sup 0/K, desorption of oxygen and diffusion of carbon monoxide became important, and the oxidation rate dropped. The rate data showed striking transitions from high-to-low carbon dioxide production rates for small variations in carbon monoxide/oxygen pressure ratios (R) below 540/sup 0/K. The surface coverages of carbon monoxide and oxygen also underwent sharp changes which have been interpreted in terms of phase transitions between gaseous and chemisorbed reactants under the reaction conditions. For low R, the collision frequency of carbon monoxide was the rate-determining step; for high R, carbon monoxide inhibited carbon dioxide production, and oxygen atom formation was the rate-determining step. At constant temperature and oxygen pressure, increasing the carbon monoxide pressure produced a metastable state which had an unusually high carbon dioxide production rate.

• OSTI ID: 6856759
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CRYSTALS
ELEMENTS
HIGH TEMPERATURE
KINETICS
LOW PRESSURE
MEDIUM TEMPERATURE
METALS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PLATINUM
PLATINUM METALS
POLYCRYSTALS
REACTION KINETICS
TEMPERATURE EFFECTS
TRANSITION ELEMENTS